Yamaha TRX850 Enthusiasts Forum

So Quan, I assume that the barrels are bored out and the actaul capacity is 900cc now?? Is that right?
Is it a noticable difference?
And of course most importantly, wossitcost?!

My question is why?

The cost of resleeving the barrels (that is right isn't it - you haven't overbored the originals?) will be fairly high and the lower compression pistons will negate the capacity increase?

1.5mm over bore and hi comp pistons is the way to go IMHO

I don't understand why either - the reason ther TDM bhoyos are doing it is to rectify the oil burning issue.
The one that I know to be done here in Edinburgh runs really well, is quiet and uses NO oil whatsoever .....job done

by doing the job yourself, and having very good connections with a bike shop (thus wholesale / cost price) means you can keep your overheads to a min.

Did this work myself so that helps.. YES the TDM900 pistons are indeed lower comp, but such is life really.. Its the direction i headed and im happy with it.

Not sure about actual power yet, as the engine in still in bits (doing other things atm)..

Quan-Time wrote:by doing the job yourself, and having very good connections with a bike shop (thus wholesale / cost price) means you can keep your overheads to a min.

Did this work myself so that helps.. YES the TDM900 pistons are indeed lower comp, but such is life really.. Its the direction i headed and im happy with it.

Not sure about actual power yet, as the engine in still in bits (doing other things atm)..

10.5:1 versus 10.4:1................less than 1% difference - a good bit of carbon will even it up in a couple of thousand miles........

ive heard that with the TDM900 pistons in a TRX block and crank, it puts it more like 9.8:1 comp ? altho i cant confirm until i do a static compression test. Ive CC'd everything and can actually assume / calc it, but id rather wait and see..

Copper gaskets in varying thickness can easy change compression 0.3:1 if needed.. But need to check valve / piston clearance and what not.. Bigger cam obviously changes this some what..

Guys.....

some German already did a full exchange with the TDM900 injection engine. Don't know the exact information, but the 'conversion' had little adjustment with de engine in the TRX frame

Here are some pictures from the German TRX site....






Very nice done I must say, makes me wonder .... my neighbour has a TDM900

obviously the TRX and TDM motors share the same case.. bar a few minor changes.. Ive not physically compared the 2, but i do know that the TDM has an extra bolt hole for mounting into the frame, and one mounting point is "tight" to get in as its cast at a different angle (like 2deg or somethin.. but it will go without damaging anything).

Electrics are almost a no-brainer and can bolt right into the stock harness.. Few extra things are needed.

Its a good option but an expensive one. Not only are you up for a whole donk, but the harness to go with it and some accessories. Can prove hard on the wallet.

Ive been having a HUGE time at work as.. err.. something "came up" as it were.. If you know what i do for a living, it would make sence..

But im still working on my TRX900 and will get around to testing on a bench with TMD900 injection when i get some time.. Will require some tweaking,, but long as it starts and idles, ill be set.. Means i can put it on a dyno and go from there..

anyway, can you track down more information on what exactually he changed and what "bolts in" and what needs extra stuff ?? id like to see if he used a stock ECU or a PC3 of which i intend to use. mounting points could prove useful..

anyway, i like his R9 logo.. interesting.. ill stick with the TR1X tho

Yep I thought so 2, R9 nicely found