The TRX900 Project kicks off

[Yoozy]

I routed mine to up in the rear fairing, I can still get at it from under where the rear seat pod goes.

[Kayla]

Something like this-

http://www.ebay.co.uk/sch/i.html?_odkw= ... w&_sacat=0

can be zip tied to the front fairing stay

[cobbadiggabuddyblooo]

Track bike was set up with a push bike bottle carrier bolted to the fairing sub frame and used a flat topped cylindrical container with a screw lid and the hose running through a hole on the top.

[coxylaad]

haha they are the same size and shape as one of the bairns bottles

thanks for the pointers everyone

[Rod.s]

Try this, it's what i used on my Cafe CB450. I did this about 5 years ago and it was quickly copied by all and sundry

This version fitted with a breather..


Final version without breather, but small 3mm hole in the cap as a vent.

[alextrx850]

Nice one, both simple and practical.

[coxylaad]

but big.

See the gaping hole between the back of the engine and the frame? I don't have that on my bike

I may go for one of those HRC overflows, or maybe a Tommy Tippee variant

[misterdimwiddy]

Could you put a baffle in the link pipe, before the can? Even a perforated disc tacked in should calm it down a bit.

I did try this with my Akra/Devil system which was bought from Pete and he told me it was one of the loudest TRX's he had ever heard.

Was concerned that it would be above the noise limit at Mallory and so made a course stainless mesh disc to fit in the large diameter header outlet before the can.

The bike ran and was fast (and quiet at 98dB) but most sessions it behaved as though it was suffering from severe fuel starvation. Usually after backing off from high revs it would falter often to the point of stalling and then pick up again and rev cleanly. It was quiote unpredicatable when it would happen and more than a bit unnerving suddenly dying half way round Gerards or into the bus stop.

Anyway, played with needle heights and got no where. Last session thought, damn it, I'll take the mesh out and it was completely cured and ran like a dream.

Looking at exhaust system design theory, it seems that exhaust gas velocity is 2-300ft/s as it leaves the cylinder but pulses or pressure waves move through the gas at 1500-1700ft/s (speed of sound is 1116ft/s) and it is the behaviour of these waves that can be used to improve cylinder scavenging and filling with fuel/air mixture. As the positive pressure wave exits the system to atmosphere, it produces a negative (suction) wave which returns along the exhaust pipe into the cylinder and the art of exhaust system design is to get this negative wave to coincide with the valve overlap period (ref: 4 stroke performance tuning - A Graham Bell).

Seems my mesh baffle disturbed this process so severely that I was getting virtually no cylinder filling at all.

Now I am at 104dB with the system open and 98 with a tube dB killer in the open end of the can.

[coxylaad]

Thanks for the info. I have done a bit chopping about of the exhaust anyway so I need to see how it works in practice. It looks the part though

104db would be fine for me. the limit at cadwell is 105db.

I am leaving it for now, no point concerning myself over something that might not even be an issue.

going to get a bit more done on it tonight and over the weekend. I want it running for the end of august so I can fit in a couple of sneaky track days in.

[misterdimwiddy]

Donnington Tues 27th Aug (Focussed Events) if you can make it?

I'm all booked.

[coxylaad]

I will try me best but I cant gaurantee I will be ready by then. the bike needs a period of running in.

[coxylaad]

update:

Rearsets now finished.
Brakes finished.
rear end finished.
exhaust finished.

to do:
small bracket for under engine
bracket for front of seat.
radiator expansion tank
a little bit of fiddling with the front fairing.

I am going to ditch the indicators for the MOT. I will wire them up but i just want the thing running now before the winter sets in, although by the looks of it I am a bit late!

pics:

[coxylaad]

[coxylaad]

I had my first ride out on the bike today, just a little wobble up and down the village but everything worked as it should and it never spat me off yey!

My initial impressions are that the riding position is absolutely spot on. its very different to a stock trx so was a bit of a gamble, but I think its paid off. My seat is a good 5 inches higher than the stock seat, and the rearsets are spaced up and back 1" The handles bars are ever so slightly lower but not that you would notice.

The bike feels so lightweight compared to my fazer 1000, its like riding on air!

Ran the bike up to temperature, the custom baby bottle expansion tank did its job perfectly, and everything else basically just worked!

Someone asked me what I had done to the bike and I started to tell the story, but then realised it would be easier to say that the only original things left on the bike are the fuel tank and the frame, and both of them have been chopped up and modified as well

Its nice to be back out on a twin









I should have it MOT'd taxed and insured on Monday. My mate is asking if I want to do the local track session at Teesside on Monday night, having my first ride out as a track day might be tempting fate a bit i think!

[sanddune51]

A great project seen through to completion,well done,a special in every sense of the word. Hope you get loads of pleasure riding it after all the effort of building it.



Mark.