Big Bore CR250


Looking for advise on going to a big bore Cr250.

Eric Gorr does 265cc big bores, but I'm looking for Max low end torque.

How big can you Go? What is the best Cylinder to start with?

This is based on my cr250-2001, so doesn't apply to the new case reed CR.

The stock KZ3-V 2001 Cyl. is a high end screamer, not my kind of ride.

Currently I have a 99 Cyl. best lowend-bottom motor per/Eric.

But, have had no work (porting) done on it.

I have a Boysen rade valve, spacer on the CRV, and 9oz. weight on the

fly wheel.

I think I could put the newer 00-01 CRV valving in it, it has 98 CRV valve


BUT, should I go Big Bore?

I have a KZ3-T which I think is a 2000 Cyl. to work with, that has been

ported by TMR (Tom Morgan Racing), the base has been milled, which I

Under stand is for lowend-bottom power, but it needs replating.

I have never had a ported cyl. Maybe I should just replate this and

forget the big bore idea?



2002+ can normally only go to 265cc due to exhaust bridge as I have been told.

2001- can go to 285cc and I hear thats a good one, I think EG's got the scoop on that motor.

With all your options, I would def consider the 285, Never owned one myself ,but havent read any negative reviews. Why not give it a go?

Put a search on TT as some others have posted on this before.:thumbsup:

I looked into this about a year ago and at the time I was dealing with madman Engineering and he steered me away from the 285 kit for my 01 he told me that the 285 made things to thin and would make my bike undependable and prone to overheating. My cylinder and head are up at Jbone motorworks's right now he had my cylinder replated and Is redoming my head and porting my engine and working on my powervalve. He recomended doing this first before I go bigbore. He said this will add tons of power with my stock bore and if I dont like it I can still go bigger.

Thanks for the replies

I guess I will talk to EG and rebuild My ported Cyl and see what he says about

going to the 265CC.


I read a long post on about Eric Gorr and it wasn't very good.. It's even suggested he has closed his doors. It was in the "Dealer feedback" section.. ktmtalk was down or I would posted a link.. Do you have a JD jetting kit yet?

I heard the same thing about Eric Gorr when I was looking around for someone to do my engine work. I was origionally going to have moto 814 do my bike but he moved or somthing and Jbone was recomended so I went to him. You wont find a more friendly nicer guy. He responds to every e-mail of mine. others have used him for honda's I think a Guy form Chillie just posted about his engine from Jbone.

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