Bought myself a yb 100 as a project it runs lovely engine is sweet, cleaned the carb fitted a new plug and cap also cleaned the air filter. the only isue I have is that the idle screw seems to do nothing at all, what are the settings for the carb aswell if anyone can help it would be apreciated. cheers

Have you not wondered why you have'nt had a reply yet?

yessss

its the X Factor

Ohh BTW weber you seem to have completely bypassed doing an intro, yeah it's not compulsary and yeah it's good manners and all that

Nope that was your generation LOL melinumem

Does the carb slide move up down when you turn the idle screw ? If I remember the YB100 was a similar setup to the FS1E both using the disc valve engine with the carb on the RH side of the engine. I remember the FS1E had a pin that went through the carb slide and located in the idle screw with a tiny spilt pin, so as you turned the idle screw it raised or lowered the carb slide thus altering the tickover speed. If the slide doesn't move when you turn the idle screw maybe the pin or locating split pin is missing. You can see the pin,spilt pin and idle screw as items 15,16 and 23 as shown here

https://www.yamahamotorcyclespares.co.uk/genuineparts/9010/5/yamaha%20yb100%2082-87/carburetor?uID=0

Hope this helps.

Tony