Hi there. Just wondering how to shorten the rear springs on an XS250 - there's a pic of a red 650 bobber on the front page of a site called yamaha650club which looks like it has some sort of ring or clamp compressing the spring(?) - or is it easier to fit a different, shorter spring if I can find a match? Also, I've seen these bikes with the tapered type air filter fitted straight onto the carby, and others which have retained the 'balance pipe'(? - H shaped tube section from carb to filter) and stuck each tapered filter on the end of it, which seems like a good idea if the balance pipe (or balance tube or whatever it is) does help performance - but does it? do I need it necessarily? if anyone has any recommendations for this type of filter on my bike, or tips on how it may alter my carb performance, negative or positive, I would appreciate any advice. And lastly, will an XS400 motor go in a 250 frame? are they the same frames? thanks.

Hi there. Just wondering how to shorten the rear springs on an XS250 - there's a pic of a red 650 bobber on the front page of a site called yamaha650club which looks like it has some sort of ring or clamp compressing the spring(?) - or is it easier to fit a different, shorter spring if I can find a match?

go for a shorter shock, lower the front to keep the bike's steering geometry

Also, I've seen these bikes with the tapered type air filter fitted straight onto the carby, and others which have retained the 'balance pipe'(? - H shaped tube section from carb to filter) and stuck each tapered filter on the end of it, which seems like a good idea if the balance pipe (or balance tube or whatever it is) does help performance - but does it? do I need it necessarily? if anyone has any recommendations for this type of filter on my bike, or tips on how it may alter my carb performance, negative or positive, I would appreciate any advice.

keep the airbox if you can, the bike was designed that way. if your changing it for other reasons,i kept my H inlet pipe so the CV carbs can operate smoothly and I went up a jet size

And lastly, will an XS400 motor go in a 250 frame? are they the same frames? thanks.

yes, but change the carbs to the 34mm.

The bottom end is exactly the same as well!!

go for a shorter shock, lower the front to keep the bike's steering geometry

keep the airbox if you can, the bike was designed that way. if your changing it for other reasons,i kept my H inlet pipe so the CV carbs can operate smoothly and I went up a jet size

yes, but change the carbs to the 34mm.

The bottom end is exactly the same as well!!

thanks for your help there drewpy. is the lowering of the forks for these bikes covered somewhere in the forum? do you change the fluid level, or is it done another way? sorry if these are dumb or obvious questions - but I'm learning. how do you up-size the jet? & what are the 34mm carbs? - are they the standard size for the 400? thanks again.

thanks for your help there drewpy. is the lowering of the forks for these bikes covered somewhere in the forum? do you change the fluid level, or is it done another way? sorry if these are dumb or obvious questions - but I'm learning. how do you up-size the jet? & what are the 34mm carbs? - are they the standard size for the 400? thanks again.

just loosen the fork clamps and let the fork tube through to lower.

34mm carbs are standar 400 carbs 250's are 32mm and have differnt choke mechanisms.

if yiour going to use cones, i suggest reading HERE

just loosen the fork clamps and let the fork tube through to lower.

34mm carbs are standar 400 carbs 250's are 32mm and have differnt choke mechanisms.

if yiour going to use cones, i suggest reading HERE

very good. thanks.