250cc Pistons......

wombat200 · Post by **wombat200** » Wed Apr 19, 2006 6:48 pm

Hi All - I have a '61 dream 250 (ca72), and am wondering what pistons I can use...... Are the CB72 & CL72 pistons the same?

I have an opportunity to pick up a 3mm oversize set for a CB/CL 72 and am wondering if they will work ok.......

Or, do I need to stick to pre-63 pistons (4 ring).

Thanks!

wombat200 · Post by **wombat200** » Sun May 14, 2006 8:10 pm

Anybody know the answer to this??

I'll be able to gain a reasonable performance increase by using the 3mm over-bore & am quite keen to use these piston......

wombat200 · Post by **wombat200** » Fri Jun 16, 2006 12:35 am

Ok, well, despite a lack of info, I bought these pistons anyway.......

They're "Hap Jones" +3mm overbore pistons, and the box says they're for a CB72.

Is there any reason I shouldn't use these in my CA72? Mines a '61 model.......

I believe they will result in lower compression - is it worth skimming the head to restore this, or will I not have enough valve clearance to play with?

Rob.

joeweir1 · Post by **joeweir1** » Fri Jun 16, 2006 7:05 am

Wombat-Not sure if this helps, but I just tore down a CA77 305cc that someone had put CB77 pistons in.They were standard bore.There must have been enough valve clearance.The valves and pistons were not damaged from hitting from what I could see.

wombat200 · Post by **wombat200** » Fri Jun 16, 2006 7:43 am

Thanks Joe, it all helps....... At least I know there's little risk of a valve collision!

How did you pick them as CB pistons, as opposed to CA pistons? Are they stamped/marked as such?

Rob.

joeweir1 · Post by **joeweir1** » Fri Jun 16, 2006 11:13 am

yes-They say CB77 on them.

LOUD MOUSE · Post by **LOUD MOUSE** » Fri Jun 16, 2006 7:36 pm

Put CA77 pistons in and increase the compression as Honda wanted it to be. ......emo