Slight smoking - valve guide seals??

[11Rider]

Hi guys, my 79 XS1100SF has only about 8k miles on it. Yet when you start it up after it's sat for a while I get a good amount of smoke out of the left pipe. Doesn't seem to matter if it's been on the center or sidestand. Doesn't use any measureable amount of oil that I can tell and once it's warmed up the smoke is gone. Any tests I can do to determine what the cause is?

[bikerphil]

Your valve seals are probably toast, common for a low mile bike, they get brittle. Smoke on startup is a tell tale sign. The head has to come off for replacement.

[11Rider]

I was hoping not to hear that, but I suspected it. In your opinion, should I just leave it as is, or go for it? I'm very mechanically inclined but never took an engine like that apart. Just wondering what your opinion is - thank you!

[bikerphil]

It won't hurt anything running it that way just as long as you keep your eye on the oil level. I ran my motor with bad valve seals for a while and it didn't really use much oil until I hit the mountain roads and ran it really hard. Long story short, my oil level dropped too low and I damaged the crank bearings. It's your call weather to change them now or later, like I said, keep a close watch on the oil level.

[11Rider]

OK thank you

[skids]

If it is a valve seal problem, once the bike is warmed-up, when you let off the throttle, that is when it would pull oil and smoke.

[11Rider]

Thanks for that tip - I'll check it out

[TopCatGr58]

Hey Rider,

You can also try some rubber oil seal conditioner you can get at the local auto parts store/Walmart....put it in the oil, its supposed to help soften the hardened rubber parts, and can help them seal better, less smoke, less burned oil. YMMV

Yeah, the replacement process is a bit daunting, having to pull the head on a dual overhead cam assembly. With only 8K on the engine, would hate to have to pull it apart just for that!

T.C.

[James England]

If you do actually change the seals (and to me, it hardly seems worth it at this stage, if you're not using loads of oil), then make sure you buy Viton stem seals and not the rubbery ones. They cost slightly more but they take much longer to degrade.

I did my Honda GL1000 stem seals and didn't have to take the heads off. I used a valve spring compressor which had little claws on it and gripped the spring, then comressed it. However, I'm not sure if it would work on the XS1100 as the springs are a tight-ish fit .... then again, it just might do the job; the arms on the compressor are slim. You need to stop the valve from dropping and I just used plastic pipe pushed into the cylinder, all coiled round and loads of it. Then I used a telescopic magnet to pull out the valve collets. It was a bit of a fiddle but much easier than taking the heads off.

[11Rider]

Thank you for all your tips - I'm taking them all into account I always thought the seal conditioner thing was a hoax but if you say it's worth a try... Any downside to it such as affecting lubricating qualities of the oil??

[MPittma100]

Valve Seals

I will advise that the right fix is to replace the stem seals. Would be a good idea to run a compression and cylinder leakage test prior to take down. This will tell you what you need to know to do to the head if more than seals are needed.

Then pull the head and have a machine shop rework it if the valves/seats need to be reconditioned. A knowledgeable machine shop will adjust the valve lash during the assembly process. They will need your cams and cam bearing caps along with the head to do so. You can replace the seals yourself (with the right tools) if that is all that is required.

Even though you are showing low mileage, it still has the 30+ year wear on it. Meaning a possibility of a lot of sitting without running or a lot of engine hours without mileage.

MP

[MPittma100]

Oil Additives

Thank you for all your tips - I'm taking them all into account I always thought the seal conditioner thing was a hoax but if you say it's worth a try... Any downside to it such as affecting lubricating qualities of the oil??

Lucas makes an oil treatment. They also make a treatment specifically (for seals) addressing oil leaks.

They claim that the additive will not affect the lubricating properties of your oil. I used it once for an oil leak, but further repair was needed.

MP

[11Rider]

Thanks again for all the advise