Hi guys.
I bought a 1982 CB 750 FB last week.
It has a 4 into 1 Motad exhaust system, and it runs pretty badly.
I have to whack the idle speed up to about 1500 to stop it cutting out. but even then it fluctuates. The bike will pull cleanly from a stand still, but sometimes it bogs in the midrange, other times it pulls all the way to an indicated 110 MPH on the clocks and only stutters at that speed (could be hitting the limiter).
Now I've spent many an hour tuning a two stroke carb (on a Aprilia RS125 which many of you US guys probably won't know of because it wasn't officially imported), but I want to quickly sort these carbs out and get as close to fault resolution before I start meticulously trying different jets and needle heights. I want a base setting.
I believe this erratic behaviour is probably caused by an air leak, but I sprayed some deodorant around the carbs and the idle speed didn't change.
Basically, in 28 year old carbs on a bike that has seemingly only done 17,000 miles, what do I need to replace straight away without even going in the carbs to have a look?
Cheers.
