Smoking exhaust

[rps1116]

Hi everyone,
I’m new here and would like to ask a question and hopefully someone will answer. I recently bought a1977 XS650 and when I bought it the bike didn’t smoke a lot at all. I had it my basement for about two and a half months and didn’t start it at all. When I got it out the other day and started it it was smoking out of the exhaust pretty bad. I started messing with the idling screw and air mixture screws to see if it would change but it didn’t. I put sea foam in my tank and added fresh gas but it is still smoking. I’ve read that sea foam can cause the smoke but I’m not sure about that. So my question is what would be making it smoke so much. I forgot to add that the spark plugs smelled like gasoline so it sounds like it’s running rich but the smoke is white. Any advice is greatly appreciated

 

[nj1639]

Tell us a bit about yourself and any mechanical skills and motorcycle experience you may have, it does help to know your aptitude for any replies you may get. Also pics! Pics are like candy to this crowd.......and like a wise man once said "We don't care if you ride a toilet, show us some pics!"

What's your compression?
Do you have a manual?
Welcome aboard!

 

[YamadudeXS650C]

Welcome!

Make sure to run the bike on the road for 50 miles before identifying any particular symptoms.
Only check the plugs after a good hard run and turn off the bike a few hundred yards from your home at a point where you were ay about 3,000 rpm, not idle. coast into your driveway.
Check your oil for gas contamination. Smell the dipstick and the hole where it goes into. Thinned out oil will get past your rings more easily.


.

 

[Its been a long time]

White smoke is usually unburned fuel so I agree, sounds like far too rich mixture.

 

[Lou_TX]

Howdy from Texas and welcome to the club!
Yooze fom Joizy? Which eeexit?

You said you added fresh fuel. But did you drain the old one? If not, it's not a bad idea. And it's easy to do with petcocks and fuel lines etc.
That way you can easily eliminate bad/contaminated fuel.

When she runs and smokes, does the smoke feel wet or greasy? Wet is steam, grease is oil.
Does she still smoke if you let her warm up to operating temperature?

One step at at time. Let us know what you find.

 

[rps1116]

Howdy from Texas and welcome to the club!
Yooze fom Joizy? Which eeexit?

You said you added fresh fuel. But did you drain the old one? If not, it's not a bad idea. And it's easy to do with petcocks and fuel lines etc.
That way you can easily eliminate bad/contaminated fuel.

When she runs and smokes, does the smoke feel wet or greasy? Wet is steam, grease is oil.
Does she still smoke if you let her warm up to operating temperature?

One step at at time. Let us know what you find.

Hi Lou

Thanks for the reply. I did not drain the older gas before I added new gas. However I did empty my tank this weekend and pulled the carbs to see if there was any varnish but they were as clean as can be which didn’t surprise me because thePO said he just put them on in November. My one concern was the pilot jet might have been too big but when I disassembled it and looked they were 12.5 by the way I’m running Mikuni VM34mm Round Slide carbs. When I put my hand by the exhaust it didn’t seem wet or oily but there was an awful lot of black soot which is why I’m thinking it’s running rich. I will be putting new fuel in the tank today and fingers crossed I won’t see as much smoke. I’ll keep you posted on how I make out. Thanks again I’m glad I reached out and you guys responded.

Rich

 

[Lou_TX]

Thanks for the update. Definitely let us know what you se with fresh fuel in an empty tank. You don't know what additives the PO might have poured in.
Soot in the exhaust indicates rich mixture but it could be just from hard acceleration, hard to tell if it's form idle.
There are plenty of threads here about tuning the carbs properly for correct mixture. And they are pretty easy to follow.
Let us know what you find.

 

[rps1116]

Tell us a bit about yourself and any mechanical skills and motorcycle experience you may have, it does help to know your aptitude for any replies you may get. Also pics! Pics are like candy to this crowd.......and like a wise man once said "We don't care if you ride a toilet, show us some pics!"

What's your compression?
Do you have a manual?
Welcome aboard!

Thank you all for the quick responses & thank you for the welcome. I have not been able to check the compression because I don’t have a compression gauge which I will get some time this week. My mechanical skills are mostly on cars and very little on motorcycles. I am a machinist so

Tell us a bit about yourself and any mechanical skills and motorcycle experience you may have, it does help to know your aptitude for any replies you may get. Also pics! Pics are like candy to this crowd.......and like a wise man once said "We don't care if you ride a toilet, show us some pics!"

What's your compression?
Do you have a manual?
Welcome aboard!

Hi NJ1639,

Thank you for replying to this thread. I am a machinist and started in the trade in my very early twenties because I wanted to build a bike and make parts for it. Most of my mechanical abilities come from working on cars and a few bikes but nothing crazy. I have not done a compression test yet because I don’t have the gage to do it with. I will try and get one this week. I have a video of the bike running and me trying to adjust the air screw and idler screw. I will try and post it ASAP. I drained the tank yesterday and cleaned the carbs and replaced the plugs. I will get gas tomorrow and fill the tank and then start it and see what happens. I will keep everyone posted on how it goes fingers crossed.

Thanks for the update. Definitely let us know what you se with fresh fuel in an empty tank. You don't know what additives the PO might have poured in.
Soot in the exhaust indicates rich mixture but it could be just from hard acceleration, hard to tell if it's form idle.
There are plenty of threads here about tuning the carbs properly for correct mixture. And they are pretty easy to follow.
Let us know what you find.

I’ll do that. The one thing I forgot to mention was I put a lot of sea foam in the tank and I’ve read that that stuff can cause smoke issues. I’ve used it on my older cars when I was younger so I figured what the hell but now I’m regretting that. I’m heading out to get fuel now. I have a video of me trying to adjust the carbs and you can see the smoke but for some reason I can’t upload it. In the meantime here’s some pictures of it As soon as I figure out how to upload the video I’ll send it to you can see what I’m talking about. Thanks again

Rich

 

[rps1116]

Hey guys

So I added fresh fuel and that seemed to cure the smoke issue I was having. I want to thank you all for your advice and will keep you all posted on how it’s riding. I wanted to take it out when I added the new gas but as I was adjusting my throttle cable the brass adjuster on top of the carburetor snapped in half. I made six new ones today at work so I should be good to go. I plan to go out after work today. Fingers crossed all will be well on my ride. Thanks again everyone I absolutely appreciate you guys

Rich

 

[Melnic]

Glad your all good

Condensation / moisture buildup in the exhaust cause it was sitting?


when it was smoking was the Smoke white or black?

 

[Lou_TX]

Hey guys

So I added fresh fuel and that seemed to cure the smoke issue I was having. I want to thank you all for your advice and will keep you all posted on how it’s riding. I wanted to take it out when I added the new gas but as I was adjusting my throttle cable the brass adjuster on top of the carburetor snapped in half. I made six new ones today at work so I should be good to go. I plan to go out after work today. Fingers crossed all will be well on my ride. Thanks again everyone I absolutely appreciate you guys

Rich

Thanks for the follow-up, glad at least one thing is solved for now.

The one thing I forgot to mention was I put a lot of sea foam in the tank and I’ve read that that stuff can cause smoke issues.

Oh that is absolutely true, a can of SeaFoam in a small MC fuel tank will create white smoke. Which is why I initially asked if you had drained the tank because I know people add a lot of winter stabilizers etc to their fuel and we wanted to test with untainted fuel to get good data.

Again, thanks for the follow-up and good luck with the other problems.