alanmh99 Posted June 16, 2011 Share Posted June 16, 2011 I bought my son a moved for his birthday and it just doesn't run right. It seems to go well for a day and then its performance goes down with every trip. We have looked at the clutch shoes, replaced the rollers with new, replaced the belt with new replaced the battery and spark plug with new. Every time its the same. Good improvement for first trip and then down hill with every trip. We are not bothered with top end performance we just want steady acceleration from start and consistent speed. There is a sports exhaust on it but l don't think this is entirely at fault. Also it does drink fuel like a demon. Can anyone give us some pointers please. Link to comment Share on other sites More sharing options...
alanmh99 Posted June 16, 2011 Author Share Posted June 16, 2011 Forgot to mention, usual top speed about 40 but now runs at 20 on the level an 10 mph on a incline. Link to comment Share on other sites More sharing options...
NEV Posted June 16, 2011 Share Posted June 16, 2011 Forgot to mention, usual top speed about 40 but now runs at 20 on the level an 10 mph on a incline. Theres a number of factors that could be at fault here Alan, but I'll start with two, you say you changed the rollers, but did you change the rollers weights to suit the sports exhaust? did you buy the sports exhaust or was it on when you bought it? I ask as usually, new aftermarket sports exhausts generally come with a set of rollers to suit that particular set up. Another thing to check is the main jet in the carb, you say it drinks petrol, it could be down to the wrong size jet, you'll need to get a workshop manual, and find out the original size, and as a rule of thumb, you go up in sizes of 2, i.e if the original main jet is say 80 then you should be fitting an 82 or 84, then you do what is called a plug chop,this is when you run the bike for say 5 mins, then take out and check the plug's colour, (black means too rich ,white means too lean,) Another thing you need to be carefull with when it comes to fitting power/sports exhausts, is that they are put on to aid performance and do add a couple of Horse Power, and this is construed as modifying the bike, something your sons insurance company would check on, in the event of a claim, so be carefull there, although if you want to gain a tad more out of the bike there is a large washer at the back of the variator, that you can "forget" to put back on, the next time you take the variator off to change rollers.Hope this helps. Link to comment Share on other sites More sharing options...
alanmh99 Posted June 16, 2011 Author Share Posted June 16, 2011 Thanks for the in depth reply. I appreciate the time it must have took. Link to comment Share on other sites More sharing options...
Moderator Airhead Posted June 16, 2011 Moderator Share Posted June 16, 2011 It's not as daft as it may sound but chack the brakes are not binding, can you feel any undue heat after a ride? Link to comment Share on other sites More sharing options...
alanmh99 Posted June 17, 2011 Author Share Posted June 17, 2011 Good point. Never even crossed my mind even though my car suffered that exact problem. Link to comment Share on other sites More sharing options...
alanmh99 Posted June 21, 2011 Author Share Posted June 21, 2011 I have now replaced the exhaust to standard and rollers to standard and the engine is still "bogged down". Also I have tightened play in throttle cable, checked for free spinning wheels, checked the plug which looks right and all that's left is the carb. What should l be doing to this? I have a jet from the yamaha dealers. Is there a way of adjusting externally before taking apart? Is there anything I'm missing????? Link to comment Share on other sites More sharing options...
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