Spark partial failure at mid to high.. Ive tried it all!!

[McQuade]

Sorry all I can't seem to add a video. But cut to the chase here. 1985 200M high low chain driven. New parts: coil,cdi harness completely rebuilt, plug(also gapped) voltage regulator, carb,fuel line with inline filter, new tank petcock, head gasket, timed both valve and ignition, blah blah there's more sure. It starts right up, idles fine. You can rev it a little, any more then half and it hammers right out but the rpm does not seem to climb much. Pulse generator is gapped BUT I'm sure this is the problem.. To me it sounds like isn't advancing properly. It moves freely but the problem is how can you tell if the springs don't have the proper rate? I can't find a new setup, and my other spare engine was doing the same thing. This is absolutely insane the hours I've put into this with the hardly helpful manual, but everything ohms out. I've eliminated fuel. Brand new carb. Please toss some ideas at me veterans!

[danbur55]

Is the airbox connected to carb?? If so try lifting the lid up and see if that helps

[McQuade]

Is the airbox connected to carb?? If so try lifting the lid up and see if that helps

The aribox is connected. Without the lid, it's louder, and it pops back through. No air filter but it did run previously like that (not ridden)

[barnett468]

Is the spark pale blue or yellow? . . what is the plug gap? . . what is the valve gap? . . check can timing again you can see if it advances . . check float level . . post photo of spark plug . . try two sizes bigger and two sizes smaller on main jet . . check for air leaks with flammable carb cleaner.

[barnett468]

Correction.check. am timing again . . check ignition timing and see if it is correct and advances . . make sure mechanical advance unit operates smoothly and returns properly.

[McQuade]

Lines upTDC on the "F" line. Moves freely but to me sounds like it advances too much and/or too fast. Is their a test for its spring tension or something?

[danbur55]

correct me if i am wrong but shouldnt it be on "T" mark not F

[barnett468]

Lines upTDC on the "F" line. Moves freely but to me sounds like it advances too much and/or too fast. Is their a test for its spring tension or something?

You can mark your flywheel at different degrees then connect a tach and check the amount of advance of different rpms like 1000 . 2000 . 3000 and 4000 etc but I doubt this is your problem but who knows who has been in there berfore you and what they might have done. . . there is no tension adjustment on that particular advance . . if it has any free play the springs are loose which may cause probs.
E

[barnett468]

correct me if i am wrong but shouldnt it be on "T" mark not F

The can should line up at tdv . . the timing F timing mark should line up at idle when using the lite . . I'm not sure what he was saying either.

[McQuade]

My apologies. The pulse generator is lined up with the pickup with the flywheel at the "f" mark. (Not running) cam time is where it is supposed to be.

[barnett468]

The F needs to line up in the timing I election hole at idle of around 1200 - 1400 rpm . . get a timing lit and check it.

[McQuade]

So I'll need a tach and a timing light? And out of curiosity, I've never seen any system that had to be set up from the start using a timing light. This must be why there is two lines on the flywheel right? Correct me if I'm wrong but the way I've done it, where the pulse generator is lined up and the "F" line, is wrong? I would have thought the entire purpose of the two lines was to set it oem advance, which from the distance between the two lines seems like a few degrees advanced. I guess I'm used to my camaro and the 11 degrees advanced. This system just makes the process annoying.

[barnett468]

If the springs are loose on your advance unit it will be advanced too far at idle so the lite will not lite up when the f is lined up

[danbur55]

From my limited knowledge as I understand these small motors the T stands for time and F is fire so if you line up TDC on F then when centrifugal advance kicks in you will be to far advanced. Unless your Camaro has been degreed in for performance cam you still line timing marks as spec maybe this will help clear things up

[barnett468]

Unless your Camaro has been degreed in for performance cam you still line timing marks as spec maybe this will help clear things up

DIdn't you mean to say Mustang?

[McQuade]

DIdn't you mean to say Mustang?

Unsure how that was relevant, but anyways. Tried both lines, tried the timing chain one tooth either way, and every combination associated with this. It is timed as it should be. I tore the advamce apart and lubed it again. Checked every gap. Flawless. Valve lash a ok.

[barnett468]

So you checked the timing using the method I suggested and the f is lined up at idle and you gasve it gas and the timing advanced?

[McQuade]

Yes, though on a seperate thread, someone said the exact opposite of what you did. I tried both ways. I advanced it while running with my hand too, and either way where it's at is where it works "best"

[barnett468]

Yes, though on a seperate thread, someone said the exact opposite of what you did. I tried both ways. I advanced it while running with my hand too, and either way where it's at is where it works "best"
What do you mean they said the exact opposite of what I did? . . I said several things

Have you tried different jetting yet?

Did you look at the timing lite to see it the lite was breaking up? . . if it was then your prob is electrical.

[danbur55]

Have you put an air filter on it as this will alter air flow that might be affecting fuel delivery. Was new carb a Chinese model as many have stated the jets were not correct size beyond this I am of little help to you

[McQuade]

I just finished reading one of the threads you and "kd only" or so thing like that helped with in 2013. Perhaps you'll remember this one. About two hundred posts, every hundred you get free steak knives. In any case, I read that and the follow up. I'm not sure how I read his discription about the noise his bike was making, the difference between misfire bogging ect. Forgive my analysis of you, but after reading that I think I'll be able to help you help me.
This post will be long an I'm sorry but I'll give you a background and the steps I followed. (I'm a licensed diesel tech though this is irrelevant other then electrical theory)

I bought two bikes, an 84 and this 85. The other was a runner but the frame was bent and had no plastic. It was more work then it was worth. THIS bike never ran. It was missing a carb. So I swapped the carb. This exact symptom happened. Hollow knocking at mid to high, speed not load specific. Thinking I bought a blown bike I swapped the engine (it's current state) changing the RUNNING engine into this trike made no difference. Not having a manual I began to individually chamge over the parts still on the previously running bike. Coil regulator, cdi. Finally complete component transfer. This is now the running bike minus the frame. I noticed the head gasket was leaking, so I pulled the engine, and freshened up the top end.
After getting more compression it ran stronger at idle and had more low end, but still this hollow knocking almost like a rod knock. But I checked the bearings so that isn't it. After acquiring a manual I purchased a new carb (same as your 2013 guy, it was too large) it made no difference. I then tried all ignition components and chasing a ghost I ended up replacing it all.

Today I checked the stator, 275.3 ohms in exciter coil. It's on the upper of the gtg (1-400 ohm)

This was when I read that post, about the exhaust being the culprit. So that's where I am currently.

[McQuade]

And by opposite" I meant on another thread, actually quite a few, most say to static time the pulse with the "f". But I tried both, and either one appeared to make any difference on performance.

[barnett468]

Lol OK free steak knives yup . . there were two such threads . . one was the Honda that ended up being squirrel nuts in the muffler . . I think KB only suggested he look there . . the other was a cdi next to an exhaust pipe that got hot from the pipe after a few minutes and would qstart missing after that and would not run properly until the cdi cooled which took around 45 minutes . . i told him to put it in the freezer for 10 minutes right after the prob occured then try it . . if it worked then it was the cdi

Anyway so you know a bit about me then lol . . there are several knowledgeable people here but far fewer are posting these days . . i have no idea what happened to kb only.

I will be glad to help the best i csn as will others that post but i took a look and it looked like you have posted 1or 2 other threads regarding this and still have the problem.

The f should be in the window with the lite when the engine is idling unless the service manual says no otherwise . . if it is lined up when the bike is off but not when it is running, the springs are too loose on the mechanical advance and are allowing it yo advance sooner than it should . . if it advances way too soon, it certainly cause eratic running at the very lesst . . if your sound is not mechanical like a loose rod or piston etc, it could be detonation from too much advance . . i have had this prob before but it would be rare and unlikely but keep in mind, it tyook 200 posts to figure out one guy had acorns in his muffler and ther other guy had his cdi laying on the friggen ex pipe.

In yor case, i would do the timing test and remove the exhaust and make sure the head pipe is clear even if you used different exhaust . . leave the muffler off if possible to eliminate that as a possible prob. . . this will make the bike run leaner than it currently is so you may or may not need to address that

Post a close up photo of the end of yhe spark plug and tell us how long it has been in there.

Try all suggestions from everyone like the one danbur posted . .

Check the timing lite yo see if it misses as i suggested.

Check valve clearance.

Could be week valve springs . . yes I know both engines did the same thing.

If the cdi is Chinese instead of a Honda one it could be the cdi unless you sealed in a good Honda one.

If none of these tests yield results then its just guessing after that. Which is not good.

[barnett468]

Please excuse the typos . . I can't erase on my phone and don't have an edit button . . since you know diesel engines this stuff should be simple for you.

[McQuade]

I'm referring to squirrel nuts guy. Essentially same sort of issue, minus the distinctive (I'm going to guess) spark knock. I do recall early on in my tinkering trying open header, but it was too noisy to hear a knock lol. I will try the timing light thing to reinterate my claim of proper timing. I do have some concerns regarding the advance. One; my pin is on my cam. I slide said advance on it.. I have a bit of play in the "key way" between the pin and it. I also have a bit of play before the weights actually start to move it. It's been twenty years since I've seen my old big red and don't recall how tight this stuff is.. I'll guess this is something to address. Also, plug check: mildly sooty, not good, not really fluffy either. Just black.
I think my main problem is trying to establish if this is fuel causing the fire or the fire causing the fuel issue lol. I'll report back in when I aquire my fathers test light, mine isn't the greatest if shape. I whacked it off the fan on my camaro checking the time. What a racket haha

[barnett468]

OK I clearly understand everything you are saying . . look at the light or point it toward the front when you rev it . . do this in a dark place so you can easily see it . . if the light skips when the engine starts missing, it is most likely the ignition unless it is so rich the gas is nkilling the spark .

You must clean the plug thoroughly . . if there is a lot of carbon, it will do exactly what it is doing . . if it does it with a clean good plug it is obviously not the plug.

Set the plug gap .004" narrower then the spec . . this will help a weak ignition.

Tell us what color the spark is.

Go into the dear b engine o. The site . . put my name in . . search for gas level or float level within the last 4 weeks . . look for a post with two carburetor photos . . set your gas level so it is just below the bottom edge of the upper carb body because it might be too high even though it is a different carb.

Clean the spark plug fist.

[barnett468]

Correction

"Go into the search engine"

[barnett468]

Your advance unit should not have any free play . . it should have tension on the springs . . this explains why the F does not line up at idle . . this may be part of your problem.

If you have safety vwire, you can try to wire the advance closed and try it right after you clean the spsrk plug lol

You may be able to bend the end of the springs on the advance to fix it. . . it should have a fair amount of tension on it

[McQuade]

Ok free play I will try to address. The cam pin to advance mech. Not sure how to repair this. The plug has less then I'll say, 35 mins total of running on it.i have a slew of them. No difference. I also did try tightening the gap. I'm ised to vacuum advances. Sooo easy. It works or it doesn't. Lol. Should it run better without the advance operating? And I'll check my float(s) the origional mikuni was in haggard shape. No rebuild kit could fix that trainwreck

[barnett468]

OK

If the gas is yellow, it is bad . . if the tank had dried up too from old gas and you put new gas in it the too will mix with the gas . . old gas will cause this exact problem in every way.

Don't worry about the loose can pin now . . it is not a problem because the inner shaft on the advance is locked into place on the can by the bolt . . the pin is just too generally line the advance up . . no big deal.


If the advance is your problem then locking it with wire will eliminate the miss but it might not rev to the max.

You can do these other things without a timing lite and you may get positive results.

I will be around for a few hours.

[barnett468]

goo,not too

[McQuade]

I cleaned the tank professionally at work, new fuel.
As a side note, the other day I was trying the choke, which operates, the engine would work about the same, but quieter as the back fire through the carb wasn't as loud. But it didn't flood out.. It sounds lean, acts lean, but plug says rich. I'll update on timing with it wired.

[McQuade]

Ok got some answers here.
Put a good irridium plug in and tried the timing light.
At idle, F line was slightly left of the notch in the case. As I accelerated it became hard to follow but moved quickly to the right /towards the rear of the bike. I mean barely touching the throttle. I turned the timing lights advance dial and the line goes the opposite way. It seems to fire without incident, no faltering that I noticed. Just the timing quickly jumped out of sight and was sparadic on position. It seems to actually be retarded by a few degrees, yet my pickup coil is turned max counter clockwise..

[McQuade]

Checked idle with my buddies fancy DVOM it was at 926 but it's lowest setting was 2cyl, so I'll wager around 1852 or so. Removed muffler, and the clip on the carb needle is at the top attempting to cute it's rich behaviour. Better but nowhere even close to hauling itself without me on it.

[barnett468]

OK . . if the pick up coil is on the left side of the engine, counter clockwise would be retarded and the F to the left of the mark would be retarded . . I would try wiring the advance closed as I suggested . .

[McQuade]

Whoops neglected to mention I did wire it solid. It would barely climb off idle. No bawls. And I forgot my clocks, I meant all the way clockwise haha. Fully advanced. In which your reply will most likely be "valves are skipped on te chain" to which I come to another digression. My dot won't QUiTE match up. Pretty effin close tho. And I tried numerous times skipping a tooth on the sprocket trying to get it on, but one tooth either way and it's way off. So that being said, I've called a priest to come exorcize whatever resides within this thing. Haha

[barnett468]

Ok . . I am stuck on a tiny fn tablet until to borrow afternoon. So its hard to do this.

please be more accurate and concise in your descriptions . . for example, you have not mentioned if it quit missing during any of this . . obviously if it no longer revs to the rpm at which it was missing before we can't draw any conclusions as to weather to miss is now gone etc.

It sounds like it might be helpful to allow it to advance but only around 1/2 of the current amount . . this would require some type of stop . . at the very least, it sounds like there is not enough tension on the springs but that being said, if it is in fact idling at 1800 the advance would already be advancing some so why would it be slightly retarded at idle?

As far as the can goes I'm not sure what you are talking about so here is some info . . the t on the flywheel should be lined up with the mark . . the one on the can great should be lined up with the mark . . if the chain is stretched, the line on the can gear will be going to the rear of the bike by maybe 5 mm or 3/16 of an inch . . the line should never be towards the front of the bike . . if it has a non stock can, it is possible that the holes in the can are not in the same location as the orig can . . this would cause the can mark to be misaligned .. . I have seen this before with some cams.

Do you know ewhat that can is?

[McQuade]

When I wired it closed, it didn't get high enough rpm to get to the "danger zone" where the issue resides. From what you describe, my chain is indeed stretched. But I've never seen an issue of this severity from that amount. The cam is OEM lobes were pristine when I checked the top end during the head gasket.

As a side note ephiphany ; what would happen if the flywheel spun on the shaft, is this possible, and should I be able to see a key way on the crank? I see one on the flywheel but not on the crank, which seems to defeat the purpose.

[McQuade]

My thinking is the flywheel shifted... As my timings retarded from the get go, how could it backfire through the carb, unless my mechanical valve timing is off from tdc?

[barnett468]

It can also do that if the ignition timing is off or it has a huge can and carb etc.

If you have a burnt/leaking in brake valve it will do it to some degree too.

[McQuade]

It can also do that if the ignition timing is off or it has a huge can and carb etc.

If you have a burnt/leaking in brake valve it will do it to some degree too.

I found a key... Under the flywheel, caught behind it.. Lol

[barnett468]

When I wired it closed, it didn't get high enough rpm to get to the "danger zone" where the issue resides. From what you describe, my chain is indeed stretched. But I've never seen an issue of this severity from that amount. The cam is OEM lobes were pristine when I checked the top end during the head gasket.

As a side note ephiphany ; what would happen if the flywheel spun on the shaft, is this possible, and should I be able to see a key way on the crank? I see one on the flywheel but not on the crank, which seems to defeat the purpose.

You need to actually remove the flywheel to inspect the key . . yes they can and do occasionally spin.

A can that is off by 5 mm or less from the mark in the cam gear will not cause this proble .

r

[McQuade]

In the bottom of the case I found a key.. I will pull the flywheel(I never pulled it)

[barnett468]

In the bottom of the case I found a key.. I will pull the flywheel(I never pulled it)

OK, I didn't see that before you posted . . yeah, thats kinda suspicious, lol.

[McQuade]

Well I have given up. That effin flywheel will NOT come off. I now have play in and out so either it moved or I beat the crank bearings out of it. Either way it will not move any further.

[McQuade]

The internal threads on the flywheel are gone by the way, so I tried a pully remover. I think it's time to take it to someone and get it done.

[barnett468]

Well I have given up. That effin flywheel will NOT come off. I now have play in and out so either it moved or I beat the crank bearings out of it. Either way it will not move any further.

the crank now moves in and out?

what did you do to cause that?

[McQuade]

As with every component I've dealt with on this bike, whoever owned it before obviously removed the flywheel. I'm taking a stab in the dark and saying an external puller was used, because the inside if the crank end, is mangled, and there are no large threads left to put the proper tool on. I suppose I'm no better as I attempted the same. I'm going to have to split the case one more level to get two arms onto the flywheel, as only one will currently fit. I'm also going to look into the origional motor and see what was up with it. I'll assume the current engine is a 200e as it has high low, but the origional was a 200m.

[McQuade]

So with both engines, I have established what I believe to be the issue. The timing chain. I can not get it tight enough. It's very loose. When I turn the engine over the chain "skips" on the front side of the engine. Not skipping a tooth but like it has too much play and binds a little. The tensioner will not make it any better. Also, if I line the cam up (dot to head mark) the flywheel T is quite far to the left of the viewing hole. Not even close. But if I line up the flywheel T line up first, the cam dot is half a link off to the right of the head mark. Have you ran into this Barnett?

[barnett468]

So with both engines, I have established what I believe to be the issue. The timing chain. I can not get it tight enough. It's very loose. When I turn the engine over the chain "skips" on the front side of the engine. Not skipping a tooth but like it has too much play and binds a little. The tensioner will not make it any better. Also, if I line the cam up (dot to head mark) the flywheel T is quite far to the left of the viewing hole. Not even close. But if I line up the flywheel T line up first, the cam dot is half a link off to the right of the head mark. Have you ran into this Barnett?

ok, as you mentioned, your flywheel might be off on the one bike so a definitive conclusion on the chain is hard to come to on that one until the flywheel timing is looked at.

as far as the play in the chain goes, yes they could both be stretched too far OR the tensioner could be bad, or the long rubber coated chain guides might be excessively worn etc.

imo, the most logical thing to do which i tell everyone, is to fix every obvious problem you find when you find it, because that could be the cause of a problem or at least one of the contributors to the problem, but even if it is not, they still have to be fixed anyway.

i just had an experience with another person somewhere, that had a very obvious prob, and they absolutely refused to do a 5 minute and $5.00 part change, because even though it was blatantly obvious to me and others that this needed to be done, they were convinced that we had no idea what we were talking about . . i just don't see why some people ask for advice because they don't know how to fix their prob, then don't take the advice that is offered because they think it is wrong, lol

Anyway, this is not the case with you at all, it just amused me, plus i just thought i would mention it because sometimes its not just one problem causing an issue, so there is no point in trying to find just one cause . . i have had cases where you fix this and the vehicle runs better, then you fix that and it runs better then after you fix several little things, it runs fine.
.

[McQuade]

I checked not via key way but the mark in relation to the piston with a fancy zip tie through the plug hole. It seems good. I aquired a three mm bolt and inserted it into the tensioner to further tighten the chain and the weird skip thing stopped. Thanks d ray's YouTube channel haha. But I wish I could put pictures and video on here but it won't upload. That would certainly help you out deciphering my canadian storytelling

[barnett468]

I checked not via key way but the mark in relation to the piston with a fancy zip tie through the plug hole. It seems good. I aquired a three mm bolt and inserted it into the tensioner to further tighten the chain and the weird skip thing stopped. Thanks d ray's YouTube channel haha. But I wish I could put pictures and video on here but it won't upload. That would certainly help you out deciphering my canadian storytelling

you can download a video to youtube then just post the url here and we can go yo youtube to see it . . we could also look it up on youtube by the title etc.

im guessing by the fact that you didnt answer my question about your bearings is because you beat the crap out of the flywheel with a hammar or used a slide hammar?
.

[McQuade]

I answered your bearing question. The previous owner demolished the internal threads on the flywheel they're all but gone. Judging by the damage I'd say an external puller was used. I attempted the same. It was quite clear it won't come off that way. But I'm out of options that way.