Valve clearance and one too large

[smagnusen]

Greetings all, been awhile.

Checking my shims and noticed a couple things:

1st, There's a difference clearance measurement depending lobe position. Perpendicular to the gasket surface there is more of a gap then parallel.

Ex. Exhaust #4 clearance between .038 and .051 when pointed up/perpendicular. .063-.076 when facing away/parallel.

Which makes me think I should check each in both positions and go by the lower number. Any thoughts?

2nd. Exhaust#4 is between .127-.152 when perpendicular, .076-.102 when parallel. Wondering why it would go large and do I bring it back to spec? Could it be carbon build-up under the valve causing the increased difference?

If so, let's say I bring it back to spec with a larger shim, and then the carbon is kicked off, and now the valve can't seal... See where I'm going with this?

[Steve]

Please re-check your clearances, but do it the proper way.

If you start at EX1, set the lobe on EX1 pointing FORWARD. EX2 will be pointing UP. Now, WITHOUT MOVING ANYTHING, measure BOTH EX1 and EX2.

Rotate the crank one-half turn (180 degrees), you will find that the lobe on IN1 is pointing UP and IN2 is pointing BACKWARD. WITHOUT MOVING ANYTHING, measure BOTH IN1 and IN2.

Rotate the crank another one-half turn, you will find that the lobe on EX4 is pointing FORWARD and EX3 is pointing UP. WITHOUT MOVING ANYTHING, measure BOTH EX3 and EX4.

Rotate the crank a final half-turn, you will find that the lobe on IN4 is pointing UP and IN3 is pointing BACKWARD. WITHOUT MOVING ANYTHING, measure BOTH, IN3 and IN4.


The reason you were getting different measurements is exactly why you have to follow the proper procedure. In the positions shown above, neither cam lobe on that side of the cam is pushing on a valve. That keeps the cam centered in its bearing, giving you repeatable readings. When you were moving the cam to different positions for each valve, the other lobe on that side of the cam was pushing on its valve, moving the cam away from the center of its bearing.

This procedure is spelled out (although not very clearly) in the factory service manual. It is also shown in the valve adjustment tutorial on BassCliff's site. There was also a recent post by member "srg", who offered THIS great write-up.

[Nessism]

Steve is detailing the factory Suzuki method. Can't go wrong following directions made by the people that designed and assembled the bike.

[tkent02]

It's not rocket science. Do it the Suzuki way. The other ways move the cam up and down in it's journal. There is more slop in the cam bearings than the allowed valve clearance.

[smagnusen]

Ah. -all makes sense, interesting about the shaft moving away from center of its bearing.

This method is NOT clear in my Suzuki GS1000 service manual, which states that clearances can be measured in either position.

[Steve]

This method is NOT clear in my Suzuki service manual, which states that clearances can be measured in either position.

Which bike?

I'll check a manual.

.

[Nessism]

Ah. -all makes sense, interesting about the shaft moving away from center of its bearing.

This method is NOT clear in my Suzuki service manual, which states that clearances can be measured in either position.

Are you using a proper factory Suzuki manual?

[Steve]

OK, I have checked the manuals.

For the '80 550, you should have THIS manual. It is available on BassCliff's site.

When you get the manual downloaded, open it up to page 82 of the pdf and start reading. You will see this:



Then you will see this:



Should look rather similar to the description above.



Moving on to the '79 1000 manual:

THIS is the manual.

It's on pdf page 28 there, but this is what you should see:



Still looking familiar?

[smagnusen]

Roger that, Steve. Will check the correct way and then get back on #4 exhaust, if need be.