The TRX900 Project kicks off

[cobbadiggabuddyblooo]

Two factors at play, you change to a larger rear sprocket,this pulls the axle point further forward shortening the length and effectively giving you a slightly shorter leverage length.
It also and ever so slightly gives you a little more anti squat because of chain pull angles.
Here is a little light reading that gives you a basic outline.
It would be adventitious to start with a spring rate set to your weight to start and if your swing arm length is slightly longer talk to a suspension specialist who is re springing your bike as more than likely he will have a program to work out these factors..

http://www.promecha.com.au/leverage_linkages.htm

[dandywarhol]

Changing the bones does affect the rising rate characteristics.

You could punt some of the shite in your back yard and get an Ohlins

Good pic - thought it was Phil Read at first glance.............................

Cobba - I'd have thought that pulling the axle forward on squat would make it squat more

[cobbadiggabuddyblooo]

That's where the chain angle comes into play.
But if you go up 1 tooth on the rear and down 1 on the front you may find the squat from the slightly shorter wheel base may cancel out the anti squat of the chain angle.
But you can have 1 tooth higher on the front and 4 or 5 teeth on the rear that may give you exactly the same gearing but chain angles and lengths may be different as you have an extra link or 2 placing you back close to centre but a whole new chain angle.

[dandywarhol]

Gottcha

[oddballjon]

Hi all you TRX nuts out there,
I've been told that one of you guys is fitting a TDM900 engine in a TRX frame.
I too am doing this, although just at the beginning stages at the moment.
I have the lower sub frame fitted, that was the easy bit, had to remove the oil tank as this fouls the frame, but will be fitting a much nicer looking TRX oil tank. I will be drilling and tapping the right hand side of rear cylinder head which lines up nicely, will make new brackets to replace the small triangle brackets,( not at the moment to sure as to were I will fix them to) and will add frame tubes to run to the front cylinder mounts.
Need to find out which of the many TDM sensors I can do without.
Possibly do away with the air box completely, and just fit sock filters.
I'm thinking a different electric fuel pump fitted (somewhere).
Will post photos when I take some in a smaller format.(watch this space)

[coxylaad]

Hi john,
Nice to see you on here. Ditch the triangle brackets, they are not required.
The 900 oil tank does fit and with that you retain the 900 oil level sensor.
Also although the lower cradle bolts straight up, if you want to reduce you headaches with chain alignment later on in the project you would like to mill off 6mm from the right hand side mount on the cradle. Have a good read through this thread. I have had this bike on numerous track days so it's fairly well proven.

[coxylaad]

quick update:

I now have a maxton rear shock installed on the bike. Honestly I cant really comment on the effectiveness of the shock as I have reached the limits of the road tyres I have on the bike and it was sliding about a bit too much for my liking.

This is a video from Croft - at around 13 mins the back end slides without too much provocation at all coming through Tower:
https://www.youtube.com/watch?v=CxY_YUpUlUY

So I have bought a set of Metzeler Racetec scrubs k1 front and K2 rear. they should be suitably sticky enough for me. They are good enough for superstock 600s in the BSB.

The next thing I have been looking into is tuning the bike. I wanted to get as much out of the engine as possible without actually pulling the engine apart. So I have the big exhaust, the open airbox with ram air filters and the power commander for the fueling. The thing I really wanted to do was open out the throttle bodies, there is a thread on here from Quantime - not seen him on here for a long time so he may have moved on from the TRX, however he had a bit of a project on converting his trx850 to fuel injection - in which he used a set of tdm900 throttle bodies which he bored out to 41.2mm or something. he had a flow bench and was convinced that the stock 38 bore of the carbs was strangling the engine at the top end. It makes sense given how well the FCR41's work, and also the fact that every performance orientated big twin in existence has massive throttle bodies that are 50mm+

So I want a bit of that. but apparently even if I could get the bodies bored out I will have a hell of a time with the getting butterflies machined to fit, as they are slightly elliptical with something like a 2 degree chamfer on the edges. Beyond the 'out of my shed' capabilities. So I had a look at other bikes with a similar layout engine. Step up the BMW F800. Parallel twin, with fuel injection running 45mm throttle bodies. awesome.

So I found a set on ebay for 40 quid, took a punt and they have arrived this morning. There will be some work to do around the fuel rail area, and maybe an adaptor to get it to flow into the head without any sharp edges but on the whole this is a big result. It will need a full remap with the power commander, but I intend to do before and after dyno charts.

I suspect that its going to help a fair bit, but to get the max out of the new parts I will need to match the head to the new TB's, which I may do, but not now.

Pics to follow.

[Silver]

Well done you. keep at it. I got a F800s to use on the road and i love it. Just been to the outer Hebrides on it. Did a steady 90 all the way from glasgow and still got 65mpg
You still going to Cadwell Saturday?
Dave

[coxylaad]

with pictures:

the stock tdm900 throttle bodies compared to the F800 items:



That's 38mm stock vs 45mm version.

Flipped round this is the side that fits to the cylinder head - F800:



Now the same for the stock TDM900 throttle bodies:



As you can see the TDM900 throttle body tapers down into some odd shape, where as the F800 one is just a tube. When you look at the TRX850 stock carbs they are just circular, and there is an adapter plate that bolts in between the carbs and the cylinder head.

This is the cylinder head for the TDM900 engine:



note the very 'un round' shape. Also note the head to throttle body rubber is not round on the inside either, its designed to make the shapes of the tdm900 throttle bodies and the cylinder head fit. I would say a cost cutting exercise by yamaha over the traditional head to carb bolt on manifold that the TRX850 has.

Not to worry, if I open the insides of those rubbers out so its just round I can then get the file out and do a little port matching so that everything flows through smooth.

Also, as a sheer stroke of luck the throttle body spacings are pretty much identical. and also the TDM fuel rail and injectors will bolt straight into the F800 bodies with a small adaptor plate.

The TPS will need a minimal work to fit. I can see this working really well.

I will be getting a dyno before and after run to see what effect all this work has, and will also be comparing it to a TRX900 with FCR41's, which by the way currently no quicker than my fuel injected bike with the 38mm TB's

Its all good stuff!

[coxylaad]

Quickshifter - Copied from the other thread:


after seeing the video of Killerwhale, his quickshifter and how awesome it looked I decided to have a look at something like that for mine. Not cheap are they?!

Anyways as it goes the power commander with my 900 fuel injection system I am running has an option for full throttle shift cut, superb. now I only need a way to trigger it. so I pulled the rear brake light switch from the other side of the bike, cleaned it up, modified the bracket and attached it to the shift mechanism like so:



jobs a good un, set to only operate above 3500rpm, with a dwell time of 60ms. It all works fine according to the multimeter, I am at croft tomorrow and it will be getting tested to the maximum(Rossi (TM) ), so I will report back as to whether its worked or whether I have ripped my gearbox apart

If it works its a free mod for me hoorah!


A cautionary tale with the power commander 3 USB whilst I am typing. I was fiddling about with the software and stuff over the weekend and noticed it need a firmware upgrade. Also I noticed that I could only communicate with the PC3 properly if the engine was running. After doing some subsequent research there is a 9v battery harness you have to fit for the PC3 to work without the engine running - how mickey mouse is that?!

anyways you can probably guess that I opted to update the firmware with the engine running, as soon as I hit the button the engine cut out as you would expect on a firmware update, and then the power went off the PC3.... upgrade failed connection lost, bike wont start.
I eventually got it going through some frantic chopping of cables to make up the 9volt supply harness and reapplied the update. All ok. phew.

[coxylaad]

track day at croft done. the diy quickshifter performed absolutely faultlessly, with no adjustment necessary.
I will post a video up shortly. well happy

[Killerwhale]

track day at croft done. the diy quickshifter performed absolutely faultlessly, with no adjustment necessary.
I will post a video up shortly. well happy

Most happy post i´ve seen all day!

[M.V.]

track day at croft done. the diy quickshifter performed absolutely faultlessly, with no adjustment necessary.
I will post a video up shortly. well happy

Very good! Pretty sure I've got a spare brake switch kicking around, time for some mods!

[coxylaad]

Videos of the croft track day. The first I have put on the quickshifter thread queuing and steady outlap included so spin onto 3:15.

https://www.youtube.com/watch?v=y37JfmRQUvM

These 2 are of sessions 5 and 6, and are from the Point of view of my father in law's bike, which also happens to be a TRX with a 900 engine in it running 41mm FCR's

Session 5
https://www.youtube.com/watch?v=N65RuVgWflE

Session 6
https://www.youtube.com/watch?v=w3p6ElEukeM
Session 6 is funny, as it involves a couple of trips across the grass


I am the dude in front with the black bike and mainly white leathers. A lot of fun was had

[dandywarhol]

I love your "out of the box" thinking throughout this project Ian. Neat quickshifter idea - if I ever get round to tracking mine I think I'd rewire the kill switch through the headlight flash switch - I've reasonable index finger/toe coordination...............................

The bike looks nice and stable and the forks look like they're working well in the first vid

How much for a trackday at Croft?