1983 XS650 Heritage Special - New to Yamaha's

[dstroy12]

Hey Guys!

Just picked up a super mint XS650 Heritage Special, 10K miles and the chrome is just gorgeous. I wanted to make a nice hardtail bobber out of it, but im not sure after picking it up... I mean its gorgeous, and I see from this forum, they are sorta rare... Its got progressive shocks and all sorts of add ons.

My first question is... while the bike started and ran idle for a little, there was a fuel shut off switch that was closed, when I opened it the right carb dumped gas everywhere... I knew right there it needed a nice carb cleaning (im a pro at that coming from old ironheads. LOL)

After reinstalling everything, I fired her up and everything was cool, rode to the gas station and back and then she died, and wont keep idle. I adjusted the idle screw but at a certain point instead on idling, it starts reving, and I mean like 4Krpm reving. when I turn the screw back down it low idles and then dies.

I read alot about syncing and am still a little lost... Also only one of my intake manifold vacuum barbs connects to the tank. the onther one is blind plugged. is that right??? seems like it would make the vacuum uneven...

Thanks!

And please let me know what you think I should do, Bob it, or not...

 

[xjwmx]

only one barb connects to the petcock and the other gets capped off. Normal. Sounds like you could have an air leak in the intake. Make sure the carbs are seated properly and the clamps are tight. Spray carb cleaner around and see if the revs go down to detect the leak.

The gas valve you're talking about isn't stock so I don't know what it is. But pouring gas out means a problem with the float valve. Hanging, dirty, worn out. Could be the o-ring around the float valve seat. Usually worn out and loose. Also check the valve clearances. Too tight an exhaust valve caused the rev symptom on a single cyl Yama I had.

If you like it as is, don't bob it. If you like to fiddle more than ride, then bob it, otherwise ride it. When you're finished bobbing it, it's not going to be some masterpiece so why bother.

 

[dstroy12]

Yeah it was agunked up float that was making the carb dump gas. As for the weird idle I did more investigating... it starts up fine. No choke. Runs for a while then starts dying off... if I give it throttle it revs and responds normally but when the throttle is released the engine stays at the rpm and sorta hangs for a second then lowers down... ideas?

 

[xjwmx]

^The hanging is another symptom of air leaking, from what I've read. Never experienced it myself.

First thing, adjust the valves, .003 and .006, with the engine cold. It might fix you. Needs to be done before carb work anyway.