Yamaha TRX850 Enthusiasts Forum

Will a TDM850 cylinder head swop out with a TRX unit? I bought a TDM850 Cylinder head from EvilBay in the hope that i might yet be able to recover my TRX. It arrived today and I'm impressed with the condition of it, its complete with EU regulation valves (straight) that seat and everything, the cam bearings points also seem to have much less wear than my head.

I had it in my head, from something I thought I read here that the TDM and TRX heads are different, but lining them up side by side I can't see a difference.

Initially I was going to throw the TDM head on my TRX and run a compression check again to confirm it is the valves (and do a visual with the head off) then swop the valves over into the TRX head, but looking at it, I'd better to just put the cams into the TDM head. Assuming there is no glaringly obvious reason not too?

TDM 900 heads ARE different, no mounting lugs being the biggest difference, but the TDM850 and TRX850 heads are identical as far as I know Neil.

TRX850 cylinder head (complete assembly) part number 3VD-11101-20 is the same as TDM850 1999-2001
You can use the parts finder tool on most Yamaha dealer web sites to easily check this stuff

Mincehead wrote:TDM 900 heads ARE different, no mounting lugs being the biggest difference, but the TDM850 and TRX850 heads are identical as far as I know Neil.

That'll be what I had in mind. Cheers Mince.

Good point Dicky, didn't even cross my mind to do a part number check.

Thanks gents.

dicky wrote:TRX850 cylinder head (complete assembly) part number 3VD-11101-20 is the same as TDM850 1999-2001
You can use the parts finder tool on most Yamaha dealer web sites to easily check this stuff

3VD is a MK1 TDM 850 number - 1991 - 1995. The suffix -20 is just a later production number. Any 850, TDM or TRX head should be ok, even the Mk1, just remember not to use the MK1 camshafts as it's a 180 degree engine. My 1996 TRX suffered from the dodgy inlet valve problem so I fitted a low mileage TDM head straight on.

dandywarhol wrote: just remember not to use the MK1 camshafts as it's a 180 degree engine. My 1996 TRX suffered from the dodgy inlet valve problem so I fitted a low mileage TDM head straight on.

MK1 Camshafts "from a TDM"? My TRX is a 1996, my plan was to fit the camshaft from my TRX into the TDM850 head...

Overlord Neil wrote:

dandywarhol wrote: just remember not to use the MK1 camshafts as it's a 180 degree engine. My 1996 TRX suffered from the dodgy inlet valve problem so I fitted a low mileage TDM head straight on.

MK1 Camshafts "from a TDM"? My TRX is a 1996, my plan was to fit the camshaft from my TRX into the TDM850 head...

Sorry, I was generalising - yep, that'll work just fine

Cheers