Carburettor/Bike problems....still!

Mihylo33

Mihylo33

I still think it's a valve.... Hanging up just enough or slightly bent to cause a run issue yet when the compression test is done the valve is forced shut.....
I hope I'm wrong and it's just a bad fuse..... Did you check the fuses?
 
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pdee4t

Yep. Checked all the fuses. I checked everything I possibly could. Been at it for 3 weeks.
It's not a bent valve, I had the head apart within that 3 weeks and they were perfectly new and straight. That's also how I know my timing is spot on because I checked the timing marks on the cam at TDC verified with crank lock bolt.
I had valves done when I did the top end about 2 months or so ago.
It's not hanging up because the leak down test would be showing an air leakage passed the valves and probably a lot more than 10%
I think it was indeed incorrect or too loose valve clearances. That can cause blowback I believe.
 
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pdee4t

I sprayed carby cleaner in the airbox with throttle open and the bike started up with the choke but will only run with the choke. Dies with no choke and dies when I use throttle with no choke. I adjusted the mixture screw and tried different adjustments but still didn't work.
What do I start looking at? Slide? Float? TPS?? to be honest im leaning towards TPS because it works at higher than 3000rpm with choke
 
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Tasmaniacs

Agreed bobkyle. Get a paintbrush in some paint thinners and go through the carby, then attack it with an air gun to blow it all out. The set it back to factory.
 
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pdee4t

yep, done all that. about 3 times now. it was all squeaky clean. all the jets were clear and everything.
in fact, some of them are even new jets.
That's why I reckon it's the TPS
 
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pdee4t

measured ohm resistance on the TPS....its screwed. 0.1 ohm reading.
looks like that's what was causing the problem.
i disconnected it and ran the bike...and the bike ran.... but same thing, only with choke.
 
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ossagp

I think you have contained your frustration well. Your testing with the carburetor off a good running bike was smart. Is your next step going to be a new TPS?
 
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pdee4t

well the carburettor i tested from my mates bike had the TPS already on it, so the test i did was not with my TPS.
and yeah, spose i'll have to get a new TPS if its giving me an 0.1 ohm reading.
 
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pdee4t

Kinda. It dies more often than not but when I am able to use the throttle with the tps disconnected it revs high and stays revving....then dies again.
 
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pdee4t

Hmm. Well with the tps disconnected and choke on it dies most the time still but when I am able to use the throttle I have to hold throttle open a bit then reach down and turn the choke off while still keeping throttle opened then it revs high and stays revving high....then dies again when I let go of the throttle.

I've only got 8% leak down percentage though with non escaping from anywhere except crank case breather passed the rings. That's why I'm going with a wild guess either tps or cdi box... But with a 0.1 reading, id say it's tps
 
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ossagp

I agree with you on having to go with guesses. But it still did all that with a known good tps? I am guessing you need to replace it anyway, but like you I am kind of grasping at straws from a distance. Some leaks show up more under vibration. Cam timing can cause some pretty crazy vacuum losses as well. You said your clearances were loose. You have checked to see that the loosest measurements are right at TDC? rotate the crank back and forth some and see if they get looser than at tdc. for curiousity, what clearances do you have?
 
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