Yamaha TRX850 Enthusiasts Forum

Ok Just a thought....for the moment

Looking at the TDM 900 lump, it doesnt look too far out to get it to fit.
Using the TDM loom etc you get 86bhp, 6 speed box,fuel injection and potentially the use of the TDM digital speedo.

You can get a very low mileage engine for around £900

So once thats fitted the possibility of tuning.
Upgrade ecu and injectors,free flow exhaust, porting and perhaps a raise in compression.

see links for main idea
http://www.mcnews.com.au/newbikecatalog ... /Page1.htm

http://www.powercommander.com/catalog/2 ... tEBook.pdf
perhaps 100 bhp+

What do u lot recon?

I reckon you should take a closer look at CULater's "TDX"

"search" is your friend

Looking at CU laters's its obviouly a TDM to start with....
I was under the impression that the mountings were slightly different between the TDM/TRX.

I could be completely wrong though

As for the search....when i try it just hangs

philk wrote:Looking at CU laters's its obviouly a TDM to start with....
I was under the impression that the mountings were slightly different between the TDM/TRX.

I could be completely wrong though

Frame is different, mounting points on 850-engine the same although the TDM uses a bracket for the upper mounting were we usually put the crash thingy.

There's only one mounting point (behind the righthand cilinder were the crashpad bolts on) on the 900 engine that wil fit. (but it isn't even drilled out) the other mounting points are non existing.
The axle on the rear of the engine fit no problem and the mount on the bottom of the engine also fitts, but that's it!
So, if your a wizard with the welder.................

On the pic you can see the mount behind the cilinder, and the new mount in front of the cilinder

I seriously looked at this when I blew my motor last summer and decided against it for a number of reasons.

You may be able to get the motor for £900 but that will not include the loom, CDI, injectors etc and the cost of those will add up. You can make the electrics work (inc the speedo with the right senders etc) but then of course you will have the extra cost of the TDM instrument cluster. I'd be surprised if you could get the bits you need for less than £300. The alternative, it to use the TRX head on the TDM motor with carbs (preferably flatslides) - about the same cost as a PCIII (ish).

Then of course, the TRX frame needs modding - not a massive job but you need to know someone who can weld. And then you'll need to powder coat the frame to tidy it all up!

And for what? OK, a 6 speed box would be nice - but then I've never felt myself wanting an extra gear. 86bhp? Only 4 more than the claimed figures for the TRX. Then there is very limited tuning potential on the TDM motor unless you want to spend big (no off the shelf big bore kit, hi comp pistons etc.). Lower mileage - perhaps? Less oil consumption - perhaps?

PM Dandywarhol if you want to know how much power you can realistically extract from a TDM lump. His has been tuned by TTS (can't remeber exactly what has been done but it involves PCIII and aftermarket cans) and that makes 88bhp at the wheel.

In the end, I opted for a very low mileage TRX lump and tuned that (again!).

Thanks for that

I agree with Phuk on this one: it's changing for changing's sake, which is not a bad thing to be different, but the tuning potential of the 900 mill is limited. The money would be better spent on cams, overbore, head work etc on the standard motor.

My engine is standard inside, but just with FCR carbs, foam filters and a full 2-2 Renegade system, power is measured at 90bhp at the back wheel.

trixynut wrote:I agree with Phuk on this one: it's changing for changing's sake, which is not a bad thing to be different, but the tuning potential of the 900 mill is limited. The money would be better spent on cams, overbore, head work etc on the standard motor.

My engine is standard inside, but just with FCR carbs, foam filters and a full 2-2 Renegade system, power is measured at 90bhp at the back wheel.

thats 2 more than Dandy Warhol's tooned 900 (which i rode in sept) i tink yer better off sticking with a TRX enjun and tooning the tits off of it, the only ting is the 900's do not use ANY oil atall atall. Although having said that, big bore kits are available fer the 900 barrels if you so wish, pistons, carillo rods etc etc can be sought out and in the early days a guy i know had all this stuff especially made fer his TDM 9 at a HUGE cost ££££$$$$$. in my expert opinion the best bet would be a TRX enjun fitted with TDM 900 barrels (left at 897cc or fitted with a 960cc kit or even larger) topped off with FCR carbs and a TRX head with wilder cams (and bigger valves if they are available and fit ??) s'all doon to munny i guess..........



ps im starting my 900 conversion in Jan. as i now have all the necessary parts required.

Anyone know the reason why the 900 engines don't use any oil?

Even after the rebuild mine uses oil like it's going out of fashion. I know it burns a bit on start-up. I also think that probably it's a rings thing, Even with the new rings my bores were slightly out of spec, but the engineer I used reckoned it would be OK wth just a hone and new rings. Personally I think it may have been a better deal to have rebored and fitted new pistons.

I'm always scratching my head when so many complain about the TRX using oil. Mine doesn't seem to use a drop, pre rebuild or after...

My first motor in this bike drank oil like it was going out of fashion (at worst a litre every 1000 miles) even after I stripped it and changed the rings.

The next motor used none at all. Then I big bored it and tuned it and iy still doesn't use a drop of oil no matter what I do to it!

Seems every one is different!

Did the first engine smoke a lot? A little? None visible?

I'm with Max on the oil burning front, I'm on my second TRX and neither one has used any oil at all despite a somewhat less than sedate level of use. Maybe they like a damn good thrashing!