i feel like an idiot. yesterday i was looking around on the net and i came across a site that had a 400cc 250r kit. it was the top end off of the pilot mated to the bottom end of a 250r. it was badass, but like a moron i forgot to bookmark the site. i was wondering if anyone has seen the conversion or knows about the site i just talked about. it looked like it would give the 250r some major *****!! thankz for reading . please reply

laterz

 

yes but why??? yes i know more power. It is a time bomb. All major big bores are time bombs. I had a 300ex punched to a 405 bt TC you would have to pull the hed every couple of races to see how the insides are doing. If not properly maintained Bye Bye $2500 motor. PSI makes a 425 motor and the kit is close to $3000. i still think you can build a 250r motor with a 330 that will work just as good with out all the hassle. Also i heard PSI has problems with the motor overheating.

 

FTZ's Site
ERIC

 

THEXOTIC1

the engine is not a big bore kit. it is the top end off of an already 400cc machine. nothing is bored out. it is not a time bomb.

 

That FTZ 400cc 250R uses a Honda Pilot (the bigger Odyssey) cylinder and head. They modify the 250R lowerend to make it work.

I haven't heard anything pro or con about that particular motor, but I have heard many good things about FTZ.

There is a guy near me who has an FTZ 265 (which uses a new Honda CR 250 cylinder) and it absolutely RIPS!!!

 

Yea but what about the whole "welded cases" thing? What exactly are they welding?
ERIC

 

this kits been out for a while now. some people are starting to use polaris scrambler 400 top ends now.

 

I'd go with a 'Polonda' Polaris 400cc cylinder setup from MP Racing...the reliability has been great (they drag race every weekend non stop) and the cylinder's power output is much greater than that of a pilot (less port correction is needed)

 

what kind of mods do you have to do to make the polaris top end fit to the honda bottom end? do you have to modify anything or does it just bolt right up?
thanks again for replying everyone.

laterz

 

Sure it isnt a big bore kit. The what is it. You are puttting a bigger bore on a 250r it is a big bore kit. PSI makes a 425 kit that is a complete cylinder head and pistion. This is their own desing not a 250r. Call it what you want it is a big bore.