Backfiring from left side, exhaust smoking w/videos

[stanleyipkis]

Hi All,

Hoping to get some thoughts, I just acquired this 1980 XS650 and it appears this baby requires some tuneups. Any thoughts on why i would be backfiring from the left side, the exhaust also appears to be smoking from the right side after a quick run around the block.

I presume the smoking is from a valve seal leak on the right cylinder. Maybe the backfiring is caused from insufficient fuel. It smells lean.

I plan on doing a valve adjustment once I get my pma and pamco ignition in. Any thoughts, tips, advice is greatly appreciated.


MIGHT WANT TO TURN YOUR SPEAKERS DOWN FIRST!!!

 

[NONclow]

I would adjust valves first. Try and fix popping/smoke problems before installing new parts, you could create more problems. Have you synced/cleaned carbs? What do the spark plugs look like?

Gotta love kickstarting w/ flip flops

 

[stanleyipkis]

good advice,


left

right

 

[stanleyipkis]

Have not sync'd cleaned carbs. I will do that in the morning.

 

[NONclow]

My eyes might be out of calibration but it looks like the left plug has more of a gap than the right, maybe misfiring Try gapping them to .028", then attack those carbs

 

[NONclow]

Also with the smoke from the right pipe are you sure the popping is coming from the left? Try searching "dead cylinder method" in the top left google bar. That should help isolate which cyl it is. Just make sure the plug wire is attatched to the plug and grounded to the engine or frame. That dual output coil voltage has to go somewhere, and since both plugs fire at the same time, the plug not on the power stroke fires on the exhaust stroke igniting unburnt fuel. I'm still suspecting carbs.

Good luck

 

[stanleyipkis]

Did valve adjustment and cam chain tensioner last week. Bike responds better and valve ticks are gone.

Carbs initially were out of sync. I dialed them in as best as I could using the manometer method and the sync screw in between. My carbs are bs34's.

Still have backfiring and the smoking is still present. Upon close inspect it appears that my boots are starting to wear and new ones are on the itinerary. I will also be taking the carbs off this weekend and cleaning them out. Up-jetting will be in order. Any other ideas before I start pulling off my carbs and putting my orders in?

 

[doctavee]

you may just need to do a rebuild. its not going to get any better. just finished mine, it was doing the same but only worse and then started spitting oil out the left header

 

[Lasper01]

Maybe try changing the pod filters to uni filters..

 

[Brian902]

Try a short run with no air filters to see if they are causing issues. Pods are recommended by the carb experts.
I personally like the all foam version rather than the type with a hard plastic insert in the end.
Like these.

 

[stanleyipkis]

Thank you for your suggestions everyone, I really appreciate it. I haven't had much time to work on my bike because I've been out of town on the weekends(only time I get to work on my bike). I pulled off the filters today and pulled the enrichment lever(for cold starts, I'm assuming this is what it's called), kicked her over and noticed that there was no backfire. But once I pushed the enrichment lever back in the backfire resumes.

Also noticed both filters were cracked so those are gone. From the looks of it, it appears need a carburetor makeover. I presume that since I took the filters off and the bike appears to run fine in enrichment mode there is a problem with the air/fuel mixture ratio. Now where do I begin?

New filters are on the list, so are carb boots, new jets are in order. Any other suggestions?

I will be uploading a video shortly, it's dark out so bear with me.

 

[scabber]

I would take the carbs off and clean them. The carb guide tells you the best method. Float levels need to be set properly. Fix the carbs and it might quit smoking.

 

[NONclow]

Sounds like a clogged pilot circuit. Time for some rebuild kits, some aerosol carb cleaner (or better yet a chem dip and solvent rinse), and an air compressor with rubber tipped blow gun.

Time for the fun stuff!

 

[jasonslackisrad]

had the same issue. sucked some crap into the carb after the bike hadn't been run for a year.

clean the carbs.

problem solved.