QuestionQUESTION: hey, i have a 1987 honda cr125, fresh rebuild just cleaned the carb.. but the thing is a little hard to start, and once it does start it will run for a few seconds then it will pop or back fired and then stall out and will only start on 1/4 throttle.. all jets are clear, i check the reeds, on the bottom one there is a little bit of space between the reed block and bottom reed itself, and i am running some old 2 stroke motor oil..( i didnt know if old 2stroke oil would hurt anything) anyways im just at a loss of what the problem could be. any help would be great.. the motor is bored .30 and have a procircit pipe, im pretty sure the needle is on the third clip and the main jet is a 165
ANSWER: Aaron, The main jet may be right check the pilot or slow jet,the stock size is #60. The reeds may still be the problem. Some of the types of reed can be flipped over to seal up prior to installation. As they wear they curl out loosing the sealing edge. If they need replaced try Boyesen Pro-Rev reeds they are a little more like about $60.00. They are carbon fiber and composite and offer a wider power band. As far as the oil,as long as it is a good quality brand it should give good protection. The backfire could be the reed valve may not close all the way and allow the crankcase pressure to back up throught the carb and disrupt the vacuum flow.
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QUESTION: Once again thank you for the help that you have provided so far. i went ahead and replaced the reeds. The bike wants to start on first kick each time but still does not rev and i still have have a bad pop or back fire and the bike will stall out. i went ahead and put fresh fuel, and kloz oil(40:1) in the bike along with a new ngk br8es plug. and still no change. the specs on all of my carb stuff is as followed. Slide is a #60, Needle is R-1468N(3rd clip), The main jet is a 165 and the other jet is a #60.Timing?
ANSWER: Aaron,At least we are on the right track. Now this part may get ugly. This could be a bad stator problem. Not all stators are a hard fail and easy to diagnose. Some weak stators will allow the bike to run but not rev up or run poorly above idle. If you are sure the carb is clean then the next step is the stator and pickup trigger coil. The part number for the stator is 31100-KS6-701.
The CDI can give the same symptoms but is harder to test and these parts are not cheap.
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QUESTION: Thanks, well i went ahead and pulled the stator cover off, then the fly wheel. The flywheel was at tdc and the stator plate seemed to be dead center in the adjustment.. made me wonder if the timing needed to be advanced any? after staring at the stator assembly for a few mins it seemed that the pick up looked to be angled a little funny. sure enough the mount on which the pick up sits on was broke. also the pickup its self seemed to be ground down some.. after comparing the stator assembly with the one in my manual it also seemed smaller than it should be.( had the same problem with the coil.) jo redneck replaced my stock coil with one off of a small 4stroke 80 dirt bike. do you think that pickup being a little off could be the problem?
AnswerAaron, Its a good possibility.The pick up could have not been gapped at .010" from the raised lug on the flywheel and it hit and ground the pickup coil down and knocked it out of whack. If it does pick up the lug it may not fire when its supposed to. If you can get the pickup back and mounted like its supposed to be use a non magnetic feeler gauge like brass to set the gap. Try around 010" it should clear and the coil may work but the spark could be weak to fire the plug.
