Motorcycle Repair/76 cb 200t
i have gotten the bike running after sitting for 25 years. i think i have a problem with the carb slides not set right or main jet needle in the wrong position. i can get it to idle but when i rev it it is slow to come back down to idle. ideas? thanks, Ray.
If you did a thorough job cleaning the carburetors, so that there is no cause for the slides to stick, then the slow to idle issue is generally traced to other areas:
Air leaks at the intake manifolds (gaskets/o-rings)
Spark advancer weights/springs are gummed up.
You can spray a little carb cleaner or WD40 or even soapy water around the intake manifold areas when the engine is running to see if that affects the idle speed/quality.
The spark advancer is bolted to the end of the camshaft, requiring removal of the points plate to allow access to the advancer unit. Snap the weights out or turn the end of the point cam by hand and see if it returns back quickly and fully. When bikes go into deep storage, often the advancer point cam grease hardens and turns to varnish, causing the point cam function to be slow. Remove the advancer assembly from the end of the camshaft and carefully disassemble the point cam from the base. Clean and lubricate with hi-temp grease, then reinstall. Clean the ignition point contact faces thoroughly and install the plate assembly. Turn the engine over until the points are at the widest opening possible, then measure the gap. It should be about .014-.016" Use point cam grease on the points cam to lubricate the ignition point rubbing block.
Once that gap is established, turn the engine over until the points just OPEN. Use a cheap 12v test light to determine when they open and make sure that the points open when the indicator mark aligns at the F mark on the rotor.
Another thing to check is the throttle cable, itself, to make sure that it isn't kinked or mis-routed, causing the slides to lift when the handlebars are turned to full lock. And, finally, the carb slides are Right and Left side specific. When installed, the slide cutaway at the bottom edge of the slide should face outwards towards the air filters. If you put them in backwards the engine will run rich and fuel foul the spark plugs very quickly.
I'll assume that you have adjusted the valves to .002" cold on both intake and exhaust, when the piston is on their respective compression strokes (they switch sides each revolution).
I hope this gives you some ideas of where to look to solve the problem.