KLX250 300cc Kit a success Mild to Wild

[Tom Forde]

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Kawasaki KLX250 300cc Big Bore Kit (Mild to Wild)
On a recent trip back to Aussie, I called into the local Kawasaki dealer. I have known the owner over the years and most of his staff race Kwakas either on or off road.

I was interested in the 300cc conversion kit for the KLX250. In Aussie, USA, Canada and parts of Europe they are imported with the Keihin 34mm Carby, which passes the strict Californian emission laws.



This makes installing a 300cc kit a piece of cake in these countries.

I was also interested in the pricing differences with Thailand.
Australia: $5,500 (165,000Bht) + on road costs and insurance,( approx $7000)
USA : $5,200 (156,000Bht) + on road costs and insurance.
Thailand: 152,000Bht + on road costs and insurance .... interesting.

Anyway getting back to the conversion kit, I bought one.

Complete with the 300cc Kawasaki Factory big bore kit, 34mm Delorto competition carb with a quick action throttle.
I also purchased a race tuned 304 grade stainless steel engine pipe and exhaust used by the Kawasaki Motocross team.

I used my good friend Liam, an ex racer and motorcycle mechanic from Ireland and now residing in San Sai, Chiang Mai to do the conversion.
He specialises in suspension setups, carby balancing, motor strip downs and general maintenance
.
You can contact him on 0822711923
Email: tzunamisuperbikes@hotmail.com
GPS Coordinates: N18deg 50.419 E099deg02.897

After a week of trial, error and frustration we got the little beast to really fly, (a few wee secrets were learned along the way, which Liam will keep to himself!)

Remember we are converting a fuel injected bike back to a carby, then upgrading to a 300cc big bore kit. It is also a brand new bike with a 1000km in the speedo (I guess I now have voided my warrantee!)

Stage 1 so far is a success

[Tom Forde]

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Oh I forgot, Stage 2 consists of fine tuning with main jets sourced from the UK and an after market 11ltr tank sourced from the US.

Unfortunately there is no large tank available for the fuel injected model at the moment.

It is difficult thing to do because of the fuel injected pump located in the tank.

Tom

[2wheels]

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Wow, fascinating info Tom.
Looking forward to reading how this transformation progresses and especially how
it all comes together on the road.

[Tom Forde]

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Hi all that are interested in history.
I was competing in 3-6day enduros for 5 years from 1972 in OZ.
A lot younger then (early 20's)
I was a privateir (I paid for bike and all costs)
In 5 years I was only deamed a non finisher once.
(not fast,but I last)

Now the reason for this thread.

In 2011 a Kawasaki KLX knocks out 18hp and peaks out at around 120km/hr in top gear with a 7ltr tank(carburated versions outside of SE Asia)

Go back to the 70's:

1972 DT250 Yamaha; 23hp with a 9.5ltr tank top speed 112/km hr
1973 XL250 Honda: 20hp with a 7ltr tank top speed 110/km hr
1975 Mick Andrews Replica Ossa 250 11litres 21hp @ 6500revs

These are the bikes I campained with in 2,3 and 6 day enduros in the early 70's.

In most respects they where as reliable and simpler and easier to ride than their 'modern cousins'.



The current KLX250 sold in Thailand and SE Asia with fuel injection, a relatevly small market is definately underpowered.
Check out the net if you are after more HP for the Kwaka KLX250....Power/hp costs money, there is no easy fix.

Cheers
Tom

[Tom Forde]

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I made a mistake on Liam's email address it is tsunamisuperbikes@hotmail.com

Cheers
Tom

[KZ]

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Interesting project!
I've noticed that you're not using a different cam; are you using the stock cam with the 300cc set-up? No changes in the cylinder head, valves, valve springs etc?
I don't know much about engines but have heard that just by polishing the head and some hotter cams you can gain a few horses. Not as much as with a bigger bore, of course.
How does the 300cc compare to the 250?

[Tom Forde]

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Well Liam and I have completed stage 2.
It took over a month to fine tune the carb, different jetting and needle settings were tried around the mountains, a lot of popping high up because of the altitude.
We finally got a good compromise with the settings.


Good nice colour

We then fitted the IMS plastic tank from the US, complete with the US carby versions fuel **** system






This is the IMS tank fitted


The finished look

I now have a KLX that can cruise on 110km/hr. with a range of 200+km before reserve.
I am sitting on the optimum rev range for power and torque: 7000/8000 rpm with enough power to pass traffic.

I have also saved over 5kg of weight by shedding the emission control and the the fuel injection mechanics.

Liam didn't have to alter any of the wiring loom, just blanked off connections and looped around the CPU.

If in the future I wish to go back to the fuel injection it will only take about 8 hrs work.

Love my my transformed KLX.

Tom

[Ian Bungy]

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I Love that Tank! I saw it in the flesh the other day and You could hardly notice the Change! Very well done without going overboard like those Huge Exon Valdez Tanks that Look so Grotesque!!! Can't Wait till they make one for the Fuel Injected Bikes!

[2wheels]

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Congrats Tom and Liam; a bold move but now you have a unique bike.

[Captain_Slash]

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Glad to hear youve got it running properly Tom, it was popping a bit when we met on the Samoeng loop last month but it sounds like its sorted now.

I wonder if its possible to keep the FI system on the KLX but bypass the emissions control to make it run better

[Tom Forde]

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Hi Col, as you have a new bike like me you have to weigh up whether you are prepared to void your warrantee.

It is possible to remove most of the emission control and keep the FI system, you would gain some power and save weight.

You would then need to spend some money to little the motor breath.

Boss snorkel, K@N Filter and a Thai copy exhaust pipe.

As you already have your bike derestricted, that would be an easy power upgrade.

Less than 10,000bht.

Cheers
Tom

[crs]

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Hi Tom. Could you say how you think this compares re. total price and performance against fitting other carb/EFI big bore conversion kits please. Also a list of sources with prices for the parts would be handy for those wishing to copy you. Cheers.