pazif Posted August 16, 2009 Share Posted August 16, 2009 hello, im new to this site so if ive posted this in the roung place im sorry. I have a Yamaha SR 125cc. the problem ive been racking my brains over should be simple but is not. the bike wont start of the starter butten. bumps as easy as you like. i checked the carb/fuel lines. there clean used carb cleaner to flush the carbs. ive changed the settings on the air screw and the ideal speed screw. when the bike is running it sound perfect. when i check the spark plug its completly cotted in carbon, think black. i clean the SP then put it back in tri again, 5 mins l8r its cotted again. ive been told it could be the oil rings or the valve stem seils. anying esle i could tri befor i buy the top end casgits?? thnx for any help. Link to comment Share on other sites More sharing options...
jordanscycles Posted August 17, 2009 Share Posted August 17, 2009 you say you messed with the air screw, now the air screw would be behind the slide, but a fuel mixture screw is in front of the slide (engine side). So if you unscrewed that you are letting in more fuel then necessary. I would bottom out the screw then back if off 1 and a quarter turns. That's where it should be in general, and will make the bike run leaner, since you're too rich. Also be careful screwing in the screw to bottom it out, if you do it too hard itll break the needle down inside, so just be gentle. good luck Link to comment Share on other sites More sharing options...
changaz Posted August 17, 2009 Share Posted August 17, 2009 agreed, too much juice! adjust idle mixture screw, give sparky a clean. kick it over a few times with the plug out to clear some petrol out, then put it in and fire away. i know in a car its all the way in and out 2 1/2 turns, but as jordancycles said try 1 1/2 and then change it as necessary. u will be able to tell by the quality of the idle. Link to comment Share on other sites More sharing options...
pazif Posted August 19, 2009 Author Share Posted August 19, 2009 thanx for the advice. i followed the book when i changed the mixture screws. but i've still got the problem. i fount that if i turn the fuel tap of when i stop and let it ideal for a wile it starts a lil easyer the next time. i was thinking of lowering the float in the carb a little bit. i just cant figger out y it would start better on a half empty carb?? Link to comment Share on other sites More sharing options...
amanda pullan Posted September 8, 2009 Share Posted September 8, 2009 hi there i was just wondering if you could help me out, i also have the SR 125cc 2001 but seemed to have lost the owners manual and i need it for the model number for the alternator and also the rectifier as my bike wont start up even if i have the battery is fully charged. could you please help me out, with how to get a new owners manual. thanks very much amanda x Link to comment Share on other sites More sharing options...
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