Having air leak somewhere..

[Serdrix]

Hello, I recently rebuilt my top end with a new jug also.

Right now I have a 310 main and needle clip set to middle, air box lid off, hemi head, fmf pipe, vforce 4 reeds.

I have stronger jetting right now because I’m on the second step of the break in procedure.

from what I have read in the past, As long as you don’t loose 1 psi over the course of 1 minute your fine, but if you loose 1 psi or more a minute you have a air leak that needs to be fixed. Mine leaks 1 psi every 2.5 minutes and I can’t find the leak anywhere.

today I really looked hard at where this leak could be but came up with nothing, the intake boot, the case halves, the cylinder head where it meets the cylinder, the tester itself, the exhaust flange, the cylinder base, nothing. If a seal inside is bad, wouldn’t it show somewhere on the outside? I’ve also checked the clutch cover and stator cover as well. Nothing.

I decided to go ahead and do the break in procedure today despite this small leak, I’m at the second part of it and noticed a rattling sounds like bad bearings. The bottom end is semi-new but it sounds more at the top so either piston slap or detonation.

Before I ride it I wanna fix this issue first because Im already a lot of money In This project lol.

OH I mix 32:1 also and use 93 octane.

Any help would be greatly appreciated!!

 

[Larry's Shee]

What I’ve seen it’s hold 6psi for 6 minutes.
How are you looking for the leak ?
What is your starting pressure ?
Did you split the cases?

 

[Serdrix]

What I’ve seen it’s hold 6psi for 6 minutes.
How are you looking for the leak ?
What is your starting pressure ?
Did you split the cases?

I have a soapy water mix, I go up to 6 psi, I haven’t split the cases.

 

[Slydog]

Spay around the Spark plug.i have had them leak around there after having heads machined.

 

[Serdrix]

Spay around the Spark plug.i have had them leak around there after having heads machined.

Yeah I did there too already and each head stud and in the middle where the cylinder meets the head. Nothing showed up. I might just go ahead and do a plug chop to see if I have any actual detonation. No high idle and not really any signs of an air leak so I’m thinking it should be fine if the plug chop comes back ok

 

[Slydog]

Slight crank seal leak?
Can check clutch side by putting the crank breather hose which is located on clutch side right behind cylinder base in a cup of water and see if you get any bubbles.

If you suspect flywheel side to really check is you have to remove cover and flywheel.
If it's that small it might be in the tester?