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Discussion Starter · #1 · (Edited)
WTF did I do? I can't believe I'm asking for "your" opinions, but let's hear them.

On New years, I put too much NOS to the 730. (miscalculation on my part) Got a little flash and some white smoke up through the carbs.

Now it starts and runs, but is way underpowered and stumlbes under hard load. Especially if you get out of it and right back into it. It doesn't die, just runs like a 1500 rpm rev limiter or something. It gets worse as it warms up.

I replaced plugs, CDI, jetted back to a previously good running setup.

If it didn't fluctuate or was hard starting, I would think it was rings or valvetrain. No smoke or noise though. I need to pull the carbs and see if I ruptured the vacuum diaphram. When it doesn't stumble, it runs fine other than being short on power. I figured the crossover tube could make it run on one carb.

Other than that, I got nothing.

Okay, lets hear from the brain trust.:D:D:D
 

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Discussion Starter · #3 ·
Sounds like ya got a handle on what to look at. Hope the rings and or cylinders aren't hurt.
From your mouth to Gods ears brotha.

It's the only thing that accounts for the itermittency. I was hoping that someone has heard of this sort of thing or had any other ideas.
 

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Sounds to me like you broke a piston land. Starts fine runs fine but when you get that engine going the exhaust gases blow past that land causeing a loss of power under heavy load.
 

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piston land...i'm not saying it's impossible...but I usually see hard starting as a symptom of that....
I'm gonna go with badhear on the diaphram on this one....
 

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piston land...i'm not saying it's impossible...but I usually see hard starting as a symptom of that....
I'm gonna go with badhear on the diaphram on this one....
I agree with FatDog! :lol:
 

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If you want to try my 38's just let me know they will need cleaned up still have sand on them:rolleyes:
 

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popped a diaghpram out of the seat under the plastic cap.

pull the filter and see if they are opening all the way.

if it doesn't seat right you hold no vacuum in the starting circuit of the carbs (that's how the chokes get their vacuum from

John
 

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popped a diaghpram out of the seat under the plastic cap.

pull the filter and see if they are opening all the way.

if it doesn't seat right you hold no vacuum in the starting circuit of the carbs (that's how the chokes get their vacuum from

John
Possibly what he said, also make sure that a carb didn't blow up out of it's manifold.
 

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Discussion Starter · #10 · (Edited)
popped a diaghpram out of the seat under the plastic cap.

pull the filter and see if they are opening all the way.

if it doesn't seat right you hold no vacuum in the starting circuit of the carbs (that's how the chokes get their vacuum from

John
Possibly what he said, also make sure that a carb didn't blow up out of it's manifold.
I checked the mani's right away.

Thanks for the input.
 

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Discussion Starter · #11 ·
The carbs seemed fine, although I guess that diaphram could've slipped back into place when I looseend the clamp. The slides seem to move well when revved now. Like a dumba$$ I didn't check it until after I pulled it apart.

I did a makeshift leakdown test and couldn't hear anything blowing buy.

I am quickly running out of ideas.

Any theories welcome.
 

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Check the ignition timing. Maybe it spun the flywheel when it backfired.
 

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Can i do that with a regular timing light?
I've done it with a timing light, but it's been years since I did it.
I do think it was straight-forward; hook the pickup to the #1 cylinder (front one, most likely, check the manual), 12v power source, pull the viewing plug and check the timing. I think I covered the hole with a rag and pulled it away when I had the light ready to go because the oil will fly out with the engine running. Wear your safety glasses. If you have a degree key, it will throw the timing mark off a bit.
Hopefully someone that's done it recently will chime in. I think VFJ has checked them with a light.
 

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I'm assuming there are other ways as well?
Make sure the piston is at TDC and see if the mark on the flywheel is lined up with the mark in the viewing hole.
 

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I had a warrior that acted like that. It wound up being a small split in the manifold. I never found it till I took the thing apart. Put it back together with a new manifold and it ran like it should
 

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Yes it is possibly, and I have seen sheered flywheel keys.
 
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