Stuck valve shim

I am using the Motion Pro bucket holder.

Removed all 8 shims from the parts bike and cataloged them.
Measured them with a caliper to verify thickness.

By the eighth shim of the parts bike I had a system and all of them came out easily with not too much prying. The tool helps a lot.

Moved on to daily rider which needs two shims removed and measured and replaced.

#1 intake shim popped out easily and its a 2.95mm. There is a 2.90 in the parts bike collection so I swapped it out.

#4 exhaust shim will not come out.

Step 1 is usually rotate cam to minimum and then rotate the bucket so that the bucket slot is in a good position to pry.

#4 exhaust bucket is more difficult to rotate than any of the previous 9 that I worked on.

Using the screwdriver that pried out the previous 9 shims the #4 exhaust shim will budge a tiny amount but no more. The shaft of the screwdriver is beginning to bend.

On the top of the head where the valve gasket sits are a whole bunch of scratches that look like a previous mechanic pried and pried to get the shim out the last time the valve shims were replaced.

Suggestions? Liquid wrench? WD40?

I have thought of trying to drill a dimple in the side of the shim and pry it out with a nail set.

 

When the bucket is being held down, and you're SURE it didn't get "missed" by the tool, do you have enough clearance between the top of the shim/bucket and the cam to lift it up, if it would pop loose? Can you rotate the shim on top of the bucket? (obviously the bucket won't want to rotate as it's been 'nipped' by the tool.) I wonder if some sort of horrible abuse befell that bucket. Good thing you have a parts bike; you might end up having to replace that bucket.

 

Are the shims usually rotatable when the tool is holding the bucket? The suction creates a "snap" when the shims pop out so I assume that the shims would be difficult if not impossible to rotate with the bucket frozen with the tool.

I use a zip tie to feel under the cam and make sure there is room to lift out the shim. I will re-check tonight and make sure there is plenty of room.

I first thought that the tool was nicking the shim and was preventing the shim from coming out of the bucket. But after re-seating the tool numerous times I am convinced that the shim is somehow jammed in the bucket.

What has to happen to get the bucket out?
Does it require the cam shaft to be removed?

 

The shims should rotate while the bucket is being held down. They're being held by what is essentially "hydro-lock" (surface tension?) but they will spin. Try it on one you're not having problems with as a comparison. I too am beginning to wonder if the shim is somehow jammed in the bucket. Perhaps a PO or PM (previous mechanic) somehow tweaked the lip so the shim is jammed in place. Now the good/bad news: The bucket will lift right out---after you pull the camshaft. I strongly recommend a disassemble/reassemble "dry run" on your parts bike. (That's what I would do anyway...)

 

It sounds like the PO dinged the edge of the bucket and now it has an edge bent in holding the shim. The drilling idea will be a no-go, the shims are hardened steel and will not drill by conventional methods. Sounds like the bucket is going to need to come out.

 

Ok guys, thats what I thought.
I will give shim removal another try with a beefier screwdriver and pick that I bought at Sears at lunch.
If thats a no-go I will figure out how to take out the camshaft on the parts bike.

Thanks

 

Yeah I wonder if all those scrape marks you thought were from the PO trying to get the shim out were actually the aftermath of whatever befell the edge of the bucket? If you turn the bucket and carefully examine it all the way around you MIGHT be able to tell why/where it is binding the shim and at least have more to go on. It does sound like you might end up replacing the bucket.

 

No joy with #4 exhaust shim.
Its is definitely much more difficult to rotate #4 exhaust bucket.

I removed intake shims from three intake buckets that had clearances of .003 .004 and .004. Using shims from the parts bike they now have clearances of .005 .0055 and .005.

My methodology with the Motion Pro tool is solid.

The exhaust clearances are .006 .006 .007 .005.

Until I am ready to tear into the cam shaft I think I can run the bike with 7 of 8 clearances good.

Thanks for the encouragement guys.

 

When I have a Shim that don't want to pop-out for me ... I rely on a simple tool I made-up just for the occasion.

I took a Big Nail over to the grinder and put a sharp point in it.
The point is fine enough to find some purchase on the Shim.
If I can get the Shim to budge-up in the Bucket; I run the Point of the Nail right into the slotted area of the Bucket and lift-out the Shim.

 

Once you figure out the "trick" it works every time so you're good there...

You will be OK for a bit but I wouldn't put it off for long. You're not too far "out" but exhaust valves live a harsher life than their brethren. I'm concerned that whatever tweakage (?) has the shim jammed also did harm to the bucket, since you say it's more difficult to rotate (than the others?) Practice on your parts bike but get that bucket swapped before you put too many more miles on it. Wouldn't want to burn a valve or anything.

 

Good news update.

On the 10th re-positioning of the Motion Pro tool I was able to pop the shim out. Its was a 265 and I have a 260 from the parts bike. Once in place, the clearance is now .0065 for #4 exhaust.

The final tally is

Exhaust
.006 .007 .006 .0065

Intake
.005 .0055 .005 .005

Wow. That was a trip.

Rick, thats a neat idea to sharpen a large nail. I will remember that next time. The screwdriver that did the best job removing the shims has pointy corners and the sharpness of the corners is what grabs the shim.

I am anxious to fire it up tomorrow and see if the "clatter" that I always hear for the first few seconds after starting is now gone.

Also looking forward to re-synching the carbs and taking it out for a run through the gears. That may have to wait as the weather is now rainy and maybe some snow soon.

Cheers

 

Valve Train Clattering is a "Good Noise"

It's when you DON'T hear the Valves that's you are in a bad situation.
Too often, people will adjust their Valves too close to get rid of the noise.

Not a problem for Valves that are adjusted by replacing Shims.
But, for Valves that have adjusters on them ... too close is bad news.

Valves you can't hear aren't getting closed enough to seal-up super-heated gases.
First they overheat and get soft.
Then, they burn-up and lose gas tight effectiveness.
You need new valves.
Lots of work.

 

I did not know that. Obviously.
Thanks for the insight.

From now on I will be happy when I hear the clatter, particularly since all of the clearances are now in spec.

 

So the blasted thing WASN'T being held down? Frustrating, isn't it? I invented at least three or four new expletives during the process myself. As Rick said, it is important to remember the valve clearances TIGHTEN as they wear, too quiet is not a good thing. Glad to hear this dragon has been slain; now for those carbs...

 

While I was popping shims I replaced two that were in spec but just barely. I popped two other ones that I did not have the next size down. I will wait another season to check again. At least I know what size to order next time.

Yeah, about them carbs..................

While I was popping shims out and in I spent some time observing the state of the oil in the cam shaft trenches.

The is no smell of gasoline in the engine now. I am convinced that the carbs are not causing gasoline to get into the engine.

The question is where/how does gasoline smell get into the air box?

When I took off the air pods from the parts bike I was overwhelmed by the gasoline smell. The pods live in the open air so the parts bike had some kind of blow back into the air box.

When I rode into work this morning (below freezing here) I did not smell any gasoline. It makes me wonder if the one used-to-be tight exhaust valve could cause some "blow back" into the air box.

Opinions welcome..........

 

From the crankcase breather, if not from the carbs themselves.

Only indirectly; I'm not quite sure whether it would create excessive crankcase pressure/blowby, unless by not being fully closed when it should might have been contributing to incomplete combustion in that cylinder but I am REALLY crawling out on a thin limb here...

 

No.
Probably not.
The valve might have been too tight; but not leaking.

If it had been leaking you would have had a problem with backfiring.
You'd have had some tell-tale backfire happening all the time indicating that the Exhaust Valve was burned.

 

Never had a backfire, ever. I have ridden something under 200 miles since purchase.

So, is it common for a the gas smell to permeate the air filter? Can it point to a problem?

 

It points to:

Blow-by past Rings with low compression.

Fuel entering the Crankcase from a leaking Float or Petcock.

 

It sounds like a compression test is next.
I did buy a meter so that may be the weekend goal to do the tests.

I do not think that there is gas in the oil so piston ring blow-by sounds plausible.