Guest Posted March 10, 2011 Posted March 10, 2011 Hi guys, I have a Gilera SC 125, which some may already know is exactly the same mechanically as the Derbi GPR 125 racing. I have heard that it runs on the same engine as the Yamaha TZR and DT-R if this is needed. Basically, my bike used to quite easily hit 75mph but for some reason, recently I have been lucky to even hit 70mph. The most I've had out of it, bearing in mind I dont thrash it, is 81mph, but now, I am sure that I couldnt even get close to that. I thought it might be something to do with my chain as it was very loose, so I got that tightened, but the effect was minimal. I know this is a very general question but if anyone may have suggestions, please let me know! Thanks alot!ADDITIONALLY: my bikes tick-over isnt great, if I start it and give it no throttle it will tick over fine, but as soon as I engage the throttle whatsoever, the revs drop and the bike will eventually cut out. Also, when I'm out riding, if I let the revs drop from say 6k in first gear to the point of needing to pull the clutch in, the bike will often cut out as well. By this time, the bike is surely warm enough to tick over so if anyone has any ideas? cheers! Quote
cypek Posted March 10, 2011 Posted March 10, 2011 From what I've heard its the old 2t Derbis that used Yamaha engines. This new ones does not.When did you service your bike last time? Change oil, filters and spark plug and it may help And check condition of the old spark plug for any issues with fuelling.Any additional advice will come from someone with more knowledge Quote
Guest Posted March 10, 2011 Posted March 10, 2011 Thanks for the reply, to be honest, I think it's about time I serviced it properly, the spark plug is slightly corroded so I may have to get a new one. Cheers anyway! And btw, my bike is a 2 stroke Quote
Fozzie Posted March 10, 2011 Posted March 10, 2011 Gilera and the Derbi were the exact same, so same engines even if replicas.It sounds like it needs a dose of new fuel with some cleaner in there to flush out the carb, a new iridium spark plug and...Check your tyre pressures!!! If they have dropped then it wont go as fast anymore so get it checked. Quote
Martyc Posted March 10, 2011 Posted March 10, 2011 Checked the compression? Could be rebuild time Quote
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