Vintage Dirt Bike Q & A

hi
can anyone help me with jetting specs for the 38mm mikuni carb for my 1973 cr250m.
it also has a read valve set up from mx360 yamaha fitted.
cheers
jim

_________________
Jim Garvey
1x honda cr250m 1973 in bits
1x honda cr250 champion dirttracker
1x yamaha tt500 dirttracker 1976
1x yetman triumph dirttracker
1x tt500 longtack speedway bike
1 x 1940 350 ariel speedway bike
1 x bultaco astro grasstrack bike antig

I pulled a 38mm Mikuni off a well-sorted 74 recently and jotted down the jetting specs. Main 320; pilot 60; Slide 2.5; Jet needle 6DP7 middle groove.

The bike had a DG head, race pipe, and was ported and it ran really well.

And the bike is for for sale with a stock head and with a stock Keihin carb if anybody needs an Elsinore.

mrmikkelsen: out of curiousity and the never ending quest for knowledge to make assorted parts sometimes work correctly, did you notice what needle jet was in the carb body??
Thanks, -Mitch

Aargh! No, I sure didn't look, or at least I didn't write it down. Given time, I'll be back into the bike again, but that won't be right away. Hopefully somebody else can do better?

Here is what I use and I am in California. My 73 CR250 has a 38mm Mikuni Roundslide. 300 mj, 25p, q-6 nj, 6DH7 #3 N, 2.5 slide.

3rd over on the top end & a circle -F pipe at the time.

frohrs1

thanks guys for the help will report back with results.
also might post a progress pic
cheers
jim

_________________
Jim Garvey
1x honda cr250m 1973 in bits
1x honda cr250 champion dirttracker
1x yamaha tt500 dirttracker 1976
1x yetman triumph dirttracker
1x tt500 longtack speedway bike
1 x 1940 350 ariel speedway bike
1 x bultaco astro grasstrack bike antig