Motorcycle Repair: Resurrecting my Yamaha Maxim 650, yamaha maxim 650, thanks in advance

Question
Hey Falcon, thanks in advance for being here =) Now -

I have a 1983 Yamaha Maxim 650 with 14,000 miles on it that I bought in good running shape back in 1996. I put 8,000 of those miles on it, took care of it, changed the oil and filter regularly, and eagerly learned what little I know about engines doing minor repairs on it.

The only problem I ever had with it was that the carburetor ‘acted a little gummy' and the bike sometimes needed time to warm up before giving it gas or the engine would cough and gutter out. You could yank the throttle and race the engine roughly but giving it just a little gas would kill it, like it was cutting off the supply. After a full warm up the bike would act just fine. I completely cleaned out the carb, though that didn't seem to solve it. That annoyance may or may not have anything to do with the bike dying, but I add it in case it could be related. .

One day I was riding to work and the engine started to sound rough in spurts and dropping power, almost like it was on the edge of running out of gas. I knew it had plenty of gas. The engine dipped down in power, and I had just enough time to get it over to the side of the road before it died on me. I tried turning it over but it just cranked. I looked down and realized that a small pool of oil was spreading from what looked like the oil overflow tub that comes out of the air filter box. Probably about a cup or two worth spread across the ground. I towed it home and there it has sat for the last six months.

I've decided It's time to break out the tools and get it back in operation myself if it's worth fixing. I just don't know what's wrong with it or where to start diagnosing it.  I don't mind cracking it open and learning more about engines, but I certainly don't know enough about them yet to troubleshoot this.  If the bike is too far gone, Id rather spend the money and time on a newer used bike.

Thanks for your help. Sincerely,

Just call me Chris or Wolf. =)


Answer
Hey Wolf.
 Start by getting the repair manual out and go over the scheduled maintainance.  Make sure that everything is correct (valves, timing, cam chain tension, etc.).  The carbs will need to be completely cleaned as well as replacing the fuel in the tank.

That oil leak is critical.  Something is causing enough pressure to blow oil out of the case and into the air box.  On the XJ550 that I used to have, one thing that always caused that was overfilling the oil, while another thing that would cause that would be an unusually dirty air filter.

Check the wiring for shorts and bad connections and see if there is a problem with the clutch switch and/or the sidestand cutoff switch.  That could be contributing to the problem.  I normally just bypass that switch anyway.

Check the things that I have mentioned and see if it starts up and runs.  Then double-check the synchro.  That won't be the crux of the problem, but it may make a small contribution to it.

Let me know what you find.
Good luck.
FALCON