Yamaha TRX850 Enthusiasts Forum

i've heard tell of a 6speed gearbox upgrade made by overracing
anyone else heard of it or know if they still make them?
just thought i'd ask here before asking stooopid questions on the OR site incase my source was talking bollox

i'm actually interested in this for a TDM as i'm about to rebuild my spare engine, but the TRX will need doing at some point in the future too.......

TonyDevil wrote:i've heard tell of a 6speed gearbox upgrade made by overracing
anyone else heard of it or know if they still make them?
just thought i'd ask here before asking stooopid questions on the OR site incase my source was talking bollox

i'm actually interested in this for a TDM as i'm about to rebuild my spare engine, but the TRX will need doing at some point in the future too.......

I think they modified a YZF750 box....but never went serial.
Should be doable....but price???

I'm all for just doing stuff just 'because you can' but a six speed box has to beg the question: Why?

Dave.

trixynut wrote:I'm all for just doing stuff just 'because you can' but a six speed box has to beg the question: Why?

Dave.

For me....i just don´t like the gearing of the TRX....it´s just insane!!

all 3 bikes using this engine have plenty of grunt at top end, they just run out of revs
would be nice to bring the revs down a little for higher speed cruising and give the extra range for better top end

also the standard gearing on the TRX means feathering the throttle until approx 30mph when filtering thru town (this doesnt affect the other models of this engine)

there was a TRX on ebay about a year ago that was a TRX engine with a TDM900 conversion, this also used a 6speed box, alledgedly off a YZF750
i didnt have the cash to splash at the time, the 6th gear is the one thing i think the newer 900 engine has over the older 850 and i'd like to sort that out, its really just a pet interest. while i have an engine apart for rebuilding (including output shaft) i though i might do a 6speed conversion
i have 3 bikes that use pretty much the same engine and a spare engine to play around with
.....and because i think it'd be interesting to do
so why not ?

"if it aint broke, take it apart and fix it"

The last model TDM has a 6 speed gearbox but I don't know how the ratios compare. Would be interesting to see if it has a higher ratio in 6th than the trx's 5th.
if so it would give it a higher top end with stock sprocket sizes.
If the ratios are lower than the trx so 6th equates to 5th in the trx box then one could fiddle with sprockets to give the same result. i.e lower revs in top gear for a given speed.
I know I keep looking for another gear when riding.
Hope this makes sense.

Steve

Hi Tony!

As far as I have heard, the 6th gear of the YZF 750 SP is the same transmission ratio as our TRiXIe - so it would be no overdrive to reduce the revs ...

Just found it:
YZF 750: 2,57/1,94/1,55/1,36/1,21/1,08 (from http://www.yamaha-yzf750.de/link2.html German site)
TRX 850: 2,57/1,85/1,43/1,17/1,04 (from Haynes)

Really not much of an overdrive ... at least, the second gear is a bit shorter

Rummaging greetings from Munich!

just run a 17 front and 41 rear. gearing is fine then.

So, the YZF is not the way to go, but how about the TDM900s, does anyone know? Would be interesting like SS says. Either an overdrive for highspeed long distance cruising, or for getting the extra topspeed if the engine's tuned...

someone on here previously mentioned the price of the over 6 speed box and if i remember correctly it was a more than 2000 poons !!

bugger....i'll forget that one then

The TDM 900 gear ratio is:

1: 2.750 2: 1.947 3: 1.545 4: 1.240 5: 1.040 6: 0.923

CULater wrote:The TDM 900 gear ratio is:

1: 2.750 2: 1.947 3: 1.545 4: 1.240 5: 1.040 6: 0.923

Hello any chance you could post some pics of your MKI 900 on here so Tonydevil & I can see them please ???

wicky wrote: Hello any chance you could post some pics of your MKI 900 on here so Tonydevil & I can see them please ???

Pics of my bike ?

i say, you need to look at some more topics

http://trx850.motomaniac.net/forum/view ... c&start=30

TDM 6 speed looks like the goods then....