85 250r 310 kit

[bingham]

Looking to put a 310 kit on my 85 250r. Who is the best to go to and can i get any site reference on this? I was looking into esr but i really dont know yet. Anyone have a 310 kit that could refer me to who did theirs?

Thanks

[KASEY]

i have several 310's .. esr,ct, and pro-x... how much are you going to do? pipe carb porting? just so you know .. A 310 KIT IS USUALLY 295CC'S its only 310 when its bored all the way to the last bore,,, they run good,,,

[1BFC]

they run good

The run real good :acr

I run a LA Sleeve 310 and am quite happy with it. Probably all of them will suit your needs.

[Yamahondaman]

a friend of mine installed a 330 kit on his from CT awile back and it RIPPED !
it had so much MORE Power that it Killed the 20 yr. old crank... had it re-done and was fine after that

[bingham]

well current modifications are 39 pwk carb, esr atc5 pipe and silencer, boyseen reeds, k&n no airbox. Standard swing arm aswell, would i need to go bigger on the swing arm? im not looking for a straight dune bike that can only shoot hills, i love to trail ride as well, just seems that i am always looking for more and more races. But dont want to be completly geared towards racing.

[JohnR.]

Get an ESR 330 kit, you can have them set up the ports for whatever you'd like. I have the mid-range one on mine and it makes a ton of usable power. You can woods ride, ice race, drag race, or shoot hills in the dunes with it. They have a great deal on them now.

John

[Yamahondaman]

another friend of mine got the ESR kit for his 86 TRX .. they said it was Ported..
IT WASN'T ! ... it was drimmel'd up and bead blasted so the regular "shmo" would say ..."WOW ... LOOK AT THIS " ! when i looked at it .. i seen that there was LOT'S of stuff that could be done... "THEM" people that sell them PRO-X Cyl's sell SOOOO Many of them thing's that they don't care about the porting because of the regular "guy" that is about to run it ... of coarse it's more power than the stock 66mm bore
But somebody like Jason Hall can "do it up" on one of those thing's !! :naughty:

[JohnR.]

I don't know. When they did mine 6 or 7 years ago they must have been doing the porting at that point because my ESR 330 stomped the FTZ 270 that Chris was running. When I tear it down to freshen it up this year I'll have my machinist look the ports over and see if he thinks there is room for improvement. He's got a ton of 2 stroke experience so he knows what he's doing.

John

[bingham]

so the esr 330 kit is really what i was aiming for but is there any other modification i would need in order to do this? new to the whole shipping out my parts and stuff so i want to get it straight for sure.

[JohnR.]

You're going to want to freshen up the bottom end, new crank and rod bearings are a minimum. I went with an aftermarket rod (I can't remember which, I'd have to check the receipts) just for added insurance and because if I remember right you need the long rod to give yourself a little extra room for the piston. I do remember that we didn't have to machine the cases at all to run the 330 from ESR.

John

[tecat-z]

They make two different 330 kits, bolt on and one that requires case machining. The bolt on has the outside of the bottom portion of the cyl turned down, so it drops in cases. The bolt on kit can't be cut out as far, since cylinder becomes very thin on bottom. We built a 330 with a non-bolt on cyl and had esr cut cases. They can explain all the details for you.

[Autophysn]

hmmmmm, so you guys have me thinking. Looks like it would be good idea to get a new crank/rod if you do any type of big bore kit, Assuming your bottom end is original, which mine is......???????

[deathman53]

I didn't have a good experience with esr's cylinders. I had a bolt-on 330. It ran very hot and didn't have that much more power. I blew a top end(crank seals), ran it longer and went back to a stock ported cylinder. It didn't have as much torque but it wasn't so much different. I later bought a 310pv from lrd and holy !!!!! it ripped, the bike was unrideable with the stock swingarm, it was a night and day difference. Much more power, smoother and easier to ride. Don't get the bolt-on, without the sleeve going into the cases, it is weaker and can break, causing much bigger problems. Also, you only can do 2 over bores, before the piston won't fit in the cases.

[Saleenster]

I watch well ported 265's run away from a standard 310 kit. If your going to upgrade cylinders, you will be much happier then an entry level 310. 330 or 350 with a 4 or 5 mil will put a smile on your face for quite a while.shens

[bingham]

well my whole motor is pretty much rebuilt to stock, had a bad experience at glamis and blew the piston through the whole motor, so being said my motor has probably 30 rides on it. But now you guys have me thinking that the bolt on is unreliable?

[deathman53]

ALso the bolt-on requires a long rod crank also. That might rule you out immedietly. The bolt-on included a spacer plate, 4.5mm I think. The skirt from the sleave sits in the spacer, NOT in the cases. If there is some twisting it could cause the studs to flex and break. This may also break the small skirt that is in the spacer.

[deathman53]

Before you get a big bore, get a trx rad valve, 38 a/s carb and a good exhuast(if you don't have one). Remove airbox lid and if you have access to hi-octane fuel, get a cr head gasket(moose sells one with most of the gasket sets and seperate). It should a good amount more power.

[JohnR.]

My ESR top end has been dead solid reliable. Wide open down the frozen lake for a couple of miles is a pretty harsh test and mine has been doing it for years now.

John

[dizasterzrfun69]

i got an esr 310 on my 86R and it rips. It's been good to me so far and i drag race the hell out of it. I had jason hall do some port work to it and im running an esr 40.5 carb on it with v-force reeds and an FTZ out of frame pipe.

[ceaserthethird]

Great tip's & details - Keep it coming guy's !