Penton Owners Group

General Discussion => Penton Talk => Topic started by: firstturn on August 15, 2006, 05:12:38 PM

Title: Question...1978 400 KTM
Post by: firstturn on August 15, 2006, 05:12:38 PM
What is standard bore for a 1978 KTM 400.  Thnaks.

Ron Carbaugh
Title: Question...1978 400 KTM
Post by: Larry Perkins on August 15, 2006, 07:18:55 PM
My memory says 82mm with the early 400 in 75 being 81mm.  If I am right do I win a prize, Brother?:D

Larry P
Title: Question...1978 400 KTM
Post by: firstturn on August 15, 2006, 07:25:46 PM
Larry,
  You are telling me what I want to hear....I thought it was 81 on the early ones and then it went to 82.  We will see what the experts say.  Thanks for your post.  I hope to see you on the way to the Reunion Ride little Brother.

Ron Carbaugh
Title: Question...1978 400 KTM
Post by: rob w on August 15, 2006, 10:04:49 PM
Larry's the winner. The 1978 400's bore and stroke is 82 x 68mm. Before that, 400's were 81 x 69mm. The '78's stock piston is the same size as a previous 400's fourth-oversize piston.
Ron, Is this for a cart engine ?
;)
Bob
Title: Question...1978 400 KTM
Post by: Dave Withrow on August 15, 2006, 10:11:58 PM
Rob,
    Once again, you've beaten me to the punch.  The info I have for the '78 400 is......now get this:
Enduro-355cc bore 81/stroke 69
MC-359cc bore 82/stroke 68

Short answer...........82.
GO PENTON!
Dave Withrow
Title: Question...1978 400 KTM
Post by: firstturn on August 15, 2006, 11:17:06 PM
Thnaks everyone for taking the time to help an ole Sachs guy.  Rob...this will g in a Kenny Roberts Flat Tracker that is currently a 250.  Thanks again.

Ron Carbaugh
Title: Question...1978 400 KTM
Post by: slvrbrdfxr on August 16, 2006, 05:01:43 PM
Now I understand why those Texas guys are always so fast !! Looks like they might be disguising 400's in the 250 class. :D Now why didn't I think of that !! Just kidding Ron !!
Dave McC
Title: Question...1978 400 KTM
Post by: firstturn on August 16, 2006, 05:17:10 PM
I thought the 250 class went from 250cc to 399cc?? Am I missing something here?  Where is that Larry Perkins....he told me that was how the class was determined.[:o)]

Ron Carbaugh
Title: Question...1978 400 KTM
Post by: Larry Perkins on August 16, 2006, 08:28:35 PM
Secrets?  I know nothing.  I see nothing.  Class?  I was late for that.[8D]

Larry P