2009 Lance Vintage quit running

[finaljudgement]

I have a 2009 Lance Vintage with the 157qmj engine. The prior owner said that it would start and run and then just die. He was right. I was stranded getting it home. It has spark, spraying starter fluid onto the air intake doesn't help. I replaced the CDI with a racing CDI from Scrappy Dog, got the red hot coil, and new plug. I checked the valve clearance and it was way too tight. I reset valves to .05mm. It started and ran like a champ. Then it died and I cannnot get it to start. Still has spark; starter fluid does not help. Fuel pump squirts gas. I replaced the orginal airbox with a performance filter. I have tried adjusting the f/m screw; no help. I am officially stumped and out of ideas.

I may be beyond help....but I appreciate any assistance.

Final Judgement

[inuyasha]

Hi
Have you checked the compression of the engine yet?
That would be what i would do next
Spark fuel and compression are the requirements for a properly running engine
Take care and ride safely
Yours Hank

[teddy554]

i dont think .05mm is right i know the in measurement is .003-.005 inch which when i do the conversion to mm it is 0.003 inch = 0.076 2 millimeter,0.004 inch = 0.101 6 millimeter, 0.005 inch = 0.127 millimeter

[teddy554]

Well i might be wrong just read .05mm but equels .002 inch but might still be to tight try .07-.08 which is .003-.004 in inches is correct have you check the gap on the plug .5-.7

[finaljudgement]

I have not checked the compression but will later today. The puzzle there is that it runs like a champ for 20-30 minutes, then dies. The owner's manual calls for .05mm but I know from reading the forum that frequently a different gap works better. Pulled the plug, it had lots of carbon. Put a new iridium plug in. I didn't check the gap on the new plug because the point is so tiny I though I might damage it.
I did find a crack in the airbox between the filter and the carb. I will plug that up and reinstall it. I did not oil the performance air filter (which is two layers of sponge). Could that be adding to my problem?
Thanks for the help and ideas.

FinalJudgement

[wheelbender6]

"runs like a champ for 20-30 minutes, then dies". Thinking back to my hot rodding days, that sounds like an ignition coil.

[qwertydude]

It could also be the ignition pick up coil. Erratic running after getting warmed up is often a symptom of a bad pick up.

[DW]

Spade clips on the coil get loose as they get warm. Just for giggles go out and make sure there good and tight. If not gently squeeze the curled metal in toward the flat end with your needle nose pliers. This happened on both my 150's, easy fix.

[finaljudgement]

I regapped the valves to .06mm intake and 08mm for exhaust. It seems to have taken care of the problem. Thanks for your suggestions; they were very helpful.

Finaljudgement

[techie610]

That doesnt make much sense to me.. EVERY gy6 I have done have the valves at .03IN and .04EX.
But, if it runs for 30 minutes, the dies?..
The valves effect it from the first stroke.
They would not just stop.
The ONLY thing I can think of is that they are made of cheap metal, that expands to much, when it gets that hot.
But I have NEVER heard of that happening.
If the problem raises again, please let us know. I am curious, and puzzled.

[finaljudgement]

Techie,

Are you missing a decimal place. .03 inches would be more than .6 mm, which would be a huge gap I think.

I agree with you about it being very strange. I wondered whether the smaller gap would cause f/m issues as the engine got hot. It is in triple digits in Phoenix already.

I have a digital o'scope which shows a good spark pattern at least through initial warmup. It is truly a mystery to me.

Finaljudgement

[techie610]

Techie,

Are you missing a decimal place. .03 inches would be more than .6 mm, which would be a huge gap I think.

I agree with you about it being very strange. I wondered whether the smaller gap would cause f/m issues as the engine got hot. It is in triple digits in Phoenix already.

I have a digital o'scope which shows a good spark pattern at least through initial warmup. It is truly a mystery to me.

Finaljudgement

.03 INTAKE.. Not Inches.. lol
.04 Exhaust.
When I was in Myrtle Beach, SC, it was 115*. And it rode perfect.
And after a 300mi ride from Yancey Co. to the beach, non-stop, it was ok.
Not the external temp.

Strange problems might have stranger causes.
Have you gone over every grounding point?
I put a ground cable from the valve cover to the frame, to stop any funny things there.
Might as well replace the VR, if you have the opportunity.