New Track Bike, new racing season

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Irvine.J
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New Track Bike, new racing season

Post by Irvine.J » Fri Sep 03, 2010 10:40 am

Ok so I finally got my new track bike... although its not "new"
So, its a 1984 GSXR-400, it has a few little things well ahead of its time however,
For Instance it was on of the only 400 CC track bikes to come out with dual piston dual front break calipers, although they completely botched the dampeners and plating them over was the only successful way to deal with it...
It has a few more HP available then most other 400 cc bikes, and even more with a good exhaust system. Being obviously a carbi bike I can also use valuable work learned from PJ land to really tune the shit out of it, hopefully extracting a few more HP.

The original bike looks like thus, and I plan to make a bunch of modification to make it a far more stream lined beast with some CFD help.
Season starts early next year, so i'll be on the track in a few weeks practicing hard for the formula 400, later the 600 superstock.

AS IS
Image

To Be (Something like this)
Image

Obviously it will need a full strip down, clean, new parts, all that shit, but the build log should be a little adventure, especially tuning time, because believe it or not, Kadenacy effect and pressure pulses are extremely important factors in exhaust tuning, with the right lengths, dia's and numbers, you can effectively supercharge your engine to a small extent by helping it suck more air under vacuum, without changing your timings, its tricky, but with a little luck, I'm hoping to pull 65 hp out of a 59hp stock bike.
James- Image KEEPING IT REAL SINCE 1982
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tufty
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Re: New Track Bike, new racing season

Post by tufty » Fri Sep 03, 2010 11:41 am

Wahey!

Lose as much weight as possible, that suzi engine is lovely but the bike itself is a bit "tubby". Getting it down to 130 kilos or so (IIRC, they were about 160 in stock "road" configuration) makes all the difference.

Should be a fair amount of tuning potential in the lump, as well.

Enjoy.

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Re: New Track Bike, new racing season

Post by Viv » Fri Sep 03, 2010 11:47 am

Hi James

Yes Simon is right on the money with what he said, lose wait first before going any were near tuning the motor, its easier, cheaper and does not affect reliability, you can go on a diet too and stay out of the gym, all that muscle takes off the top end ;-)

400s are insanely good fun

Viv
"Sometimes the lies you tell are less frightening than the loneliness you might feel if you stopped telling them" Brock Clarke

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Irvine.J
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Re: New Track Bike, new racing season

Post by Irvine.J » Fri Sep 03, 2010 1:43 pm

One thing I found very interesting on this bike is how straight through the exhaust system is, it says to me there is some serious tuning potential with the right amount of tweaking. The stock pipe I can probably shave 4 or 5 kilo's off, currently I weigh in at 91.5 kg but * all fat, took ages to buff up so i'd rather loose the weight off the bike then me :D LOL
It redlines at a mere 12 000 which is odd for a 4 stroke 400, but i've been told it rides like a 2 stroke, should be super fun.
Simon the model i have is actually the earlier 84, it is the long wheel base version, its very skinny actually, with a super agressive seating position, the later 84-85 models went a bit shorter and more fat, this one is kinda... i dunno, reminds me of a japanese fighter cockpit, small, cramped... kamakazi style. I'll take some pics later tonight cause its 11:30 pm here and time to get the grinders going and make some noise :D
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Re: New Track Bike, new racing season

Post by tufty » Fri Sep 10, 2010 1:18 pm

Irvine.J wrote:It redlines at a mere 12 000 which is odd for a 4 stroke 400, but i've been told it rides like a 2 stroke, should be super fun.

Simon the model i have is actually the earlier 84, it is the long wheel base version, its very skinny actually
I meant "tubby" weight-wise, not in terms of physical layout :) Lose everything you don't absolutely need to up your power to weight ratio.

Yeah, the little 400s ride very much like the RD 350s, bugger all below 6K, a bit of handy "poke" from 6 to 9, and then crazy stupid time from 9 to 12. They have no torque, so expect to be wringing its neck all the way.

One of the better weight loss regimes you can apply once you're past the obvious stuff is to lose the starter motor (and battery if you can). Dunno if the ignition's CDI or TDI, probably the latter, that has implications on what electricals you can dump.

Oh, and lose the vacuum petcock. No end of trouble, those.

also, ahem

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