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250 MotoX 2 stroke motors

#22

#22

Joined Oct 2008
6K Posts | 5K+
In Cider
Looking for a 250 Superkart next year and while i've decided on a chassis, the engine chpice is still undecided. The most popular engine in the class is the Honda CR250 as its cheap to maintain etc but two bad points are that karters seem to charge the earth for raced tuned ones (that in reality are nothing special) and the CR vibrates very heavily according to a number of my sources.

I'm looking at getting a wrecked MotoX bike for the engine then building one up from there, the three engine choices are Rotax 257, Yamaha YZ250 and of course the Honda CR250. There are some others but i've already ruled them out. So does anyone know much about those motors?
 
<div class='quotetop'>QUOTE (#22 @ Oct 15 2009, 06:20 AM) <{POST_SNAPBACK}><div class='quotemain'>Looking for a 250 Superkart next year and while i've decided on a chassis, the engine chpice is still undecided. The most popular engine in the class is the Honda CR250 as its cheap to maintain etc but two bad points are that karters seem to charge the earth for raced tuned ones (that in reality are nothing special) and the CR vibrates very heavily according to a number of my sources.

I'm looking at getting a wrecked MotoX bike for the engine then building one up from there, the three engine choices are Rotax 257, Yamaha YZ250 and of course the Honda CR250. There are some others but i've already ruled them out. So does anyone know much about those motors?

Whoa Whoa Whoa.... slow down there big boy. First you need to graduate from an 80cc kart, so start off on that. No one must like you, at least not enough to warn and stop you from going out there on a 250cc Superkart and hurting yourself.
 
<div class='quotetop'>QUOTE (SuperShinya56 @ Oct 15 2009, 06:48 PM) <{POST_SNAPBACK}><div class='quotemain'>Whoa Whoa Whoa.... slow down there big boy. First you need to graduate from an 80cc kart, so start off on that. No one must like you, at least not enough to warn and stop you from going out there on a 250cc Superkart and hurting yourself.


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Go and try to annoy someone else loser...
 
<div class='quotetop'>QUOTE (#22 @ Oct 15 2009, 04:01 PM) <{POST_SNAPBACK}><div class='quotemain'>
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Go and try to annoy someone else loser...


Like I told you, whenever you're ready to play with the big boys let me know. My offer still stands, just name the time and place........ 80cc, 125ccc, 250cc, whatever you want just let me know.
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Back to reality...

I'm a huge fan of Yamaha smokers but don't have the type of knowledge you're looking for 22. But these guys do The Two Stroke Shop... OK now stop drooling...
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<div class='quotetop'>QUOTE (Mick D @ Oct 16 2009, 03:44 AM) <{POST_SNAPBACK}><div class='quotemain'>Back to reality...

I'm a huge fan of Yamaha smokers but don't have the type of knowledge you're looking for 22. But these guys do The Two Stroke Shop... OK now stop drooling...
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Cheers Mick, i'll have a gander at that later....
 
what vintage/age motor are you looking at? if they are new/nearly new then i would suggest the CR would be a better choice than a YZ. i cannot give you any opinion on the rotax, have no experience with that particular lump. i am assuming that for a kart, you want a top-end biased motor? the cr engines are historically revvers and are also reliable. Yzs are more mid-range delivery and might not be as useful around a kart track?

performance mods ... first on the list would be a new pipe and competition reeds. to try and stop/tame the vibration, crank balancing and an engine blueprinting would be a good idea but thats quite a big job. word to the wise, chasing horsepower is an expensive game on any engine, its cheaper to learn to drive better

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(jk)
 
Over here in the states everyone and their mothers run the Honda CR motors. They are proven race winners. Some do run the Yamaha YZ's but not many. As for the Kawasaki KX..... NONE. So there you go #22, get yourself the Honda CR250. As far as your driving skills, or lack thereof, goes.... can't help you out on that. Well..... first thing you need to know is what an apex is.
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<div class='quotetop'>QUOTE (BigAl @ Oct 16 2009, 10:33 AM) <{POST_SNAPBACK}><div class='quotemain'>what vintage/age motor are you looking at? if they are new/nearly new then i would suggest the CR would be a better choice than a YZ. i cannot give you any opinion on the rotax, have no experience with that particular lump. i am assuming that for a kart, you want a top-end biased motor? the cr engines are historically revvers and are also reliable. Yzs are more mid-range delivery and might not be as useful around a kart track?

performance mods ... first on the list would be a new pipe and competition reeds. to try and stop/tame the vibration, crank balancing and an engine blueprinting would be a good idea but thats quite a big job. word to the wise, chasing horsepower is an expensive game on any engine, its cheaper to learn to drive better

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(jk)


Hi Al, thanks for that, i'm seeing a guy tomorrow for some more info. Being an engineer and having serviced all my engines i'm pretty confident with them. If i go CR I'm looking at the post 2001 motors as they are crancase induction, but also have a bigger crankpin and some other bits so they are more bullet proof, even if some people claim they are slightly slower than the pre 2001 barrel induction. I remember my TM K8 125 ran a 3 bearing crank, now that was bulletproof! Its interesting what you said about the CR Vs the YZ though, because over here one reason the CR is more popular is apparently it produces more raw torque than the YZ courtesy of having a longer stroke. Interestingly its not just top end you need for the kart. Sure we would be on full throttle more than a bike with the same motor but having been sick of screaming 125's for years it will be nice to have something a bit more tractable!
Oh and don't worry, I know only too well about the price of chasing horsepower. I looked at a kart spec CR the other day and it was a dog! Scored barrels and everything, but because it had some tuners stamp on it the guy wanted £1600 for it! Plus most kart tuners fit retarder boxes onto them and I for one hate them, I have a number of biker friends who've had serious accidents when the retarder box has failed so to start with i'll be sticking to the stock ign, but fitting Vforce reeds and some other funky bits, as long as the motor stays reliable i'm happy. Exhausts aren't a problem as there are tailor made ones on the market.

I'll let you know how I get on tomorrow.
 
<div class='quotetop'>QUOTE (#22 @ Oct 16 2009, 09:57 PM) <{POST_SNAPBACK}><div class='quotemain'>Hi Al, thanks for that, i'm seeing a guy tomorrow for some more info. Being an engineer and having serviced all my engines i'm pretty confident with them. If i go CR I'm looking at the post 2001 motors as they are crancase induction, but also have a bigger crankpin and some other bits so they are more bullet proof, even if some people claim they are slightly slower than the pre 2001 barrel induction. I remember my TM K8 125 ran a 3 bearing crank, now that was bulletproof! Its interesting what you said about the CR Vs the YZ though, because over here one reason the CR is more popular is apparently it produces more raw torque than the YZ courtesy of having a longer stroke. Interestingly its not just top end you need for the kart. Sure we would be on full throttle more than a bike with the same motor but having been sick of screaming 125's for years it will be nice to have something a bit more tractable!
Oh and don't worry, I know only too well about the price of chasing horsepower. I looked at a kart spec CR the other day and it was a dog! Scored barrels and everything, but because it had some tuners stamp on it the guy wanted £1600 for it! Plus most kart tuners fit retarder boxes onto them and I for one hate them, I have a number of biker friends who've had serious accidents when the retarder box has failed so to start with i'll be sticking to the stock ign, but fitting Vforce reeds and some other funky bits, as long as the motor stays reliable i'm happy. Exhausts aren't a problem as there are tailor made ones on the market.

I'll let you know how I get on tomorrow.
good luck and hope you find a good motor.
RE the stroke of the cr. its the same as that of the yz, its the rod length that is longer. this give a little more dwell time at TDC and BDC plus slightly lower piston speeds. that means an engine that is more comfortable in the higher rev ranges. the trade-off is a more focused power band. a yz has a better spread of power which makes it easier to ride but then you are not using the engine in the dirt are you...
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<div class='quotetop'>QUOTE (SuperShinya56 @ Oct 16 2009, 08:53 PM) <{POST_SNAPBACK}><div class='quotemain'>Over here in the states everyone and their mothers run the Honda CR motors. They are proven race winners. Some do run the Yamaha YZ's but not many. As for the Kawasaki KX..... NONE. So there you go #22, get yourself the Honda CR250. As far as your driving skills, or lack thereof, goes.... can't help you out on that. Well..... first thing you need to know is what an apex is.
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SS56 the guy that made this video definitely had you in mind

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Cheers everyone, spoke to a guy in the know yesterday, and have pretty much decided to go with the Honda. I can get an old bike motor and it only needs a few mods to get it to kart spec so it should be good.

Decided on a PVP chassis too, isn't this thing a peice of art?!

PVP_kart-Y_2004.jpg
 
<div class='quotetop'>QUOTE (#22 @ Oct 19 2009, 07:15 AM) <{POST_SNAPBACK}><div class='quotemain'>Cheers everyone, spoke to a guy in the know yesterday, and have pretty much decided to go with the Honda. I can get an old bike motor and it only needs a few mods to get it to kart spec so it should be good.

Decided on a PVP chassis too, isn't this thing a peice of art?!

PVP_kart-Y_2004.jpg


FKIN awesome dude....

good plan to go with the honda motor its very strong

if id seen this before i woulda said the honda moto also to because....

KX motor wouldnt touch it...kwak tinker with it every year but never seem to get it quite rite.

RM motor ummmm no thanks

the YZ motor is very good and power delivery is nice, but in a bike... my fav all rounder
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the CR motor
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even tho its not my fave pakage in a bike from a kart point of view it would be my choice to... it offers very strong pulling power its just feels more raw compared to the YZ motor.

GOOD LUCK WITH YOUR PROJECT... keep us updated
 
Not sure if this`ll be any help but there is a chap that was reccomended to Shaky Bynre (RGV 250 rebuild) called Darren Lane,shithot with 2 strokes apparently.Anyhow ,he is now rebuilding Shaky`s engine.All the best.
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<div class='quotetop'>QUOTE (DRILL @ Nov 5 2009, 02:42 PM) <{POST_SNAPBACK}><div class='quotemain'>Thats the stuff I saw at Mallory Pidgeon,bloody good!!!!
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yeah might even google some stuff on where/when karts/super karts are racing.2010
 

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