XS250 - 360cc barrel change

[festasextremis]

I have a 1978 xs250 special that i would like a little more HP added to, and i have heard from multiple sources that i can swap the barrels from a 360 onto the 250.

Has anyone tried this, and to what degree of success?

I have enough experience to make it work. Just ask...

 

[RadlagerMike]

The first Series of the 250 Motor Block are able to put directly the one from the 400 ccm on it, later types need to be spindled up

From outside view the is no chance to check that without dismounting the cylinder bank

 

[festasextremis]

When you say series, do you mean single cam, then twin cam? Or '76 to '78?

 

[RadlagerMike]

250, from 1978, twin cam and the wholes in the engine Block with the size to fit the 400 ccm (Piston`s about 65mm)

 

[festasextremis]

O.k., i think j get it.

I have the earlier type engine, than yours.

My engine is a single cam, i will have a look at the holes when i do the top end.

 

[RadlagerMike]

if all has been dismounted then it is not a Problem to spindle up the motor block in german the tool is called (Wohlhaupter)

 

[festasextremis]

Yes. A boring head. I will send it to the same shop i send all my boring work. They do cast iron sleeve fitting.

 

[RadlagerMike]

Those things i am doing by myself

 

[festasextremis]

Those things i am doing by myself

How are you machining the cylinders? With a veritcal boring machine or a milling machine?

 

[RadlagerMike]

In German it is called "Fräsmaschine"

 

[festasextremis]

Milling machine. Nice. Would do a beautiful job with that Wohlhaupter. Have you made any big bored xs400s, or do you re-sleeve other engines?

 

[RadlagerMike]

Mothly done on Yamaha SR500 / XT500 to get up to 620, 640 or 700ccm