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A couple of my lightweight 4 stroke racers

Started by soonerbillz, March 29, 2021, 02:59:46 PM

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soonerbillz

While I'm working to get my R5 project in high gear I thought I would share a few pics of some of my 4 stroker race bikes.
They are Kaw EX250's ... They have been a blast to build and race!

I wasn't certain whether to put this thread here or in the Racing section.. but here I go.

This first one I built from a box of parts.. I bought the parts as a bulk garage clean out and was the first one I built a number of years ago.
The fairings are home made using bit and pieces of sheet plastic and street fairings. I modded the bike by fitting EX500 forks and wheels, brakes so I could get into modern 17" wheels and use good race rubber. The better 500 brakes and stainless lines really helps in the slow down part and I modified the suspension with a Gixxer 750 rear adjustable shock set up the forks with self modifies springs, pvc spacers and better oil.
The bike handled way better than a stocker from 1995 which is to say it was just a better pig!
The engine was pretty stock.. just 2mm over pistons and a dialed in adjustable cam gear and some head work. The exhaust was a home made 2 into one header and a pipe and silencer off a Yam TT650.. loud as hell but with jetting the combo made real good power for what is was.. I still have this bike.. and hope to get back in shape just for fun!
That's me at old Texas World Speedway getting in the way of all the fast riders ... I miss that track.. sad they tore it down :cry:

soonerbillz

#1
This next bike was more of a improved redux of the first one.
Again a basket case job built from a few boxes. It's motor though was built to super sport level with forged pistons and bored out. a reworked lower end a modded cam and quite a bit of head work by some friends. Another home built exhaust with a better can.
The suspension in the rear had another Gixxer shock but this time sent off and modded for better performance and it worked really well.
The front got a set of built CBR3 forks that I was able to installe by taking the stock EX250 triple tree and punching the stem out and then doing the same to the CBE triple and swapping them.. I had a buddy tig weld it solid and it let me bolt on the CBR forks like they came factory.  That way bigger brake was a killer improvement! The CBR triple reduced the rake considerably so it turns like a real track bike should.
all around this was a excellent bike and I let my much faster friend Robert use it for two seasons and he was getting on podium every time.. it was so cool to see my bikes actually winning!
I still have it.. mothballed.. I need to get it out and have some fun with it!

The bottom pic is my smiling buddy Rob with the bike after he got his first podium on it!

soonerbillz

#2
Last here unlike the earlier pre gen EX250's... is a 2015 EX250R that fellow racer used for a couple of seasons for sprint racing.
He did quite a bit to the bike as far as suspension including Traxxion fork carts and tuned adjusters plus a very nice Ohlins rear shock. besides race fairings stainless brake lines and a Scott damper the bike was pretty stock. As a favor to me he donated the bike for my endurance teams use. We ran many races and did pretty good but we crashed it a number of times, blew up a couple motors and generally thrashed the hell out of it.
Currently it sits in my barn waiting for something.. not sure what!

m in sc

excellent choice for trackday bikes.  :clap: great little bikes. also.. just fyi, the carb diaphragms interchange with 1st gen concours ones, and carb bowls and gaskets. since you have multiples this may be helpful. 


I had an ex250 once. 'slightly modified'





soonerbillz

Nice conversion!  Bet it was lively.
And yeah .. the EX is a excellent tracker.. cheap, easy to find parts and work on..
most importantly.. crashes well!

m in sc

this is true they are great track bikes because they are tough as nails, dirt cheap and almost anything bolts on.

Inov8

Cool trackers, Soonerbillz. All you really need to get in the game and have buckets-o-fun on the cheap. Easier to learn to stay off the brake and carry more speed in the turns on something lighter and relatively low powered. I found out the hard way that it's difficult to unlearn bad habits you develop by starting on a bigger bike. Apologies for the hijack to follow:

Mark, it's crazy how OEM looking the EX/R5 is. Please post more about it. Was this ever a build on the old forum? More details, please.
I'll just shut up now and go back my Crayons and coloring book

m in sc

it was, did a full build thread, and that was the point. No one ever paid it any attention to it until i started it.   :dawg: actually an rd top end. ;)