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I'm also after a particular Bultaco 175 that put my '65 160 (less than 2500 org miles) in the weeds a few weeks ago in the fall giro..;))
For Beth's question, my 175 vert race bike has the 180 hap jones type pistons in it, and they work well, ie;, runs well, nice enough power, not Branson power, but nice for me (begining racer)
thoughts, ideas, best practice ?
dch.
From: Michael Bateman <michael.bateman@...>
To: CB175RaceTech@yahoogroups.com
Sent: Thursday, October 2, 2008 2:25:46 AM
Subject: RE: [CB175RaceTech] replacement pistons for a CB175 race bike
Those are hap jones pistons. They don't work well for the 175, the
compression ratio is lower than stock. They sort of work for the 160, if
you reshape the top of the piston for reduced compression (they make too
much in a 160) - but note that the domes do fit up in a 160 combustion
chamber.
However, even if you do go to the trouble of making them work in your 160
you'll have lots of problems with the cast iron skulls leaking between the
skull and the cylinder head (combustion leaks - comes out as a little bit of
a spooge around the spark plug hole). Even if you oring the cylinders.
Michael
>
> These are on Ebay right now:
>
> http://cgi.ebay. com/ebaymotors/ ws/eBayISAPI. dll?
> ViewItem&item= 330273997323& ssPageName= ADME:B:WNA: MOTORS:1123# ht_500wt_ 0
>
> My CB175 has low compression; worse on one side. That side had kind of a
> fouled plug. Got
> to tear into it so might be time for a bore job and new pistons. Should I
> stay away from
> these and just get some a bit oversized?
>
> Thanks; Beth
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