thesickness Posted October 20, 2012 Share Posted October 20, 2012 Hi, got the bike idling fine but it just wont rev out past about 5 or 6k. I have uploaded a video to youtube here: Had the carb to bits a few times and it all looks good, only thing I noticed was I have an 82 main jet and the book says 88...? It will sit there idling happily all day just wont rev well, it has a new barrel and piston (am6 engine and dellorto phbn12 carb. Choke on/off makes little difference Starting to think it might be electrical as the bike had been left out in the rain before I got it and every electrical connection was corroded, all connections gone through and fixed now though...new ht lead and plug cap. Exhaust isn't blocked Things I havent tried is the coilpack, reed valve (looks ok in appearance)... Would trying a new carb be a good idea as I can get a used one off ebay fairly cheap, although as i say the carb LOOKS fine, all jets clear, the only thing I did notice is there is a passage that goes into the float chamber with a connection for a pipe on the outside of the carb... not sure if this is supposed to have a pipe on or not? It performs the same way with the pipe open or blocked with a rubber cap... Any help greatly received! Link to comment Share on other sites More sharing options...
dt502001 Posted October 20, 2012 Share Posted October 20, 2012 Sounds like it's starving for fuel,try and fill a spray bottel with gas and spray into the carb as your reving it up. Link to comment Share on other sites More sharing options...
thesickness Posted October 21, 2012 Author Share Posted October 21, 2012 Sounds like it's starving for fuel,try and fill a spray bottel with gas and spray into the carb as your reving it up. I have just taken the carb off and had a look at the reed valve, it looks good. tried spraying some petrol down the throat of the carb while idling, it didn't really do anything. The screw in the middle of the carb that moves the throttle slider works (moving it alters idle speed) but the screw on the back of the carb with the spring on (mixture or volume? ) doesn't seem to do anything,as its revving you can turn that screw any number of times and it doesn't change much at all... revving slowly does not help, it doesn't seem to rev clean to 5/6k then hits the brick wall it revs a bit crappy at all times other than idle... Link to comment Share on other sites More sharing options...
Moderator Airhead Posted October 21, 2012 Moderator Share Posted October 21, 2012 whats it like with choke ON ? It could be an electrical issue though...Have you tried another sparkplug? Link to comment Share on other sites More sharing options...
thesickness Posted October 21, 2012 Author Share Posted October 21, 2012 whats it like with choke ON ? It could be an electrical issue though...Have you tried another sparkplug? The same, no difference.. Link to comment Share on other sites More sharing options...
Moderator Airhead Posted October 21, 2012 Moderator Share Posted October 21, 2012 I asked two Q's , not sure if you are refering to 1, 2 or both? Link to comment Share on other sites More sharing options...
thesickness Posted October 21, 2012 Author Share Posted October 21, 2012 I asked two Q's , not sure if you are refering to 1, 2 or both? Sorry, choke on or off no difference and no I haven't tried another sparkplug although the problem was there right from the top end rebuild I did with a new plug at that point.. Link to comment Share on other sites More sharing options...
Moderator Airhead Posted October 21, 2012 Moderator Share Posted October 21, 2012 Try one anyway, that symptom is so familiar I had that a lot as a kid with field bikes...anyway they're only a few £'s so nothing to lose. Still sounds electrical ignition related to me Link to comment Share on other sites More sharing options...
Harshana Posted October 22, 2012 Share Posted October 22, 2012 If nothing wrong with the carb. Better to check the another spark plug. it sounds like something wrong in the sparking or else there might be a block of air. however better to check with another plug... Link to comment Share on other sites More sharing options...
dt502001 Posted October 22, 2012 Share Posted October 22, 2012 +1 on the spark plug ,,but ididn't sugest to spray fuel in while ideling but to spray as you reving it up..to check that it wasn't a lack of fuel at higher rpms to eliminate the carb being the problem Link to comment Share on other sites More sharing options...
pyro plim Posted October 22, 2012 Share Posted October 22, 2012 Sounds like a duff spark plug.I have had brand new ones be no good.Have you tried gapping the plug both ways.Wider/narrower. Link to comment Share on other sites More sharing options...
thesickness Posted October 23, 2012 Author Share Posted October 23, 2012 +1 on the spark plug ,,but ididn't sugest to spray fuel in while ideling but to spray as you reving it up..to check that it wasn't a lack of fuel at higher rpms to eliminate the carb being the problem Yeah sorry, I did spray fuel during idling and accelerating - no difference.. Sounds like a duff spark plug.I have had brand new ones be no good.Have you tried gapping the plug both ways.Wider/narrower. Changed the spark plug for a brand new un, still the same, grrr!! next move is probably try the coilpack then back to carb, Link to comment Share on other sites More sharing options...
Moderator Airhead Posted October 23, 2012 Moderator Share Posted October 23, 2012 Yeah sorry, I did spray fuel during idling and accelerating - no difference.. Changed the spark plug for a brand new un, still the same, grrr!! next move is probably try the coilpack then back to carb, yeah, the HT cap next, then the coil Link to comment Share on other sites More sharing options...
thesickness Posted October 23, 2012 Author Share Posted October 23, 2012 yeah, the HT cap next, then the coil daft question but can the caps go bad? Visually it looks perfect but I guess it is a cheap process of elimination.. Link to comment Share on other sites More sharing options...
YPVS TONE Posted October 24, 2012 Share Posted October 24, 2012 Defineatly sounds like an ignition problem like plug,cap or coil. Trying running the engine when its dark or in low light and look around the plug, cap and coil area and see if you can see if it's sparking or shorting anywhere. Link to comment Share on other sites More sharing options...
thesickness Posted October 28, 2012 Author Share Posted October 28, 2012 Some further investigation today, I tested the wires from the stator looking for 2 readings as per manual: Red /white -pick up 120ohms approx (yes correct reading, about 121ohms) green/ white-loading coil 730ohms approx (NOTHING- NO READING!!) Could anyone explain this in laymans terms, could this be my running problem? Link to comment Share on other sites More sharing options...
Moderator Airhead Posted October 28, 2012 Moderator Share Posted October 28, 2012 yes of course it could, what does 'no reading' mean? Older style meter need to be switched to the 2K Ohms setting in order to measure 730 Ohms Link to comment Share on other sites More sharing options...
thesickness Posted October 28, 2012 Author Share Posted October 28, 2012 yes of course it could, what does 'no reading' mean? Older style meter need to be switched to the 2K Ohms setting in order to measure 730 Ohms Sorry, thanks for your time, electrics are my weakness. and not great on multimeter OK so on pickup (red/white) I get 116 multimeter set to 200- within manual spec and on loading coil (green/ white) I get 665 multimeter set on 2000 - out of manual spec which is 730 +- 35 Link to comment Share on other sites More sharing options...
Moderator Airhead Posted October 28, 2012 Moderator Share Posted October 28, 2012 well then out of spec suggests you need a new one, Link to comment Share on other sites More sharing options...
dt502001 Posted October 28, 2012 Share Posted October 28, 2012 just a quick ? did you zero the test leads on the mulitmeter before taking your readings,,,I have seen the test leads on the meter lie big time and you get false readings.Easly the diff your getting. Link to comment Share on other sites More sharing options...
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