mcferreira100 Posted October 13, 2013 Share Posted October 13, 2013 Bike going great from 5000rpm upwards..below that its sputtering and not idling. Wondering now about the oil/fuel mixture. Its running on the autolube system and someone suggested it may be drowning in oil..so he suggested a hotter plug. I`ve noticed in the manual the oil delivery can be set so wondering if I should fiddle with it. Link to comment Share on other sites More sharing options...
blackhat250 Posted October 13, 2013 Share Posted October 13, 2013 Aye mac" can you not get it to idle by adjusting the idle screw. this lifts the slide, your bother seams to be on the pilot side , get it to idle at 2000 rpm, then screw ther air screw fully home. this should make the engine stummble[ ritch] then we know the pilot is working, next screw the air screw fully out, the revs should rise , this way we know the pilotjet is big enough, Do this and post back,,, Oh what colour is plug,? Link to comment Share on other sites More sharing options...
mcferreira100 Posted October 14, 2013 Author Share Posted October 14, 2013 Screwing airscrew home does not seem to make much difference..but screwing it out does make revs rise. Also took it for a spin with airscrew out and it ran a lot better at low revs..like its not getting enough air with standard setting. Idling weird though..when stopping it idles high for awhile then slowly starts to die..and you can hear its like its not getting enough fuel unless you nurse the throttle. Turning the idle screw seems to have no effect until I`ve made quite a few turns..then idling jumps up or it dies..but no matter what I do with the idle screw, when idling revs always eventually come down till it dies. Plug looks ok I think..it is a new plug. I have just noticed a leak by exhaust manifold..will need a new gasket. Link to comment Share on other sites More sharing options...
Moderator DirtyDT Posted October 14, 2013 Moderator Share Posted October 14, 2013 If setting the carb up correctly doesn't help and the bike revs, when you let the throttle off it keeps high revs and slowly comes down, doesn't idle and tries to die without constant blipping of the throttle. Sounds like classic crank seal issues. Do you know when they were changed last? Link to comment Share on other sites More sharing options...
mcferreira100 Posted October 14, 2013 Author Share Posted October 14, 2013 No idea..probably never. Link to comment Share on other sites More sharing options...
dt502001 Posted October 14, 2013 Share Posted October 14, 2013 Air head went through this with you about checking the crank seal,the plug looks decent colour. For the few bucks it's going to cost to change the crank seals your better off to do it now,better safe than sorry when it blows up from a leaky seal. This will also rule out a faulty seal an alow you to consentrate on the carb alone. and tune it. Paul also did a article about using a wide band 02 sensor to tune his bike,, as your looking to build a few bikes it would be a good investment as you don't have alot of experience in tuning and could swap it from bike to bike Setting up a carb is like tuning a pinao done right it works beautifull but you need a trained ear,you need alot of time and a soild understanding of what your doing when you adjust 1 thing it changes another part of how the carb works,,every bike is set up from the factory to run with the carb for that bike only no 2 bikes run exactly the same., all the settings in the manual are just guide lines.so even if you go buy a new carb dosen't mean it will run right The guys who tune for race teams keep recods of everything air temp humidity altitude and spend 100's of hours on a dyno to prove what they have done works the way they want it to. 1 Link to comment Share on other sites More sharing options...
mcferreira100 Posted October 14, 2013 Author Share Posted October 14, 2013 Yeah I agree, especially 2strokes are not easy to tune and I don`t have enough experience..I should stick to 4stroke bikes. I tried airhead`s test spraying Q20 on the crank seal on the magneto side but don`t seem to note much difference...but the idling is so erratic its difficult to tell. Would both seals need to be changed or can just the magneto side be done? Link to comment Share on other sites More sharing options...
Moderator Airhead Posted October 14, 2013 Moderator Share Posted October 14, 2013 If you've sprayed Q20 and you were good with your aim and it didnt change anything then It's safe to assume the magneto side seal is OK. If the seal on the clutch side is passing then the bike would be smoky and have the erratic idling possibly, this is because it would be burning gearbox oil as well as 2T oil, theres a rough n ready check of that seal also Pour some clear liquid into a jar or a testube would be better still, something like paraffin or white spirit etc put the gearbox breather pipe into this container, start the engine and play around with the throttle and note if any bubbles come from the pipe or if the liquid level drops any (thats why a tube would be best because it doesnt hold much volume) Link to comment Share on other sites More sharing options...
JimR Posted October 18, 2013 Share Posted October 18, 2013 hmmm I had this back in the 70's with a brand new DT175mx, the speedo showed a "row of duck eggs" (zero miles). It turned out to be the carb body (a progression hole blocked) .... back in the day we had to replace the whole carb but perhaps a sonic clean of the body may help Link to comment Share on other sites More sharing options...
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