75 XS650 ignition problems

[awd92talontsi]

I'm new to this site so my apologies if this is in the wrong board.

I picked up a 650 for 20 bones last year and got it running. problem is the right cylinder cuts out on for decent periods of time. leading to plug fouling.

I have replaced the plugs, wires, and coils. the points appear to be within spec. the only thing i see left in the ignition system is the condenser. i'm not sure what exactly this does. since there is only one of them i can guess is that its working cuz the other cylinder isnt having any problems.

any ideas?

thanks
bryan

[pgg]

awd you might have to shift attention to the right hand carb.

[John]

Condenser

Bryan, all the condenser does is prevent the points from arcing when they open, by storing electricity, preventing arcing across the points. That wouldn't affect just one cylinder though.. The carb float may bet set too high, it may have mis matched jetting, the main jet needle may be set too high, causing flooding on one side. How about the cylinder compression on that particular hole?

[awd92talontsi]

i just rebuilt the carbs and cleaned them out um-teen times. however i will check the float height this weekend. and get new a few more plugs so i can mess with things. i made sure the floats float and the needle valves are also new.

the jets that are in there are all stock sized with the needle at leanest position. i still need to work at tuning the mixture screw.

bryan

[strom]

I saw a great big XS 650 site somewhere... maybe they can help. But welcome anyway and post some pics of the bike...
I love old horrors like that... dunno why...
my (guess why) ex always told me that I bring junk into the house... I like my old junk XS...

LP

[randy]

My guess is a sticky exhaust valve. HTH.

Randy

[awd92talontsi]

i havent been able to find a good discussion board for the 650 yet. thats why i tried you guys. aside from a compression test how do i tell if an exhaust valve is stuck?

bryan

[randy]

I would run it until the problem shows up, and then immediately do the compression test. That will show the status of the cylinder sealing, but it won't identify wich valve may be stuck slightly open. To do that, you need to send compressed air down the spark plug hole and listen for the hiss. It will be either at the muffler or the carb.

Randy

[mitch]

650 sites

hope these sites help you out
www.yamaha650society.com
www.650central.com
www.xs650parts.com
thats just a few there are others , ......................MITCH

[nashville_bill]

Try this link and then click on the "Technical Questions" email link to ask the 650 experts.

http://www.yamaha650society.com/

[sksxs1100]

you forgot www.mikesxs.com for parts

[nashville_bill]

I wish there was a MikesXS for XS11 parts. Do you have the new catalog?

[awd92talontsi]

yea Mikes XS is awesome. i bought some parts from him last year and as soon as school gets out and i get to working i will buy some more.

How alike were the 650/1100's? i know the 400/650's shared alot of the same components but havent heard much about the 1100.

yesterday, when i was playing with the bike the other cylinder was having the same problems instead of the right one. when it got warmed up though it ran like a champ and i put about 5 miles on it.

also in neutral at mid throttle it was popping all over the place. does this mean lean / raise needles?

thank again for your help

bryan

[randy]

If the problem is showing up on both cylinders, it sounds like carb problems. Or bad gas?? First replace the gas, then I'd give the carbs a thorough cleaning, replace worn parts and float adjustment.

randy

[nashville_bill]

While you are checking things, check the carb boots. I had to replace the ones on my '81 XS650. The idle was all over the place with a lot of popping and poor running when it was cold.