Yamaha TRX850 Enthusiasts Forum

Can anyone tell me the difference between TRX 850 camshafts and the TDM 900 camshafts? Only thing I can find on the TDM is lift, no duration, opening or closing...... are they the same or not? If not are they a viable upgrade?

Cheap and easy way is a regrind on the cams.
Kent are a popular choice with a few variations on lift and duration.
1.....
Yam9 is a good choice for std motors with an extra 0.3 lift and 12* extra duration on the inlet and 2* on exhaust.
The 240/240* Only gives you 4* extra overlap so doesn’t impact too much on the dynamic compression of a std motor but the extra inlet duration moves the opening to an optimum position.
Will give you healthy gains in midrange torque and a 2-4 extra HP at peak.
Will easily accomodate the std CV carby’s .

2....
They have another option that is 252/252* with 0.5mm extra lift but this impacts on a std motor and decreases the dynamic compression so the losses in the low and midrange really cancel out any gains up top. You’ll need 11.5:1 or higher compression to get these to work correctly.
There are a few other options out there but Kent these are the best bang for bucks.
3.....
V2 /Over Racing asymmetric camshafts 249/256* 0.3mm extra lift are rare as hens teeth and no longer available but similar regrounds are available from a friend in Germany.

cobbadiggabuddyblooo wrote:

3.....
V2 /Over Racing asymmetric camshafts 249/256* 0.3mm extra lift are rare as hens teeth and no longer available but similar regrounds are available from a friend in Germany.

I expect these to be in the OVER engine (currently as spare).
German friend = Huby?

Correct Robert
3* less duration than the V2/Over cams on inlet and exhaust but you get 0.5mm lift.
Asymmetric ramp profiles so faster opening and slower closing

you very to the point Cobba...
So I need Yam 9 cams......

Really good drive out of corners and you can notice the power tap being turned off once past peak torque around 7,000rpm. It’s still making HP but just feels like someone turned off the tap.
But you get good gains in the midrange and just the tuning of the cams but work really well within the boundaries of the std compression.
Do the head gasket mod to sneak in a little more while at it and keep the std 142 main jets and airbox and see how you go if you remove the air filter.