Are my valve seats are deteriorating?

[Darkstar]

I'm going through oil fast. When I bought this it had 7000 miles on it and it was losing 0.15ml per mile. At 12,000 I was losing 1.2ml. Now at 17,500 it's at 1.4ml. I have no visible leaks on the exterior of the engine or beneath, and the compression is in spec. There's no smoke from the exhaust, or soot on the muffler, and no smoke at start up. I ride it very hard and get 45-50mpg. It's at the point now where if I go for a long (500 mile) ride I have to bring a whole bottle of oil with me. Exhaust valve shims were super low when I replaced them over the winter, so maybe they got burnt before that?

- How do I test valve seat sealing?
- How much would it cost for me to replace them? Need valve compressor and grinding compound, anything else?
- How long would it take me?
- Can I do it on the bike?  I dont have a garage

[The Buddha]

Usually the unknown oil disappearance happens at the rings.
The usual cause is because the bike over heated at one point in its life. Not hot enough to damage anything, but hot enough to cause leakage past the rings.
You might as well put guide seals and cut a 3 angle job when you're pulling the head.
And no cant be done with engine in the frame and cant be done without a covered nice and dry work space.

Cool.
Buddha.

[mr72]

Usually the unknown oil disappearance happens at the rings.
The usual cause is because the bike over heated at one point in its life. Not hot enough to damage anything, but hot enough to cause leakage past the rings.

Yeah that's because the oil control ring gets stuck in the groove.

You might as well put guide seals and cut a 3 angle job when you're pulling the head.
And no cant be done with engine in the frame and cant be done without a covered nice and dry work space.

The shop that did my top end rebuild left the engine mounted in the frame. Pull the head, pull the jug, not impossible, right?

[The Buddha]

You can do it, mainly by pulling the studs that hold the cyls and head on. You take off the valve cover and the camshafts and you take off the nuts off the studs and put a pair of locking jam nuts on and tighten them against each other and unscrew the bottom one pulling the stud with it. Doable, but it is bad for the motor. You're wearing out aluminum threads in the case that Suzuki never intended you to remove.
Ofcourse, if you did it carefully and only 1 time in the life of the bike - wont matter much.
Cool.
Buddha.

[mr72]

Ofcourse, if you did it carefully and only 1 time in the life of the bike - wont matter much.

Well certainly this will be the only time it gets done on this bike while I am the owner.

[Darkstar]

You might as well put guide seals and cut a 3 angle job when you're pulling the head.
And no cant be done with engine in the frame and cant be done without a covered nice and dry work space.

Weird, compression for both cylinders is 140psi...in spec. And the bike pulls like a champ. How many more miles do you think I can ride before risking a major breakdown?

[mr72]

If it's oil control rings then it will not likely ever cause a breakdown and also will not affect compression.

If the compression is good then just ride it and keep adding oil. IMHO. If you get tired of adding oil you can hire out a top end rebuild. There may come a time when the oil burning accelerates a lot and then you will wind up rebuilding because it fouls the plugs and you can't ride it a day without putting a quart of oil in it.

The fact that the oil consumption has increased may be alarming. I'd want to get to the bottom of why. An overheating event would cause a sudden increase in oil consumption that probably wouldn't change much after that. A progressive oil consumption problem may indicate bad rings. Re-check that compression. Are you revving higher? Accelerating harder? Riding with more engine load? Is the compression getting worse at the same rate as the oil consumption increase? Maybe the "ride it very hard" is why it's burning more oil. Maybe you rode it less hard 5K miles ago and the difference between your 1.4L/1k miles and 1.2L/1k at 12K miles is just riding style.

For even the most ambitious do-it-yourselfers, a top-end rebuild is something you generally pay someone else to do.

[Darkstar]

A progressive oil consumption problem may indicate bad rings. Re-check that compression. Are you revving higher? Accelerating harder?

Indeed. I was getting comfortable with it in the beginning, but now I spend more time in the 6000-9000rpm range, racing around like a knucklehead. I'll check compression again and also try riding easier to see if it eats less oil like before. Local shop is quoting $800 for top end rebuild, ugh. Any way it could be carbon build up? Ive heard of people trying Techron

[The Buddha]

Yea Just keep oil level filled, I was down to 300 miles per qt and never had an issue.
Cool.
Buddha.

[Darkstar]

I was down to 300 miles per qt and never had an issue.

that's a relief, thanks man

[J_Walker]

my bike eats oil.. I thought all GS's did this.. belly of the beast with air cooled engines...

[Darkstar]

my bike eats oil.. I thought all GS's did this.. belly of the beast with air cooled engines...

curious, how much?

[gsJack]

My first thought upon reading your first post above was you never really know how many miles are on a used vehicle you purchase.  Here are a couple of my posts on oil consuption up to 100k miles on my GSs.  They definetly use more oil than the 4 Hondas I had before the 2 GSs.  By the way, my 02 GS had 140 psi compression in both cylinders at 100k miles.

http://gstwins.com/gsboard/index.php?topic=65707.msg788021#msg788021

http://gstwins.com/gsboard/index.php?topic=65516.msg784949#msg784949

[mr72]

my bike eats oil.. I thought all GS's did this..

Mine doesn't. Hasn't burned a drop as far as the dipstick can tell in about 1100 miles (since the rebuild).

I ride it pretty conservatively and did just have the top end rebuilt.

[Atesz792]

I was down to 300 miles per qt and never had an issue.

that's a relief, thanks man

Just read my signature
Also, IIRC Buddha used something like straight 60 grade in that particular bike.
I would be interested in startup temps though...

[J_Walker]

my bike eats oil.. I thought all GS's did this.. belly of the beast with air cooled engines...

curious, how much?

Before the valve head gasket started seeping. about 1 QT every 2k miles.
After the valve head gasket started seeping. about 1.5 QT every 2k miles.

[Darkstar]

are you talking about the large head gasket, or the multiple o-ring gaskets beneath?

[HPP8140]

I've had many GS & they eventually eat oil with miles, especially anything prolonged over 7k rpm.

[J_Walker]

are you talking about the large head gasket, or the multiple o-ring gaskets beneath?

the big rubbery one at the top. I think its the only "big rubbery" gasket up top, rest are the paper like ones, or the metal one [actual head gasket]

[Darkstar]

rubbery

you've got me thinking that maybe i have an oil leak that i havent considered. i mean i dont have any smoke so where the hell is the oil going? maybe its leaking out of a gasket and burning off slowly on the front grill, or dripping out of the oil cooler when its under pressure and then onto the pavement, so i never see it?