Drifter Posted January 11, 2011 Report Share Posted January 11, 2011 Sorry to bother you people so much lately :) ...but my carb is going crazy... None to low throtle is fine Full throtle is perfect ...half throtle is almost not working at all...it just missfires and nothing realy happens. I actually got more acceleration on 20% throtle, than 70%.... ? How can this be when both high and low is perfectly fine... I dont understand that magic carb-thing (tooo oldschool for me) ;) Quote Link to comment
datsunaholic Posted January 11, 2011 Report Share Posted January 11, 2011 Plugged jet, bad accelerator pump, or really bad vacuum leak. Plugged main primary jet would show up off idle, no matter how hard or soft you roll into the throttle. Full throttle would work (kind of) because the secondary would kick in, and the accelerator pump would give it enough gas to get up to the secondary. Bad accelerator pump would show up when giving throttle quickly, or under load. If rolling very slowly into the throttle, it wouldn't be noticeable at all. Bad vacuum leak would be indicated usually be a very high idle and no power. A dead spot would be noticeable under load, but not so much when free-spinning (out of gear). Quote Link to comment
Drifter Posted January 11, 2011 Author Report Share Posted January 11, 2011 Bad accelerator pump would show up when giving throttle quickly, or under load. If rolling very slowly into the throttle, it wouldn't be noticeable at all. Thanks, good answer. To me it sounds like the acceleratorpump as you say. It is noticable at freespin. when i give throttle quickly it dies for a half second before starting to fight its way up the revs... Is this a internal part of the carb. Can it be fixed easely, or is it a full overhaoulin of the carb... i`m gonna change it to Yamaha R6-quad carbs in 3 mounths, so just need it to work until spring :) Quote Link to comment
datsunaholic Posted January 11, 2011 Report Share Posted January 11, 2011 If it's a stock 2bbl Hitachi carb, the pump is that thing with the bellows and a lever on it. It's a plunger. I think... I'm not too sure about A-series carbs. Quote Link to comment
Drifter Posted January 11, 2011 Author Report Share Posted January 11, 2011 i wish my english was better.... so its a mechanical pump on the carb?? :) *looking stupid* hehe Quote Link to comment
datsunaholic Posted January 11, 2011 Report Share Posted January 11, 2011 It's a plunger pump that's attached to the throttle linkage. When you push the gas pedal, it adds extra gas for acceleration. It operates much like a syringe (and is about the same diameter as a small one). Quote Link to comment
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