Yamaha TRX850 Enthusiasts Forum

...TDM 900 enjun to reduce oil consumption & 6-speeder
...and in spring perhaps the TTS 937cc high comp kit, it should move some then!

Good project, but why?

900 motor with a PCII will be 85-90bhp which is the same as a 850 with FCR's and a pipe

and do you need 6 speeds on a torquey big twin?

Just asking...

But a 900 running FCRs should make a little more...

The TDM 6 speeder is actually a wider ratio box with stupid ratios for a sports bike.Most people fit the trx gearbox in the tdm cases. From another thread-
Re TRX vs TDM engine. No real changes have been made to the TRX engine since 1997. The TDM engine is still in production and has many improvements over the TRX including stronger rods, stronger small end pin, clutch improvements, detail crankcase mods, plated alloy barrels, an air injection system which can easily be modified to provide crankcase vacuum, camchain tensioner, more alternator inertia and probably more that I am not yet aware of. The six speed box is a disadvantage for a sports road bike. Its ratios are chosen for an adventure bike and not suited to a fast road bike. The TRX was never a big seller and parts are going to become more difficult to obtain into the future. For me, the TDM engine offers more potential. As far as I know, the only difference in the engine mounting points is the head. I would modify the frame to fix that. I would love to compare a TDM and TRX gearbox to see if its feasible create a hybrid between the two using the TRX lay shaft and first gear and maybe fourth and fifth to create a true close ratio six speed. And then theres the fuel injection, using either the stock ecu and a power commander, or for ultimate flexibility a megasquirt which would be easier to fit to a TDM engine as it has the sensors already fitted, including a cam position sensor. On a side note, has anyone looked at a YZF450 or WR450 piston? This would bring a TDM or TRX out to 957cc and they are relatively cheap.

trixynut wrote:Good project, but why?

900 motor with a PCII will be 85-90bhp which is the same as a 850 with FCR's and a pipe

and do you need 6 speeds on a torquey big twin?

Just asking...

My gearbox feels as it doing it´s last dance and £ will not be much more for a 14000km 900 vs. an overhaul of my enjun.
And although i got gaskets and pistonrings ready here for a hone to reduce oilconsumption i would prefer NO consumption! ...and my 878 kit with those bits should generate some £ also.
...and then we have the "why....because i CAN"

lenny wrote:The TDM 6 speeder is actually a wider ratio box with stupid ratios for a sports bike.Most people fit the trx gearbox in the tdm cases. From another thread-
.

If i´m correct the 900 runs 16/42 sprockets and a friend who testran one said it was a wheelie machine standard.
My thoughts are that it would be better to run it at 17/40.
Will be interesting run the enjun with my TRX race head and flatties, also got programmable CDI so we can optimize easier...

And here we go....

That`s blooody clean! I`m guessing a low milage donor?

Mincehead wrote:That`s blooody clean! I`m guessing a low milage donor?

Yup, 14tkm!

Info from the German TRX forum

http://www.mototwins.de/product_info.ph ... 0fffad3113


Adapterplate to mount the 850 oiltank on the 900 engine.
They are also happy to inform You how to get the 900engine into the TRX frame.

Maybe usefull

B-art

B-art wrote:Info from the German TRX forum

Adapterplate to mount the 850 oiltank on the 900 engine.
They are also happy to inform You how to get the 900engine into the TRX frame.

Maybe usefull

B-art

I got the adapter mounted already, nifty piece of kit!
Brummer on the forum has helped a lot, he only write in German though so...but pics say more that 1000...
He did a genious solution on his where he don´t have to specialorder front sprocket, but i´m not going that far...i think!

Why not keep the stock 900 tank (with oil level sensor already installed )

Having ridden a mk2 TDM850 with the ridiculously low 1st and the TRX with the ridiculously high 1st I find the 6 speeder in the 900 is fine for road use - a higher overall gearing would create a larger jump between every ratio. From memory, only 1st gear is different in the 850 TRX and TDM - the other 4 are the same (the post'99 TDM had a different set of ratios altogether)

My lightly tuned TTS 900 engine is nicely fettled and setup with a lovely sharp pickup at anything over 2000 rpm - much livelier than a stock TRX. I haven't ridden an FCR setup 850 so can't compare. Oil consumption virtually nil at 30,000 miles and the motor is still sharp. Akras and a dyno set Power Commander map help I'm sure. If you choose to use the 900 injection system there's a repository of various maps at Carpe TDM http://www.carpe-tdm.net/ipb/index.php?showtopic=8723 and I've one for a 900 with Kent cams I'd be happy to send to you (it might even be in the repository - can't remember jack shit there days )

I think a well setup 900 engine in a sorted TRX chassis would be a really useful road/trackday tool

dandywarhol wrote:Why not keep the stock 900 tank (with oil level sensor already installed )

I think a well setup 900 engine in a sorted TRX chassis would be a really useful road/trackday tool

According to the one´s who made the change the 900 oiltank won´t fit the frame...
Will start off with FCR´s since i have ´em, and inlets/ports are matched up...head needs to be lifted over from the TRX anyway. Bigger job changing the cablestem, and also i got a programmable CDI in my bike so i can switch maps from a computer.

Hope it will be a nice setup, just got to get my Matris cartriges in the front as well...time to get to it!!

High comp pistons bought and it was a bargain!
Sat for 800km in this bike, dyno 2-6th....

What? No pictures??