EC300 top end on EC250?

[ColtonW]

I have read in several places that you can simply swap the cylinder, head, carb off the EC300 onto the EC250! Is this true?! When you do, do you get the full power of the 300 or no? Is is any year 300 on any year 250 or what?

Thanks guys!

(And I'm sorry I am sure this was already answered, but I had alot of trouble searching, thus I hadn't found my answer! So, if I has already been answered, please post the URL to save everyone some time and head ache!
Thanks again!!)

 

[seitz64]

300 kit

hi! its true very easy to do. need 300 top end --cylinder, head ,piston w/rings ,you must use a carb spacer ,the 250 carb will work with a re-jet afew gaskets ,transfer the 250 power valve its done afew hour job ,,youll love it .good luck

 

[ColtonW]

Wow! It sounds too good to be true! Once it is complete, is the power very similar to the 300 from the factory or what? Why can't you use the 300 powervalves? Is it any year cylinder on any year 250? Sorry for so many questions.. this just seems soo cool!

 

[seitz64]

300 kit

if your 300 cyl. has the power valve in it use it they are the same! not sure about the year cross over ! the finished motor would be the same as an [oem]motor! ive done this swap on my 03 250 and have all the parts to do my sons 06 this summer. like i said its really simple with the rb mods the bike is really easy to ride & it flat out flys!! again good luck

 

[FFRDave]

I never used a carb spacer

I never used a carb spacer for my 05 250 to 300.

All the powervalve parts fit nicely and the bike IS actualy much mor powerful than I expected it to be.

When I first got the bike home, I had RB Designs adjust the Squish band, later I had my carb. plated and bored.
I have a MC 250 also, and I am considering the 300 upgrade for it as well. The carb is already plated and bored on the MC.

Awsome bikes, these....

 

[jostby]

FFRDave, who did your carb? RBD? I keep thinking about having it done (just because ) but my XC is such a beast as it is I don't know if I really want to.

 

[FFRDave]

RBD did my carb mods

My bike got better and more managable to ride.

The plate helps to improve therottle response at less than half therottle, by separating the top of the intake from the bottom. Its just a little crisper and more percise. If I am way down there at 20% therottle, going up a big hill, I can just open it a tad more to 25% or 30% and get juuuuussst that little bit more.
If I am wound out in third gear, that is where that extra mm of bore comes into play.

 

[jiauka]

You actually need the carb spacer if you have the boyesen reeds, otherwise the tip of the reeds broke sooner or later, if you have the V-force reeds the spacer is not needed.

have fun,

j.