1979 Honda CR250 jetting

[JP84]

Hi Gents,

Does anyone have any good jetting specs for a 1979 CR250? I am rebuilding one at the moment but the plug and piston in it at the moment are very black so it was running very rich I  think. It will have a DG pipe and Boyesen reeds when complete.
Any tips appreciated.

Cheers

[TT5 Matt]

i remember the workshop manual had all the jetting infro in relation to the altitude you were at,i know the jetting i used at morgan mile long track wouldnt run in the bike home at broken hill without changing the main jet and putting the hotter plug back in but at morgan the pipe ran a nice tan colour with a slight trace of oil on the end of the silencer maybe your needle/needle jet are worn out since there 30+ yo now unless its hardly been ridden.

[JP84]

I think you may be right, the needle is pretty worn and the Carby
is a mess overall. I found a teaspoon of sand in the float bowl when I pulled it to bits. I have ordered a brand new nos Carby to replace the worn one. Still, I'll need some ideas in what the best jetting set up would be for the new one.

[TT5 Matt]

hi JP
see if you can get the factory workshop manual that came with the bike new or at least a photocopy of one,they should be on ebay or someone here might copy the carb section pages for you.i found the settings in the manual fairly spot on especialy when going someone thats a different altitude to where you live coz the graph in the manual will guide you for the changes needed and save you alot of time rejetting