Honda 250 es/sx owners. interest in high compression piston

[oscarmayer]

I'm trying to see how many people would be serious about getting a high compression piston for their sx or es. (same top ends)

According to weisco, we would have to purchase 12-14 pistons all have to be the same bore size, and compresion hiegth.

I was thinkinf of a 11:1 compression as you can still run normal 91 or better pump fuel octane and you can just go up a jet change like from a 130 to a 135 or 140.
(on a stock top end performance top end requires larger change)

I was also thinking of about a 1.5mm overbore. This would give us a small increase in CCs while still giving us 1 more hone job if needed. (2mm is max size). the research i have done and testing woudl give is somewhere in the high 260 range at a 1.5mm over and a 2mm max is in the low 270cc range. (assuming all heads are equil and not decked)

if your seriously interested and are willing to soend about $175 per piston (shipped) then post up.

I need 2 and so does SCRAMCHARGER318. so that's 4 down.

Here's a list i'll start and how many.

Pistons buyer Total # (4-5 so far counted for need 14)
Oscarmayer 2-3
SCRAMCHARGER318 2

[SWIGIN]

they dont make an 11:1

if they would make it you would heve to give them the measurements....i doubt they are going to alter there machines for one small run.

better see what they will do before going to far

[Twilight]

Have you tried asking if they already make the size? I wanted a piston for my CR500 Pilot, and they told me they didnt make any for the cr500 that was the size I needed. So I gave them the measurement and they found one that was a perfect match almost.

[oscarmayer]

ok everyone, again this is a CUSTOM run. no they do not make a pisotn for this motor. they make it for the 4v 250x not the 250es/sx that's 2v. so they can pretty much make it any compression we want and any size.

I did ask about things that may fit, but the 4v has the valve ressess incorrectly cut since it's a 4v not a 2v liek the es or es.

ONLY way to get some high comp pistsns is to do a custom run. I need 2 pistons minimum. another guy sayd he'd take 2, so that's 4 down for sure. that leave about 8 or so more left for someone else to step up to get if they are interested.

you CAN run this with stock setup. just get your jug bored/hone to correct size. Advantages are it will give you more power and a lot more torque. (about 4-5 more hp and 3-4 more torque.

[SWIGIN]

my point is that they never made a 11:1 before so without a ton of math and headaches they might not do it.

just over 10:1 and 12:1 is the norm and i'd bet weisco has made them in the past and has the measurements on hand for them.

no need to get smart, i hear you loud and clear.....just saying if you get guys wanting 11:1 pistons just be sure they'll make them.

[oscarmayer]

i wasn;t getting smart. i wasn;t sure if you understood what i was saying. they guy ont he phjone told me it coudl be any compression and any size. they would be totally custom. they would use the trx250r (4v) as a base since it's the same bore/stroke but has 4 valves, and then could add a thou or 2 to increase comp just a bit.

-------------------

so any takers on pistons? if they can;t do 11:1 then they will do the 10.25-10.5:1 ones copying the 4v head. still better than stock 9:1.

[SCRAMCHARGER318]

they're has got to be more people interested in this, i read posts on here all the time sayin they want more power out of there es/sx 250, if you run a 11:1 piston and a big web cam you would notice a outstanding diffrence, but the piston is the start, i only need 1 but if this is going to be a 1 time thing i gotta get 2 just to have one layin around, this may be your only chance to get a high comp piston for these, it's not like poweroll will make them again, the sx is too old now. and anyway i rather run a wiseco just becuase everybody uses them and loves them.

[oscarmayer]

anyone? bump for interests

[peco250sx]

if i still didnt owe money on my sx i would but 175 is too much for right now

[oscarmayer]

:( we need more peps wanting power! you guys realize that $175 shipped to your door is not much for about a 5-6hp increase on a stock top end and about a 7-8 hp increase with web cam and springs and some port matching work and carb tweaking right? it's cheap power.

[Dirtcrasher]

I gotta jump in only because I WAS the huggest 250SX fan on earth. My motor is built as much as it can be for the most part.....

It's great fun and has it's limitations, but all in all, I rarely ride it....

I like to jump and the SX can jump but I've bent so many swingers by now that I gave up. I wanted to strengthen it, better the rear shock and in the end I found the best choice to be a 200X or a 350X.

I'm not downing it, because I'd be a hypocrite :D but the 600$ I dumped in my motor which if this piston gives you 5-6HP, I guess I got allot more but I still don't ride it....... I grabbed 2 of the 10.5:1 pistons from Powroll for 25$ a pop a few years back - still have 1 kit somewhere :naughty:

This may be why it's hard to get a group buy. I was pretty happy with my SX with a 350X carb, a Cobra pipe and no A/B lid. I just got greedy.... If suspension and geering changes were available it would be more worth the power upgrade....

[Blown 331]

I'm just gonna throw my opinion out there to try to help so just take it for nothing more than that. But I think you might have a little more interest in a lower compression ratio and a smaller bore size. I say that because 11 to 1 on an air cooled motor isn't a good idea on pump gas. Especially in the ES. On a summer day working and air cooled bike with 11 to 1 on 91 octain just isn't going to work. And I think 1 or .5mm would be a better choice. I doubt many 4 strokes are on their 2nd and 3rd bore and I wouldn't want to waste my extra bores. By that I mean when boring a cylinder I like to go the least amount possible and it still clean up.
And totally off topic, is it possible to get the 250X head on a 250SX?

[oscarmayer]

i don't really care if we drop to a 10.25-10.50:1 raito myself. i just figured the little extra would do good.

the reason behind the bore being 1mm-1.5mm is if your going to bore it, why not get some extra out of it too? more dispalcement will yeild more power and torque. it costs the same $ so why not? it sitll leaves you room to do 1 more bore if needed later on and that means goign back to stocker size, or getting another cyclidner and boring it if you purchased a spare piston. *hint hint*

i understand and i'm not locked solid on any of the settings. if we get enough interests for a smaller size, I'm ok with that too. I just want some pistons for my trikes!!!!!!

if someone is interestein jumping on with us, please let me know. I want everyone to know, you wili only be paying for actual costs of everything (piston being made, shipping from weisco to me, then to you as they won't drop ship to you directly). NO profit will be attemtped to be made from myself.

[HondaSXRider85]

i may be interested. not right now, as i have some outstanding speeding tickets to pay for still.lol but in a few weeks, or months maybe. doesnt sound like this will be happening any time soon though, so i think i have time. my sx is feeling weak after 24 years, and the kickstarter is slipping occasioanlly now, so i gotta tear in anyways. i would like a 1mm or 1.5mm over with at least a 10.5:1 comp. ratio, although 11:1 sounds good.lol email me when theres some headway on this. thanks in advance. nismomudrunner@hotmail.com is my email.

[racerxxx]

Hey guy's don't know if this would help or not, but I remembered this thread ( http://www.3wheelerworldforums.com/showthread.php?t=94810 ) from a while ago about swapping a TRX300 motor into it, and a little further into the thread there's talk about a 400 big bore kit. I found this http://www.fourstroketech.net/trx300products.htm

You may put out a few extra bucks, but you wouldn't have to worry about getting a group buy. And as the old saying goes:

"There's no replacement for cubic displacement!":naughty:

Not sure how much of this is feasible. I agree with you on looking for more power out of the 250, but I for one am very satisfied with the power from sport horse.

That 390 does sound cool though!

[The Goat]

I'm curious, how does a piston change equate a 5hp difference in power?

the 250 is what, 16hp or so at the crank (and I'd say I'm being generous considering what the trx300 puts out)? so a piston is supposed to give you an additional 33%
increase in power?

is the four valve head swap possible? that would see some power....

I also say the 386 kit I suggested would crunch the sx gear box... I've seen it crunch the 300s and the trikes are likely built lighter

[BWINDEY]

Did anything ever come of this??