jlo 295 metallic pinging

[radioactiveboyscout]

I recently purchased a Max II with the JLO 295 in it. After performing a Mikuni carb swap to get the engine running I've noticed a metallic pinging coming from the engine. I don't supposed this is a normal JLO noise? I understand 2 cycle thumpers can be noisy but I'm concerned it might be the piston slapping the head or something.

[countrybumpkin]

Take spark plug out and roll engine over by hand and see if you feel any resistance. Also make sure spark plug is right and not too long. Could have some carbon build up in head if it had carb issues.

[Don]

Do you know the main jet size you're using? If you're way lean the engine can ping.

[radioactiveboyscout]

It turns over smooth. That is the first thing I checked after I bought it. I compression checked it and turned it over to look at the piston skirt etc.

Mixture is a good point. The Mikuni carb I bought off of ebay was from a snow mobile and came with a main jet of 117.5, pilot of 40 and a 5DP7 needle. It starts fine. Not sure if those jets are good for 6000 ft which is where my house is at?

[brian v]

On my jlo 400 the outer cover on the clutch was lose and was making a metallic sound I tightened the big but on the side of the clutch now the clutch is quite. but it still has a slight ping/rattle at idle I am not shire what is causing it rattle hope this helps

[Don]

This is going from memory and I haven't worked on a 295 in a while, but I think we always started with a 135 jet and went from there. Hope this helps.

[radioactiveboyscout]

Thanks for the feedback. I'll check your suggestions. Over the weekend I ran it quite a bit and noticed that it only makes the noise near idle. So it's likely something loose that is resonant at the idle frequency.

[brian v]

OK let me know what u fined out