Tight Valves

[NWDave]

So tell me if this sounds right, last night I get started on the valves.  Cut to the point I pull the cover off and align the indents on the cams and goto measure the gaps.. every shim is too big and I can't even get a 0.03mm feeler between the shim and cam.  I even went back and watched kerry's video again and did it his way by rotating the engine until the lobe was 180 degrees away from the shim.  No dice still they are all too tight.  Luckly the bucket compressor tool came in today so I can pull the shims tomorrow and measure them.  Has anyone else had this happen?  I would think that the shims would wear down and be too thin causing loose valves over time, not tight valves.

[trumpetguy]

It doesn't sound right.  Something is wrong if EVERY shim is tight.  I had one exhaust valve tight and the bike didn't run right.  With all the valves tight I'd expect it to run like crap.  But I doubt that's really happening.  How many miles are on it?

It's not the shims that wear -- they are super hard.  The valve seats and the valves themselves wear so that the valve gets deeper into the head.  Since the valve stem is pressing up into the bottom of the shim, clearance gets tighter as wear occurs.  The exhaust valves wear MUCH more rapidly than the intakes.  A post only two days ago discussed this.  GS Jack posted his valve adjustment records compiled in over 100K miles of riding a GS500.  http://gstwins.com/gsboard/index.php?topic=38012.0.

Check:

1.  Are you sure you are using a mm feeler gauge?  Be absolutely sure.  Inch feeler gauges are much more common -- I had to special order the ones I use to measure valve clearance.  0.03mm is a hair less than 0.001 inch.  If you mistakenly used a 0.003 in feeler (instead of a 0.03mm), you are at roughly 3 times the clearance on the GS, and every valve SHOULD feel tight at that clearance!

[galahs]

I have a mate who's a motorcycle mechanic and he says "if you can spin the bucket then you should be ok"

I wonder how much faith I should put in his methodology. 

[NWDave]

I can spin the buckets, and I ordered the feeler gauges from the guy that sells them on ebay (as per the wiki writeup).  And I'm not kidding I can't get the 0.03mm feeler to pass between any of the cams and shims.  And this bike has always been a problem child, it has trouble idling and has since owned it.  The plugs get dark nasty carbon buildup, I've rebuilt the carbs, adjusted the needle posotion and gone over the jets.  Now I am starting to think it was the valves all along.  SOB!  Anyone else have any input?

[NiceGuysFinishLast]

Sounds like mine. My intakes are both at .05, well within spec, but both exhausts are < .03, and the bike quit running. I need to find someone local with that tool to loan me instead of buying one. Good luck with the swap!

[trumpetguy]

Buy yourself a test shim (2.30 or smaller).  Pop each shim out one at a time, pop in the test shim, then measure the clearance (like Kerry's video). and calculate your replacement shim sizes.  I was able to swap around some shims and only buy one when I adjusted mine.  I had one exhaust valve super tight (off the seat) and others were tight but not off the seat.

I was totally amazed how much more torque the bike had at low RPMs once the wayward exhaust valve was back on the seat and proper clearances were set all around.  Much more difference than rejetting the carbs!

[NWDave]

Buy yourself a test shim (2.30 or smaller).  Pop each shim out one at a time, pop in the test shim, then measure the clearance (like Kerry's video). and calculate your replacement shim sizes.  I was able to swap around some shims and only buy one when I adjusted mine.  I had one exhaust valve super tight (off the seat) and others were tight but not off the seat.

I was totally amazed how much more torque the bike had at low RPMs once the wayward exhaust valve was back on the seat and proper clearances were set all around.  Much more difference than rejetting the carbs!

I know what your saying, but I thought all you had to do was pull out the shim thats in there and then measure it.. cross-reference the chart in the repair manual and use the recommended size. Correct?

[gsJack]

I have a mate who's a motorcycle mechanic and he says "if you can spin the bucket then you should be ok"

I wonder how much faith I should put in his methodology. 

Works for me, been doing it that way for 130k GS miles.  I've been thinking in inches for 75 years so I work in inches.  Spec is .001-.003" and I use a Craftsman feeler gage set that comes with a .0015" min thickness blade.  This one wrinkles and breaks rather quickly and has been gone for some time and I've been using the .002, .003, .004 and .005" blades now for a long time.  If it is tighter than .002 and I can turn it freely with the finger tip I call it .001 and let it go unless I have a shim handy to change it.

Intake valve shims really have never needed changed on my 2 GSs for all those miles.  If I change an exhaust valve shim I usually go over spec to .004 or .005" depending on what shim I have available.  Exhaust valves keep getting tighter and I've never had one get looser.

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

I bought a Motion Pro valve shim tool and never used it, I use a couple of screwdrivers or a screwdriver and wedge to change shims.  I've never used a test shim, if it's tight I measure the shim and get a couple smaller ones to try.

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

You know how it is with old dogs and new tricks.   

[simon79]

Hmm, interesting topic...
There must be something I miss
1000 km/600 mi. ago I checked my valve clearances. Mainly 'cause it had been 6-7000 km/4000 mi. I have had my bike, and didn't know its previous history, but also I wanted to actually see its innards.
Anyway: popped valve cover off and found out that one exhaust valve (left) was <0.03 mm ...and yes, I use a metric feeler gauge I couldn't slide the 0.03 mm blade between cam and shim (I proceeded as per Kerry's method).
Thing is, my bike actually runs fine. No sputtering, no problems starting both with cold and warm engine, fuel mileage ok (50-ish MPG), maybe just a little hesitation at 7000 rpm when accelerating, but that's all. No clicking from the engine, no strange sounds, no whatever.
I also took it at my dealer's, the mechanic guy listened to the engine, and said "Oh well, I could take your bike in for valve adjusting, and I'd have to charge you 200+ bucks to give you back a bike that runs exactly as before. It doesn't click, it idles wonderfully at 1000 rpm, I see nothing wrong with it. You're fine, don't worry."

Is having just one valve out of spec asymptomatic?
Or maybe I did something wrong when measuring freeplay?

Oh, just for precision's sake, I think I had some exhaust popping a couple times on the motorway, and the other day when starting a cold engine the exhaust made a loud bang But in 4000 mi. so far, that's all.

(Sorry for the threadjack. )

[galahs]

A bloke I know said his GS occasionally sounds like it misses (knocks) at idle accompanied by a bang from the exhaust (like a small backfire) but goes fine once warm and when riding.

I said it could be a weak spark or tight valves. Anything else it could be.

[Affschnozel]

A bloke I knew had his GS running like crap , cleaned carbs few times with no luck ,I measured clearances and all were super tight , all 4 less than 0.03 , buckets were hard to turn by finger ,he ran it like that since he had it . After shim replacement needless to say bike ran instantly fine. He sold it right after I fixed it for him   

[simon79]

>galahs:
This puzzles me a bit.
[Warning: Possible ]
Tight valves should give more issues when the engine is hot, as far as I know...
Little freeplay and hot engine => heat makes cams, valve shims and whatever expand => freeplay gradually decreases till possibly zero => valve doesn't close perfectly => lack of compression.
As for me, I have no relevant/frequent problems at warm/hot engine.
[End of possible ]

A bloke I knew had his GS running like crap , cleaned carbs few times with no luck ,I measured clearances and all were super tight , all 4 less than 0.03 , buckets were hard to turn by finger ,he ran it like that since he had it . After shim replacement needless to say bike ran instantly fine. He sold it right after I fixed it for him   

...D'OH!!!!!

[gsJack]

>galahs:
This puzzles me a bit.
[Warning: Possible ]
Tight valves should give more issues when the engine is hot, as far as I know...
Little freeplay and hot engine => heat makes cams, valve shims and whatever expand => freeplay gradually decreases till possibly zero => valve doesn't close perfectly => lack of compression.
As for me, I have no relevant/frequent problems at warm/hot engine.
[End of possible ]

A bloke I knew had his GS running like crap , cleaned carbs few times with no luck ,I measured clearances and all were super tight , all 4 less than 0.03 , buckets were hard to turn by finger ,he ran it like that since he had it . After shim replacement needless to say bike ran instantly fine. He sold it right after I fixed it for him   

...D'OH!!!!!

VALVE CLEARANCE INCREASES AS THE ENGINE WARMS UP.  Aluminum expands faster than steel as the temperature increases.  This lifts the cams up and away from the buckets/shims  on a overhead cam engine with an aluminum head as it warms.  An engine with zero valve clearance cold will have plenty of clearance hot.

I was having trouble with the old CB750 once long ago and decided to check this out.  I warmed the bike up and pulled the valve cover on the hot engine and valves that had .003-.006" clearance cold then had .015" or more clearance hot!

When my 97 GS ran rough cold and then smoothed out as it warmed up it had a tight exhaust valve.  Re-shiming the exhaust valve for clearance then made it run smooth cold with the proper amount of choke.  If a bucket is hard to turn with the finger tip when cold then it is a little tight and needs re-shimed.  Except in the very rare case where a bucket is fit too tight in the head bore like I had on the 02 GS when it stuck open and broke a valve one cold freezing morning.

NWDave, check your compression cold, don't need a compression gage, use the old finger in the hole method. Pull the plugs and hold a finger firmly over a plug hole and crank the engine with the starter.  IF it blows your finger away with a loud pop you have compression cold and your problem is elsewhere.  Check both cyls this way.  If you can rotate the buckets freely with your fingertip you have a bit of clearance.

[galahs]

Would using a heavier weight oil in fact make valves tighter due to the thicker film in-between the bucket and shim?


Could that be the problem with cold starts this user is experiencing using a 50 weight oil
http://gstwins.com/gsboard/index.php?topic=37390.0

[gsJack]

Would using a heavier weight oil in fact make valves tighter due to the thicker film in-between the bucket and shim?


Could that be the problem with cold starts this user is experiencing using a 50 weight oil
http://gstwins.com/gsboard/index.php?topic=37390.0

Don't think the heavier oil makes much difference as far as valve clearance goes but it can mak a difference in compression on a worn engine.  But it also makes the engine run hotter than the recommended 10W-40 does and could cause more pinging aka gas knock under load on hot days.

I broke my 97 GS in on 10-40 dino juice and then ran the 15W-50 Mobil 1 full synthetic for about 50k miles.  The 97 progressed from reg to mid grade to premium fuel to keep it from pinging on hot days under load the same as my previous 4 air cooled Hondas had.  When I went to the 15W-40 heavy duty oils I found I could go back to only reg grade fuel year round without the gas knock.  I've used only the 15-40 oils in the 02 GS and it remains knock free year around on reg gas.

[simon79]

>gsJack:


...D'OH!!!!!!!!!

Now I get the point...Thank you so much
I had a good idea in putting the disclaimer in my post.
I didn't pay attention to differences between the two materials (aluminum & steel).
Thanks very much again

[CndnMax]

I hear some type of clicking/taping noise from the engine when its cold, would that be a sign of an out of spec valve?

[trumpetguy]

Anyway: popped valve cover off and found out that one exhaust valve (left) was <0.03 mm ...and yes, I use a metric feeler gauge I couldn't slide the 0.03 mm blade between cam and shim (I proceeded as per Kerry's method).
Thing is, my bike actually runs fine. No sputtering, no problems starting both with cold and warm engine, fuel mileage ok (50-ish MPG), maybe just a little hesitation at 7000 rpm when accelerating, but that's all. No clicking from the engine, no strange sounds, no whatever.
I also took it at my dealer's, the mechanic guy listened to the engine, and said "Oh well, I could take your bike in for valve adjusting, and I'd have to charge you 200+ bucks to give you back a bike that runs exactly as before. It doesn't click, it idles wonderfully at 1000 rpm, I see nothing wrong with it. You're fine, don't worry."

Is having just one valve out of spec asymptomatic?

Just because it's tight when cold doesn't mean it's tight enough to be off the seatand thus affect the running.  It may run OK now but if you don't adjust that tight valve it will eventually affect the way it runs.  That's why you Suzuki says to adjust them! 

If the bucket turns by hand, you're probably just a touch below 0.03mm (Some racers actually adjust intake and exhaust this way to gain a tiny bit more cam duration when the rules say you must use stock cams).  Check again soon and make an adjustment then.

The test shim is handy but not essential.  I do have an extra 2.30 shim if someone wants it.  $10 shipped in USA (what I have in it).  Send me a PM if interested.

[jgreth]

I'm about to do my valve clearance check.  Where would I get shims from if the clearance(s) are off?  Any recommendations or does AutoZone have them?

[trumpetguy]

I'm about to do my valve clearance check.  Where would I get shims from if the clearance(s) are off?  Any recommendations or does AutoZone have them?

Suzuki dealer or online.  Autozone won't have them.  Hell, every Suzuki dealer I went to didn't have them either.  The 4 valve engines use a much smaller shim and that's what they usually stock.  I ordered mine online at http://crc2onlinecatalog.com/valve_shims.htm.