Yamaha TRX850 Enthusiasts Forum

Hi all.
I'm in the process of rebuilding my race TDM Mk1 which has a TRX engine and CDI.
I'm in the process of fitting a set of barrels from a TDM900 and a set of Wiseco 11.5:1 pistons.
I will still be running the BDST38 carbs, a K&N in the TDM air box and an exhaust to fit the TDM but to the Akrapovic dimensions.

What jetting would suit the set up?
I'm just looking for a starting point before some dyno time.
I don't want to fry anything before I get to use it!!

MadAd wrote:Hi all.
I'm in the process of rebuilding my race TDM Mk1 which has a TRX engine and CDI.
I'm in the process of fitting a set of barrels from a TDM900 and a set of Wiseco 11.5:1 pistons.
I will still be running the BDST38 carbs, a K&N in the TDM air box and an exhaust to fit the TDM but to the Akrapovic dimensions.

What jetting would suit the set up?
I'm just looking for a starting point before some dyno time.
I don't want to fry anything before I get to use it!!

Just ran a dyno on: TRX900, wiseco 11,2:1, FCR41, akrapovic 2-1, head job,etc.
Super mech had to go up in size from the 878cc TRX and it was fitted with 170 main fuel and drilled main air to 220
I really think you should chuck the airbox and either do dynojet stage 3 or take out the wallet for a set of keihins!!

The wallet is playing hard to find after getting the barrels and pistons else there would be a set of FCR41's in there too!!

I was concerned about chucking the air box as I have heard the CV carbs are hard to set up without it?
I had thought of using some velocity stacks on the CV carbs to see if that helped but it's all heading into a bit of a grey area for me.
Also not sure how the bike would look without the air box?
See attached (if I managed to get it to work!!)
Although I may allow me to move the fuel tank up front again?

Me likey Not real pretty but I like your thinking

Gald you like!!
Pretty was not aim it's more function over form!!
Wait loss was the main goal and I got the TDM down to 175kg wet!!
That pick is about 2 years old now and I have since changed the forks and swing arm!!

Killerwhale, I have had a look about and can't find a stage 3 Dynojet for the TRX.
Do you know where I can get one from?

MadAd wrote:Killerwhale, I have had a look about and can't find a stage 3 Dynojet for the TRX.
Do you know where I can get one from?

I know trixz in here had it on his but he´s moved on from the trx...check with dynojet?

Umm not good Dynojet only list a stage 1!
Odd thing is they do a stage 3 for the 91 - 96 TDM??
Going to have to check my info and see if the early TDM was jetted the same, I know the carbs were the same type.

Have you tried Factory Pro?

Urgh completely forgot about Factory Pro!!
Just been and looked and they for a Carb kit 1.1 with Ti needles which I would get the emulsion tubes with as mine are looking a little egg shaped!!
Has anyone any experience with the 1.1 kit? There was little to no info as to what was in the kit and if it would go far enough for what I need.
I have sent them an email so will report back any findings!!

MadAd wrote:Urgh completely forgot about Factory Pro!!
Just been and looked and they for a Carb kit 1.1 with Ti needles which I would get the emulsion tubes with as mine are looking a little egg shaped!!
Has anyone any experience with the 1.1 kit? There was little to no info as to what was in the kit and if it would go far enough for what I need.
I have sent them an email so will report back any findings!!

Yeah - they were a pig to setup with the sharp taper on the needle for road use and I ended up using their tubes and stock needles - the whole shebang should be ideal for your use though - the needles give an instant mid range/top end richness.

from my experience:
FactoryPro emulsion tubes and Ti needles with std cv carbs, K&N air filter in std airbox(no modification) with a stepped 2-1 system and DB killer.
std main jets, needle in the middle clip groove and mixture screws 3 turns out
without the DB killer, there was a 'hole' in the 3-4thou range when you snapped the throttle open.
perhaps raise the needle a notch or a size up on the main without the exhaust restricter, but my setup seems to work fine on the road.
cheers
fung

Thanks all the info is greatly appreciated!!
Will post up results from the dyno run, when I get there!!
Lots of building to do yet!!

MadAd wrote:The wallet is playing hard to find after getting the barrels and pistons else there would be a set of FCR41's in there too!!

I was concerned about chucking the air box as I have heard the CV carbs are hard to set up without it?
I had thought of using some velocity stacks on the CV carbs to see if that helped but it's all heading into a bit of a grey area for me.
Also not sure how the bike would look without the air box?
See attached (if I managed to get it to work!!)
Although I may allow me to move the fuel tank up front again?

Bit of a random one but what wheels are you running on your tdm?

Mark the wheels I'm running are TRX front and Bandit 600 rear.
Needless to say I had to make up some spacers!!