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Valve Adjustment 16v

Larry D

Larry D

Forum Sage
Past Site Supporter
81 GS750L.
Going to do a valve adjustment while the bike going through it's rebirth.
I have some questions from Mr Basic's excellent tutorial.
I've looked extensively in the forums for these answers but no luck.

1) Does the tachometer gear o-ring need to be viton, like the carb o-rings ?
2) He refers to cylinder #1-#2 etc... are they numbered they same as the carbs ? Left knee to right knee sitting on the bike ?
3) Is there a better pic of the 9mm lock bolt and where to measure with feeler gauge ?
4) What the heck are half moons and their purpose ?

Larry D
 
1/? probably
2/Left to right as sitting on the bike.
3/ Not that I am aware of. I will source one for you.
4/ The fit into the cylinder head at the end of the cams and allow you to see the cut outs in the cams. They hold the oil back.

Suzuki mad
 
Hi Mr. Larry D,

Referring to: http://members.dslextreme.com/users/bikecliff/images/16valve_adjustment.pdf :

Larry D said:
81 GS750L.
Going to do a valve adjustment while the bike going through it's rebirth.
I have some questions from Mr Basic's excellent tutorial.
I've looked extensively in the forums for these answers but no luck.

1) Does the tachometer gear o-ring need to be viton, like the carb o-rings ?
Click to expand...

I would suspect, yes, since there is a bit of heat to deal with. I always order OEM.

2) He refers to cylinder #1-#2 etc... are they numbered they same as the carbs ? Left knee to right knee sitting on the bike ?
Click to expand...
Yes. #1 cylinder is at your left knee when you sit on the bike.

3) Is there a better pic of the 9mm lock bolt and where to measure with feeler gauge ?
Click to expand...
The picture on page 7 shows quite clearly where to put your feeler gauge. Measure both valves. Don't worry, it will become very obvious once you get in there. There should be a manual on my site that will be helpful to you (16-valve 750).

4) What the heck are half moons and their purpose ?
Click to expand...
Here is a picture of half moons( those black hard rubber things shaped like "half moons"):

coverlift.jpg


Here a picture of the half moons removed:

nohalfmoons.jpg


The "half moons" form the oil seal on the outside ends of the top of the head. They are also available in aluminum and are somewhat more permanent. And to be honest with you, I don't know why the top of the head is shaped that way. I can only speculate that it is necessary for some manufacture or assembly aspect. I'm sure one of the really smart guys knows the real reason.

Let us know how your valve check goes. Keep us informed.

Thank you for your indulgence,

BassCliff
 
Last edited:
1) Does the tachometer gear o-ring need to be viton, like the carb o-rings ?
Probably. Anything that needs to withstand heat and oil/gas products would be better with Viton.

2) He refers to cylinder #1-#2 etc... are they numbered they same as the carbs ? Left knee to right knee sitting on the bike ?
Yes and yes. I can't imagine why they would change the numbering. People are confused enough when it's the same.

3) Is there a better pic of the 9mm lock bolt and where to measure with feeler gauge ?
The locknut is on the rocker, directly over the valve. You use the feeler gauge directly over the valve, too.

4) What the heck are half moons and their purpose ?
The half moons are rubber plugs. Their purpose is to hold back oil, but why are they there in the first place? The bearings for the cams are line-bored to assure that they are all in perfect alignment. The only way to do that is to continue out the side of the head, then fill in that gap with a half moon. As Suzuki mad mentioned, it is also useful for viewing the notches on the right ends of the cams, but I try not to take out the half moons just to view the notches. If they are not leaking, do not disturb them. If they are leaking, get new ones.
 
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