Help identify 310R cylinder & suggest head

[250r'en +TCB]

Hey guys,

I am doing a full resto on my 85 R and need help identifying the big bore cylinder. Basically, I bought the cylinder used almost a decade ago off ebay or a 3WW member. The cylinder is ported AWESOME and makes a ton of power! :D But it occurred to me I don't know the manufacturer of it so I was hoping by posting some pictures I could get some answers.

Also, I want to get a head and dome to put on this cylinder (I was running an OEM head). I was going to buy an ESR head but it says on the website they only work on ESR and ProX cylinders. Can anyone recommend a head and dome that will work?

Thanks in advance guys!

223322223323223324

[bkm]

That is an OEM 250r cylinder. Pro Design still makes a Cool Head for the oem cylinder.

[deathman53]

yes it is, I am looking at a 85 cylinder and its identical expect the color

[KASEY]

what is the bore size on that?

[250r'en +TCB]

Kasey:

It is going to be a 73.5mm after I bore it. Obviously just under that now but the mechanic I am working with to rebuild the engine said that is going to need to be the next bore. I found the pistons available from LA sleeve but they are $200 retail which seems high! Problem is who else makes a 73.5mm piston besides ESR and it says theirs only work on ESR and Pro-X cylinders....

[RIDE-RED 250r]

Sounds like what you have is an OEM cylinder with a LA Sleeve 295 sleeve installed in it. I'm guessing it is at 72mm bore now??

I don't see why the Wiseco pistons from ESR won't work with your cylinder... You don't have to jump right up to 73.5mm either. Eddie offers them in .25mm increments, so if you can just go to the 72.25mm piston I would do that. Why take more bore jobs away from yourself in the future?? Plus, I am not sure what the limitations for max bore size is with the 295 sleeve kit anyway... It may not be advisable to go that large with a 295 sleeve... I would check with folks who have more experience with the sleeve kit to advise on the max they can go..I would contact ESR and see if they what they say about running those pistons in an LA Sleeve 295.. His cylinders utilize steel sleeves as well, that's why I'm not sure why they couldn't be used. BTW, the pistons that come with an ESR Big Bore kit are Wiseco.... http://www.eddie-sanders-racing.com/product_p/esr-big-bore-piston-kits-.htm

Also, it should be noted that LA Sleeve offers .010" over (72.25mm) pistons for their 295 sleeve. Price is $140. Why do you want to skip over so many bore sizes??

In the past, ESR offered a head that worked with the OEM cylinder, and if I recall, you had to send your cylinder to them to have O-ring grooves cut in it as the replacement heads use O-rings as opposed to gaskets. You may be better served to see if you can get your OEM head re-worked to match up with your big bore sleeve, if it hasn't already been done. Dome profile, capacity, and the squish band can be altered by a shop that knows what they are doing. I have never looked into having an OEM head re-worked so I am not sure who to recommend for this.

Duncan Racing offers heads that they say can be used with stock cylinders. They also offer stock head rechambering. http://duncanracing.com/buyersguide/hondatrx250r.html#INDCOMP