280 Kit which cylinders will fit ??

[Brett72]

I am planning on putting a 280 kit on my 2004 XR250. I am wondering firstly what’s involved?

Is it just a new piston, a hone with a new sleave for the cylinder and new jetting to suit?

Secondly I would like to get a second-hand cylinder for the 280 mod so I can keep my stock barrel and piston if I have any troubles. What year model cylinders will fit a 2004 engine and head? Only 96-04 or were the earlier cylinders the same too?

Cheers

[redrider7202]

i'd say stick to post 96 just to be safe. Others might fit, but you never know.

[creeky]

I am planning on putting a 280 kit on my 2004 XR250. I am wondering firstly what’s involved?

Is it just a new piston, a hone with a new sleave for the cylinder and new jetting to suit?

Secondly I would like to get a second-hand cylinder for the 280 mod so I can keep my stock barrel and piston if I have any troubles. What year model cylinders will fit a 2004 engine and head? Only 96-04 or were the earlier cylinders the same too?

Cheers

You will not need a new sleeve, only a bore and hone to fit the new piston. If you use a 77mm piston, you will still have one oversize left. Richer jetting will be needed. Use a '96 and later cylinder.

[XR250rdr]

richer jetting? bigger bore usually requires leaner jetting.

[creeky]

richer jetting? bigger bore usually requires leaner jetting.

I have put together several 280s. If the exhaust is opened up, foam filter such as a UNI, the 280 will need at least a 138 main and a 45 pilot. This is for riding from sea level to around 1500 ft. elevation.

[XR250rdr]

can't lump other mods in then say the big bore needs richer jetting.

[creeky]

can't lump other mods in then say the big bore needs richer jetting.

Only speaking from experience.

[yater]

richer jetting? bigger bore usually requires leaner jetting.

The opposite has been true on my bikes (I don't have an xr250 yet). I've read this on the internet but it hasn't been true in my experience.