Are the 250SX main jets the same style as 85 250R ? Looking to rejet

[whyzee]

Are the main jets interchangable ? I have just about every main jet for the 85/ 86 R . do the fit the 85 250SX ? I don 't have a service manual to check.
I added a K+N air filter and instantly noticed increased throttle response. Plug seems a little on the white side though ?? Do you think just adding an air filter will require a bigger main jet. Everything else on the bike is stock ( airbox lid, exhaust, etc ) Thinking of a 135 main, but do not want to rejet and rejet and end up back at the stock jet. Anyone else running a K+N filter only and rejet ?
Thanks for your time !

[3Razors]

They don't interchange, they are different series. If you are just changing the filter but keeping the lid on, I would not rejet. But if you take the lid off I would bump the main size up 1 number. Keep an eye on that k/n filter, they let too much dirt through without a prefilter on.

[whyzee]

They don't interchange, they are different series. If you are just changing the filter but keeping the lid on, I would not rejet. But if you take the lid off I would bump the main size up 1 number. Keep an eye on that k/n filter, they let too much dirt through without a prefilter on.

Thanks for the help 3Razors. You just saved me hours of messing with my bike :)

[3Razors]

Your welcome Whyzee. Nice to get a thank you for help