setting valves

[thomkat219]

Have an 04TRX450r. Polished and ported, std. bore and piston. HMF slip-on. Open air box with Uni filter and proflow adapter. Jetted with 180 main.

After the 1st 8 months of ride time, the intake valves were cupped. Installed new ones.

Another 8 months has passed, and I am going to an 11.1 Wiesco piston, std. bore. Also new intake valves and seals.

I race harescrambles in Ar. and Tx., so lots of either tight woods, or just flat out wfo.

Question? When I install the new intake valves, do I leave them a little loose, or set them a little to the tight side?


Thanks, Thomkat

[exracer131]

well hey they tomkat, i am assuming when you say the valves were cupped it was from carbon build up between the valves and the seats. the next question was it the stock valves that were cupped or some you put in yourself? why i say this is when the valves were installed they might have not been lapped right???? if they are lapped correctly before you install them i would shim the valve at the stock tolerance( to tight the valve might not have a tight seal, to loose is just hard on the valves and cam.

[thomkat219]

The first set that were cupped, were stock, and had never been checked in 8 months. They were cupped from wear, not carbon. I don't really know what the set in there looks like, but they have not been check in 8 months. The quad runs great, and always get the wholeshot. I just want to freshen everything up, and going to a higher comp. piston. Stayin std. bore and using stock valves. At stock prices, you can afford to change them regularly. Just curious how most guys set up there new valves. Getting it right on might be the way to go. Thanks, Thomkat