Clogged jets - or air leaks?
The net result is the same.
It might sound like he has clogged jets, but the reality is that all the rubber pieces on a 30+ year old bike are going to be rotten.
All dried out, broken, cracked & crumbling... everything rubber, possibly plastic too.
Specifically check the carburetor mounts holding the carbs on the motor, and also the mounts behind the carbs connecting them to the airbox.
You really need to take the carbs off to do this correctly, but what you often find is giant cracks in the rubber manifolds.
These cannot be seen until the rubber is bent/stretched/deformed... then it's like "hey lookit that - that's trashed".
Sometimes these old parts will even disintegrate into crumbles while trying to remove them!
Any tiniest air leak between the carb and the motor will sabotage the carbs venturi effect (the speeding-up of the mixture, generating low pressure above the needle jet, and also of course the idle circuit).
So in this scenario it's much more likely air is getting in than fuel is being blocked - but it could easily be both.
You should (as mentioned) rebuild the carbs anyway, as they are full of rubber and plastic pieces, and your floats probably don't anymore.
Quick fix - hose all rubber manifold parts down with armor all, and hose down carbs with WD40.
Tighten up all rubber manifold clamps (if they're not siezed solid).
Check and re-tension all carb fittings, ie. the screw-top of old carbs where the cable goes into the carb and connects to the slide.
Try and find any potential air leaks and put them out of business!
Your carbs also may or may not have a thin rubber accelerator-pump diaphragm, which is probably no longer intact & pumping.
Old bikes are great! You just have to replace all the original rubber parts on them...
Thanks Chris
