Callin out the 250r engine gurus 250r builders? combos for great power stock cylinder

[slamdak8782]

Ok heres the problem I have a 250r I just got it and I want to know the best dome to run? Would a 265 or a 295 be better? I want a 250r with good bottom end and even better top end and mid range. I was going to do 295 bore. Is that the best bang for the buck? Seems pretty good to me. I am not opposed to running the 86 piston with my stock 89 long rod and the spacer plate. I have a guy here who does bore work cheap so a new sleeve isn't all that bad price wise. I I also read about wiseco racers edge pistons that were cut so you could port for better performance. I want a combination that absolutely rips and the best I can do without buing the esr 310 or anytthing like that. Iknow how to build an engine but im very new to the 2stroke and thought maybe someone could steer me in the right direction. :confused: :D

[zedicus00]

well lets start on the intake side and work our way through.

get a good highflow airfilter, some sware by the foamy jobs, i personally run a K&N with a waterproof outerwears.

carb, dont be afraid of beeing to big, get atleast a 38A/S keihin carb, im running a 40 keihin PWK and still hav good low-mid power.

reeds an intake boot. soft reeds allow better bottom end but flutter at high rpm, hard reeds cut out a lil bottom end but dont flutter in high rpm range. there r dual stage reeds that supposedly allow good bottom end and dont flutter but im not fond of them. i do run a set in my girlfriends blaster though. i use a ported v-force 3 carbon fiber reed setup with an aluminum intake that was also ported, did cut out a lil low end over a softer reed but they hold together great and r worth it i think

topend, the 295 resleeve is a good kit, mine is on its last bore which takes it to about 303cc, mill the head, u want around 190lbs if yur runnin pumpgas, that will help the lowend grunt some, and PORTING is key, it will gain u more power then just getting the big bore kit. i persoanally use C-Leigh-racing...

exhaust has the most effect on where the powerband is, so get a good one, ESR, or sparks or sumthing like that.

ALSO make sure all yur bits match. dont get a low end reed and carb with a highend port job and pipe, u will castrate yur engine.

[Eddiesanders250]

he said it right there.

[beerock]

I would say dont resleeve it to a 295 unless its on its last bore and there no more left. even then it may be wise to just put a new sleeve in it and start at 249cc, the reason being is if you blow your top end you have a bunch of over broes to go through before resleeving once again. If you go with a 295 sleeve you are limited on the amount of overbores i think its 3 over bores.
the othe rproblem wiht that is if you blow a top end bad you may not be able to rebore the 295. If you get gouges to deep in the cylinder the onyl thing you can do is resleeve it again.

if you dont care about that then go for it.

I have heard issues with too much heat with the 295 resleeve for the stock jug. its definately doable, you might want to set your eyes on a ftermarket radiator in the future to keep the motor cooler then the oem radiator can do with a 295 sleeve.


in review, i think all you need is a really good port job good pipe, 38mm or larger carb and a good reed cage, i use a cr250 rad valve and its has power everywhere and is the best cage for power all around. if you jump to a 295 great go for it, but im thinkin about reliability and the amount of over bores you will be able to have.

are you sure your machinest is capable of resleeving a stock cylinder? you need special machines for it. its easier to resleeve a pro x jug then a stock jug.

if you dont mind getting into a complicated setup like a 295 sleeve in a stock jug then go for it. Just make sure the people you are working with know how the 250r mtoor is. common problems with the 295 sleeve are overheating and blown head gaskets.

if you just get a killer port job now and figure out the motor set up maybe later on you can resleeve it to a 295. I will be doing a similar setup soon on my stock jug cyliinder that is ported to the hilt. BUT i went through 7 over bores and 400+ hours on that cylinder before i decided to resleeve it to a 295. this isnt going to be a regular 295 either, it will be stroked to about 320cc using a ktm rod and piston. It will feel just like my 265 did but with alot mroe bottom end grunt. the port job will be almost the same as i have run it for a long time and know it.

im rambling, but my point it, if you have alot of over broes just get a really kick *** port job and once your overbores are done with THEN think about resleeving it.

another thing, if you do resleeve it to a 295 I myself would definately think about putting in a new crank and main bearings. if you make this a big bore motor on the old crank theres no telling how the crank will react to the torque increase...

[zedicus00]

good points, i forgot to mention that i didnt go to a big bore sleeve untill i crcked the stock sleeve and it needed redone anyways...

ive never had over heating issues, and ive ridden on 100+ degree days. just for security i add 2 20fin inline coolers though.

also hav it all cryoed, its WELL WORTH the 100$ to hav an entire top end treated.

[slamdak8782]

well supposedly it already has a rad valve lrd pipe and i think it it something like 10 or 15 over not sure just put back togethor by Robbie Arnold. looks to be sound and runs good but probably could be a lot better. It still has the stock carb. on it. Thanks for the advice. I think im going to give the porting a whirl. I mean what do i have to lose cylinders are like 100 bucks now so I aint scared. I ported my 400ex and It will smoke a stock 450r. Thanks for the good info. Anyone else got opinions on the perfect setup. Can you use 4 stroke carbs on a 2 stroke?

[beerock]

id say first hting to get is a 39mm carb seems like you want the most power so go with the 39 not the 38 a/s

[Tom TRX250R]

To answer your question about the carbs, no you cannot use four stroke carbs on a two stroke, and I would definately recommend getting a bigger carb and porting. You could also try a cool head with adjustable domes to bump up your compression, it will help with low end. If money is an issue, you could shave your stock head or run a stock gasket and it will have the same affect as the cool head just not being adjustable and cool as well, split it into three pieces, and run one of the thinner gaskets. Also do a compression check afterwards because you may have to run race gas depending on the compression.

[baker250r]

To answer ur 295 question.... i have a 295 and i also have the bigger radiator and a few in line coolers to drop the degrees. it runs cool enuf for me. but id reccomend a bigger rad on anything bigger than 265 IMO

[MX wannabe]

hey guys im really new to this whole 2 stroke thing i am gonna buy an r and was wondering.... the whole bike is stock and in rough shape but im getting a pretty good deal on it... so i was wondering what should i do cause i have to rebuild it this winter but i am sooo lost cause u guys talk about resleeving and overboring and stuff like that i just want a bike that is gonna kill 400exs it doesnt have to be the fastest bike in the world but it has to boogy if someone could give me a step by step on what i should buy for the motor work and if u want it would be great if someone could recomend parts to buy like suspensionwise... so thanks

[baker250r]

first off dude... start with a good pipe... then work ur way over to a air filter.... then reed cage.... then carburetor.... after thats all doen with... then look into gettin a port job. and if ur in it for racing... dont forget about suspension.... ur only as fast as the suspension

[ESR250R]

Originally posted by beerock
id say first hting to get is a 39mm carb seems like you want the most power so go with the 39 not the 38 a/s


is there something wrong with running a 38mm a/s over your 39.... i, along with alot of other people run a 38mm and ive never had trouble with the carb, performs great and was easy to jet. please inlighten me on why you think the 39mm carb is so much better than the 38.

[zedicus00]

you may loose a touch on bottom end but the bigger carb will hav more topend power. i ran a 39mm on a stock bore jug. im running a 40mm on a 295. my engine builders running a 42mm on a 265.

A/S carbs are great for woods riding an stuff though.

[MX wannabe]

thanks alot thats a starting point and now im not so lost lol thanks

[beerock]

Originally posted by zedicus00
you may loose a touch on bottom end but the bigger carb will hav more topend power. i ran a 39mm on a stock bore jug. im running a 40mm on a 295. my engine builders running a 42mm on a 265.

A/S carbs are great for woods riding an stuff though.

exactly