CR250 piston in the 2001 EC 300?

[GGRider01]

I heard somewhere that you could run a piston out of the last Honda 250's in the EC 300. They're both 72mm, but are there any differences that would prevent it from working? My searching skills just aren't cutting it for this bike so I'm sorry if this has been answered before.

[Zman]

I put a CR250 piston in a EC250.

[GGRider01]

Well, since no one knows and since I've got a '03 CR250 that'll surely need a rebuild one day, we'll just find out one of these days and I'll add my newfound knowledge here.

[Zman]

According to the Wiseco website the 2003 CR250R has a stroke of 72mm and a bore of 66.4mm. That is the same as a GG 250 Engine. The GG 300 bikes have a bore and stroke of 72mm.

801M06640 $152.00 66.40mm STD Displacement: 249cc
Stroke: 72.00mm

[memphis2857]

Cr250 definitely won't font in a 300.


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[webmaster]

Ping Jim Cook here. From what I recall - if he was having a cylinder replated - he would sometimes use a cr250 piston. But CR250 piston definitely cannot be used as a direct interchange.

jeff

[GGRider01]

Ok, I just misunderstood then. I noticed the 72mm on the jug of my CR and assumed that meant diameter not stroke.

[Jakobi]

Originally Posted by Zman

According to the Wiseco website the 2003 CR250R has a stroke of 72mm and a bore of 66.4mm. That is the same as a GG 250 Engine. The GG 300 bikes have a bore and stroke of 72mm.

801M06640 $152.00 66.40mm STD Displacement: 249cc
Stroke: 72.00mm

Big variable will be with the actual piston (dome/flat top) and its relationship from the pin to the head. It's really not worth while pursing when you can order a wossner forged piston and rings for reasonable prices.

[Zman]

I fully agree there are many variables and a few more include weight, transfer port window size and shape. The below link covers some of the differences and modifications I needed to make to use one in a well worn XC250 cylinder.

http://www.gasgasrider.org/forum/sho...t=cr250+piston

I still have not run that spare XC250 engine, but I expect it will be fine.