A few 'tips' to check if you HAVE EXCESSIVE BLOW BY 117

[Marky-Marc]

Check the following FIRST:

Compression check
Leak Down Check

Check your Compression to make sure both cylinders are within tolerances....
Check your leak down WITHOUT pushrods FIRST with engine at TDC - if it passes, adjust pushrods...

THEN, with PUSHRODS adjusted, bring Engine to TDC perfectly, have someone STAND on the REAR brake and check leak down...if it FAILS WITH pushrods in and they are adjusted correctly.....

Check your Oil Pump Relief Valve....

I had a huge problem figuring this one out...bike has perfect compression, perfect leak down with pushrods out, blow by was like a faucet at operating temp at high RPMs with Pushrods in....but my leak down failed EVERY time with pushrods adjusted and someone standing on the brake......

What was it?

OIL PUMP RELIEF VALVE......#13&#14 in attached diagram....

If you pull the spring out, use a small magnet to pull the 'valve' out...if it's HARD to get out, by that I mean, if it does NOT come out easily with the magnet, it is dirty and sticking.....then clean your oil pump the best way you deem necessary without removal...clean your valve and spring or get new ones (they are cheap).....

I put a new 'valve #13' and a new spring #14 in...and that solved the problem....blow by went away COMPLETELY....

Oil up a NEW valve after cleaning, put it in....and it will help with the blow by......

Just thought I'd share, there are other issues that can cause blow by as well...

Cheers.....

 

[knothead]

Check the following FIRST:

Compression check
Leak Down Check

Check your Compression to make sure both cylinders are within tolerances....
Check your leak down WITHOUT pushrods FIRST with engine at TDC - if it passes, adjust pushrods...

THEN, with PUSHRODS adjusted, bring Engine to TDC perfectly, have someone STAND on the REAR brake and check leak down...if it FAILS WITH pushrods in and they are adjusted correctly.....

Check your Oil Pump Relief Valve....

I had a huge problem figuring this one out...bike has perfect compression, perfect leak down with pushrods out, blow by was like a faucet at operating temp at high RPMs with Pushrods in....but my leak down failed EVERY time with pushrods adjusted and someone standing on the brake......

What was it?

OIL PUMP RELIEF VALVE......#13&#14 in attached diagram....

If you pull the spring out, use a small magnet to pull the 'valve' out...if it's HARD to get out, by that I mean, if it does NOT come out easily with the magnet, it is dirty and sticking.....then clean your oil pump the best way you deem necessary without removal...clean your valve and spring or get new ones (they are cheap).....

I put a new 'valve #13' and a new spring #14 in...and that solved the problem....blow by went away COMPLETELY....

Oil up a NEW valve after cleaning, put it in....and it will help with the blow by......

Just thought I'd share, there are other issues that can cause blow by as well...

Cheers.....

Makes total sense it couldnt relieve itself of oil pressure because of the sticking relief valve and out the breather it goes or the back of the crankcase if the hose isnt connected to the breather.....glad you figured that out that will sure help alot of folks when if it happens to them....i will remember this.....

Well i had a similar experience this year in Sturgis....first day the old vintage dog run like shit didnt have hardly no power, way to much fuel....so i thought i jet it this evening when i get back to the camper....well i changed the jets in it that evening...next morning left out and runned like shit but not as bad.... i thought no way it is to rich now what is the damn problem...i said the hell with it ride it im here to have fun i will worry about it later....well next day i started getting blow bye and actually started leaking oil around the valve cover....i was like what the f#$k....well the Th3infamous and us was riding and it dawned on me going down the road check the damn exhaust gaskets....sure enough when we stopped the exhaust bolts where loose and im mean loose....never ever had one do this to me....tighten the bolts up and no more oil leaks or running like shit...it solved the problem....back pressure cant hurt one if its to much or not enough