Front forks Question?

[Mudgrip46]

What size were the forks on 250 Pentons in 1976,1977,1978? Were they all the same and will they interchange. How about later forks? Swingarms? Will the newer alum  2 shock arms retro back to 77? Thanks for the patience to answer for me.

Mudgrip46
77 penton 250

[tim bowers]

MG, I believe the forks are all about the
same. Checkout eurodirt.com for an after-
market aluminum swingarm. They are pretty
trick looking. Effective? I do not know.
I will leave that up to the Penton experts
here at POG.

TB

 

[Mike Lenz]

In 76 they went to leading axle 35mm ceriani forks. 77 had 35 Marzooks. 78-81 had 38mm marzooks with increasing travel thru those years.82-83/4 they had 40mm Marz, and 84 on they had upside down WPs. 76 thru 80 will interchange. 81 they went to a longer stering stem with all else the same. 82 they went to a different bearing set up. The hot set up I feel would be to run 38mms on the 75-77 class and the 40mms on the 78 and later classes. The 81 "fluted" damp rods are the best of the 38 forks I feel. And the 83 silver 40mm forks work pretty nice. I bored out 38 trees to run the 40s on my 80 420. I also modified a alum swing arm to fit a 78. 76/7 would be the same thing. You have to use a 79 or 80 swing arm from a 250 or 400 with the old engine and you have to mill out some metal on the bottom  sides and front ,bend the plate down and weld it to get the needed engine clearance for those frames. You also need to move the shock mounts back. If you want I could try and take some pictures of the one I did on the 78. MY em adr is [email protected]