Rebuilding a G320 - Is the case gasket needed for spacing/clearance?

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Knotical

Knotical

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Hello, got a novice question here; is the gasket between the two crankcase halves necessary or can I get away with a decent 2 stroke case sealer alone?

I've got a freshly rebuilt G320 piston port with a +2mm stroker kit and Bartolone top end. I let it sit 24 hours inside to cure, and it fired right up and idled nicely. Another 24 hours later I took it out to run it and can hardly get the thing to idle, and whenever any throttle is applied it dies. No luck with tuning the carb. I used Permatex Ultra Black sealant and I believe the gasoline dissolved the sealer as the idle smoothed out when I sprayed some light oil around the case seam.

Now I'm getting ready to pull it back down to redo the case seal and I'm wondering if I must use a paper gasket or if it's acceptable to use a quality case sealer like Yamabond alone?
 
Knotical said:
Hello, got a novice question here; is the gasket between the two crankcase halves necessary or can I get away with a decent 2 stroke case sealer alone?

I've got a freshly rebuilt G320 piston port with a +2mm stroker kit and Bartolone top end. I let it sit 24 hours inside to cure, and it fired right up and idled nicely. Another 24 hours later I took it out to run it and can hardly get the thing to idle, and whenever any throttle is applied it dies. No luck with tuning the carb. I used Permatex Ultra Black sealant and I believe the gasoline dissolved the sealer as the idle smoothed out when I sprayed some light oil around the case seam.

Now I'm getting ready to pull it back down to redo the case seal and I'm wondering if I must use a paper gasket or if it's acceptable to use a quality case sealer like Yamabond alone?
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Yes the stock case needs that gasket. Even though it is thin you still need in order to get the correct crankshaft end play.

Some of the aftermarket billet stuff does not have it but if it came with one you are going to want to run it with one.
 
smokinwheel said:
Yes the stock case needs that gasket. Even though it is thin you still need in order to get the correct crankshaft end play.

Some of the aftermarket billet stuff does not have it but if it came with one you are going to want to run it with one.
Click to expand...
Thanks, I'll get one on order.

Any harm in using a light coat of sealant on that gasket? Or do you all usually install them dry?
 
smokinwheel said:
Dry with a gasket.
The only time for a sealer like Yamabond would be with billet cases that do not use a gasket.
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Sounds good.

One last question, any value in the graphite stuff over the standard paper? DDM has them for the same price
 
Knotical said:
Sounds good.

One last question, any value in the graphite stuff over the standard paper? DDM has them for the same price
Click to expand...

I honestly do not know if it makes a difference or not. I never tried a graphite one myself.
As long as the thickness is the same it probably won't hurt anything.
 
Just a note from the motocross world. Whenever you DO need to use sealer, if it will be exposed to gasoline, use Yamabond or Motoseal. Otherwise gas breaks down regular RTV. Especially ethanol gas. I use Motoseal when deleting the base gasket on chainsaw jugs, to get a slightly tighter squish to boost the compression.
 
Z71mike said:
Just a note from the motocross world. Whenever you DO need to use sealer, if it will be exposed to gasoline, use Yamabond or Motoseal. Otherwise gas breaks down regular RTV. Especially ethanol gas. I use Motoseal when deleting the base gasket on chainsaw jugs, to get a slightly tighter squish to boost the compression.
Click to expand...
Exactly this. RTV it’s not what you want to use in this kind of situation.
 
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