So i just fixed my fuel lines, and the bike now starts right up, but when it idles or when i pull in the clutch it jumps to 4,000 rpms. i don’t know if it’s a tuning issue or how to fix it

 

Hi

In my experience there's 2 main causes. Firstly vacuum leaks - anywhere extra air is making it to the cylinders will cause the revs to climb. Check Carb boots are sealed and not cracked, and particularly on these bikes the air cut off valve hoses on cyl 1 and 4 as the hose deteriorates and cracks. Often they're on the edge of dying until you remove the carbs and disturb them then suddenly big vacuum leak.

The other main cause is over compensating with the idle control screw when the mixture is weak. So if your pilots are miles out, it won't want to idle so people then turn up the idle to stop it stalling. Then if you blip the throttle it will want to hang up. How many turns out are you?

Also make sure choke/enrichment plungers not stuck open on as this also opens up another air source to the engine which causes revs to sit high.

Regards

​​​​​​​Dan

 

This is weird. And Dan is right. Check the vacuum. But start with something basic first. Loosen your clutch cable and try that. Adjust your idle screw. Does the bike smell like it’s running ritch?

i just finished rebuilding my bike and there are tons of little issues that come and go!

-Denali