help with a bike problem

[chr|s sedition]

My dad's friend sent him the below email to fwd to me (he knows I ride), and was lookign for some tech advice. This is beyond my knowledge. Any of you smart people got any ideas?
____________

I've got one hell of a problem w/my bike._ It's a '94 Honda CB1000-awesome ride, never a stumble 'till now._ Symtoms: when I first start it up w/the choke on full it used to take up to 30 seconds to warm up then I would turn off the choke & away I'd go._ Now the bike very quickly starts to rev way high but if I turn off the choke it stalls._ Then, if I ever so slowly slide the choke lever back, the idle surges, almost stalls & then surges again etc._ At this point if I give it any gas it will surely stall._ I've been completely through the entire fuel system from the airbox_(replaced the air filter $$$) to the carburetors which I took apart._ The jets were clean, no cracks in the slide diaphrams, no obvious problems there._ I've changed the spark plugs (old ones looked fine), drained the gas & replaced it, checked the vacuum, etc._ The only mechanical thing left is to check the valve clearance but I'm not optimistic._ My next step is to confront the electrical system (I'll start w/the ignition pulse generator) but I'd like to rule everything else out before I engage that demon.

[ChR1s]

Running lean due to gummed up carbs? The orifices/passages in the idle circuits are very small (some so small that you can barely see light through them), and are easily clogged up with this reformulated gasoline if the bike is left to sit for very long.

[black]

sounds exactly like my bike...old gas and dirty crabs( nothing visible to the eye though)

changed the gas, clened hte carbs( everythign, clened air filter gapped the plugs and lubed the cables etc. and everythign was fine...)

[Tricky Mike]

Yup...
I'd pull the tank, drain it... give it some fresh gas.
Pull the carbs, clean the jets/needles and re-sync them.
Maybe some new plugs too...
Also (obviously) check the airbox for chipmunk nests...

[Sidewinder]

Originally posted by black
sounds exactly like my bike...old gas and dirty crabs

Dirty crabs ewwww

[mikeb]

sounds like my bike. mine still idle's way high on the choke at start up. i can adjust it without stalling though. i had a big hesitation problem this year. first time i replaced the air filter and it was fine for the most part. second time i replaced the plugs and fuel filter. runs real strong now. still could use a carb cleaning and synchronizing.

i blame the shit there passing off as gas now. i've heard of alot of problems this year especialy with carbs on older bikes.

[Awesome]

Did you try just getting a few guys and lifting it onto the deck?

[Degsy]

vacuum leak, fer sure.

degs

[rebelpacket]

Originally posted by Degsy
vacuum leak, fer sure.

degs

What he said. Either in the boot of the carb, intake manifold, diarpraham or somewhere, thats whats happening.

CV carbs need suction to pull gas through with the air. If they dont got it, they dont pull gas!

[SVRACER01]

Originally posted by rebelpacket
What he said. Either in the boot of the carb, intake manifold, diarpraham or somewhere, thats whats happening.

CV carbs need suction to pull gas through with the air. If they dont got it, they dont pull gas!

yeah.. what he said. i was thinking manifolds also. (the rubber boot between carb and head) might have a crack in one that he cant see or its not sealing properly around the carb or head

[chr|s sedition]

thanks all...I'll pass the info.

-chris

[R7]

This new ethanal gas is causing all kinds of problems with carburators. The smallest parts are what corrode/gum up first, which is your idle circut

[SSearchVT]

+1 for the vacuum leak. Check all the hoses, boots, etc. A quick way to check - with the bike idleing, spray either carb clean or WD-40 on the intake boots and around the area (BE CAREFUL!!! - it's flamable, and can eat paint.) and listen for a change in the idle speed. Good luck...

[richw]

Cracked carb rubber manifold and vacuum caps. I just smear a little black silicone rubber sealant on them.

Fills in the cracks, glues them up, if done noce gives a nice sheen to boot.

You might also find it with a carb balancer at least the idle leaky one would be WAY different low then the better ones.


Also if you can idle there is the old propane trick where she'll run better if the leak sucks propane (not lit) from a torch.

Also if not done I would make sure each carbs dribble chock rod moves freely. I belive they rely on a spring to move them the last little bit that seals them off. (not sure never had the courage to buy a Honda)