how come you never see ATC 250R's with 265cc kits?

[sx250heath]

For my birthday brother(barrett8) gave me most of a 1986 250R rolling. chassis, so I will be tarting to build it soon. I plan to go big bore with this. bike (265,310 or 330). I know back in the day that 265 was popular with trx guys but I have not seen an ATC in this size,why? I would also like to know what big bore kits you guys recommend.

[JasonB]

i havent heard of that one; it seems like a lot of people go with the 310 and 330 kits from ESR and the other builders out there. I did! I also had a 300 kit built for my air cooled 83 250R bike too. But ya never heard of a 265, were people maybe doing incorrect math and thinking that boring like 20 over equaled that much more displacement?????

[Mosh]

stock jug bored .080" over is a 265cc.
One of the best running stockish cylinder R's I ever ridden had a Trinity ported jug at 265.

[Kintore]

Im running a 265 Duncan powervalve motor, MX porting with a +4 hot rods stroker, and a 18cc head to boot. Kicks harder than my 450 conversion does!
I love it! won a decent amount of races with it, felt like I could beat the living snot outa it with no issues. I had to setup for MX and it pulled WAY down low. Thing runs wicked, people who have rode it love it.
Mosh helped me wedge it in there,
Picture of the motor-
http://i3.photobucket.com/albums/y92/JoshBall/ac88_1.jpg

[sx250heath]

Thanks for the info. I will be trail riding and maybe some play racing with this bike. I want to try and keeps the cost some what low. Relibility is very important also. That motor looks like piece od art kintore

[atc300r]

You might want to just freshen up the bore to the next size.The liquid r in stock form is a beast.Then you will have bores left for future rebuilds.Unless your on the last few bores.

[sx250heath]

I am buying a motor that will need to be completely rebuilt. so I I figure is now is a good time to do any mods I will want to do while it's apart. I really thinking about a 310 kit.

[atc300r]

Makes sence.Good luck on the build.I have a 85 and love it.Also love the 81 250r with DG pipe and head .and 83 300r.

[bkm]

Back in the day the 265 was the size engine limited for MX and that was the reason they ran it. If guys would have had a 310 limit, that's what they would have run.

[GO OVRIT]

Yea it was a class size limit. I have a 310 engine with similar porting to one of my oem cylinders, and the 310 is stronger. However for the same money it took to get the 310, I could have had the oem ported and flowed and had an even stronger setup. The 310 with equl port and flow work will be stronger. The 310 is really only 295 on the last bore with a stock stroke.