Vintage Dirt Bike Q & A

I purchased a IT465 (1982) the other day, it has a fresh rebuilt, I was thinking the bike would be a rocket but there is NO power ban what so ever! It has tons of bottem end then goes flat till you shift... top speed seems great but getting there takes FOREVER, my 84 kdx200 eaqts the IT465 in every gear
any ideas in what I need to look at? Im mixing it 32/1
found small crack in expansion chamber but it is really small

how quick are these IT465 supposed to be? I would think they should have a ton of power?

Timing off maybe.

If the piston was installed backwards during that rebuild, the loss of power would be described just as you have. Later, when the ring end catches on a transfer port and munches all those new parts, you will know for sure.

Pop off the cylinder head and make sure the arrow atop the piston points toward the exhaust side of the motor. If the arrow points back toward the carburetor, take the top end apart, replace the gaskets, and put the piston in with the arrow facing the exhaust.

If that's not the case, you might have a rat living in your airbox, or a wasp nest in your silencer. Make sure both the intake and exhaust are obstruction free just to be sure.

Good luck,
Jon

i welded the small crack on the expansion chamber and the power picked right up! but it blew the weld after only 10 minutes... But seems to be the problem, thanks for the replies guys!