[sajohnson]

Anyone know if you can put a 2008 450x carb on a 2005 250x.

My understanding is that the 250r and 450 carbs have a 40 mm manifold and the 250x have a 37 mm.

My guess is that it will fit but will have to change jet sizes and a few other things to make it run smooth.

Any input / help?

[sajohnson]

A buddy of mine needs to replace his carb. He found a 450x carb and wanted to know if it would work. So I said I would post for him to find out.

Thanks for info.

[crfsonly]

you are correct about the sizes of each: 250X 37mm, 450X 40mm. these size differences are carefully chosen to match the motor's intake volume. honda moved to 40mm on the 250R and many felt like that was too large for a 250cc motor. it think it absolutely would be for the 250X. the 250X head is significantly different than the late model 250R head. in addition to head differences there are compression ratio and cam differences between the late model R and X models. i doubt you'd be successful with just a carb swap.

what is it you are trying to accomplish?

ken