450 4stroke

Mark Morrison · Posted: Sun Oct 24, 2004 5:20 pm Post subject: 450 4stroke

Who's thinking about going to the four stroke next year and if so what brand motor?

Howie Idelson · Posted: Sun Oct 24, 2004 5:25 pm Post subject:

I have a cfr250 that I am currently building on a new Firstkart chassis.
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Howie Idelson
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Randy Domikis · Joined: 22 Jul 2002 Posts: 266

Thank you EKN and John F. for taking on this new task.

Randy Domikis

Charlie Tackett · Posted: Mon Oct 25, 2004 5:09 am Post subject:

WIth the new gen 4-strokes, their are several issues to look at. One of the primary ones is that you will be fabricating most of the parts necessary to adapt the engien to a kart. With the Cannondale we initially ran, it was everything from scratch. With the CRF450, a number of the same itmes from a CR250 were usable, such as the rear motor mount, same countershaft gears and alignment, etc. One important consideration should be given to whether or not it is a wet sump or dry sump engine. Fabricating and plumbing a dry sump engine system is a bit more complicated than simply filling a crankcase with oil!!! It is definitely doable, but just something else you have to consider.

Johnny West · Joined: 03 May 2002 Posts: 1185

Howie, You may want to look at the chassis MFG, I don't think the chassis will meet the spec's of the class. First kart is a 125 chassis. Unless they are making a 250 chassis now. just trying to help.
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Johnny West/West Racing

Howie Idelson · Posted: Mon Oct 25, 2004 7:59 pm Post subject:

I didn't think there was a class for my kart. I'm hoping I can run in one of the 125 classes. Any ideas?
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Howie Idelson
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Larry Dobbs · Posted: Tue Oct 26, 2004 9:39 am Post subject:

back to 450 4strokes, I am considering a 4-speed Yamaha verses a 5-speed Honda. Any opinions for or against?

Mark Morrison · Posted: Tue Oct 26, 2004 6:00 pm Post subject:

Larry we are going to Sears point Thanksgiving weekend to test our 450 we decided to go with the YZ 450 from Yamaha the price was right Smile

.The motor is mounted in the Anderson just working on all the little stuff.

Charlie Tackett · Posted: Wed Oct 27, 2004 5:34 am Post subject:

Larry, the first time we ran the CRF450 on a track was at Laguna last year. We took a wag at gearing. First session out, he never even got into fifth!! And that was with a very mildly modded motor...basically stock. The power characteristics of the 4/'s is such that having more gears is not as essentially as it is for the 2/'s and their narrower power band.

If you want to go blue.....the WR450 does have a 5-spd.

Debbie Kuntze · Posted: Wed Oct 27, 2004 8:09 am Post subject:

FYI-IKF has approved:

For a probationary 1 year evaluation period allow 4 Stroke single cylinder motocross engines up to 450cc to compete in class 21 and 22. Engines allowed: Honda CRF, Yamaha YZ. OEM parts only. Starter assembly may be removed and plugged. Engines may be modified to allow for use of external electric starter. Carburetor open, max venturi size of 42 mm. Exhaust system open; must meet IKF noise limit of 95 DB. Weight: 460 pounds.
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Debbie Kuntze
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