Penton Owners Group

General Discussion => Penton Talk => Topic started by: skiracer on August 06, 2021, 12:22:12 PM

Title: 81 250 cylinder
Post by: skiracer on August 06, 2021, 12:22:12 PM
Can someone explain to me why there's a bar that goes across each side of the liner at the bottom of the cylinder.  The 74-79 cylinders don't have that. Doing some quick measurements it appears the two types are otherwise very similar.  Going further, if those bars were removed, would that cylinder work on a 76 bottom end?

1976 250 MC5 Original Owner
1976 Penton 175 XC
Title: 81 250 cylinder
Post by: Carl Hill on August 07, 2021, 06:57:06 AM
That's interesting. I should have looked closer when I had my 81 top end off. Just FYI, my 81 really doesn't feel any faster than my 74. Power is a bit more broad, but 74 has more of a "hit". The 78 I used to ride ( different porting than 74) really felt the strongest.
Title: 81 250 cylinder
Post by: skiracer on August 07, 2021, 07:17:02 AM
Thanks Carl!

Quotequote:Originally posted by Carl Hill

That's interesting. I should have looked closer when I had my 81 top end off. Just FYI, my 81 really doesn't feel any faster than my 74. Power is a bit more broad, but 74 has more of a "hit". The 78 I used to ride ( different porting than 74) really felt the strongest.

1976 250 MC5 Original Owner
1976 Penton 175 XC
Title: 81 250 cylinder
Post by: Mike Lenz on August 08, 2021, 12:40:12 PM
yes  i put an 81 cylinder on a 78. Worked very well. Porting is really the same as a 79 or 80 cylinder though if you want to keep the orig look. Just make sure the old style cylinder has the three finger boost port.