250 CDI with 350 top end?

[Lowflying]

I got an '85 RZ250 recently. It has 350 barrels and head. The 250 carbs are shot, but I have sourced some good used 350 carbs. Also getting a 350 oil pump to keep things from seizing up.

It has a 250 CDI. Will this thing run ok with the 250 CDI (better than with the 250 barrels anyway) or am I wasting my time unless I find a 350 CDI?

Any input appreciated as I am new to 2 stroke bikes.

Cheers guys.

[JonW]

you should really have a 350 cdi, and defo ditch those 250 carbs and the original 250 pipes if you have the ones with the separate end cans, the 31k style should be fine tho. Good on you for finding the correct pump and asking the question, rather than just running it as it was.

By '85 most 250 parts were restricted in some way. I did a thread about swapping these parts around on your year of bike on the rdrz forum which might be worth checking out, it had info from everyone Id spoken to about the conversion.

[Lowflying]

Thanks for your input. PM sent.

[EPApolice]

Google up rd lc crazy he has all the combos that you can use listed on his site. Just for the record the if you use the 250 carbs apart from changing the jetting you will also need to change the needles or else you will run into top end power issues when you go scratching. I think you need the slides as well.

[JonW]

I was told that the 250 carbs have smaller interior passages and I do know that the ones with the external jets have those fixed and not removable which the 350 ones have.