[Trefmawr]

Well it's getting warm enough to do serious work on the bike, and so I tried another starting today, but without much success. I noticed something though, and I think it has to do with the valve timing. When turning over, air is pushed out of the carbs, as well as the exhaust. When I was spraying starter fluid in, and then cranking it over, it would just shoot back out at me. Logic dictates that there should be suction there correct? Am I just stupid? (Yes ) I thought I had the timing punches lined up correctly when installing the cames, but maybe they're a touch off. I will be checking tomorrow.

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Le Canuck
My Bike on Flickr

 

[jbranson]

If the cams are right...check the valve clearances...if they are too tight and holding the valves open it will push air back out the intake. If the valves have the right clearances then it might be time for a valve job as air is leaking back past the intake valves.

If everything is correct and it still happens and you have a race cam installed....well sometimes they have so much valve timing overlap they will spit back out of the carb when you roll them over.

If it's really pushing out the carb with some power instead of just spitting some...then it's probably the cam timing or valves way too tight....or even a bent valve if it's just one side. If both sides are doing it almost exactly the same...that points to a timing problem or radical camshaft...cause it's unlikey both valves are equally bad, or mis-adjusted.

That symptom is usually one of my most dreaded things to see after assembling and engine.
JohnnyB

 

[Trefmawr]

New development:

Today when I tried firing it up again, with gas and starter fluid, it sounded like it caught one ignition (like a small bang) then the carbs flew off with a loud pop. I had them on pretty tightly too, enough so that I couldn't pull them off without great effort at least. It smelt like something had been burned, so maybe it fired once?

Either way I don't think it's supposed to shoot the carbs off like that...

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Le Canuck
My Bike on Flickr

 

[jbranson]

Nah man, that shit happens all the time...I gotta put my carbs back on like ten times a day...sometimes they even blow off during a race and drag alongside on the ground by the throttle cable.

Sounds like you have a serious timing issue...I'm not a expert on that bike....but sounds to me like the cam timing or ignition timing is way off...cam might be "180 out" if that is possible on that bike...meaning it's exactly opposite of where it's supposed to be.

But...it's obvious the ignition fired while the intake valve was way open...which is not supposed to happen. BOTH carbs came off? That definately sounds like a cam or ignition timing problem.
JohnnyB

 

[joe c]

definitely. you might have jumped a tooth on the cam, or the timing is just way outta whack.

hey jb, you know, if theyre that problematic, you should jst get rid of them.

seriously. just take them off, and throw them away.





jc

aaron sent my wheel!

 

[Trefmawr]

Man. I'm one dumb bitch. So I had the "correct" TDC Mark on the timing advance, but the wrong piston mark. I had my cams backwards! My god I feel so dumb, but so relieved now that it's fixed. And guess what?

She fires!

Now all I have to do is figure out what's up with my accelerator pump, as when I turn the petcock on, gas just starts dumping over the 2nd carb. I lost the little rubber grommet that goes on the rod connecting the pump and the throttle body, but would that make such an impact?

I must have forgotten to clean something...

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Le Canuck
My Bike on Flickr