High HC in Right Cylinder

[ihaxs650]

My stock 1980 Yamaha XS650 special is getting more than 6 times the amount of HC in the right cylinder vs the left cylinder. I am getting a popping at idle and on deceleration from the right cylinder only. I believe this is causing the right cylinder to operate at a higher temperature than normal. I am looking at a clutch drag issue when hot and I believe engine temperature is part of the problem.

The 1st picture is the right cylinder at idle. Notice the HC at 4023 ppm.

The 2 picture is of the left cylinder at idle.

Notice the HC at 666 ppm. At 3000 rpm the HC is relatively the same for both cylinders, I am using the left cylinder as the baseline and I interpret the right cylinder has a lean-misfire. Most likely too much air.

Here are the numbers from my FT500 Ascot a thumper.

Notice the CO number of around 9%. This mixture was achieved with a jetting kit from Thumper Stuff. This upgrade was an absolute must for the thumper.

My goal is to resolve the popping issue from the right cylinder " the lean-misfire'" and than fix the co issue as I believe they are separate issues.

I would appreciate any comments or help in the popping from the right cylinder. The bike seems to idle just fine besides the popping but my hearing is not that good. I have not started any other diagnostics.

 

[ihaxs650]

I think I found the answer to the popping from the right cylinder. Pulled the plugs and the right plug is oil fouled and the left looks normal. Check for vacuum leaks by the carb boots and found none. Next I ran a compression test and came up with RC 50 PSI and LC 105 PSI. Looks like both cylinders are below specification. I did not think that low compression would cause high HC. I did not think this bike would run on such low compression and the difference between the cylinders are mind boggling. Now I am wondering if low compression will cause that cylinder too run hotter than normal?

 

[weekendrider]

What is HC?

 

[5twins]

With 50 PSI I don't think it much matters, lol. My best guess is hydrocarbon count. I'd say put the fancy sniffer away and grab the wrenches.

 

[ihaxs650]

What is HC?

Weekendrider, HC is short for Hydrocarbon or un-burnt fuel getting out to the exhaust. Basically wasted gasoline..

 

[ihaxs650]

With 50 PSI I don't think it much matters, lol. My best guess is hydrocarbon count. I'd say put the fancy sniffer away and grab the wrenches.

5twins, Yea, have to agree with you, the bike has over 30k so I cannot complain.