I am trying to help a coworker with his 83 45 Magna.
It has the symptoms of carbs badly out of sync, won't idle down, eratic idle, idles down till it quits.
I put my carb sticks on it and the engine doesn't produce enough vacuum to pull the mercury out of the reservoir.
I checked the intake boot clamps, tightened them, did a compression test, 120 lbs on all 4.
Spark at all plugs, opened each bowl drain and got fuel out.
Even if the carb jets are plugged the engine is still pumping air so I would think I should get a vacuum reading.
Is it possible that the carb diaphragms are leaking causing the low vacuum reading?
Also, I have heard of the cam wear problems on these engines
Is there any particular mileage where this shows up?
Any ideas/suggestions would be appreciated.
George Krumholz
I am going to take a wild guess and say the bike has sat for a while???
The idle jets are clogged and will need to be removed and cleaned. Then I bet majority of the problems will go away.
Some carb sync tools have a plug in the vent to the mercury tubes. Some have a short hose that is pushed onto a plug molded into the body of the sync tool.
What RPM is it idling at? I agree with Greg that it likely has some plugged jets. Try bringing the idle up and see if you get a vacuum reading. If not, something in your measurement system is not working.
Cam wear issues are hit an miss on these bikes. Some will run for the life of the bike and never have an issue, others will have it within 10k miles. I you work on the carbs, pull the valve covers at the same time and check them out. If there is no issue, then it is time to decide if your buddy wants to spend the money on an oiling kit or cross his fingers. If he is going to keep the bike for awhile, the oiling mod is cheap insurance.
Good luck.