250 Scrambler Head swap

[Beltandbraces]

Hi one and all,
Grateful to be part of the forum!
I have purchased a1970 250 scrambler. It came (as a non runner) with a 350 barrel and head, is this arrangement ok?
Any thoughts are much appreciated.

[Duccout]

Hi,

We need more info! You cannot run a 350 barrel on a 250 unless it is cut down, is that the case, or is the engine fitted with a 350 Crank?


Cheers,

Colin

[Beltandbraces]

Thanks for that Colin, interesting!
I got a ‘spare’ barrel with the bike which is shorter.
I will measure both barrels.

[Eldert]

ID a barrel is simple : 250 has 8 fins . 350 9 fins and 450 10 fins

but like always there is one exception : the square barrel 350 mototrans has 10 fins .

Eldert

[Beltandbraces]

Thanks Eldert
In that case I have a 250 and a 350 barrel!

[Jordan]

Heads interchange between 250 and 350.

[Beltandbraces]

IMG_6920.jpeg

The bike came with the 350 barrel fitted, piston seized.
The 250 barrel was a spare.
Any advantage performance wise in using the 350? If indeed I can, some contradictory info above!

[Jordan]

I think the OD of the cylinder sleeves differ, where they fit inside the crankcase hole.
Measure these three.
The taller 350 cylinder needs a longer vertical bevel drive shaft than the 250.