Yamaha 225 DX won't start, PLEASE Help

[71satellite]

Hello everyone,

I'm new to 3 wheeling, and am having problems with my 84 Yamaha 225 DX.

It does have compression (hard to turn over by hand without using the relief valve), and it does have spark ("blue" spark - checked by grounding plug to the motor), but it will not fire at all. I am using Starter Fluid sprayed down the carb throat, but nothing at all.
I have an electric starter, so it is no problem to turn the motor over and over.

I have already done the following:

-replaced spark plug
-Tried replacing coil with another one (from a Honda...just had to make an adapter for the trigger wire)
-disassembled and cleaned the carburetor
-checked with an inductive timing light to ensure that it is actually firing

I have not done the following yet:

-actually measured compression (my compression tester doesn't have an adapter that fits the motor)
-checked valve timing (I don't have a clue how to do that with this motor)
-bought a service manual (haven't found one locally...anyone know if there's a PDF on the web somewhere?)


ISSUES:

This trike was bought "as is". It doesn't have an igniton key (the harness plug that would go to the key is missing), but all the rest of the wiring is intact. Not sure if that would matter, since I get spark anyways. I did try jumping the red and brown wires together (according to the Yamaha wiring diagram I found, that's what should happen for "RUN"), but no change.

I haven't been able to get the push-button start to work, but connecting a battery directly to the starter lead on the relay works fine.




To me, this is a simple motor, so if I have compression and spark, why won't it even fire???

Any suggestions would be greatly appreciated. Please be as specific as possible, and thanks a lot in advance. I just don't want to randomly replace part hoping that something will work.

Feel free to email me at chrishelmer@hotmail.com as well.

Chris

[Unclediezel]

Im guessing from your SN your a Mopar fan as well--
Basically your right -it should start- If the electric start still works- See if you have suction at the throat of the carb-(Opposite of compression is vacuum)
Where are you putting the starting fluid?

[edog]

Did you check the inline fuse?

[traxxasx]

my ignition key slot is gone, i would pull her over till it top dead center then a lil down, pull the plug stick some gas in her replace the spark plug, lift the realase valve, and give her a few good pulls, see if she starts over/

[Dads]

Have you checked the valve settings??

[71satellite]

Hello everyone!!

WOW, thanks a LOT for all the replies. This is a great forum!

To answer everyone's questions:

-yes I am a Mopar guy. I'm in the process of building a sweet 360 right now (as we speak it is on the engine hoist, ready to go back in tomorrow when I get my new motor mounts)

-I will check for suction at the carb. I have been spraying starter fluid into the carb (with throttle open) and directly into the spark plug hole as well. I've tried turning over and over...to make sure I hadn't "flooded" the cylinder with fluid.

-I did check the fuse. It was blown when I first checked it, but it has not blown again since I replaced it.

-I haven't tried putting straight gas in the cylinder yet (thinking that started fluid should ignite if anything will) but I can try that too.

-I have NOT checked valve settings, as I don't know how to do that. Any suggestions?


I hope to check these things out in the next day or two (I really do have to get my 360 back in my car first). But if anyone else has ideas, please do keep them coming!

Thanks again for everyone's responses.

Chris

[Unclediezel]

One Thing I forgot to mention- Is the exhaust plugged up?

[edog]

Yes,check the valve lash.If it smells like strong gas smell at the muffler,it could be pushing to much fuel into the piston chamber.

[71satellite]

Hi again,

Wow, I can't believe how helpful you guys are.

The exhaust is a fancy custom rig (big chrome pipe, and what looks like a honda motorcycle muffler), so I don't think it is plugged (although I will take it off and check with compressed air).


Re: valve lash.....can you please describe how to check that on a Yamaha motor? It is certainly possible that the intake valve just isn't opening (but then again, when I've sprayed fluid directly into the spark plug hole, that should still ignite).

Thanks once again,

Chris

[freewheel3]

[QUOTE=71satellite]Hi again,

Wow, I can't believe how helpful you guys are.

The exhaust is a fancy custom rig (big chrome pipe, and what looks like a honda motorcycle muffler), so I don't think it is plugged (although I will take it off and check with compressed air).


Re: valve lash.....can you please describe how to check that on a Yamaha motor? It is certainly possible that the intake valve just isn't opening (but then again, when I've sprayed fluid directly into the spark plug hole, that should still ignite).

Thanks once again,

Chris[/QUOT
#1 Make sure engine is cold.
#2 Remove both valve covers.
#3 Remove the timing window plug from the left side crankcase cover (by the recoil)
#4 Align the "T" mark on the flywheel with the pointer on the crankcase. (look in the hole)
#5 Make sure the piston is at TDC on the compression stroke when you have the "T" lined up. (You know you are on the correct stroke when there is play in both valve rockers)
#6 Check valve clearance first before you make any adjustments. Intake = .002-.004" & exhaust = .004-.006"
#7 If you have to make adjustments, loosen the lock nut on the adjusters & set your clearances. Hold the adjusters in place when you retighten the lock nuts (10 ft-lb)
Also pay attention to the way the Intake valve cover comes off, don't put it back on upside down. (the ridge inside the cover goes at the top) The exhaust cover is self explanatory.
Also, gap the plug @ .024-.028"
Hope this helps.

[edog]

I did this to my tri moto after owning it for 2 years.WOW what a differance it made.Easyer starting faster through the gears,better gas millage,more torqe.

[71satellite]

OK, Here's the Latest:

-I checked for vacuum at the carb. Yup, there is definitely vacuum.
-I checked the exhaust. Yup, the exhaust is definitely open (I can feel the air being expelled)
-I tried adding a bit of gas directly into the cylinder. Nop. Still nothing.

Thanks for the advice about checking the timing and valve adjustment. I'll print it out, and hopefully checking things over tomorrow/Thursday.

MAN this is annoying. I don't understand how fuel in the cylinder won't ignite if there is spark!
Any way of determining if I have a "weak spark"? The spark is blue - which is a good sign as far as I know. Also, using my inductive timing light, I can see that the coil is sparking regularly (and a lot) when the starter is turning everything over.

Well, hopefully the valve/timing issue will be the solution.
Thanks again everyone.

Chris

[Unclediezel]

Ok-- You have a timing light which means you are competent enought to understand Ignition principles--
You stated electric start is not working by the button----In the wiring diagram there is a connection from the button to the cdi unit. The purpose for this connection is to establish Correct -"IGNITION TIMING" for starting. By bypassing the start button -CDI has no way to establish a base point.
If you need a diagram -I have the haynes manual -I can scan it for you
Just a shot-But from experience Even poor compression will start a motor, but it wont run right. Thumb over the spark plug hole , anything that puffs when you crank should be sufficient.

[firefirefire90]

i duno if this i same with yammies but check your pulse generator and your strator.

[Unclediezel]

yes - Its the same- a pulse coil is responsible for timing the sparkin conjunction with the CDI unit.

Woa--woa--woa-- Did the crankshaft key break off????????????????????

[71satellite]

Hi again guys,


I checked compression this morning (my compression tester doesn't have an adapter for the spark plug hole, so I just "held 'er in there real good" to get a reasonable idea of compression numbers). It hit 130 lbs, without proper sealing, so I think compression is fine.

This starter bypass issue.....interesting. I will check into it for sure. However, just out of curiosity's sake, what if I was using the pull starter (which unfortunately I am not as the spring thingy inside is shot)?

A few days ago I rigged up an adapter so I could spin the starter pulley with a speed wrench/impact gun, but I wasn't getting any fire then either.

I will write Unclediezel and get the haynes manual pages I need, and take it from there.

Thanks again everyone! The next update will come soon (hopefully)

Chris

[71satellite]

Hey guys,

Well, here's what happened. It was recommended that I:

1- Check the starting circuit to see why the starter button wasn't working.

I checked the sky-blue neutral wire with a test light, and eveything was OK.
Then I bridged the red and brown wires in the Main Switch harness, and located the starter cut-off relay. Applying the starter button does NOT cause the relay to click. Sooooo, I think I found the problem (i.e. the relay). I was wondering how to bypass the relay (there's only 3 wires, sky-blue, red, and red/white). But anyways, this is the minor part of the issue.

I was told that you needed to press the Start Button to Establish a Base Point for the CDI. Well, I tried just pressing the button (even though the relay isn't clicking over), but that didn't help.

So is a relay the only electrical problem here? And can I just bypass it for testing purposes?


2- Check valve timing

I popped the timing window, pulled the two valve covers, and turned everything over.
Pretty simple, intake opens as piston sucks down, intake closes and piston travels up. At the top of that stroke is "TDC" when the ignition should be firing (after which, piston travels down, then exhaust opens as piston travels up.
I watched it over and over, trying to make sure I had it right.
WELL.....my crank "T" and "F" marks (which are very close to each other on the crank) were 90 degrees OUT from the valve timing (i.e. both valves closed). So I figured I had found the problem. The piston was at the bottom of the bore when the spark plug was sparking, not at the top!

So, I carefully pulled the upper timing gear bolt, rotated the motor to TDC, then realigned the timing chain and reattached the upper timing gear.

3- Check valve lash.

Both intake and exhaust were pretty tight, so I use a 0.004" feeler gauge and set them.


The moment of truth...it all had to work now right?

Wrong. Not only did it not fire, but after 20-30 seconds (intermittent) of rolling the engine over with the starter, I heard a "PING", and discovered that the exhaust valve rocker arm had snapped.



Crazy.....I didn't think these were interference motors, but what else could have caused the exhaust rocker to break like that? Then again, I'm surprised just the starter motor could generate enough force to snap it.


Well, what did I do wrong? Obviously now I'm going to have to take the motor apart...but I still don't understand why it isn't firing?

Does anyone have suggestions? Should I just try to find an exhaust rocker arm somewhere and cobble it back together? Was I right to change the timing gear? What is the problem with this motor?


Thanks again for your help, looking forward to your suggestions,

Chris

[slothminx]

The rocker broke because when you "fixed" the timing you actually put it out of time. thus when you went to turn it over piston met valve and the rocker gave way.

I would count on a bent valve aswell.

Starter motors can power me on a KLT in gear up a steep hill there that powerfull(although not recommended).

Now this may sound slighty dumb but you sure your turning it over the right way?. If i were you instead of using the starter i would have put it in 4th gear and pushed it to bump start

At the relay there will be two BIG wires coming in from the battery and going to the starter. A way to test these would be to get a screwdriver and short the two terminals.

On the vavle clearences i would think you set them about right maybe too tight but that wouldnt screw the rocker.

Will

EDIT: another thing i do WHENEVER ive had an engine apart is spin it over 2 or 3 times by hand to check nothing is hitting and it spins freely

[71satellite]

Hey everyone,

Well, after pulling the top end of the motor apart to get at the broken rocker (thankfully the valve didn't bend), I decided to check the flywheel, and wouldn't you know - the Woodruff key had sheared.

So, I wasn't on crack when I thought that the valve timing was off from the crank position, the flywheel had rotated on the crank causing everything to "look wrong".

Fortunately, the local Yamaha dealer can get a new rocker arm and Key, so in a couple of days I'll bolt it all back together and see if this will actually run when everything is lined up right.