Lakester k class engine options?

[Haaland]

Hello,

I have been dreaming of building a lakester for probably 15 years. Over the last 2 I have been toying with the idea of a blown gas k class lakester. What engines are people running in this class? From the rule book it needs to be 30.99ci or 507cc. Engines I have looked into are 500ex, 300-400cc two strokes, Dual trx250r engines, and most recently a phaser 500 snowmobile engine.

The phaser seems the best option stock putting out around 80hp and people have turboed  them up to 140hp. Plus they are already efi.

- Alex

[tortoise]

600cc sportbike motors are very well developed. Destroked to 500 with a suitable cam ought to make good power.

[Haaland]

Thank you. I will start looking that route. Destroking or sleeving cylinders never crossed my mind.

[grumm441]

A number of the 600cc sports bikes also have a 400cc variant.
Some of them share bore size and spacing but have a shorter stroke crank
G

[Stainless1]

You probably don't want to sleeve... could crowd the valves a little too much.  My thoughts have leaned toward the RZ 500 or a destroked 600...  Don't worry, we destroked a Busa a bit over 9/16 to make it under a liter.  There are a coupe of places that will do that.

[jpm49c]

What company did the destroke for you "Stainless"?  Thanks!

[Stainless1]

Marine did the crank, I trashed it on the Dyno during a 30 second 12K pull, so then I had Mile High Crankshaft fix it, true and polish it... Crankshaft Dave said he would destroke one for me it that one didn't hold up... has done 16 five mile pulls and several shorter ones on the Great White Dyno so far.

[Milwaukee Midget]

I'm a fan of destroking as well, but consider this - find an easy-to-develop 1 liter and remove two pistons.

There are a ton of hi-zoot 1 liter bike engines that I think this trick would work well on.

Welcome aboard, Alex! 

[Jack Gifford]

You thinking blown or n/a? Gasoline or 'fuel'?
As of a few years ago the blown SCTA records in K-lakester were quite "soft", at least 25 mph under unblown records. [or my tired eyes misled me....]

[panic]

Remember that de-stroke may mean too high rod ratio, heavier piston, lazy TDC breathing.

[Milwaukee Midget]

Remember that de-stroke may mean too high rod ratio, heavier piston, lazy TDC breathing.

Not to mention a very busy series of valve and piston events in close proximity during overlap.

[salt27]

I know of at least two Honda CBR600 engines that have been destroked to 500cc's that compete at Bonneville.

  Don

[Rex Schimmer]

I like your thinking about runninig Dual trx250r except multi engines are only allowed in the streamliner class and the large motor cycle classes. I would really try to see if you could find something in a 500 cc two stroke, Bonneville is all about horse power and a good two stroke will make more than a four stroke of the same displacement. I would look at some of the snowmobile engines as some of them are big power. Another thought would be the Yamaha twin cylinder, water cooled, two stroke that they ran in one of their ATV several years ago, I have hear some pretty big numbers for them also. Brant and Speranza ran a small Honda four cylinder (destroked  600 I think) and they are pretty good engine builders. The record is 202 so you need a good car with a good shape and some pretty reasonable hp, probably 125 +.

Rex

[Haaland]

Thank you for everyone's responses!! The plan was to run blown gas.  I have started to look into bigger engines.  Again, thank you all so much very helpful.

-Alex

[NathanStewart]

I'm a little late to the party but I know guys that run 600cc bikes in 450cc Super Bike road racing classes by disabling one cylinder.  Having a custom crank made for destroking ain't gunna be cheap.