My new Small Reed Top End failed the pressure test.  I am really bummed. Wanted to go to Silver Lake Sand Dunes next weekend.

So it is pressurizing the transmission when I block the vent tube. This means is the PV or the clutch side Crank Seal. The leak is so bad that I can't keep air pressure in it and spray for leaks around the PV.

Note: The PV was just installed with new O-rings. I did the double o-ring mod at the little bearing.

Could a bad crank seal leak this bad? Any tips on narrowing this down? What risks will I have if I put this together and run it? Any input is appreciated. This motor started well and did not have any erratic idling prior to this rebuild. Just low compression. It also had stock jetting. If it is a crank seal, why didn't cause any issues? 

yes it could leak that bad. mine was doing the same thing. come to find out my cases were **** around the clutch side crank bearing. hello another set of cases

That was the issue with my other Zilla and I had documented it on the old site. I hope I don't find a crack. That would be a major let down. You know though - I did not find ANY tranny oil in the crank though. My other bottom end that was crack filled the crank up. 

Ill post a picture later today on my setup.

The pressure test is I am coming to realize is Good and Very Bad.

Good in that it will detect a issue and save a motor.

Bad in that it usually means you were close to having your sh*t running but now there is something else f*cked up!!! 

UPDATE:

I tore the clutch cover off. New territory on this bike. PO had a OEM gasket smothered in gray sealer!! Anyway I was pumping it with air and narrowed the sound down to the PV. So I proceed to open and close it. move it in and out (that shaft has alittle play in it). The orings must have seated because it all started to hold pressure.

Whewwwwww..............now I need a new gasket.

Here is my set-up for CrustyOreo. Notice the Intake and Exhaust are blocked so the motor can be tested.

The major parts are a small pump, a manifold, and a low PSI pressure gauge. This gauge is from Harbor Freight and is used to measure fuel pressure and vacuum.




 

Oooohhhhhhh that's a good tip. 

Pressure checking any engine with a power valve sometimes takes hours.................and then you find the leak was some where down stream of the exhaust port window where it does not affect the air fuel mixture.   You need a put a inflatable balloon in the exhaust port between the port window and the power valve to eliminate power valve related leaks when pressure testing. 

If they do not affect the AF ratio, is there a need to detect them?

that's where mine leaked.


Also, make sure your tester doesnt leak anywhere.

Jerry, what kind of balloon are you using? I tried looking for something durable enough for this, but havent had any luck.

Quote from: MotorGeek on September 27, 2013, 08:01:07 am

Quote from: Nopick on September 27, 2013, 04:07:09 am

So, does it need a little dab of silicone or a new, more compliant, boot?  Or a 500 Fanatic AL intake? 

A lite coat of fuel resistant sealer on both sides of the gaskets will usually fix a problem like Rider414 shows in his picture.

The picture with the leak is with brand new gaskets and it leaked! I seemed to remember guys telling me to use the semi-harding sealer like you would for the case halves. It spreads easy. After sealing it, it held like a champ. The new motor I went a sealed it up also. The lesson I learned is that even with new gaskets, there could be leaks.

Case bond works great but I hope I am not the next guy that has to take the motor apart.  Sometimes it takes dynamite to get cylinders off that used case bond on the base gasket.

Any of the Permatex Ultra blue, Ultra black, Ultra grey works real well. 

We use 3 Bond 1211 on most gaskets in our shop.  1211 is expensive and has a short shelf life.  The Permatex Ultra xxxxx series of sealers performs real close to that of 3 bond 1211.