Can't fix vacuum leak

[Tristan Gillett]

Hello. Recently, I switched out the cylinder on my two stroke, and after doing so, I have a really bad vacuum leak. The RPMs pretty high, as if i'm holding the throttle half way, and in neutral, it skyrockets. As of right now, I have sealed the carb mounting spot with heat resistant caulk, made a new head gasket out of silicone gasket maker, as well as made the carb level. I have also made a gasket for inbetween the intake manifold and the intake hole on the cylinder. Anyone know what else I should do? Will gasket maker be strong enough for a head? I can add pictures if anyone requests any. Thank you for any help.

 

[Greg58]

Did you replace the base gasket when you changed the cylinder? That is a problem leak area, the head gasket is re-useable, I would go back to it.

 

[Tristan Gillett]

I didn't replace the base gasket. Didn't even think to check there. Is the head gasket the metal piece that sits inbetween the head and the cylinder?

 

[Chaz]

Yes, the head gasket is metal. The base gasket is thicker fiber type.

 

[Tristan Gillett]

Ok, thanks for telling me. I'm still learning about motors.

 

[Chaz]

This is a great place to learn. Here's a link to help you locate the vacuum leak:
https://www.howtomotorcyclerepair.com/how-to-diagnose-motorcycle-vaccum-leaks/

hope this helps.

 

[bairdco]

Before you do anything else, put the metal head gasket back in. It's designed to seal as the temperature heats up and cools down. Thermal expansion and contraction, basically.

Silicon gasket sealer is not gonna work.

 

[Larry Trotter]

It must be getting fuel also some place, are you sure the throttle slide went in properly when you replaced the carburetor?

 

[Tristan Gillett]

Before you do anything else, put the metal head gasket back in. It's designed to seal as the temperature heats up and cools down. Thermal expansion and contraction, basically.

Silicon gasket sealer is not gonna work.

I put the metal head gasket back.

It must be getting fuel also some place, are you sure the throttle slide went in properly when you replaced the carburetor?

Yes.

For the most part, it's fixed.