Hi everyone,

I wonder if I could seek ssome help please. I've recently bought a second hand 04 290. Yesterday I went riding for a long period of time & found me fighting with the bike a little. It wasn't until another sherco of similar vintage to mine arrived at the trials park that I noticed the difference. 

I will try to explain the issue. 

When I start up the bike the tick over is revving away then when I blip the throttle it is quiet high revving & it seems really high. The other bike riding around didn't sound anything like mine it seemed to sound a lot more relaxed & smoother. 

I found a video on YouTube of a guy messing with the screws on the carb. I've given those a few turns to the same setting he did but it's not really done a great deal to change the way my bike is revving. 

Any suggestions would be a great help.

 

Thanks Si

Sight unseen it sounds like your engine is running lean, check the position of the cir-clip on the main jet needle, that setting is easy to alter and makes a significant difference to how rich or lean the carburetor operates, one screw adjusts the low speed fuel circuit and the two adjustments together might need attention, idle adjustment screw is in addition to the 2 fuel/air ratio adjustments and all it does is push the throttle slide open slightly.

Carburetor cleaning particularly in the emulsion tube which is located in close proximity to the main jet needle is critical, or that can also make the machine will run lean.

Reed valve is another service item that can cause your machine to sound different than one that is operating correctly, make sure the reed valves are closing sufficiently to be light tight when you inspect them.  ... remove and hold the reed cage assembly up to sunlight and if you see light shine past the reeds you found a problem.

 

Thanks for the advice, I'll take a look at it this week & see what's what. 

 

Si