February 27, 20197 yr I bought a bucket of parts 1998 (US) Gas Gas TX 320 that I'm using for an EV conversion (longer story here) I was looking at the motor and saw what appears to be wood or cork in the crank counterweight, its feels like soggy wood when I touched it with a probe. Is this OE? I haven't owned a 2T since I was a teenager with a gas stand up scooter. There used to be home made or aftermarket "Stuffed" cranks that reduced the crank case volume to increase the intake velocity and primary compression. That said, wood still seems to be an odd choice if this was the goal of GG or someone else. It doesn't matter for my purposes as I'm doing an EV conversion, but curious nonetheless.
February 27, 20197 yr Your assessment regarding stuffing is correct. I don't know if it was OE or not, but "modern" 2T trials bikes use high primary compression ratios. This yields a lot of torque at low engine speeds at the expense of greater pumping losses. The exhaust systems are usually quite simple and don't benefit from a large crankcase volume. The holes are for balance factor, so if they are plugged, it's with a low-density material. Often, a sheet metal cover (think automotive frost plug) is pressed into place. I have seen cork epoxied into place as well. The fact that it's still there says the material has decent longevity. Edited February 27, 20197 yr by konrad Is anybody happy with their first draft?
February 27, 20197 yr Author 7 minutes ago, konrad said: Your assessment regarding stuffing is correct. I don't know if it was OE or not, but "modern" 2T trials bikes use high primary compression ratios. This yields a lot of torque at low engine speeds at the expense of greater pumping losses. The exhaust systems are usually quite simple and don't benefit from a large crankcase volume. The holes are for balance factor, so if they are plugged, it's with a low-density material. Often a sheet metal cover (think automotive frost plug) is pressed into place. I have see cork epoxied into place as well. The fact that it's still there says it has decent longevity. I would expect something like a polymer insert, Silicone, etc. for an OEM job. Cork/Wood just seems out of place, but as you indicate, it's a 21 year old motor and it's still there can't be too bad.
February 28, 20197 yr Pretty wierd and most likly not stock.I use to do stuff like that when I was a teenager lol.I used cork and jb weld back then.Never had anything fly apart but also did not notice any power change.I tried regrinding a cam for a go cart one time as a kid (brigs motor)Ran like hell in a go cart for about 5 minutes.
February 28, 20197 yr Many used cork in the day and it is likely factory. New ones would be modern plastic. Besides, my old crank still gets wood, and I am much older.
February 28, 20197 yr Author 19 hours ago, copemech said: Many used cork in the day and it is likely factory. New ones would be modern plastic. Besides, my old crank still gets wood, and I am much older. Many OEMs or many owners?
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