Valve guide job - do I need to do them all?

[Ola]

My bike is burning a bit of oil, reading through other threads it seems like it matches the symptoms of poor valve guides or their oil seals. I'll be pulling the head to fix some broken exhaust bolts (and replace with studs and capped nuts), might as well get more done while I'm in there!

But the guides are $14 each and 16 of them + 16 oil seals will do a dent in my meager summer touring budget. Is there a way to see if some are bad, and then replace only those?

While I'm in there, should I pull the cylinders and look at the rings? Compression is good, although slightly lower on #1. Sticking or poor oil rings could also be the root cause, but I'm worried about getting in over my head.

Symptoms:
Consumes 1 quart pr 1000 miles, approx. Varies with how much my wrist is twising.
Smokes slightly from the left pipe when cold.
No plugs look oiled.

[tkent02]

You most likely only need the valve stem seals, unless the bike has very high mileage.
The old seals get hard and sometimes they don't seal so well. Unless it is visibly smoking I wouldn't even worry about it.

[mike_of_bbg]

But the guides are $14 each and 16 of them + 16 oil seals will do a dent in my meager summer touring budget. Is there a way to see if some are bad, and then replace only those?

First, welcome. Do you have the factory service manual? If not, you can probably find it here:

http://members.dslextreme.com/users/bikecliff/

There's probably a procedure to check valve guide tolerance involving a dial gauge. Then you can measure, and know. That's if you can borrow or have such a tool already. Else you'll just end up spending as much as the guides cost. Personally I agree with Tkent about just replacing the valve seals. But then that's just my opinion, and I'm cheap...

While I'm in there, should I pull the cylinders and look at the rings? Compression is good, although slightly lower on #1. Sticking or poor oil rings could also be the root cause, but I'm worried about getting in over my head.

Yes, you should pull the cylinders if you remove the head. Primarily because you can never be sure if you have disturbed your base gasket when removing the head. It would be a shame to pay for new gaskets, slap it all back together, then have the base leak and have to do it all over again. It IS possible to replace the valve stem seals with the head on the bike. There was a recent thread about that, which the search function would probably turn up. It's easier on the 16V motors, apparently.

Symptoms:
Consumes 1 quart pr 1000 miles, approx. Varies with how much my wrist is twising.

It IS a 25-year-old air-cooled bike, after all.

Wait - Quarts? Miles? Norway? What's going on here?????

Smokes slightly from the left pipe when cold.
No plugs look oiled.

Blue smoke? Smoking at start-up could also be fuel accumulating because your carb needle valves or your petcock is having issues.

Personally I'd go after replacing the valve stem seals with the head on and see if things improve.

[Ola]

Thanks!

I had a user before, it got eaten by a purge I think. And yes, quarts and miles - in my internet using years I've learned to cater to the crowd, who are helpful Americans and only some of them think liters and kilometers are a communist conspiracy.

It's great news that I can get the seal out without taking the head off (that sentence sounds like a killer whale complaint call), but since I am (most likely) removing the head anyway to have a machine shop drill out some broken exhaust bolts - including the bits of bolt extractor still stuck in there - I might as well get some more things done. Decoking the chambers and exhaust ports would probably also not hurt.

But yeah, 16 valve guide oil seals, a tool to compress the spring and a magnet/tweezer to catch the cotter bits, that should do it right?

And the smoke is white and very wispy, I think you might be right about fuel issues. I have some other fuelling/breathing problems, the bike bogs down at WOT in the mid range, so I'll make the downtime count and do a proper inspection of the carbs as well.

[chuck hahn]

Heres my opinion...Youre gonna have the cam off anyways, so whats a few more minutes and bucks for the OTHER seals..besides doing them all removes any doubts if it still smokes and burns oil. At least youll know all the seals are new.

[Ola]

It's not going to be cheap on my meager budget, the guides are $14 each and I need 16 of them...plus tools for extracting and reaming according to the manual. But a fair point nonetheless, since I'm in there I might as well get my money's worth.

[tkent02]

Except you almost certainly do not need the guides, only stem seals.
Cheap stuff.

[bbjumper]

I feel your pain

First of all you live in one of the most beautiful places on the planet. Last time I was there was about 20 years ago but I have always wanted to go back.

Back to business, my 850 had very similar issues, high oil consumption with good compression. What I found was bad valve stem seals and stuck oil control rings. I really wouldn't be too concerned about valve guides, as mentioned earlier they are very durable, once you get the cams and valve springs off you will be able to get an idea if you have an issue just by checking for movement of the valve stem in the head. If they rock back and forth at all you have a problem and should check measurements.

I honed the cylinder, replaced the rings, new OEM gaskets and seals and reassembled. I went from about a qt. per 1k to almost zero consumption, can easily go between oil changes without adding any. It is an air cooled engine and if you like twisting the throttle they will use a little.

Definitely a job you could handle with basic tools, a good machine shop can do all the head clean up and measurements, re-cut the valve seats if needed and hone the cylinder.

My GS runs like a new bike, lots of power and very smooth.

I look at it as an investment, this one is a keeper.

Cheers

[sk843143]

On a car engine you wood be right to replace the gides......on thes bike engines the valves are verry well set up........they do not wear.......so no need trip replace

[Ola]

You're right, it's a wonderful country for riding bikes in! With the current gas prices, it's ok to have something that's slightly frugal as well. Is there any way of knowing my oil rings are bad without taking the cylinders off? And if they are bad, do I need oversize rings or will regular sizes do? Doing the piston rings is still on the too-scary side of overhaul planning so I haven't read that much up on it...

[mike_of_bbg]

Well, like I said before, if you're going to take the head off, you'd better do the base, which means pulling off the cylinders. There should be some ring measurements you can take in the service manual.

[Ola]

You're right, as long as I am removing the head I might as well go all the way. Oh god. Not today though. Need to read.

[bbjumper]

You're right, it's a wonderful country for riding bikes in! With the current gas prices, it's ok to have something that's slightly frugal as well. Is there any way of knowing my oil rings are bad without taking the cylinders off? And if they are bad, do I need oversize rings or will regular sizes do? Doing the piston rings is still on the too-scary side of overhaul planning so I haven't read that much up on it...

First, don't be intimidated by this, you have a great resource here at GSR. On BassCliff's site in addition to a ton of info there is a link to the factory service manual. It's all pretty straight forward and not rocket science. take your time, handle it one step at a time.

You will have the head off to address the valve stem seals, as far a knowing the condition of the oil rings it's pretty much academic. Unless you have a ton of miles on it or there is other damage like scoring of the cylinders and pistons they should be fine, you should be able to hone the cylinders and install new standard size rings. Once you have it apart you can take a look, inspect and measure to know for sure.

In my case I have a friend that is experienced in these and he was able to get me to a machine shop that was knowledgeable and qualified to work on the head and check everything out.

Cheers

[Ola]

I have about 108 000 km on it now, have owned it since 78 000. I don't know if rings have been done before. If it's any help, here are some shots of the exhaust ports from when I snapped some exhaust bolts last spring.

From 1 to 4:









I don't remember my compression numbers but 2-4 were close in the 140s - 150s with 1 slightly lower, might have been 130 or so. I don't remember double checking my technique but I do remember not bothering to as the results were all good. I suppose good top rings is fine, but does not rule out poor oil rings.

For general interest, I also mounted a bar:

Test fit:



Improved ergos ALOT!



Also dropped the forks so the tops are flush with the triple tree. Slightly slower steering, but improved feel.

[Ola]

And what the heck, some riding pics as well.











Last one if the farthest away from home I've been on a bike, Tuscany, Italy.


edit: more pics on my Flickr if interested: http://www.flickr.com/photos/olamarvin/