Yamaha TRX850 Enthusiasts Forum

I know this topic has been covered before. However, I want to find info on the stretched valve issue.

Please post if and when your Trx850 valves failed, with engine number and kms.

My Trx850 is a 1996, engine no 4NX002573, 37530km. No issues and no oil consumption.

the valves dont stetch, the inlets just wear, normal valve wear. This then results in heat retention and premature wear of the valve stem seals.

You can diagnose it by seeing your clearances tighten up significantly. Stock shims will be about 1.80mm, if you are using 1.60mm or smaller safe to say your valves are worn

Also, being a big twin its not unusual to see glazing on the bores, which will also result in oil consumption.

That said oil consumption is only an issue when it becomes excessive, say greater than 1ltr per 1000km.

Mine is a 96. Dont know about the engine as it was replaced at some point and has no number stamped on it, just 4NX and then blank

Plenty of pictures here from when I did the top end on mine, you can see the wear on the valves are shine on the bores

http://www.trx850.com/phpBB_forum/viewt ... &start=165

I couldn't get any gauges in and low power so went the whole shebang with new valves from Kedo in Germany. 35ish thousand k's

Ghunter wrote:Please post if and when your Trx850 valves failed, with engine number and kms.

What do you mean by "failed"? 33633 Miles here or ~54000km, nothing catastrophic yet but did the valve clearances at 25568 miles or ~41000km.

Is it time to sell?

UK model engine number4UN - 0064xx

Mine started at less than 10,000 miles. Its a '96. Poor starting and exhaust popping til it was warm. Checked clearances, 4 were minus zero clearance. That's a genuine.mileage too!
What I find strange is the TDM came out with the identical engine in 96 and I've never heard of any of them with tight clearance syndrome