Why am I Pinging

[cmotodad]

89 cr500 motor, 89.25 prox fresh bore,39 PWK, PC pipe. Did some jetting over the weekend and could not get a midrange ping to go away. From too rich to a ping. No middle ground.I am going to check static compression today. Runs good with the 175 main 40 pilot and a needle I had in my box. The DGN needle was too lean even on the bottom clip. Any ideas? Thanks, Bob

[AlisoBob]

The DGN needle was too lean even on the bottom clip. Any ideas? Thanks, Bob

Sounds like you have an air leak...

[plynn41]

X2 on the air leak.

[cmotodad]

What is the easy way to check for an air leak? Starting fluid around manifold, carb, base and head?

[100hp honda]

never heard a stock bike ever having that problem. probly a loose pipe spring you hear

[AlisoBob]

What is the easy way to check for an air leak? Starting fluid around manifold, carb, base and head?

Its most likely the left side crank seal.

[pstoffers]

Try a DGL the DGN is way to lean if you ride on the pipe!!!

[AlisoBob]

WFO, it dont matter

[pstoffers]

WFO, it dont matter

The pipe starts working befor WFO!!!

[Kuma]

What gas are you running? I had pinging when loaded down in the sand, needed something with a little more octane than pump gas.

[cmotodad]

I was thinking of mixing 50/50 race pump just to see if that helps. I know the race gas richens a little but I do not want that hassle.

[yota]

leak down test is pretty easy to do.

[dubious01]

did you ensure your head gasket is big enough for that bore?
did you cut the head squish band larger to match the larger bore?
lastly, I have had a prox short cct around the exhaust port, due to the narrow face of the piston as roostius has explained and shown pictures of, and it was unjettable, at least not to perfection, and I had to go REALLY FAT!

Toss the Prox in the dumpster.
Even a stock exhaust port will get short cct on anything larger than a 90mm bore from my own personal experience. Probably smaller too though.

[2T500]

did you ensure your head gasket is big enough for that bore?
did you cut the head squish band larger to match the larger bore?
lastly, I have had a prox short cct around the exhaust port, due to the narrow face of the piston as roostius has explained and shown pictures of, and it was unjettable, at least not to perfection, and I had to go REALLY FAT!

Toss the Prox in the dumpster.
Even a stock exhaust port will get short cct on anything larger than a 90mm bore from my own personal experience. Probably smaller too though.

x2 on the above, use some ether engine easy start spray around any likely suspect area's to help find an air leak, engine revs up as it sucks it in, intake boot, left hand cover off .. not on any seals directly, get high on to much of that stuff or pass out so maybe do it outdoors

[Tharrell]

A leakdown tester is very easy to build, probably less than 20 bucks.
I can't find pictures of mine but this is pretty close.

[nmdesertrider]

Fixed me too- DGN too lean on a couple of bikes

Try a DGL the DGN is way to lean if you ride on the pipe!!!

[cmotodad]

I went to a new needle. DCK I believe sounds better. I will give a report after a ride

[AlisoBob]

The "C" has less taper.

Less taper is leaner from 1/2 throttle to full throttle.

[cmotodad]

I may be mistaken. I will check and let you know.