Yamaha TRX850 Enthusiasts Forum

When the valves start to close down? Is it more difficult to get decent acceleration down low?
Last time I had them done I think, believe it or not, it was the inlets closing down, and not the exhausts. Doing lots of overtime to get the dosh to get them serviced. Even got back on the pushie for the commute to work (and to lose some weight)

Bob

Wombat Im no expert but performance should improve slightly when the clearence tightens up. But when they close up completely you start to lose commpression when hot so your symptoms should be hard to start ( when hot ) and backfireing or a change in performance between a hot and cold motor. I did my valves at 42000km and they were all tight bar the two inlet valves closest to the centre of the motor. They should not need redoing till 84000km. If your worried about it you will have to get the feeler gauges out you will have to buy a ''o'' ring for the water pipe and some cooant you should be able to reuse the tappet cover gasket as it is made of rubber. How long since you changed the spark plugs? Maybe carb problem worn needles or something like that. Good luck with it.

DOBBO wrote:Wombat Im no expert but performance should improve slightly when the clearence tightens up. But when they close up completely you start to lose commpression when hot so your symptoms should be hard to start ( when hot ) and backfireing or a change in performance between a hot and cold motor. I did my valves at 42000km and they were all tight bar the two inlet valves closest to the centre of the motor. They should not need redoing till 84000km. If your worried about it you will have to get the feeler gauges out you will have to buy a ''o'' ring for the water pipe and some cooant you should be able to reuse the tappet cover gasket as it is made of rubber. How long since you changed the spark plugs? Maybe carb problem worn needles or something like that. Good luck with it.

Dobbo, that pretty much sums it up. Starts up cold quite easily and runs fairly well when cold. Only use it lately to commute 12km to work. When she warms up the performance down low seems to suffer a bit, above 4,000rpm it runs quite well. Does seem to cough and stall a bit when started hot. Got basically a full service bar valve adjustment back in August (I think?) at 66,000 and for two months it has been running extremely well. Spark plugs were changed at last service. I was always putting in iridium plugs, and at every service they take 'em out and replace them with the bog std ones Emulsion tubes were changed about 2 years ago, I had Factory Pro ones installed but after the shop (different shop) installed them the bike ran like an unrideable dog, so back in the shop and they moved the needles to richen it up a bit. A friend of mine from MAW (motorcycle and accessory shop here in Sydney) told me that the genuine Yamaha ones are best as FP needles are stepped and not a smooth taper and therefore wear quicker again. That was 10,000kms ago and I wouldn't be surprised if the things were worn again. I've had all these symptoms before (tight, sluggish motor below 4K)........ So many things wear out at exactly the same time........$$$$$$$$$$$$ Oh to win the lottery, eh?

Bob