Yamaha TRX850 Enthusiasts Forum

Just bought my trx and its great, I have also got a bare frame and log book as well, I love the std bike but I cant just look at a spare frame it needs turning into a bike.

I need help deciding what forks, wheels exhausts swinging arm etc
can some one give me some tips I am ok with the spanners but dont have lathes milling machines ect so and deviation from stock will have to be bolt on, is it worth getting a 900 tdm motor.

Iwould be gratefull for any advice tell me what your trx would be like if you had the time to build it...............................

Vicar

ive often thought of getting another trx tbh but have to many bikes as it is, however i would love to get another and go down the strip off all the extras route and put lightweight wheels on it along with 878 fcr's custom exhaust under the seat maybe chrome or other metal coating to the frame along with modified bodywork. Killerwhals bodywork is the best ive seen so far but i would love to get some pure carbon fibre unpainted r1 stuff to fit

Re TRX vs TDM engine. No real changes have been made to the TRX engine since 1997. The TDM engine is still in production and has many improvements over the TRX including stronger rods, stronger small end pin, clutch improvements, detail crankcase mods, plated alloy barrels, an air injection system which can easily be modified to provide crankcase vacuum, camchain tensioner, more alternator inertia and probably more that I am not yet aware of. The six speed box is a disadvantage for a sports road bike. Its ratios are chosen for an adventure bike and not suited to a fast road bike. The TRX was never a big seller and parts are going to become more difficult to obtain into the future. For me, the TDM engine offers more potential. As far as I know, the only difference in the engine mounting points is the head. I would modify the frame to fix that. I would love to compare a TDM and TRX gearbox to see if its feasible create a hybrid between the two using the TRX lay shaft and first gear and maybe fourth and fifth to create a true close ratio six speed. And then theres the fuel injection, using either the stock ecu and a power commander, or for ultimate flexibility a megasquirt which would be easier to fit to a TDM engine as it has the sensors already fitted, including a cam position sensor. On a side note, has anyone looked at a YZF450 or WR450 piston? This would bring a TDM or TRX out to 957cc and they are relatively cheap.

lenny wrote:On a side note, has anyone looked at a YZF450 or WR450 piston? This would bring a TDM or TRX out to 957cc and they are relatively cheap.

I think the water jacket might be too thin to take it out that far. I do like the idea of a nearly-1000cc TRX though...

Fuel injection? Nah. FCRs FTW!

edit- YZF400 pistons are 92mm which would give 897cc

I think the water jacket might be too thin to take it out that far. I do like the idea of a nearly-1000cc TRX though...

Do you mean water jacket or cylinder sleeve. I'm pretty certain a tdm barrel could be machined for a slightly larger sleeve. Can't see the problem with the water jacket.

Fuel injection? Nah. FCRs FTW!

Fine if you want to limit to 41mm, but if you want to go to 45mm and still have a bike you can ride in traffic, fuel injection is the only way to go. Reminds me of the points vs electronic ignition arguments of a time past.

One word....... Rotrex!

lenny wrote:

I think the water jacket might be too thin to take it out that far. I do like the idea of a nearly-1000cc TRX though...

Do you mean water jacket or cylinder sleeve. I'm pretty certain a tdm barrel could be machined for a slightly larger sleeve. Can't see the problem with the water jacket.

Fuel injection? Nah. FCRs FTW!

Fine if you want to limit to 41mm, but if you want to go to 45mm and still have a bike you can ride in traffic, fuel injection is the only way to go. Reminds me of the points vs electronic ignition arguments of a time past.

Sorry Lenny, I meant the cylinder sleeve might be too thin to take a much larger piston and as for my comment on fuel injection, it's a personal thing- I just don't like injected bikes.

i hate injected bikes aswell never ridden an r1 thats injected that i like as much as the orginal less user friendly (read easy) i prefer the charachter of carbs and the fcrs are thre daddy imo

Thanks for your thoughts on Tdm vs Trx motors I am not looking for any big power increases, I have Kawasaki Zx10r for the scfi warp drive, I am new to the Trx only done 250 miles on it so far its got blue spots and master cylinder Art cans k&n forks dropped ect its loud and nimble its very nearly perfect but what I need help with is building the best handling Trx

Do I use r6,ri zxr cbr, frorks what will fit my yolks, steering stem. What swinging arm do I fit Ducati Triumph single sided, r6 ri yzf wheels for a 180/55/17 what has been fitted and how hard was it. I know anything can be made to fit but I dont have a lathe or milling machine.

I cant leave a bike alone. Victor

Triumph single sided arm fits, as do VFR400/750 single swingers too.Not sure of the spacers or bearings needed but Kayla could help you with that.
R1 or 6 forks work well, as do FZR1000 or YZY750`s.
YZF750 swingarms are popular too but larger rear boot slows drop in to corners a tad.I`m not going that route myself, keeping the 160 tyre for the `nimblemess`.

Thundercat forks work well and fit straight in the TRX yokes using all the TRX bits and bobs. You need a couple of small spacers for the wheel but that's about it. An early R6 front end (including the yokes) might fit straight in, but I haven't tried so can't be sure. USD isn't always better than RWU

Anything else that fits straight in the TRX frame isn't really worth bothering with to be honest. All the good stuff needs a stem swap (at least). I've got Thunderace forks (48mm rwu) in my bike and a Thunderace back end, mainly because it cropped up at the right price and at the right time, plus it keeps the TRX looking reasonably standard with rwu forks and a non-braced swingarm. The YZF750 and Thunderace back ends go straight in (but there's nothing wrong with the TRX arm- it's a lot lighter than both the Thunderace and YZF750 'arm- and a 5.5" wheel will go in with little trouble)

I can do you spacers or machining work to fit stuff to the TRX (I have a spare frame to make stuff fit)- have a look at my thread in the 'Members' Services' section or click the link in my signature to my (very bad, I know) website.

I was going to use the standard arm in my bike, but couldn't find one at a reasonable price (I modified the one I had to fit an FZR400) so bought the Thunderace arm instead as I had the YZF parts to suit it

Triumph single sided arm fits

A bit misleading Mincehead. Requires front of swing arm chopped off, front of swing arm narrowed to fit between frame tubes, new front bearing tube welded to swing arm, new suspension linkage mount welded to swingarm, both sprockets respaced. I only know this because I have all the bits.

Well that`s cleared it up then Lenny.
I only knew they fit after seeing another TRX with one, didn`t know all that was entailed in making it happen though.I wouldn`t do it myself, too much weight sapping BHP.

vicar wrote:Iwould be gratefull for any advice tell me what your trx would be like if you had the time to build it...............................

Vicar

I'd build mine exactly the same as it is now with the possible exception of a full fairing (an d a few other bits which I've got planned)

phuk72 wrote:I'd build mine exactly the same as it is now with the possible exception of a full fairing (and a few other bits which I've got planned)

Kind of the same here, except I'll be putting a bolt-on subframe on next time and I'll do the TZ fairing properly. I miss the clip-ons Some 3 spoke Dymags would be nice.