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carb HELP!!?!?
- bdecho
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For some reason the bike absolutly will not run without the choke on. When the choke is on the engine will race, and if i turn the throttle it immediatly dies. I have no idea whats going on with the thing. Also, there is a vaccum port on the fuel petcock that is not hooked up. Would that have anything to do with this running condition, and if so where would i run the hose for vaccum for it??
Thanks for your help!
Regards, Brent
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- bdecho
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Regards,
Brent
Post edited by: bdecho, at: 2007/09/17 14:43
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- bdecho
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- Patton
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... At mid throttle while cruising I lose power....
Might be obstructed fuel tank vent. Test by running with fuel cap loosened.
1973 Z1
KZ900 LTD
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- Patton
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... I have the pilot screws out about 2 1/2 turns....
For OEM carbs, FSM says 1 1/4 turns out from lightly seated, so 2 1/2 would seem much too lean for pilot circuit. Would re-set to 1 1/4 turns.
1973 Z1
KZ900 LTD
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- bdecho
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Post edited by: bdecho, at: 2007/09/18 17:51
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- Patton
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I thought that turning the screws out would richen the mixture not make it lean... are you sure? I turned them in, then back out to 1 1/4 turn and it didn't change a thing. I still can't get it to idle, when i rev the engine it still cuts out about 1/4 throttle. The gas cap didn't change a thing either. The only thing that i haven't tried so far is replacing the accelerator pump, and i'll have to order one, but I doubt thats the source of the problem. Any ideas??
Was looking at the FSM covering 79KZ1000 showing side pilot air screws on A1 and D2 (unscrewing allows more air for leaner). Re-read your post and noticed C2 (cop bike), so checked parts diagram which shows both side pilot air screw and bottom pilot mixture screw and no accelerator pump.
So am befuzzled. Are carbs OEM? Do they have BOTH side located pilot air screws AND bottom located pilot mixture adjustment screws (unscrewing allows more mixture for richer) AND accelerator pump? If answers are "YES" -- then sorry I don't know about these carbs with dual pilot adjustment screws and accelerator pump.
Post edited by: Patton, at: 2007/09/18 19:23
1973 Z1
KZ900 LTD
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- Patton
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Am sure that unscrewing side located pilot air mixture screws allows more air into the pilot mixture which leans the pilot circuit fuel mixture.
Am also reasonably certain that unscrewing bottom located pilot mixture screws allows more fuel mixture which enrichens the pilot circuit fuel mixture.
Others more knowledgeable about your particular carbs will render better advice.
1973 Z1
KZ900 LTD
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- bdecho
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- Patton
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... carbs have only one pilot screw on the side of the...unscrewing the pilot screw leans the fuel mixture correct?... have to take the carbs out one more time and put the 105 mains back in because i have a little backfiring on deceleration...will put the 15 pilots back in too since it seemed to idle better with them....
Thanks for the report.
Yessir -- unscrewing the side located pilot screw leans the fuel mixture (by allowing more air into the fixed amount of fuel being drawn up into the pilot jet).
But thinking size of main jets is unrelated to backfiring on deceleration. And that smaller pilots might possibly increase the backfiring. Believe the backfiring is being caused by some other reason.
Per FSM, the A3 and D2 standard pilot jet is #15 for OEM Mikuni VM28SSx4 carbs (but as noted, maybe not the stock carbs).
When people disagree with me, it's usually because I'm wrong. But at least I smell bad. :lol:
Good Luck with the tuning!
1973 Z1
KZ900 LTD
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- tjettim
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can make.Finding some smoothbores or 1978 Z1R
carbs will be the second.I threw away my points
in 1978,never looked back.The 1979 pumper carbs
were hard to adjust,I bet Sudco sold a ton of 29s
in 79.
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