Some help/advice?

Hi there

Am looking for some advice on what on earth is wrong with my bike? He has just been serviced, MOt'd etc and the front brake assembly replaced as the master cylinder was broken. Now when rev'ing engine to change up a gear he is very jerky, for a moment won't pull forward causing a kind of kangaroo hopping type motion.

Also noticed when riding with my partner on another bike that my speedo is reading worng, says I'm going faster than I really am about 50% of the time anf the rest of the time seems to read ok..

Went back to guy who serviced it yesterday and he adjusted carburetor but this hasn't helped.

Any further advise as to what could cause this?

As Cats partner this is my 2p worth, cant comment on the kangaroo jump as its hard to see in my mirrors, but there is definitely a speedo issue. Going up to 55-60 out of southwick Cat reckons she was seeing 60 on the speedo but my 'dero was leaving her for dead. My best estimate was that she was doing 40-45 mph at best. Also her bike stalled before she stopped pulling into the layby the other side of Rode. Engine sounds okay on tickover but I'm no expert so dont take my word for it!

Speedo drive refitted properly if they had the front off to do the brakes, as for kangeroo'ng reving to change up? Try closing the throttle on the way up and can it open on down changes. Do you ever ghost the gears? Check clutch cable/lever is adjusted correct and i'd check the carb floats aren't stuck and plugs are in right. Could be something was disturbed during the recent work and not put back. Get garage to put it right

what bike is it?

That would have been helpful wouldn't it! What a thing to miss.

Its a Sym 125.

Have actually had some help from a friend's father and bike is running much smoother now so am hoping we've solved issue. He took carburator apart, cleaned it and checked air and oil filters, also adjusted air/fuel ratio as it wasn't set quite right and he seems better again.

The speedo still not quite right so am gonna have to take that to service place again but will be able to get there now!

Thanks for the assist, will refer back if it turns out to not be sorted!

sounded like a block carb jet

Was it layed up before the MOT??? The speedo could be either the cable or the instrument. The fuelling sounds like carburation, but check the spark is healthy as well.