Yamaha TRX850 Enthusiasts Forum

Happy new yr to all too.
New about it for 6 months and just had to find a way of getting it out of the country...

Import monster was the way I got it from Japan to Australia in the end and shipping/ commission and GST alone cost me about $900 just to get it in a container and shipped to my door.
Sat in their warehouse in Japan for about 3 months and is finally on its way so I should have it by February.

^ that is epic.

I hope that you are going to strip it down once you get it so that you can taunt us with pics of the internals (and let us all see how it is done)

cobbadiggabuddyblooo wrote:Took a while Robert but finally got my Over 6 speed close ratio box..
Picked up a complete Over spec motor including rods, 6 speed , pistons and 2mm O/S valves with some long duration 8.9mm lift cams and port job.
Was a spare race motor from mid 90’s that’s been tucked away in a garage for 20 yrs.
Couldn’t believe my luck...

Awesome!

waiting for the comparison test between that and your SP build.......

Good find Brian - more than that - fantastic find!

Motivated once again I went into the man cave to finally fit the TDMR40’s I have for the white TRX.
Removed the air box and took off the std CV carbies and the first thing that was apparent is the inlet rubbers. Shot to pieces so into the spares and put on a new pair of genuine rubbers.
Looking into the inlets I was amazed at what I found. I knew the inlet valves had been replaced recently but who ever did the service needs a clip over the ears.
Inlet ports had was partially covered with tiny black balls of a gritty feeling material.
Rod to the rescue and informed me from the photo, has the bike had a foam filter fitted. When they degrade and mix with oil /fumes from the breather you get this same outcome.
But it’s the original airbox and K&N Filter fitted.
So I went back to look at the airbox and found the culprit. The foam fitted around the airbox to seal it under the tank was degrading and falling apart especially under the inlet horn.
Opened the airbox to find how this was getting past the K&N filter.
There are 4 tangs that sit against the air filter to hold it hard against the box to help seat it.
Great for the std plastic framed std air filter but with a flexible K&N rubber frame the centre 2 actual sit the other side and allow air to sneak in under the removable air box horn section that allows you to access the air filter.

So if you have a std trx , check the foam surrounding your airbox. If degrading remove it all. If you have a K&N filter fitted find a way ( maybe a drop of sealant to hold the filter hard against the box in the centre before fitting the horn or lid.

I’ll post photos when on the lap top or view on Facebook

I dealt with the TPS today to suit the TDMR40’s due the TPS mounting on the opposite side of the throttle shaft to the std Mikuni’s.
Mounted on the opposite side reads the voltage from approx 5v at 0% throttle to under 1v at 100% throttle.
Changing to 2 outer pins around fixes this issue and changes the voltage reading from the tps the correct way so 0% throttle is the minor voltage reading to 100% throttle being the higher voltage reading.
Remove the white retaining clip , then with a small jewels blade driver you unclip the pin and remove the wire and pin from the block.
Swap the two outer pins around( brown and black/brown) and clip back in place.
Turned on and calibrated in the Ignitech program and all done.
First ride and noticeable difference and has taken the hesitation upon opening the throttle away.

Brake pad info
Brembo 30Y05 pad size.. 71.1mm x 55.5mm x 8.7mm
DP sintered
SDP 630 HHT

Blue spot info
69.8 x 51 x 8.8mm
DP sintered
SDP 418

Phone call on the weekend and the Thundercat forks I picked up for the white TRX are completed.
Modification being to remove the orifice style cartridges on comp and rebound ( same as fitted on the YZF750 forks ) and retrofitted some Yamaha shim style MT compression cartridges and the rebound cartridges are from a GSXR.
I chose to run an R6 rear shock so it’s in being rebuilt and damping curves altered to suit the TRX specs.
The R6 red spring will match the red frame and RSU forks will still give the trx a std looking format.
Now to decide which motor to use.
Plans are to fit the 6 speed / Over spec motor, FCR’s into the black TRX and put the Over system on there too.
Leaves me 3 motor choices for the white one.
Std motor , std with higher comp or the Arias motor
TDMR’s and choice of Akra 2-1 or Nojima race system.
So much for my plans to keep the white one fairly std

So glad to see that you are still working on decisions. My choose would be the arias motor with the nojima exhaust. Never heard of that, makes me curious.

Now it’s time to try and find as much tech info as I can on the Over 6 speed.
I sent Don Stafford in Melbourne a message as I know he was the Over Racing Authorised dealer here in Australia and had a fully kitted Over racing TRX he raced back in their day.
Sold that tho for $19,000 with all the spares 13 yrs ago but hopefully he’ll still have some info.

Ok German Supertwins forum to the rescue...
Over/YEC gear ratios ........ Std trx
1st 2.923 ( 38 / 13 )..... 2.571 (36/14)
2nd 2.187 ( 35 / 16 )..... 1.850 (37/20)
3rd 1.777 ( 32 / 18 )..... 1.429 (30/21)
4th 1.500 ( 30 / 20 )..... 1.174 (27/23)
5th 1.272 ( 28 / 22 )..... 1.037 (28/27)
6th 1.125 ( 27 / 24 )

Next quest is I lifted the barrels today to find slipper skirts on the piston plus H Beam Conrods.
Now I need yo find out of the titanium rods used for the trx where a H Beam as they look very similar to the Carrillo rods I already have.
I didn’t remove the pistons all the way from the barrels so in hignsight next time in the garage I should just remove them and weigh the pistons while at it and have a jolly good look at things.

cobbadiggabuddyblooo wrote:Next quest is I lifted the barrels today to find slipper skirts on the piston plus H Beam Conrods.
Now I need yo find out of the titanium rods used for the trx where a H Beam as they look very similar to the Carrillo rods I already have.
I didn’t remove the pistons all the way from the barrels so in hignsight next time in the garage I should just remove them and weigh the pistons while at it and have a jolly good look at things.

And post pics