cylinder leak down help

[tmwmoose]

All the years I've had my 02 107" and have done leak down tests its always been 10 to 20 percent (snapon unit) and both cylinders reading the same.  I'm having some issues with my motor and performed the L D test yesterday got 20 percent tried a comp test but the starter says no way Ray. This is the second set of rings since the motor went back together this time last year I have maybe 10k on the new bore and like 7k on these rings. Anyhow WHAT I want to know when I read were folks claim their getting less than 5 percent is that a big bore (mine is 4.125 +.030) with STD HASTING RINGS gapped per manufacture spec's usually around .017-.020 ? is that at just few new miles ? is it there at 10k?? I realize actual combustion is a lot different than a 100psi out a gauge  I could run a air brush gun off the air coming out my breather hose lol. If and I'm sure I will go back in this top end i will want to look into the gapless rings this time Ive never tried them. As always thanks guy's

[prodrag1320]

10% is too much here,20 % is time for a tear down

[tmwmoose]

10% is too much here,20 % is time for a tear down

Thanks Kirby, I understand thats your policy but you didn't answer my question 

[turboprop]

Moose, my brothers bike is a 124" with hastings rings, almost 30k miles on the engine, last week it was at 4%, engine was cold, newer gauge set off the Matco truck. -Ed

[Jeffd]

does it run good? smoke etc?  seems excessive so if it runs good I would try a different leak down tester just in case.  Even snapon can have issues.

[tmwmoose]

Thanks Ed, see here is my dilemma I'm H-D mech since 77 when I learn new things I apply them like heat cycling and with Axtell's instructions and after that I run the motor easy pretty much like S&S has stated for years I keep it like 22k-31k for a good 750 miles .I tell my customers ride it like you have been boozing and the cops are on your as# go easy!! no lug no high rpms no heat. My SNAP ON single gauge must work crap I had a oil burning evo in last month that read 10 percent lol (valve seals shot). I honestly can say I have never read a leak down like you experienced .I wash ,wash,wash and wash ,set ring gaps and assemble what is this old as# overlooking my motor's don't come back just mine don't comply

Jeffd, Runs ok there should be more but that's in my head probably , the rear cyl is rich, while idling an easy blip of the throttle emits a dirty light smoke out the rear pipe ,roll it on easy and let off not so pronounced and I can cancell the accell pump , again while idiling nail the throttle and the rear emit's black (gas) smoke and the motor does use some oil its just that the smoke is not white/blue.Rear plug is darbrown/black front fairly clean .Its just the old why doe's my bike do the weird stuff lol !

[turboprop]

Not sure how you are measuring leakdown with a single gauge.

Just to make sure we are on the same page. The first gauge measures the regulated air pressure, the regulator is adjustable and set to 100 psi. The second gauge measures the cylinder pressure.  Leakdown equals 100 minus the cylinder pressure.

If you would like to try a second opinion I will send you my gauges. -Ed

[tmwmoose]

Here's a laugh I bought a new one 5-6 years ago a dual gauge unit that are most common and just my luck the second gauge the leak down one read the same as the air inlet side I felt suspect about it and found on the web how they work and how to make your own fairly simple two gauges and a adjustment valve the design requires a small hole I forget maybe .070 or something like that between the two gauges well guess what the one I bought had nothing only fittings just my luck so I JB welded it shut between the two and drilled the hole , now reads pretty much what the snap-on unit reads . The snap-on unit says on the gauge 60psi max inlet which I've done but makes no diff .But in the end if the needle is on the 20 mark it's on the 20 mark 20 percent right? Ed maybe I can get lucky and post a pic of the snap-on unit. I also have a new 1.4 starter at the shop If I can get some free day off time tomorrow I may install it and try a comp test again.

[86fxwg]

Were are u putting the piston when ur doing ur test?
Engine hot or cold?

[turboprop]

Send me an address. They will go out tomorrow.

[tmwmoose]

Ive done leak down's on cold and warm motors tdc comp in gear brake pedal locked down . Sometimes I remove the push rods and check with the piston and diferent spots in the cylinder. The other day my motor was warm

[tmwmoose]

Send me an address. They will go out tomorrow.

Thanks Ed   pm sent