1100G low compression, burns oil.

[Redman]

[[[ NOTE: Thread started May 2020. THen project stalled out.
Project resumed Sept 2021, Post #31. ]]]

82 GS1100GK, 83thousand miles. I have had since 2005.



Last few years has been burning oil. Oil turn black in about 150 miles. I would get reports of puffing on shifting (seals, right?) and would also get reports on blowing smoke under acceleration (rings, right?). For long trips, I would need to carry oil. TO Brown County (~300 miles) would need to top back off half or 2/3rd quart when got there. Uses more at high speed or if lots of acceleration.

Oh, speaking of acceleration, it hasn't had much capacity for such anyway.

A couple years ago I checked compression, was in the range of 110 to 120, and improve some with a bit of oil. I have known that have needed to do something. But between not really being a gear head, and not wanting to work in cold garage in winter (not hot humid garage in summer), and not wanting to have it down during riding time, and just general hesitancy, I havent done anything. Well, now that have the RT here, this spring, if ever, is the time to do it. Pretty much knowing that I am not well experienced at this, dont really have all the tools, and will be needing guidance from the fine folk here.

Checked compression again, and was even lower yet.
90, 100, 90, 85 (and that 85 pumped up slower).
With a little oil: 135, 170, 200, 140 (the 200 had maybe too much oil, shot out while checking an other)

With out have a complete plan, I got started.

[Redman]

As Jake said to Elwood: "Is that serious ? ?"

#4 piston




Was looking at the burnt on oil all four piston (and head), and it took me a while to notice that didnt have the burnt on oil on #4 piston exhaust valve recess. (#2 has a slight hint of same)

#4 exhaust valve

Looking around the edge of the valve, I dont see any deformation, but maybe cant see what need to see.
Is some jagged edges where the bakeon oil has broken off, but edge of valve itself seem round all the way around.

I dont think I can depress valve myself to remove valve for further inspection.
(which you might say is further evidence that I should not be doing this myslef.)


What anybody think?
Maybe chunk of burnt on oil broke off and held valve open a little bit, recently, but is gone now......

Maybe valve is not operating smoothly and not returning quick enough sometimes.......

??

I dont recall any unusall loss of power, nor clatter or any such last fall.

Other thing. In 2006 right after I got the bike, I had head off. Every bolt seemed greatly overtourqued. THree or 4 of the cam cap bolts snapped as soon as touched them it seemed. I took head to machine shop (non existent now) and they got them out, but had to drill out, and put in those helicoli spriral things. And they changed out the seals (I gave them a Vesrah set, yah, I know, before you guys told me better) and they lapped the valves some. Well, now, on my dissassembly, two of those bolts, part of the helicoil came out on the bolt and it looked pretty smooth.
And two exhaust bolts came out kinda hard.

(I have chatted with a couple of the fine GSR folks, and have something of a tentative plan. Am posting here for further discussion of options. And so you can snicker at me.)

Oh, and all the cylinder walls looked shiny smooth. No scratches. No crosshatch hone marks like I have seen in other engines. As hard as I try, I can not feel any groove nor "wow" near the top, like folks have said could detect if cyclinder wall wear.

[Rich82GS750TZ]

Dave, sorry no help with you valve issue. But when I first saw your pics, I thought your were showing a perfectly cylindrical hole through your piston. Was contemplating how that was even possible.

[Burque73]

That's good timing to have your BMW at home now, Dave. Hey, speaking of timing?? Piston-valve contact!! Did you happen to check timing before pulling the head off.

I hadn't heard about those troubles in your head before. Pun intended. Glad you have this experience, but sad you have to experience it again.

[Redman]

T. . . . . . . Piston-valve contact!! Did you happen to check timing before pulling the head off.....

Check cam timing ?
No. Wasnt thinking of any such thing.
Was thinking of ring & cylinder wear, and not knowing much about how to check whatever, or if need oversize anything or what.

[prichmon]

Low compression issue you have already found. The compression check and putting oil in the cylinders defined you need at least rings at least.

Valve spring compressors run 20-40+. I believe the GS uses 30mm adapter for the springs. I'm getting ready to do a GS650 head and hope to have a spring compressor tomorrow.

Its a little late but a leak down test would have been helpful to help isolate any other problems. Specifically shooting air into the cylinders at TDC would define several valve/head problems. You could bolt the head back down depending on the condition of the gasket attempt to perform the test. However the gasket may not seal very well.

A poor option to test the sealing of the valves is to turn the head upside down and pour water in the combustion chambers. If it leaks out you have an issue.

I would pull the jug and start taking measurements and inspecting all parts.

At bare minimum you need the following:
Rings and hone of the block.
Cylinder head and parts cleaned for inspection.
top end gasket set.

Once everything is cleaned and inspected you know better if you need the more expensive parts such as pistons, bore job, valves, cam or a replacement head. Follow the manual step by step and you will be fine.

The one picture shows valve to piston contact. I would be suspect of that valve in particular. Have you done your valve adjustments as stated by the manuals?

If you're not comfortable doing the inspection and head work I'd take them to a trusted local machine shop. You'll pay a little more but it works out to cheap insurance for the repair.

Good luck

Rich

[allojohn]

I have little to add here but I'm going to enjoy you getting stuck into this Dave, all ahead full!

[bwringer]

That's a pretty normal amount of crusties for an air-cooled engine that's been burning oil. Even that chunk in the middle of that valve is not unusual.

But yeah, that piston/valve contact ain't right. Get the valves out, and roll that suspect valve across a table; you'll see pretty quickly whether it's bent.

The cause of the contact is hard to say. If it's just one, it wasn't the timing.

My guess is that the valve guide seals departed the realm of sealing long ago and the accumulated burned oil turned into a primeval tar and made that valve stick in the guide. (This happens to lawn mowers all the time.)

In that case, the valve might have just gotten tapped back into place and may not even be bent, and it's quite doubtful that the head is damaged. Hard to tell with all the krusty krusties how hard that contact was. The valve guides might be a little worn; this might be a good candidate for a good machine shop to measure the guides. Installing new guides is possible (requires deep-frying the head, though; you have to heat it up in hot oil), but it's also possible to have a machine shop knurl and ream the inside of the guides.

So I would say soldier on with disassembly and see whatchya got.

Looks like new pistons are NLA in any size, but you can get rings in standard and .05mm oversize.

Overall, if I had to guess, the bores are knackered at 84K. I probably wouldn't bother measuring, since oversize pistons aren't easily available. (Yes, I'm aware there's probably some bony-fingered gnome somewhere in Michigan who will make a set of custom pistons in exchange for a firstborn and a few limbs... and your firstborn is probably way too busy to serve as currency anyway.)

Your best/cheapest option will very likely be to haunt fleaBay and CrackList (and the GSR Parts Wanted) for a much fresher set of jugs and pistons, or maybe even pull a whole 1100G/GK engine or bike out of a barn somewhere. You don't need a title, just a carcass. Might get all kinds of other useful stuff too.

Shouldn't be too hard to find something with 25K or less. Give it a light flex-hone, install a fresh set of standard rings, and it should chooch just fine for many years to come.

[Burque73]

Check cam timing ?
No. Wasnt thinking of any such thing.
Was thinking of ring & cylinder wear, and not knowing much about how to check whatever, or if need oversize anything or what.

Yeah, I figured that would be a logical place to lay the blame for contact there. Maybe not...

[dorkburger]

Dave, I'm assuming that you're considering options / a way forward at the moment.
Exdirtbiker on here had an engine for sale a while back. I dont recall if was an 1000 or 1100. It was a G though. Might be worth a check.

[Buffalo Bill]

No biggie. Disappointing to see valve contact with piston, but fixable. New springs are available too.
If you give the head to a good shop, mo e-z.
Tracking down a NOS head gasket, possible. I found one on ebay this winter.
Shipping delays caused by downsized staff, meh…that's a bummer. I'm waiting for a tach cable to be shipped.

[GregT]

As Bwringer has said, if it's just one valve it isn't the timing.

This sort of thing - an odd valve hitting the piston - is common on older OHC cars. Jags and Alfas do it if the car has sat for a while.
The valve which is open when the engine is stopped sticks in the guide - and gets smacked when the engine is restarted.

Sometimes you get lucky and don't bend the valve - but generally all that's seen is lower than normal compression.
One or more valves not seating correctly.

The guide and seat should be undamaged. Springs I'd expect to be within spec. Just replace whichever valves won't clean up straight and the stem seals.

[Redman]

. . . . . . . . . . . . .

I did find a OEM NOS head gasket for $40 , shipped, the other day.

Opps, might arrive on our anniversary here.
Opps, I thought I learnt not to let that happen.

[Steve]

I keep telling you Dave, you need to talk Mrs. Redman into moving your anniversary date.

.

[Redman]

Well, with the 84k miles, and the 2 suspect exhaust bolt holes, and 2 or more cam cap bolt holes with the helicoil repairs stripped out, and maybe a damaged valve...... I am leaning heavy toward replacement head and cylinders (eh....pistons) from a much lower mileage donor.
I have a good line on such from a fine GSR member.
I will want to have donor head rebuilt with new seals (maybe find local shop, or send to other fine GSR member).

But will be a couple weeks before can make the trip to donor site.

THe donor engine might possibly be in a rolling frame.
Anybody need a rolling frame (has title), 82 GS1100G . . . ?