The TRX900 Project kicks off

[coxylaad]

Second track day done, was better than the first. really starting to get to grips with the bike now. I hadn't rode a proper sports bike for years and it felt a little alien to me.

I am really impressed with the pace of the bike, I expected the litre sports bikes to be streaming past me on the back straight but they arent really, and the braking on the thing is out of this world! Still having a little problem with the front mudguard touching the radiator on heavy braking. My forks are definitely bottoming out as I have done the cable tie test. I cant understand of all these trx's with R1 forks no one has had this problem?

I am having a little bit of a problem with the rear spinning up out of corners (no its definitely not because I have casey stoner levels of ability) but I think that might have been down to too much pressure in the rear tyre. I will let a bit air out for the next one.

some excellent pics by a very friendly track day goer.

[dandywarhol]

Looks like a lot of forward biased weight towards the front coxxy - tail high/front low. although the forks are being compressed by cornering (impressive angles for a noobie ) there doesn't look like a lot of reserve travel on the forks for heavy braking.

You could try lowering the back a bit and raising the front - it would help with yer Stoner/Mccoy spinning antics too

[coxylaad]

Hi Al, what makes you think there is a forward weight bias? The tail on my bike is about 4 inches higher than stock so it does give the impression of a little arsend up. I was definitely bottoming the forks out on heavy braking, but look at the rear swing arm position in relation to the horizontal - the back end is quite compressed too is it not?

Also something to note that is a big long 180 degree corner so I wasn't really on the throttle much - that compresses everything does it not?

I have just actually lifted the back up about 15mm with some shorter dogbones. I may have to take them out?

I appreciate the input Al. I think it has the makings of a great bike, it just needs some proper setup.

[fung]

Perhaps it is your spring rates?
Racetech have a calculator on their website.
Cant hurt

[coxylaad]

I am going to setup my static sag and go from there.

Next track day is a week on Monday, more testing required

[dandywarhol]

Yeah, the seat might be giving an optical illusion, the swing arm does look about right. I'm not a big fan of shorter dogbones - they can really upset the spring rising rate curve.

I'd do as you've said and setup the sag - including your weight on the bike - static sag with just the bike alone is pointless.

[coxylaad]

What should I be aiming for front and rear for track use?

I have read 25mm and 25mm for the track

[dandywarhol]

Can nobody help coxxy out for TRX track suspenders set up?

If nobody gives an answer I'd suggest around 30mm rear (in line with the spindle) and 40mm front with the rider on the bike - any thoughts track experts out there?

[coxylaad]

well I have now got a nice 30mm sag at the rear, and a 5mm sag without me on the bike, which from what I have read is pretty much where I need to be.
I didnt have my full riding gear on so a may be a 1 or 2 mm more but I am happy with that given the bumpy nature of some of the local track.

the R1 front however is no good. I am aiming for 35mm at the front, but with the preload adjusters round right in the closest I can get is 42mm. I need stronger springs - or I need to nick the maxton front end from my fazer that is sat in the garage - yes I think I will do that.

has no one else discovered that the R1 forks are soft as the preverbial? my dad in law has a 2002 R1 and he regulary bottoms the forks out with fast riding.

That cant be right.

[Kevtrx849]

I never used my R1 front end in standard trim. I put all new internals in and it is very nice (.9 Racetech springs). You can see in the top photo where it travels too by the zip tie on the right leg. You could always try longer spacers or pack it up with washers to give more compression.
Cheers, Kev.

[QuickDraw]

I noticed the R1 front was softer. To get the right sag measurements I had to adjust my front to max preload, and the rear to only 2 or 3 up from the minimum (I have shorter dog-bones which is probably affecting spring rate too).

If I were much heavier than 80kg I'd have needed new front springs I reckon. I've had the back wheel off the ground during emergency braking (bloody wallaby!) but never bottomed out.

My settings are aimed at best compromise between road & track. I ended up with Front bias softer, rear bias harder.
Front: static 20 loaded 34
Rear: static 7 loaded 19

I'm really happy with the way it rides and handles, especially with only a stock rear shock. Huge improvement over stock arrangement (but then, that was never really set up to proper measurements either). If I want to get it the front & rear bias the same to see what it's like, I'll have to change either the front or rear spring rate, my preference being the front.

[coxylaad]

Thanks for that its good info.

I am swapping the forks out over the weekend, and I am confident I will get into the range I need.

If you have wind the preload right up then its an indication that the spring is too soft. Apparently increased preload is not the same as a stiffer spring rate, although I am not sure how much difference it makes.

Anyway I will keep you updated with some more pics. I may even paint it over the weekend just for the crack

[cobbadiggabuddyblooo]

I know the 98-02 R1 forks are 25mm shorter than stock Trx and also have 130mm travel compared to 120mm on the stock Trx and later model R1's. they have a different offset on the trees also giving you a longer wheelbase. Go back to the std dogbones and you'll find better power delivery through and out of the corners too plus will be more stable on those faster sweeping corners.( if your sag is set correct) get a static sag measurement with the wheel off the ground. Unladen sag with just the weight of the bike should be around 10mm more and laden sag with you on the bike adding another 25mm (35mm total). Try that as a starting point. If 130 mm travel on the front end (98-02 R1) try a static to Unladen of a 12mm

[cobbadiggabuddyblooo]

Preload only takes up initial load on the spring itself and weight of the bike and to get the correct sag with your weight. Once sprung to your weight the fork or shock will work to its optimum through travel if a linear spring is used with the damping of the fork/shock.. This is where you also find the correct dogbone length will be adventagious on the rear with the ratios working on travel have not been compromised. Try a ride height adjuster on your shock if you really need to play with lifting the rear end.

[coxylaad]

Evening.

Just an update:

I installed the stiffer maxton R1 forks to the TRX and set the sag up front and rear to what it should be. I selected some damper settings that were similar to the standard settings for the R1 forks on the R1 and the R6 shock in the R6.

Got to the track and took 6psi out of the rear, down to 29 cold, and set away.

A huge difference to how the bike handled. it was extremely predictible and allowed me to push a bit further into the corners and get on the gas bit earlier coming out them. Very happy

At the end of the first session however my custom fuel tank spring a leak. It must have been the vibrations but the brazing where the overflow pipes come developed a pin hole which petrol was streaming out of. The night was cut short, or so I thought - as we all stood round scratching out heads our very own Projection Components Michaela stepped forward and suggested I go get a bar of soap and fill the hole with it, as its one of the few things that petrol does not attack. so long story short I borrowed a bar of soap from the bog, caked it round the affected area and completed the nights riding. The soap repair is still in place now and its still not leaking! nice one dude I think everyone was amazed!

anyways. Things to do now.
1. Link pipe needs modifying, its the first point of contact on a right handed bend by a considerable margin.
2. Make up some proper mounts for me camera.
3. Go ride some more!

We have all booked Cadwell for 18th October. Would be great if we get some more people down!