1996 CR 250 trying something different need input!!

[chris38]

Hey guys!
I have a 96 CR 250 which uses a dome top piston. I was wondering has anyone ever tried running a RM or KX piston with the CR cylinder? Both pistons are 66.4 bore and are domed. But the RM and KX has windows on the intake skirt. Is there any advantage to this? Has anyone tried this?

Thanks
Chris

 

[Ol'89r]

Hey guys!
Is there any advantage to this? Has anyone tried this?
Thanks
Chris

There are many more things besides piston size to consider. Port timing, location, pin location, pin size, compression, just to name a few.

It would be better to send your cylinder out to someone that has a clue and have it ported for the type of performance you are looking for.

 

[chris38]

I just didnt know say if they did fit would there be any advantage to it

 

[Matt90GT]

talk to Eric Gorr. But you can make your own port windows in the stock pistons. See a few guys that use to run a few honda SX teams in the 90s do that to them.

 

[Ol'89r]

I just didnt know say if they did fit would there be any advantage to it

The piston is designed to work with the cylinder it is intended to be used with. Taking one piston from one brand and installing it in another brand will usually not work, even though they are the same size in diameter. Each manufacturer uses their own port design and placement. The cut-a-way on the piston has to match the port size and placement in the cylinder.

The dome is also critical and has as much to do with squish pattern as it does compression. The shape and angle of the dome has to fit the head and be the same angle as the squish pattern in the head.

The wrist pin on one engine may be the same diameter as the wrist pin in another brand but, the placement of the pin in relation to the deck heighth of the piston is usually not the same.

If you take a piston from one brand and match it up against another brand, you will see many differences between the two pistons.

You can modify your existing piston like Matt suggested by cutting new windows in the skirt or machining the existing transfers but, unless you really know what you are doing, you would be better off to let someone like Eric Gorr do the work for you.

 

[chris38]

Ok guys thanks for info it was a really big help!! How would I get ahold of Eric Gore

 

[Ol'89r]

eric-gorr.com/contact

 

[Pete Payne]

one popular mod to the 96 and older cr's is to install the flat top piston from the 1997 thru 2001 cr 250 . Also u can install the head drom the 97 thru 2001 . There is also more to be gained if the head is machined to optimize squish clearance, MSV and comp ratio

 

[whenfoxforks-ruled]

Watch the head stud lengths if you have a differant head, there is some variance. Get the head that the spark plug sits straight, not angled. Vintage Bob