fixing no clearance at smallest shim problem

[ntouran]

My right-hand exhaust valve has no clearance with the smallest (2.15 mm) shim. It's been growing fairly rapidly, and my poor bike has very little compression now. I have a 1997 with 30k miles. the other valves mostly stay put, but this one is out of control.

I read in this older post that you can take the cams off and grind down the valve to gain clearance back. Following up on that, I have two questions:

1. How hard would that be? It looks like I'd have to get the cams off, disconnect the exhaust system, and remove the cylinder head to get to the valves. I've only ever gotten the head cover off before! This is my first bike. Is the head going to come off without too much trouble, or are all the bolts going to break or something and force me to shamefully trailer into the shop? Besides, it looks like I need special tools like valve spring compressors? I'm not opposed to getting a few tools and digging in, but I don't want to get in too far over my head.

2. Isn't the valve just going to keep on growing for whatever mysterious reason at the same pace until something goes horribly wrong? Would it be better to replace/rebuild the valve?

The shops in my area (Seattle) are quoting $350 just to get the head off and look for the problem, so I'm feeling rather inspired to do it myself. While I'm in there I might as well just rebuild the whole thing right? Then I'll really be in over my head. I'd be willing to spend something like $500 to get all that done if anyone knows a reasonable shop in the area.

Thanks in advance guys. I really miss compression.

[bobthebiker]

pull the head yourself, and either get another head or rebuild yours.

[BaltimoreGS]

Sounds to me like you might have a burnt valve.  Replacing a valve is a fairly involved undertaking but if you are mechanically inclined I don't think you will have a problem.  Supposedly you can do it with the engine still in the frame but I find it a lot easier to drop the engine out of the bike and sit it on a table to work on.  Good luck   

-Jessie

[commuterdude]

If you need a thinner shim have your 2.15 surface ground a few thousandths thinner maybe.

[kylegod]

ugh this is what im dreading when i do my valves this month. hopefully all goes smooth. That how to video on here, (damn i can remember his name), is amazing and very thorough. So that shed a lot of light on how to do it. I am just having the worst luck ever with this bike so I am just expecting the worst.

[Pigeonroost]

kylegod; you are probably recalling Kerry's valve video.

The valve and maybe the valve seat are burning.  Its not really a fix to simply grind the stem shorter, the burning valve and seat will just errode progressively faster.  Remove the head and have a local auto machine shop restore the seat(s) and fit new vavle(s) as necessary.  Your local Suzuki dealer probably outsources that kind of work to a a machine shop anyway, maybe you can find-out who they use.  Or, there is a member of this forum that seems to take in this kind of work.

prs

[trumpetguy]

Whatever you find, fix it absolutely right the first time.  Don't shortcut, don't do a temporary fix (like grinding on the valve stem), unless you have LOTS of free time and would rather mechanic than ride.  Your time is the most valuable thing there is.   Spend the money, do it right, save your time, and RIDE.

[BaltimoreGS]

Whatever you find, fix it absolutely right the first time.  Don't shortcut, don't do a temporary fix (like grinding on the valve stem), unless you have LOTS of free time and would rather mechanic than ride.  Your time is the most valuable thing there is.   Spend the money, do it right, save your time, and RIDE.

+1

-Jessie

[bobthebiker]

Whatever you find, fix it absolutely right the first time.  Don't shortcut, don't do a temporary fix (like grinding on the valve stem), unless you have LOTS of free time and would rather mechanic than ride.  Your time is the most valuable thing there is.   Spend the money, do it right, save your time, and RIDE.

AMEN.   

there is no excuse for poor quality fixes when the right one is cheaper and much more long term.

[gsJack]

ntouran, when my 97 GS got down to a minimum 215 exhaust valve shim as it was approaching 80k miles on the clock I was thinking of a thinner shim for a fix as I posted in the old thread you linked above but the 97 GS was totalled before I got to it and replaced with my current 02 GS.  I'm surprised you got to a 215 exhaust shim on your 97 at 30k miles, I made my first shim change at 39.4k miles on the 97 and my first shim change at 31.2k miles on my 02 GS.  Your valve must have been run tight for a long time.

By tabulating my valve check results for both bikes I discovered that one exhaust valve that was set on the tight side of the tolerance on each bike was burning fast and the other exhaust valve and both intake valves with greater clearance were not.  I decided to increase my exhaust valve clearance on the 02 to more than .001-.003" spec and have had no further exhaust shim changes in almost 40k miles since the last change.  Shims are now all still between 250 and 265 and I expect them to go to 100k miles that way.

Thinking changes over time and if I had your 97 now I would pull the head and replace that 215 valve.  I would lap that new valve into the seat to see how the seat was and to see if a suitable size shim would result and go with it that way if it looked OK.  Grinding the seats just makes the shim size smaller requiring grinding the valve shim to get back to a mid size shim.

I had an exhaust valve break on the 02 GS at about 21k miles starting it one freezing morning caused by a bucket that was fit too tight at the factory.  I pulled the head and lapped in a new exhaust valve and have over 50k more trouble free miles since then.

http://img.photobucket.com/albums/v443/jcp8832/valveclearances.jpg

[cHa0s]

there is no excuse for poor quality fixes when the right one is cheaper and much more long term.

yea.. a member of our board killed a valve. he replaced the head gasket. after reinstalling the head, he didn't check the right position of the chain. he took the spanner, set it to the crankshaft and... crack. i sent him used valves and he got help from aother member. but he replaced the hole head because he had no tools to remove the valves

[ntouran]

Thanks for all the information! I think I'd be able to get the head off myself (doesn't seem like a huge deal). From there, I could either try to replace the valve myself with a new one, or just find someone who would take the whole head in their shop and take it from there (I know nothing of lapping, etc.).

If I decide to get a valve spring compressor tool and pull the valve myself, will it be obvious whether it's the valve stem, the valve seat, or both that are burning and need to be replaced?

[BaltimoreGS]

Completely off topic but I'm curious about your avatar, wedding or prom?  The pics too tiny for me to make out clearly.

-Jessie

[The Buddha]

I's say it was a manufacturing defect, bad valve prolly ... sadly, good luck getting suzuki to warranty that ... if I were I dunno Car Czar, I'd make suzuki eat that ... as well as the seca 600 I had that ate a tooth on the starter idler gear that was in the middle of the cases, to get it you had to split it, and of course the famous misubishi diamante heater core blows and spews coolant onto the black box and kills it ... nice Mofo's, doing it since the 91 model, all the way into 2004. I'd make mitsu eat that all the way. If you wanna do business in my market, it should not have multi year, multi generation problems that are clearly manufacturing defects, or design defects.
BTW I would also limit parts cost at retail to 2 X of car cost ... as in take a car apart and buy it in parts, it should be 2X ... that is it, and I'd also put in rules saying nothing should cost more than 2 X parts cost for labor ... I mean a $2 O ring will not be 900 bucks labor to replace.
Common sense, sheiteheads ... common sense.
Cool.
Buddha.

[ntouran]

Completely off topic but I'm curious about your avatar, wedding or prom?  The pics too tiny for me to make out clearly.

-Jessie

haha. It's a wedding. I rolled in with the suit on under leather and met my bridesmaid date on the street outside. She demanded a pic and it turned out to be most excellent. Bikes aren't even fair.

[cHa0s]

If I decide to get a valve spring compressor tool and pull the valve myself

to do the work one time, it isn't worth. thats my opinion.

will it be obvious whether it's the valve stem, the valve seat, or both that are burning and need to be replaced?

maybe the seat is burned, maybe it's not. this question can be hardly answered.

[gsJack]

If I decide to get a valve spring compressor tool and pull the valve myself

to do the work one time, it isn't worth. thats my opinion.

will it be obvious whether it's the valve stem, the valve seat, or both that are burning and need to be replaced?

maybe the seat is burned, maybe it's not. this question can be hardly answered.

Valve spring compressors are expensive but I borrowed one from my son for my broken valve repair.   You can make one like dgyver made from a 6" c-clamp and a piece of pipe to put it back together if it's worth fixing after you get in there and check it out, some have taken valves out by placing a socket on top of the spring and hitting it with a heavy hammer causing the keepers to pop out.  Only hard part is getting started.  

http://gstwins.com/gsboard/index.php?topic=13672.msg116193#msg116193

If the seat is real bad it might be time to look for a used head assembly but you don't know until you check it out.  I'd check the compression cold and hot first before tearing it down.  Finger in the hole compression test good enough, no gauge required.  If you don't have compression on the bad cyl when cold then check it hot.  Valve clearances increase greatly as the engine warms.  When my 97 had a tight exhaust valve a couple times it would run very rough starting cold and then smooth out within a minute or so as the head heated and clearance increased restoring compression.  Not much to loose by pulling the head if you want to fix it since you'll have to do that anyway to put a used one on it if yours can't be fixed.  There's a fair amount of valve stem sticking out that can be ground off if necessary to get room for a nice size shim and clearance, we use to adjust valves on the old flat head Ford V-8 that way back in prehistoric times:

[ntouran]

Well the compression was hideous. Even warmed up, I'd get popping and could barely make it up hills. It was terrible. Anyway, so I got the head off and decided to just go all the way and take a look at the cylinders and pistons too. It was fairly straightforward, with the hardest part being getting the cylinder head off the studs with the engine still mounted (it can be done!). Not bad for having never done any kind of engine work before. Hopefully I didn't lose too many washers into the crank case.

Below are pictures of what I've got. So far the plan is to take the head into a shop and have them inspect and replace all the valves, especially the one with no clearance. With the pistons out, I was thinking about taking them and the cylinders in for honing and re-ringing. Should I replace the pistons, or is this kind of carbon normal and cleanable? I see good results here so maybe I can get them that clean. Any benefit to getting new ones?

Here are the valves in the head:


The one on the right has the suspected burning valve.

Meanwhile, while I had it all apart, I took the extra 15 minutes to get the cylinders and pistons off, thinking I might as well redo the rings and stuff while I've got it all apart (right?).

Again, the one from the suspected burning valve side is on the right.


Here's some detail of the side of a piston:


So how am I looking?

[BaltimoreGS]

Hard to tell from the pic but it looks like that exhaust valve on the right hand side looks recessed into the head.

-Jessie

[ntouran]

A few more pics of the suspect valve. If it's recessed, does that mean get a new head? Or can the machine shop handle it? I'd show the valve if I could get to it but those springs are pretty hard to compress. Need that c-clamp tool.