4 stroke in 250R frame???

[LT250RMan]

I was thinking of building a 250R with a 4 stroke engine to MX race with, what are your guys thoughts on what i should go with and what size of engine?

[flying dutchman]

get a TM engine
its an engine of from an italian build mx bike and they are fast as hell it will beat every other hybrid quad out there like crf and yzf

[2StrokeGod]

Originally posted by LT250RMan
I was thinking of building a 250R with a 4 stroke engine to MX race with, what are your guys thoughts on what i should go with and what size of engine?
WHY?

[TampaBoy813]

I would put a jet motor in it....then it would be a little faster then the R motor

[Zedicus]

Originally posted by TampaBoy813
I would put a jet motor in it....then it would be a little faster then the R motor

HAH! i love it! yeah 4-strokes in R frames are blasfemy around here.

[LT250RMan]

(1)Because its easier to race with a 4 stroke than a 2 stroke, (2)Way more reliable,(3) They don't stink like burnt oil all the time or smoke always (4)WAY MORE TORQUE!

[Scottt89]

I'm not sure as to your history with 2 Strokes, but I have had a Z400, a Banshee and a 250r. None of my 2strks smell like "Burnt" Oil, they don't all smoke all the time if you get a good premix with the right ratio. As for Reliability, I changed the oil on my Z400 just like I currently do on my Banshee, 250r and YZ250. Actually, the 2strokes are all easier(No oil filter, easier to refill then the Z400). I can't argue with the Torque aspect of a 4stoke, but if you are a good rider, you can win with either.

[250R-Dee]

Well, you are wrong about the reliability issue because 4-pokes require more maintenance than our beloved 2-strokes. The smell of correctly mixed premix is the bom diggity!!

Many 4-poke motors are too tall to be fitted into the 250R frame without doing some serious hacking. You will be better off buying an aftermarket frame for a hybrid setup or using a 400EX frame.

[LT250RMan]

i meant RELIABLE not that there easier to mantain, a 2 stroke will wear out a lot quicker than a 4 stroke, a 2 stroke fires on every stroke, comparied to every 2nd stroke like a 4 stroke, making the 2 stroke rev higher and run hotter there for will wear out quicker than a 4 stroke will,,,, (scott89)


Would a TRX450R engine fit in the 250R frame???

[250R-Dee]

The 450R motor is too tall for an OEM 250R frame.

Rebuilding a 2-stroke is simple. Any monkey with a wrench can do it.

[LT250RMan]

Is there any 4 stroke engines 300cc and up that would fit or are they all to tall?

[250R-Dee]

A 300cc motor?? What class are you planning to race?

The YZ426 and YFZ450 are good candidates for making a hybrid.

Hybrid search (http://www.exriders.com/vbb/search.php?s=&action=showresults&searchid=1270012&sortby=lastpost&sortorder=descending) in the 250R section.

[Zedicus]

put it in a 400ex frame, yull save yurself a lot of headache.

350X engines firt R frames with the leest amount of work for doing a 4 stroke R conversion.

[midwestrider]

you can put a crf450r in a 250r frame, but its a REALLY tight fit. the 350 x is a great fit.

[LT250RMan]

Really!! a 350X will fit?? thats cool, a bunch of people said a 4 storke will be tall for the 250R frame, But if a 350X will fit i'll go with that if it does'nt weigh to much more than the 250R engine,,,, Does the 350X have good power to race mx with??

[midwestrider]

i had a 350x motor, and it kicked ***, you can bore them out and they are bullet proof. with my stock 350x w/exhaust i would pull 416 all the times. work them over and they'll keep up with 450s

[LT250RMan]

I was talking to Lonestar Racing and they told me that a 350X will be a headache to put in, they told me to go with a YZF450 or a CRF450R they will fit just have to make custom engine mounts, they done it before, I think i will go with what Lonestar Racing says.

Should i go with the honda or yamaha engine????

[LT250RMan]

oops i meant a YZ426F

[midwestrider]

idk, i never had a problem putting it my 250r frame, but to each his own i guess....lol

anything in a R frame will be fast because its in an R frame lol

[LT250RMan]

ya R frames are nice mx frames but i dont want a 2 stroke mx quad, i want more torque, and dont like the look of new 450's but like R frames, so i want to build a 4 stroke R frame with a yz400f or a yz426f

[250r4life]

go sell your 250r, and go buy one of the new 450s... finance it if you have to... it will be so much better in the end- from so many aspects... ive said it too many times... trust me- just go buy a 450

[elementryder]

boy yall got it wrong if its a open class you gotta run a ktm 520

[Jay87]

Originally posted by elementryder
boy yall got it wrong if its a open class you gotta run a ktm 520

there a big heavy pos. my gas gas 300 can whoop up on one of them.

[Jay87]

Originally posted by LT250RMan
ya R frames are nice mx frames but i dont want a 2 stroke mx quad, i want more torque, and dont like the look of new 450's but like R frames, so i want to build a 4 stroke R frame with a yz400f or a yz426f


torque blah. if ur running a hybrid ur gonna be in open anyway, get a 330 or even 350 pv and u will have less maintence and have a damn fast quad.

[bubbag]

where are u in alberta? I think for all the headache u would be better to just go buy a new 450? or a used one....

[LT250RMan]

Why? I dont want a production quad, everyone has a production quad where i live,, i live about 1.5 hours from red deer

[Jay87]

just drop a 330 or 350 pv in it and nothing will touch it lol.

[atvmxr]

I am in process of a 350XR conversion and it is a major PITA. I started it about 2 years ago before the 450R's came out and since then I am kicking my self all the time now becuase a 450R would have been a much much much better route, but now I have to finish what I started.

[Slinky]

i have a 350RX and its definately not comparable to an R...my buddies R with a 265 walks all over my hybrid...and weighs about half as much.
i only use my quad for trail riding so it doesnt bother me, for an mx quad i'm definately going to be building a true R..i have an 88 frame sitting in my garage right now.
its a waste of time to do the 350RX....just get a new 450....

oh and 2 strokes are way easier to work on!

[LT250RMan]

Originally posted by Slinky
i have a 350RX and its definately not comparable to an R...my buddies R with a 265 walks all over my hybrid...and weighs about half as much.
i only use my quad for trail riding so it doesnt bother me, for an mx quad i'm definately going to be building a true R..i have an 88 frame sitting in my garage right now.
its a waste of time to do the 350RX....just get a new 450....

oh and 2 strokes are way easier to work on!

Thats because its a 350 free air in a liquid cooled chassis, I want to use a YZ400F or a YZ426F engine in mine , i'm not going to use a 350X engine

[rockman]

let me know how this works out, i've been thinking about doing the same thing. I too have heard the yz426 engine fits in nicely

[hondaracer263]

will a 400ex motor fit in a 250r chassis?

[koh0001]

I built a hybrid because I'm old and I need a reason to hang out in the shop with the guys. I enjoy the work more then anything....My 330r Smokes the 450r I just built( stock motor). I've put 90 hrs or more on this motor ( 330) and I havn't had any problems with it. I run 927 oil and it smells GREAT... everyone asks if I'm running race gas. I don't think ones beter then the other. It's what YOU WANT to do not what everyone else is doing. I can do anything to my 2-stroke, and I don't have a clue about the 4-strokes... so I'm going to have to pay someone to do my motor work.

If this was the only bike I have, I'd stick to the R They've been goood to me and you can work on them for less $$. Just my 2 cents.:D

[LT250RMan]

I'm kinda thinking about using a stock 400ex frame, do you guys think its a better idea using the 400ex frame instead of a stock 250R frame for the yz400f engine conversion??

[danbobsR]

please do..... alot more 400 frames out than there are 250r frames probally get one cheaper

[Jay87]

Originally posted by koh0001
I built a hybrid because I'm old and I need a reason to hang out in the shop with the guys. I enjoy the work more then anything....My 330r Smokes the 450r I just built( stock motor). I've put 90 hrs or more on this motor ( 330) and I havn't had any problems with it. I run 927 oil and it smells GREAT... everyone asks if I'm running race gas. I don't think ones beter then the other. It's what YOU WANT to do not what everyone else is doing. I can do anything to my 2-stroke, and I don't have a clue about the 4-strokes... so I'm going to have to pay someone to do my motor work.

If this was the only bike I have, I'd stick to the R They've been goood to me and you can work on them for less $$. Just my 2 cents.:D

this guy talks sense, 2 stroke is easy to fix and the 330's rip dont need to be revved as much and produce alot of power. will smoke a highly modded 450.

[LT250RMan]

ya a 330 power valve would be nice, maybe i'll build one of them after this projects done.