RM265!

[Coop]

I've used Eric Gorr in the past and would recommend him.

Currently his web site is being updated so you can't get to see very much right now, but hopefully it will be done shortly.
http://www.eric-gorr.com/

His ideas about big bore kits are worth thinking about. He uses pistons that are readily available, so you don't have to worry about buying expensive or rare custom piston kits. It's a smart way of doing it as Todd and others have found out.

Take this with a grain of salt since it's he said/he said, however on the kdxrider site several guys have had bad experiences lately with Eric's work. Things like Eric sending them back different engines than they sent it, different cylinders with helicoils installed instead of their clean cylinders etc.

I used to be very active on dirtrider.net (not the magazine) around 10 years ago, and Eric used to post there answering questions and we talked a lot on the site and through email. I always thought Eric seemed like a stand up guy. Sounds like maybe he has gotten a little too busy and had to sacrifice some quality of service to get work out on time. Hopefully those are isolated cases.

[Watson777]

Nice lookin bike! So, my question is this. Do big bores compromise reliability on the 2 strokes like they do on the 4-strokes? I know on say 250F's if you do a lot of motor work or a 290 big bore they become very unreliable and also require a sh*t load more maintenance than a stock bike. Anyone know of anyone good on the West coast that does big bores? Would love to put one in my woods bike once I have a job again!

[factoryX]

two strokes handle big bores fine, if not the same reliability with the stock bore.
http://www.maxrpms.net/shop/index.php/motorcycle-kits/mk-yamaha/yz250.html?SID=nqhchm6jbb2p9u3o1b27rm7ba7

[Two Stroke Todd]

Here is what i have learned through the process of this build. Only two shops in the U.S. have the 280 pistons for the RM. One is Eric Gorr and the other is Boyeson. I tried to purchase one from boyseson but I was unable to. At the time i was pestering Dag for one I had no idea he had other things on his plate. So we called up wossner who makes the pistons for them. These are top quality units! But at 200 plus for one I decided at that point to go with the 265. WHY? Because I was told the 280 is pushin
the limits of the RM cylinder and the the 265 kit was far more reliable. The inner head gasket is the limiting factor on size. I've been told the 265 is very reliable so long as you use a quality crank as in no hot rod rod kit! I went with the pro X rod kit. My motor guy says this is far better than the hot rod rod kit and very affordable compared to stock. Reliability was a major concern for me because I dont like to rebuild bikes more than twice a year. I try to do two top ends every season and a crank every other year this time i came up a few months short on the crank before it went. Again a hot rod kit! On the YZs I"m told 285 is the limit with the stock cylinder and head gasket? I hope this helps answer any questions. Tomorrow I'm gonna really try to put a few hours on my new motor! I"ll let you guys know how it goes.