polaris scrambler 400 cylinder on a 250r bottom

[joshridina400ex]

anyone have any info on this project? pics?

[honda300EXtreme]

Is that even possible??

[f150mann]

all odds would lean to hell no, but, nothings impossible

[honda300EXtreme]

thats what i was thinking i have never even heard of doing this before

[honda300EXtreme]

thats what i was thinking i have never even heard of doing this before

[wilkin250r]

It has been done a few times, commonly called the "polonda". If memory serves, they are the same stroke.

Most often with hybrid motors, you need to do extensive welding and case modifications, relocating base studs to fit a cylinder from a different motor. With the Polonda, however, all those modifications are made to the cylinder. The only mods to the case are standard case boring to accept a larger sleeve. You could later switch back to a standard Honda cylinder, because the studs weren't relocated.

The cylinder needs fairly extensive mods, as well as a spacer plate to fit.

[joshridina400ex]

wilkin250r do you know where i can find more info about doing this?

[honda300EXtreme]

huh... i never knew that... i learn something new every day ;)

[wilkin250r]

Originally posted by joshridina400ex
wilkin250r do you know where i can find more info about doing this?

Not really. A google search for "Polonda" will give you several hits about general information. People that have done it, the results, possible a dyno run or two. But I really don't think you are going to find SPECIFIC details on how to accomplish it.

You'll learn that you have to weld/move the water passages, but you won't learn how/where to actually move them.

You'll learn you need a spacer plate, but you won't get details on the thickness.

Several different pistons can be used for different size configurations, but you won't find any details on how to get those pistons to fit the stock 250r crank.


I've been able to find links describing the power and feel, and rider's reviews, but I haven't found anything on the DETAILS of building the motor.

[rundrave]

heres a link, not sure if you all have seen it:

http://www.atvsource.com/articles/product_reviews/2001/112601_mpracing_polanda_engine.htm

also I thought I saw some talk of this over on gen3usa.com

http://www.gen3usa.com/forums/viewtopic.php?p=27952&highlight=polonda#27952

[250rmike]

there used to be a 250r site years back that had a couple of them on there not sure if the sites still around though and for the life of me i cant remember what it is. try to search for some good 250r builders i think trinity might have made a spacer or a kit one of the big engine builders back in the day used to do it look through old dirt wheels at the ads i dont have any of mine handy nor do i know where they are

[outlaw319]

I seen where its been done and how to do it in an old "dirt Wheels" or "3&4 wheel action" magazine. I have the magazine somewhere around here....if I remember right it was an sand dragger named "Orange Crush" it had N.O.S. on it too.

[bwamos]

I've seen the old Honda Oddesy top ends used on the 250r bottom end. I beleive it's a very close fit-up.

[Colby@C&DRacing]

MP Racing in OR actually designed and use to do the engine work. I don't know if they are still in business?

[Colby@C&DRacing]

http://www.atvsource.com/articles/product_reviews/2001/112601_mpracing_polanda_engine.htm

Polonda motor

[trailwart]

there is a big thread on it on planetsand.com in the 2stroke technical section.

[mxduner]

I just seen one on ebay a couple weeks ago, went for good cash.