Removing Cams - Question

[cajun31]

If the compression is still good on that cylinder then I would also say that it is the valve stem seal.

[Radioguylogs]

Cams are out, and head is off.

Went smoothly, thanks to your collective advice.

Just like bikerphil said, the head was not a problem to break lose. A few light bops with a rubber mallet and it came free easily.

Surprised the studs have almost no rust. Nice.

Note: Head de-torqueing sequence is backward in the Clymer's manual. Clymer copied the diagram from the FSM. Clymer didn't notice the instruction in the FSM say to go backward from the tightening sequence, and then the FSM shows a diagram of the tightening sequence, which is a bit confusing. I had to look at the tightening instructions in the FSM to double-confirm what they meant.

More to follow.

[Radioguylogs]

BTW: Manual says to clean carbon off piston crowns but don't disturb the carbon ring at the top of the cylinders.

Do you guys think it's better to try and clean the pistons, or leave them? Seems like an unnecessary risk to get crud down into the rings.

[DiverRay]

If it's a LOT of carbon, you need to clean them. If it seems to be a thin coating, just leave it. I would work on what the exhaust ports now look like. An easy way to clean carbon is put some Berryman's B12 on the carbon and let it set for a bit. It will take the carbon off without scratching anything. Or you can wait until you have it back together, run until warm, and then spray some B12 into the carbs until it dies. Let it set for 20 minutes and then fire it up. DO NOT do this with the garage door closed!!

[bikerphil]

I think the same, leave alone unless excessive. Definitely clean the head though. If you need to scrape, use a rounded edge tool such as a thick feeler gauge, still have to be careful though.

[Radioguylogs]

Time for an update.

I did clean the head and the pistons.








I installed the new valve seals and got the head back on a few weeks ago.

At first I found three valves clearances had shifted to the low end of the spec due to light valve lapping. I re-shimmed those and measured the compression.

I got 155psi on all four jugs if I let the engine turn over about 20-25 times for each reading. I was pleased they all were the same and they were favorable.

After measuring the compression, another intake valve has clearance at the low end of the spec. Must have had some crud under the valve. I am still waiting for an ordered shim to adjust that one.

Mainly, I wanted to report the results, and thank everyone for their help on the sequence to remove and install the cams. It went easily and now it all makes sense.

[Radioguylogs]

As a side note, it's apparent that the Vesrah head gasket is made so you delete the seal around the chain tunnel (at least I hope so ).

Here is the old gasket laying top the new gasket:

[bikerphil]

Yes, that cam tunnel seal has been omitted from the aftermarket and OEM head gaskets for many years now.

[DEEBS11]

Mike, nice job on cleaning up that carbon. How did you end up doing it?

[Radioguylogs]

For the head, I mostly used a plastic cheap plastic shoe horn that had big radii on each end and a knife-like die parting line. I used Goof-Off and lacquer thinner to help. I also used a Dremel brass wheel and scotch bright to help along the way.

I used a brass wheel on the bench grinder to clean up the valves.

For the pistons, I mostly used a Swiss Army pocket knife blade that was more like a scraper than a blade. Then I hit them with the Dremel brass wheel.

I cracked the shoe horn using it as a shoe horn after I was done, but here is what I used:

[DEEBS11]

Looks great Mike. Simple tools and some elbow grease.

[Radioguylogs]

I got everything reassembled several weeks ago, but I have been waiting for the snow to melt before tried running it. No sense putting gas in it then letting it sit.

I started it a few days ago. It started easily and NO SMOKE !!!!!

I sync'd the carbs, then gave it a few revs to 3500 RPM to see how the sync behaved. I noticed #3 cylinder was going high on vacuum when the other three were going down as it revved up.

I few seconds later there was an unpleasant sound, so I shut it off immediately. It was so fast I don't remember the sound. Maybe a "chuh-chuh-chuh" pulsing sound. It made me fear a bearing failure because it was not a clanking noise one would get from a valve train problem.

I briefly started the bike for a second or two to hear the sound. At that time it sounded like a can opener, like a whiny gear train.

So, based on the nature of the sound, I was most worried about crank/rod bearings. I drained the oil. and did note a few small metal flakes...concerning, but not really a smoking gun. The volume of oil was about 3 quarts- a little low, but within the acceptable operating range. There was no gas in the oil. No probable cause for a bearing to fail.

I was thinking the problem must be related to something I did during the recent operation. I was preparing to take off the valve cover and make sure everything was in order....and remove the cam chain tensioner and look for any trouble there.

Before I started removing the valve cover, I measured the cold compression: 150/150/140/150. Hmmmmm; #3 has 2 strikes against it since it had the same compression as the other cylinders before I ran the engine. Also it had the wonky vacuum behavior as the failure occurred. I began to wonder if the head gasket had leaked.

I re-torqued the head bolts. I was shocked to find that almost every head nut tightened about 1/8 turn before the torque wrench gave me the correct 25.5 ft-lb. I can't believe the heat would compress the gasket that much. Will it be OK to just re-tighten it? (PS- Not sure if I oiled the head studs before installing the nuts)

After retorquing, #3 cylinder compression was 150 psi., same as the others

Soooooo, I am thinking to go ahead and try starting it again before I take off the valve cover. It doesn't seem too risky with fresh oil and no symptoms when I turn the crank by hand or by starter motor.

Your thoughts are appreciated.