Help or opinions on this issue.....STILL NOTHING!!!!

[Dirtcrasher]

First off, I feel like an IDIOT!

All I did was pop in a Barnett clutch in the 350didyRX

I have spark, lots of compression and it should be at the right time because Honda is not known for stator or flywheel failures.

I only had 108 octane race gas for the 200X. I put about a gallon in the RX there but no mix.

The trike is backfiring, popping etc but will not run. NOTHING was touched when I popped in a clutch; I got VR1 10-30 oil today and filled it up and this is how that turned out.

Could the race gas on a 10.25 piston engine with open AB lid and Supertrapp exhaust create this issue?? I'm NOT a parts changer but I'm running out of time which may cause me to toss in another crate motor and or electrical system.

I am on a Trikefest CRUNCH time! And now that trike that ran perfect is dead......

Does any of this make sense to anyone?? I know I'm stressed but yesterday this was a 1 to 2 kick trike; Now it farts and backfires. I guess I'll go get some 93 tomorrow morning and if that does not work, I will move on to the stator (although I have a nice spark) and I doubt that is the issue.

I cleaned the carburetor spotless, have no intake leaks so I am lost. I think this crunch time is killing my brain.

Any thoughts?? Just ran great a day ago. Put in oil, cleaned carb, adjusted decompression cable, clutch cable and now it's not running.

Thank you for any help, thoughts or suggestions :beer

[just ben]

I didn't have a clue until the very end of your post. My best guess would be the decompression cable adjustment is a little too tight.
Or did the issues start before you adjusted the cable? My only other thought would be bad fuel.

[atc007]

Clean the carb bud. :) New plug 1st. But I bet you got a rogue piece of crap in a jet.

[El Camexican]

Race gas dies a terrible death. If it's not fresh it won't burn.

[MattDragontamer]

Yea.. I don't know... But to answer your fuel question....

As you probably know, different engines are designed to run different type of fuel.
You have to take into consideration the type of engine, the conpression ratio and the temperature allowences.

In order to make a simple example, i will use the standard pickup vs the sports car.

A pickup is designed to haul and produce high torque with little rpm. In order to achive this, the fuel used is low octaine (85) which burns at a low compression ratio (lets say 5:1 for argument sake) but the low octaine produces a slow burn of the fuel and runs hotter. A byproduct of this is visible smoke and large rads.

The sportscar on the other hand produces mid torque with high rpm. In order to achive this, the fuel used is high octaine (91) (or higher) which burns at a high compression ratio (lets say 10:1) but the high octaine produces a fast burn and runs cooler.

With this said, we have all heard the tale, higher octaine gas will give you better performance.
Well... No. You might as well just throw your money to the wind.
The only way higher octain fuel will give you better performance is if your engine is designed or rebuilt to handle high compression and high rpms.
So if you are racing, and are running a stock engine, check the manual for the recomended fuel consitration.
Many times you can tell if you have the wrong fuel for your engine is if the engine is poping even though the timing and valves are clean.
A high octaine fuel will be hard to start and will burn just as the exhaust valve will open thus creating a explosion in the exhaust... Thus the pow! And a little flame out the back.
The loss of power and missfires will increase over time.

The use of low octaine fuel in a high compression engine will result in the eventual distruction of the head. The fuel will ignite prior to spark by compression alone. Common results are blown tops and holes right through pistons.

For small engines that run mid-high rpm, high torque but are air cooled... Most common thought is high octaine fuel. Which is somewhat correct. Again, depends on your engine.
Most small engines will run high octaine because of their design. They are air cooled, thus burning at lower temperatures will keep the engine from overheating. That's why mall engines usually will have a high ratio for their size.

Racing engines will usually do one of two things to get the power out of their engines.
Bore it out and increase the volume, but will use a higher/thicker piston to compensate for the added volume to keep the ratio the same or increase the ratio (squish).
The second way is to longstroke. This is usually done on dragters. The cam is machined for it and the pistons are made with reinforced walls and dimpeled heads that try to get the most compression without getting in the way of the valves. I'm sure you have seen those pistons with the "B" like groove in them. The high quality ones are designed to pool the gases into the center of the piston to a small concentrated point. They look like 3 circles indented on the top of a piston.

Anyways, if you are mixing race fuel into your stock or light modified engine, you are doing more harm then good. Race fuel is usually 116 octaine or greater for extreme compression ratios in the 20:1 range. This will lead to the buildup of carbon and slow burns out the tailpipe.
Cool effect at night, not so good otherwise.

For most trikes built back in the day, 85-89 octane is the way to go.
So drain the fuel and get some low octaine fuel in there it might be the case.

In addition, lower octaine fuel will ignite even with weak spark.
High octaine needs very hot spark.

[Dirtcrasher]

Race gas is 1 day old. Plug and fuel filter were changed at 3AM last night; I did the obvious stuff first and the decompression cable was adjusted per shop manual.

I only used race gas because I only have race gas :lol:

I'll mess with it in an hour, got to bed a 5AM.

[Billy Golightly]

I would wiggle some wires around. Also, I'm not sure if the 350X is a 2 or one wire exciter/pulse setup to the main firing coil, but I have had those get loose or come unplugged on my 250R when just changing a plug (by wiggling/moving the wire around to get the plug in and out) and that caused the issue. I've ended up where I actually silicone around those plugs onto the coil anymore so that it doesn't happen as easily.

[muthey]

I believe quote you said this was on a 200x, well I have not been in a 200x motor, but a regular 200 and such but the pulse generator cam pin can fall out if you forget to put the bolt back in. I have done this on occasion, and it causes similar issues. Don't rule out fuel octane as of yet but I would check that as well.

[muthey]

sorry reread the first post and you are working on a 350x, I have not worked on one of those motors so I don't know if anything I just said has any relevance or not, if not ignore my posts

[jays375]

I've run 110 with no issues.Even put it into small engines.I would lean towards electircal issues.Like broken wires at the stator or cdi unit.

[ironchop]

Any luck yet, Steve?

[Dirtcrasher]

Alrighty, got 4 new tires on the truck and a camper today, so, I am on spot with that aspect.

I like the wire ideas, but I have a great spark.

I have a flat blue spark, spotless carb, fuel in the cylinder with great compression and no stupid overlooked issues. This thing is DEAD!

You guys know as much as me and if I'm lost, thats bad.

Tomorrow, I build an intake for the 200X and thats a MAYBE as well.

I have fresh 93 in this 350RX here and not a spit, cough or backfire - NOTHING.

This is a crate motor, this does not happen to a Honda; I have never seen it......

Please DO NOT ANSWER without starting from post #1

Can ANYONE have anymore information than previously?? If I can't get this to run in 1 hour tomorrow, I'll stay home for 10 days and leave the phone off; Vacation, MY WAY.........

Thanks for any help but don't list the obvious please and thank you.

[shovelryder]

I'll just say don't fret. Bring it with and we will gitter figured out.

[Dirtcrasher]

I hate to take that chance, my regular 350X runs great but can't be raced......

What do I do, change a stator and coil and CDI when I have a flat blue4 spark??

All I did was change the damn clutch. The day I figure this out, I'll piss on myself because I am LOST and I am never LOST.....

I'm not driving 16hrs plus to fail.

What happened? I got the 108 octane out, WTH is going on??

This was put away running 100%, I knew I had abused the stock 25yo clutch, rode it the day I was doing the swap to get the oil warm and this is the result. Man, a person can only take so much after I bled all out what I did today!

[shovelryder]

What day ya gettin there man? We will be lined up like a pit crew and runnin before ya get set up. Ya got fuel, ya got spark, ya got compression........... I wanna fix it just ta see ya piss on yerself!;).... Gotta be timing..... But..... What did u check spark with? An insulated tester? Or just a plug against the head? C'mon now..... We will get it.

[emmie357]

I would have guessed timing issue (you haven't checked it yet?)
That's always been the cause of backfires and popping for me...

Now it won't even backfire... open the valve covers and check if the valves are opening and closing properly.

[wonderboy]

Hey DC,

I'm trying to think of things that would have been touched during the clutch job. Is it possible that the decompression cable mechanism isn't back together correctly? I'm not sure if it's possible, but when the right side cover is put back on, maybe the decomp parts inside the case are messed up and possibly holding your exhaust valve open a bit. Without good compression (due to decomp not working right) I'm thinking it could cause what you are describing.

I hope you figure it out.

EDIT: I'm not sure if it will kick over very well with a 10.25 piston and NO decomp cable, but maybe as a troubleshooting step, just quick disconnect the cable end up at the head and see if it will start.

[6speedthumper]

Well you've covered all the bases that I cover. Have you taken the intake manifold off and inspected the o-ring? If it's original, it's 28-29 years old, and could have dried to the point of cracking. Or, just shrunk. Also, have you taken the plug out of the head, and cranked it over with the fuel off to clear the cylinder of any fuel? Could be that it is loaded up from all the kicking without starting.

[6speedthumper]

Hey DC,

I'm trying to think of things that would have been touched during the clutch job. Is it possible that the decompression cable mechanism isn't back together correctly? I'm not sure if it's possible, but when the right side cover is put back on, maybe the decomp parts inside the case are messed up and possibly holding your exhaust valve open a bit. Without good compression (due to decomp not working right) I'm thinking it could cause what you are describing.

I hope you figure it out.

EDIT: I'm not sure if it will kick over very well with a 10.25 piston and NO decomp cable, but maybe as a troubleshooting step, just quick disconnect the cable end up at the head and see if it will start.


That is a possibility, but, I don't think that is very likely by way of it's design. I could be wrong. It's been 4 months since I put my engine together. The bottom end anyway. Makes me want to run out to my shed and grab my manual to look things over.

[6speedthumper]

Have you checked the flywheel key? Maybe it has sheered, and the plug is not firing on the compression stroke, or, is firing a few degrees off. It sounds like there is either a mechanical or ignition related timing issue, intake air leak leaning things out, or some type of carb issue. You're confidant about the carb. You do have compression. You do have a strong, blue, spark. Installed a new plug (although it could be a lemon). You said you have inspected the induction system. It has to be something so simple it's stupid. I'd look at the flywheel key, even to just cover that base as well...

[atc007]

You said carb is spotless. You took it off and blew it out with air AFTER this problem arose right? I Know you're pissed,so bare with us lol... I'm posting this as much as for others to see more than you. For those of you that don't know. For this guy to ask for help. This is NO run of the mill problem.. NEW spark plug. Not a "good" one. New. Watch the valves work,both sides. Unhook the dec cable. Try her. If still nothing. Flywheel key. Then, OHM out your ignition.. But at this point.. I aint gonna lie. You HAVE a good running X sitting there right? Be a parts switcher for a few minutes! Grab the coil and cdi off the runner. I HATE to say that. But it will get you further quicker at this point. Wish we were closer. Let us know,

[El Camexican]

A shot in the dark, but what the heck. This happened to a buddy a while back. He stuffed a rag into his intake tube the last time he washed it and forgot to take it out when he put the filter back on. It would fire, sputter, flood and die.

[Frankencelery]

DC, you've helped me on so many things, I wish I had something brilliant to say, but I have no idea beyond the suggestions already posted. I am of course very interested in hearing what it turned out to be, when you finally get to the bottom of it. I've certainly had that kind of apparently unrelated problem saying, "But I never even TOUCHED anything else!!!"

[Dirtcrasher]

Hey DC,

I'm trying to think of things that would have been touched during the clutch job. Is it possible that the decompression cable mechanism isn't back together correctly? I'm not sure if it's possible, but when the right side cover is put back on, maybe the decomp parts inside the case are messed up and possibly holding your exhaust valve open a bit. Without good compression (due to decomp not working right) I'm thinking it could cause what you are describing.

I hope you figure it out.

EDIT: I'm not sure if it will kick over very well with a 10.25 piston and NO decomp cable, but maybe as a troubleshooting step, just quick disconnect the cable end up at the head and see if it will start.


BINGO!!!! I am ashamed that I try to give others my best advice and I guess I assume I do it right but I am human and open to an criticism :lol:

I loosened the adjusting nut, rather than the lock nut. It held the exhaust valves open too long and I'm certain bent the valves. It does blow off my finger but when I put a gauge on it, this fresh motor was not in spec.

So, the motor is out, I am now replacing the new head with another head, just have to transfer it all.

I made an incredibly MONSTER mistake and it only hit me when I was getting my truck fixed today and something in my acorn sized brain clicked! I got home, tested it and sure enough, there is leakage.

I'm upset that I didn't use an actual gauge 1st, but usually if it blows your finger off, your good.

So, tonight I shall either swap heads or just valves, we'll see how it all goes. Every day a week or 2 prior to TF is PUSH PUSH!! And I forgot 1 tiny step and this is what it did. And the whole motor must be removed to repair it!!

I'm human and very upset with myself, but very lucky to have numerous "take out" motors. Tomorrow or late tonight, it will run........

Thanks to all that replied, an engine needs fuel, good spark at the right time and without enough compression, fuel cannot be sucked in. And thats how it all went SOUTH!

In conclusion, a compression gauge should have been used when it would not run but when you have your mind set on the issue, things get overlooked.

A warning to all, if you touch anything in relation to the decompression cable, make sure you do it right!! As far as the 350X goes, you must adjust the valves and THEN adjust the decompression cable. Mine was loose in the direction you don't want it loose, I overlooked it and thats how it goes. Sometimes we have all the information either in our head or on paper but I have no problem admitting that I DID THIS!! Mechanics fault, not anyone else.......

Won't screw that up again. If I built that whole 200X in 20 days, I can certainly fix this!

Thank you all for your help; Had I provided you with the PROPER information, the 1st person that replied would have known the probable answer. MY BAD!!

I'll get it done and running tonight; C-YA at TF14 !! :beer

[6speedthumper]

Don't worry yourself too bad, man. It happens to the best of us. I'm a mechanic, and have wracked my brain on many occasions. Either with a problem on a customer's car that's come into the shop, or in an instance such as yours. There are just too many things going on in our lives, too many interruptions, too many "over practiced maneuvers" (if you will) that you leave something out, etc... It's often the simplest thing, and you get so frustrated looking into all the avenues that you THINK it could be, and all you succeed in doing is not seeing the forest trough the trees. Glad to hear you got it figured out, and that you'll be making TF. Wish I could say I was going but am just too busy.

[6speedthumper]

Oh, that decomp adjustment is kinda jacked, imo. I was ultra observant when adjusting mine when I built the engine. Don't much care for that set up, lol.

[shovelryder]

Ha! I'm a certified mechanic. I once rebuilt a harley motor from the crank up.... It was missing and popping.... And pulled the motor back out and all the way down again..... Here it was just a bad condenser. Brand new and junk outta the box. Veeeery easy to overlook simple chit! Glad ya found it!

[Dirtcrasher]

Well, OK. All valves are perfect.

Decompression cable was removed for pressure test, throttle wide open kicked numerous times with low compression results.

Head gasket is perfect, spark plug is sealing. Head was left upside down with gas in it, no leakage. Valves were put in my lathe, perfectly straight.

Now I understand why someone posted a couple weeks back that they wanted to set there 250R on fire, I share that same thought.

I give, may god help me because unless I dream of a possible other problem, I'm unable to diagnose this problem........

[6speedthumper]

Ha! I'm a certified mechanic. I once rebuilt a harley motor from the crank up.... It was missing and popping.... And pulled the motor back out and all the way down again..... Here it was just a bad condenser. Brand new and junk outta the box. Veeeery easy to overlook simple chit! Glad ya found it!

I hate when that happens! I just had a similar instance jetting my 400ex carb last weekend. I kept having a lean reading on the plug at WOT, and by lean I mean white as an albino! So I kept throwing larger mains at it. Still the same exact color. Looked over everything I could, took 8 discs out of the Supertrapp, went over the entire induction system, etc... Wasn't until I plug chopped the idle circuit again and I saw that the plug's color had not changed that I caught on to what it was. I had plug chopped the idle before and had it spot on, but, with a different plug. Why I changed plugs I can't remember. Anyway, I put another plug I had previously used before the EX carb, and what do you know, got it all dialed in. Turned out to be a bad plug out of the box, and it was driving me up a wall.

[6speedthumper]

Well, OK. All valves are perfect.

Decompression cable was removed for pressure test, throttle wide open kicked numerous times with low compression results.

Head gasket is perfect, spark plug is sealing. Head was left upside down with gas in it, no leakage. Valves were put in my lathe, perfectly straight.

Now I understand why someone posted a couple weeks back that they wanted to set there 250R on fire, I share that same thought.

I give, may god help me because unless I dream of a possible other problem, I'm unable to diagnose this problem........



Fried piston ring perhaps? Cracked or broken? That would be the next step with the head seemingly functional.

[6speedthumper]

Have you done a wet compression test?

[Trike_crazy]

It has already been said but it could be the flywheel key. My dx did the same thing. It had great spark, rebuilt carb, valves adjusted ect. A buddy of mine told me to check the key. Sure enough it was sheared in 2. I hope you get it figured out.

[Dirtcrasher]

Fried piston ring perhaps? Cracked or broken? That would be the next step with the head seemingly functional.

No, no, no, This was a trike I rode hard. But, it had a crate motor built with a cam and such. Ran perfect, very strong. Had not been rode since I got hurt on Oct 5th but 2 weeks ago I took 4 fast laps and it was great; Then I changed the clutch. I am LOST..........

I really thought it was my bad and I figured it out but I did not.

[Dirtcrasher]

It has already been said but it could be the flywheel key. My dx did the same thing. It had great spark, rebuilt carb, valves adjusted ect. A buddy of mine told me to check the key. Sure enough it was sheared in 2. I hope you get it figured out.


Thanks bud but without at least 160# compression, you would have to pop start it every day.....

I've never had a Honda flywheel key die on me. The compression is low and cannot suk in the gas. I can only imagine that something is hanging up the exhaust valves with the decompression set up. Something very odd has happened here.

[Dirtcrasher]

Have you done a wet compression test?

Meaning a tablespoon of oil to temporarily seal the rings?? Cylinder and piston are mint. This motor never ran till 1 year ago.

Also, You gotta remember, I rode this at home on my track only to warm the oil enough to drain it fully, to put in a clutch. No time between.

[Vealmonkey]

Well DC, I'm no genius, but if this stuff didn't happen till you changed clutches, then I would be looking there. Maybe check the thickness of your clutch plates or steels. Check all your measurements in the clutch basked assembly. Changed out gazoos clutches a while ago and was having issues.

[fabiodriven]

Do me a solid and please check the flywheel key buddy. I suggested it first thing, before this thread was even started. If I was right then you're cooking dinner all week. :-)

No worries either way, this is why we have a herd of three wheelers.

[atc007]

I went to bed pretty sure it wasn't the head/cable.. Wish I was wrong. You said compressions low. Put oil in it for wet test!! That IS the next step. I agree,snapping a ring would be NUTS. But could have happened. After that. Put a couple teaspoons of fresh gas,or the dreaded starting fluid into the carb w airboot off. See if it will run being fed.If it won't. You are gonna have to check that flywheel key.. I agree, I've never changed one on a Honda. EVERY other brand,yes. Did you throw the known good CDI and coil at it yet?

[oile]

Maybe it jumped an tooth on the cam ? Check can timming

[atc007]

He was in there last night . Cam Timings on.

[6speedthumper]

Meaning a tablespoon of oil to temporarily seal the rings?? Cylinder and piston are mint. This motor never ran till 1 year ago.

Also, You gotta remember, I rode this at home on my track only to warm the oil enough to drain it fully, to put in a clutch. No time between.


And if you did a wet compression test and the numbers go up substantially, then it helps to point you in the right direction. Certainly not going to hurt anything. It's part of the elimination/diagnosis process. I've seen some stupid things happen really quick, out of the blue, on all different types of engines. One day/hour running great, they next, either running like trailprotrailprotrailprotrailpro or not running at all. Most things are like a heart attack; you don't know it's going to happen till it does. If you think something with the decomp mech is keeping the exhaust valves open, try pulling the decomp cam out of the head and doing another compression test. That totally removes the decomp mech so there is nothing to keep the valves open.

You're down to low compression, there are but only so many things that can contribute to that. You've established that it is getting fuel, spark, no intake leaks, valves aren't bent, valve seats are good, head gasket is good... But you have low compression. What's left? Low compression is contributed by a mechanical problem, as you already know. Those problems include: bad head gasket, bad rings, bad piston (hole in crown), bent valves/damaged seats, something keeping a valve open, valves adjusted too tight, or timing issue. You've eliminated the valves and seats, the head gasket, and I know you would have set timing when you put it back together after pulling the head and it doesn't sound like you messed that up from all of your posts. So, you are left with piston/rings, or something keeping a valve open. I wish I had the bike in front of me so I could have some hands on time with it instead of internet diagnosis. But, unless I'm forgetting something this early in the morning, that's what you are left with.

[fabiodriven]

I just left Steve's, guess I'll spill the beans. He had the bike completely apart today and it was assembled when I got there. I jumped on and kicked it over 4 or 5 times with the choke on, nothing. I shut the choke off and held the throttle wide open. Second kick it fired up, apparently for the first time in days. It just ran for a second but Steve was ecstatic. I kicked it a couple more times and the compression just up and left. We didn't even look at what was happening at that point as we are out of time right now. We pulled out his regular 350X and one kick, ta-daa! We've both been working like animals and Steve is very understandably stressed, so he's moving on to other things. He's upset about not having his crown jewel but for fawks sakes, he's going to Trikefest. He's still in the shed right now. I've not showered yet and I gotta be up for 4:30 just like every day, hopefully no more 13 hour work days this week. That porked me as well.

[atc007]

Just go and have the time of your lives guys.. I KNOW how bad this sucks Steve. But forget it,leave it behind. Go enjoy yourself! After what you've came through in the past 9 months,it's just great you can go and ride anything!

[6speedthumper]

Damn, that just blows!!! I sure wish I could be of physical assistance.... Sucks to be at this end of the problem and not actually lend a hand.

[ironchop]

Damn. Thats cuttin it close.

Fabio.......man, you're a standup guy and a good friend. Im glad you guys tag teamed a solution to this. Im dying to know what the f#&$in issue is but that can wait until well after TF is over, I guess.

See you there.

[DohcBikes]

One minute it runs, then the next it has no compression. Kinda sounds like a valve is getting stuck.

Have fun at Trikefest.

[just ben]

If you guys have the room bring it anyway. There will be more than one good wrench there and bunch of parts Im sure. As an added bonus it would be hard to lose if it doesn't run LOL.

[Dirtcrasher]

We do not have the room. I have an intake 1/2 built for the FCR on the 200X, that will come and old faithful. The 86 thats never been opened and ran hard.

Today I tore the whole motor down, inspected everything, measured everything and hours later I had 190psi and everything worked perfect. WOULD NOT START!! Put ether in the plug hole, kicked and not even a fart.

Fabio came over just as I began the bonfire and he kicked the snot out of it and it farted!! We were both psyched. 4 more kicks it lost all compression. An hour later as I stole the tires off of it, I kicked it over and it had TONS of compression again, WTF?? I disconnected the decomp cable and it still would not run.

In all my experience, I have never been this stumped. I even stole the whole stator cover and flywheel, checked the key and nothing.......

Lots of spark, 190psi, ether dead into it, perfect carb, in time, tried another stator and flywheel, no bent valve, no decomp cable to hang up; Does that cover it all??

I have been here since 1998 with near 15K posts 75% of which helped people (others were "nice machine, nice work yadda yadda" ) and I AM STUMPED!! Does that say anything??

I have built allot of motors and some that came in pieces in a box and haven't failed until this. The suspension is so good on that RX and I have to leave it home. Maybe I'll just leave it outside and build another one............

3AM, GOODNIGHT!!

[Bren_downe]

I'm definatley not a mechanic… but… have you tried putting the old clutch back in? It ran with the old clutch, new clutch and nada. It may not be the problem but tearing it down again you may find the solution.

[atc007]

Sounds like a very small burr on a valve stem/guide now.. Gotta love engines ,they're so marvelous when they work ! I am so sorry about this Steve,but.. Go have some fun now!

[6speedthumper]

We do not have the room. I have an intake 1/2 built for the FCR on the 200X, that will come and old faithful. The 86 thats never been opened and ran hard.

Today I tore the whole motor down, inspected everything, measured everything and hours later I had 190psi and everything worked perfect. WOULD NOT START!! Put ether in the plug hole, kicked and not even a fart.

Fabio came over just as I began the bonfire and he kicked the snot out of it and it farted!! We were both psyched. 4 more kicks it lost all compression. An hour later as I stole the tires off of it, I kicked it over and it had TONS of compression again, WTF?? I disconnected the decomp cable and it still would not run.

In all my experience, I have never been this stumped. I even stole the whole stator cover and flywheel, checked the key and nothing.......

Lots of spark, 190psi, ether dead into it, perfect carb, in time, tried another stator and flywheel, no bent valve, no decomp cable to hang up; Does that cover it all??

I have been here since 1998 with near 15K posts 75% of which helped people (others were "nice machine, nice work yadda yadda" ) and I AM STUMPED!! Does that say anything??

I have built allot of motors and some that came in pieces in a box and haven't failed until this. The suspension is so good on that RX and I have to leave it home. Maybe I'll just leave it outside and build another one............

3AM, GOODNIGHT!!



Damn man, I'm really sorry to hear that this is still giving you all his trouble. It makes zero sense. You've covered all the bases that I would, have looked into and over everything... This is just not making sense. I feel bad for you, DC. I hope you get is solved so we can all know what the he!! is going on with that engine.

[Trike_crazy]

Idk if it would help but if the valves are sticking maybe you could leave the covers off while doing a compression check to see if you can catch the valve sticking? Maybe the idle screw got set to high? Had a wheeler come in like that. Set just high enough it wouldn't start. I know that doesn't answer the compression issue though

[ironchop]

I had one valve keeper fall out of the valve spring retainer on an XR that did something similar

sure does sound like a slow valve stick and after awhile under the spring pressure, it finally seats again later giving you compression

sorry to repeat the above opinions...I`m just agreeing

[Gag_Halfront]

I don't know if it'll be any help, and it's too late now for TF, but I had an old XR that did a similar thing to me once. It turned out that it had slipped the cam chain. When I took it apart nothing looked wrong. Put it back together and it started. half a lap around the yard and it slipped the chain and died again. The second time it took the exhaust valve out with it. :-(

I had checked the valve timing when I put it back together but I hadn't actually checked before I took it apart. I had assumed the problem was a gasket or a bent valve so I just pulled the head off. If I had checked the valve timing _first_, I would have found the problem but it just wasn't one of my assumptions so I missed it.

The slow/sticking valve theory is a good one also, but the way you tell the story reminds me of what that XR did.

[Dirtcrasher]

Well, the timing is still on, I did watch the valves and nothing hung up. The motor was a take out new motor. The valves are straight and verified with a machinists dial indicator. I lightly oiled them for the guides and they are smooth.

TRUST me, I know there are only a few ways to lose compression but this is ultimately the hugest problem I have ever had this many issues with.....

I 100% appreciate all your help and I hope I didn't get snappy. If I did, it's not you it's me, just like a girl dumping you, :lol:

[C.J]

My X does the exact same thing. I have to roll the engine over about 5-6 times before it catches compression. Then one or two kicks it lights off. But mine needs a top end rebuild.

If the compression isn't going out the head,, it's gotta be going down the cylinder.

You've double checked the rings I assume? One of the 350 Ranchers we used to have did that. Ran great, killed it, wouldn't start back up. Oil scraper had come apart and ate the cylinder and crapped out the compression rings.

My blaster did the same thing too but it was the source coil. But it still had compression each kick though. It was running great, I killed it, filled it back up, wouldn't start.


This is DEFINITELY the weirdest thing I have ever seen. And I literally grew up in a bike shop here in Louisiana so you can imagine the stuff I've seen from these rednecks arse engineers LOL.


But yea man. The compression HAS to be going down if everything is tip top shape in the head.

[DohcBikes]

Not to beat the valve thing to death here...

You mentioned measuring the runout on the valves. Did you measure stem to face runout as well as stem runout?


I was also going to say kind of the same as what ironchop said, that possibly theres a faulty keeper, and possibly it is causing some funky side load on the valve.

In either case, the valve could still move up and down and look fairly normal, yet not mate well with the seat at times.

Also agree with C.J., if it aint going up, its going down. But you already know all this stuff....just a couple more thoughts.

In response to the post below, a leak down test will not show the issue unless you do it when the compression is absent. I would like to hope DC has already done a leakdown test, as that would be one of the first things to do when experiencing an intermittent compression problem....

This one really is a brain teaser, and it's plain to see your frustration, and we all know you'll get it figured out in time. Everyone wants to be the one that suggests a correct fix to Dirtcrasher lol....

[6speedthumper]

One thing I totally forgot about, until now, is to do a leak down test. That'll point to the problem.

[danbur55]

just the pits but had a thought and probably out in left field but weve all done dumb stuff (if we admit it) could the rings be sticking in their grooves some or heaven forbid be on upside down know youll find it after you go enjoy yourself at TF

[ironchop]

Murphy's Law:

What does not start right before Trikefest, will certainly start promptly after Trikefest is over.

[RubberSalt]

what are the valve stem clearances? Are they sticking at all when heating up?
Are the valve spring binding?
Is the valve adjustment to tight?
is the head warped? Is the cylinder warped?'
Ring condition is a question to. I a ring sliding around/broken?

I hate to say this, but at this point.. I'd remove the engine and tear it apart and inspect everything as it went together. This can only be a few things, but until they are checked, you can rule them out as a problem. With the rings being a possibility, That's a tear down.

Ignition timing would have to be correct if it was all et the same. spark confirmed.
Fuel issue - carb is clean, gas is new to you. Doesn't sound like fuel though.

I'd inspect valve lash for starters. Odds of a broken ring is possible after a good run, it would seal up. After cooling It wouldn't be able to seal.




Just laying my thoughts out here. Painful to see a post like this.

[Dirtcrasher]

I beat the snot out of all my motors but I maintain them.

The RX went to TF last year with no issues. Then New York, couple rides in NH and then I got hurt at Jerrico SP? Never started it again until a month before TF and it ran super; I only run VR1.

The motor was completely torn down yesterday. The valves were placed in a collet in my lathe and face and stem runout were checked. Because this has a hardened cam in it and after what had happened, I pulled them to check them and they ar AM springs with TI retainers. I used my valve spring compressor, popped in the valves and poured gas in the upside down head, no leak. So, after more inspection, rings weren't sticking and I reassembled. So much compression without the decomp cable and nothing.

Right now it's in my shop with compression again, maybe it's the full moon :lol:

Frustration sailed away a day ago and I focused on the old 350X and the 200X (man do I hope that thing runs!!)

Anyway, Hope to see some of you at TF, I'll run a rear plate stating "DC" so you can come and bust my balls :D

Thanks guys!! Can't say you guys didn't help, plenty of good information in this thread!!

[beets442]

When I changed my clutch I had my trike on its side to make it easier to put back together and had the seal leak/seep into the flywheel/stator side. Got mine to run but not very well. Cleaned it up,changed seal runs great.

[6speedthumper]

I beat the snot out of all my motors but I maintain them.

The RX went to TF last year with no issues. Then New York, couple rides in NH and then I got hurt at Jerrico SP? Never started it again until a month before TF and it ran super; I only run VR1.

The motor was completely torn down yesterday. The valves were placed in a collet in my lathe and face and stem runout were checked. Because this has a hardened cam in it and after what had happened, I pulled them to check them and they ar AM springs with TI retainers. I used my valve spring compressor, popped in the valves and poured gas in the upside down head, no leak. So, after more inspection, rings weren't sticking and I reassembled. So much compression without the decomp cable and nothing.

Right now it's in my shop with compression again, maybe it's the full moon :lol:

Frustration sailed away a day ago and I focused on the old 350X and the 200X (man do I hope that thing runs!!)

Anyway, Hope to see some of you at TF, I'll run a rear plate stating "DC" so you can come and bust my balls :D

Thanks guys!! Can't say you guys didn't help, plenty of good information in this thread!!


Heck yeah, lots of folks pulling together (and their hair, lol) to give suggestions. I really can't wait to find out what the problem is, because this has me stumped as well. Being that everything checks out, what else is there to make it have good compression on one kick and not the next? God, I wish I had it in front of me.

[RubberSalt]

is it possible that the timing chain is stretched and not seating the valves correctly?

[6speedthumper]

You ever get this figured out, Dc?

[Dirtcrasher]

I am still cleaning and organizing after Trikefest.

Jason Hall got that 200X running so good that I'm focusing on that for now.

All my money is on this: Found lots of carbon on the head and piston; I bet there is carbon in the ring grooves but I was so dead set on valves I didn't pull the jug (MY BAD!!). Clock was ticking so I had to MOVE on what was stuck in my head.

I have a ported head for it and a 39mm FCR carb, so I'll tear into it soon.

I'll definitely post up the results and thank you everyone for your help!

I must be about 2 sizes too large on the main jet.....

[danbur55]

lots of carbon, maybe some flaking off then holding valve just enough to lose compression guessing you have an answer or at least possibilities

[shortline10]

I would just pull start that puppy and make it run !
The piece of trash will remove it's self .
I have seen this before on the 350x