Yamaha TRX850 Enthusiasts Forum

In my case it started with very bad starting! With a cold engine i couldn't use the choke, once it was running and you pulled the choke out just a few MM it killed the engine. It also wouldn't idle on a cold engine, when the engine headed up there where no problems.

My bike did a little over 40.000km's when I checked the valve clearance. All the inlet valve's had 0 clearance (or less)! All the outlet valve's where still between tolerance.

I went to the local shop to get new valve shims I used the diagram from the Yamaha service manual the get the correct shims. But the shims where wrong, it had some clearance but not enough (0,012 max). With the new clearance I looked up the correct shims again. When installed it was better but still a little off. CIL 1 was all good (0,15 ~ 0,20) but CIL 2 was a bit tight somewhere around 0,12 but is went for it and put the bike back together.

With some struggle with the timing it went all well, test start up went good but when the engine headed up there was a small valve tick noticeable. Using a stethoscope I located the valve noise at inlet CIL 1 (the one with the correct valve clearance!) CIL 2 is silent.

My tip is to check your valve clearance at 20000km and don't set them to the subscribed clearance (0,15~0,20) set them a little tighter (0,12) this will prevent valve noise
I think Yamaha's subscribed clearance is a little big so it will last longer (it looks good in the service manual; check valve clearance at 42.000km)

A tight valve clearance won't hurt your engine, a wide clearance will!

My little tip for today!

I think you will find the reason you had issues with the first lot of shims is that you had a -neg clearence. what you should have done was fitted the smallest shim you had then recheck them to give you a bace clerance to work off.
justa note to those planning on doing the job.

That is what I try to tell with

All the inlet valve's had 0 clearance (or less)!

I should have made it more clear maybe.

lars wrote:
A tight valve clearance won't hurt your engine, a wide clearance will!

My little tip for today!

Wrong... tight clearances or no clearances will hold the valves off their seats. This will result in difficult to impossible cold old starting and if you get it running a very good possibility of burnt valves.

Loose clearances my be noisy when cold but as the engine & oil heat up they quieten down. The clearance is there to allow for the differential expansion of the metal components when hot. In other words the cold clearances are set to allow some clearance when warm, so one again you do not burn valves.

DFH

Hmm, this is sounding more and more like my 24.5,000 miler.

Glad I'm having the clearances done in a couple weeks, as it's my daily transport.

lars wrote:In my case it started with very bad starting! With a cold engine i couldn't use the choke, once it was running and you pulled the choke out just a few MM it killed the engine. It also wouldn't idle on a cold engine, when the engine headed up there where no problems.

My bike did a little over 40.000km's when I checked the valve clearance. All the inlet valve's had 0 clearance (or less)! All the outlet valve's where still between tolerance.

I went to the local shop to get new valve shims I used the diagram from the Yamaha service manual the get the correct shims. But the shims where wrong, it had some clearance but not enough (0,012 max). With the new clearance I looked up the correct shims again. When installed it was better but still a little off. CIL 1 was all good (0,15 ~ 0,20) but CIL 2 was a bit tight somewhere around 0,12 but is went for it and put the bike back together.

With some struggle with the timing it went all well, test start up went good but when the engine headed up there was a small valve tick noticeable. Using a stethoscope I located the valve noise at inlet CIL 1 (the one with the correct valve clearance!) CIL 2 is silent.

My tip is to check your valve clearance at 20000km and don't set them to the subscribed clearance (0,15~0,20) set them a little tighter (0,12) this will prevent valve noise
I think Yamaha's subscribed clearance is a little big so it will last longer (it looks good in the service manual; check valve clearance at 42.000km)

A tight valve clearance won't hurt your engine, a wide clearance will!

My little tip for today!