Jetting again

[Cox76y]

No engine was cold. Throttle was closed..I will try it again tomorrow with the engine warmed up..
JC

 

[Pygmygod]

Need to be wide open throttle when doing compression test.
And kick several times until the needle stops going up.

 

[Cox76y]

Ordered a leakdown tester on ebay. Should arrive early in the week. Just wanting to double check where I have to block off on this engine. Obvious points are the exhaust and intake. What about the powervalve, anywhere else??
Thanks
JC

 

[Cox76y]

OK,
I finally got the leakdown tester. !st place that failed once everything was blocked off and clamped up was the slave cylinder. I cant find a parts diagram for it anywhere. Does anyone know if there should be a gasket here?? Also would this likely be the source of my problem?? Could be other leaks however this seems to be the main leak at the moment.. It looks like there should be a rubber grommet however there is nothing.
thanks

JC

 

[(F5)]

Eh?? What are you pressurising? There should be no connection between the crankcase and the gearbox where the slave lives, plus the gearbox has a breather.

 

[Gasser Nate]

Unless it is leaking through the right hand powervalve bearing into the gearbox...

 

[(F5)]

Oh yeah, swine to try block off. But that would still just come out the gearbox breather.

I'm confusing engines, is it behind the kick lever?

 

[Gasser Nate]

Gearbox breather is at the top of the barrel above the right power valve cover confusingly! I?d say he has blocked off the hose and given the air no where to go. Yeah they can be a pig to block off!

 

[Cox76y]

Thanks gasser Nate and F5 for the reply. Yep, your correct I have blocked off that hose. (wrong thing to do??) I have also blocked off the intake and exhaust as well as the powervalve drain tube. I was under the impression that if I block all external outlets then it should be able to hold 5psi..

Can someone please advise me as to the correct procedure for a leakdown test. Pressure is input through spark plug hole in cylinder. I am pushing about 5 psi through it.
thanks in advance again.

Jc

 

[Gasser Nate]

Thanks gasser Nate and F5 for the reply. Yep, your correct I have blocked off that hose. (wrong thing to do??) I have also blocked off the intake and exhaust as well as the powervalve drain tube. I was under the impression that if I block all external outlets then it should be able to hold 5psi..

Can someone please advise me as to the correct procedure for a leakdown test. Pressure is input through spark plug hole in cylinder. I am pushing about 5 psi through it.
thanks in advance again.

Jc

You are doing it right, it is just that the air pressure is leaking around/through the right hand power valve bearing. Then into the gearbox via the breather passage. Might be worthwhile getting a new test bearing with rubber seals to pop in for testing only then pop the metal shielded one back in afterwards. They shouldn’t cost more than $5-10 from a bearing supplier. You can even leave that cover off while testing to spray some soapy water around the bearing to see if that is leaking.

 

[Cox76y]

thanks gasser nate.. Your a man of immense knowledge. My next question, can I push this bearing out from the left side if I remove the powervalve??

regards
JC

 

[Gasser Nate]

thanks gasser nate.. Your a man of immense knowledge. My next question, can I push this bearing out from the left side if I remove the powervalve??

regards
JC

I have built a fair few motors in my time mate, thanks! Yeah you can tap it out from the other side.

 

[(F5)]

For the first 10 mins most leaks you find are in your test rig.

 

[coble]

Any updates on this thread?