OzVMX Forum

Clubroom => Tech Talk => Topic started by: big mac on May 01, 2013, 05:48:36 pm

Title: Piston ring pin relocation
Post by: big mac on May 01, 2013, 05:48:36 pm

I have a DT yamaha piston that I am going to use in a cooper 250 motor, I need to move the ring location pins does any body know how to do this & what material the pins are made from. Any info would be a great help.
Thanks Rory

Title: Re: Piston ring pin relocation
Post by: Tomas on May 01, 2013, 06:50:54 pm

when i was about fourteen i had to replaced one of those pins that was missing on a piston i got for my JAWA 50. got a piece of brazing rod, taped it in the pin hole, filed off the rest of it , rings on, piston on, cyliner and head on and off for a ride. worked well.

Title: Re: Piston ring pin relocation
Post by: cemotobull on May 01, 2013, 07:37:12 pm

Can you just turn the piston around and cut/alter the piston skirt or does another port get in the way?

Title: Re: Piston ring pin relocation
Post by: JohnnyO on May 01, 2013, 07:47:40 pm

I've done it years ago by drilling a small hole where the locator has to go then breaking the other end off the drill bit and grinding it to length then pressing it into the piston..

Title: Re: Piston ring pin relocation
Post by: TT5 Matt on May 01, 2013, 08:15:35 pm

get a single ring dt1 mx piston and no mods required,as to turning the piston 180 degrees don't do it as the piston pin hole is slightly offset.coopers use dt1 head gaskets as well

Title: Re: Piston ring pin relocation
Post by: cemotobull on May 01, 2013, 08:32:48 pm

The 180 degrees works for bully's as the pin is central. Unsure of the yammys

Title: Re: Piston ring pin relocation
Post by: big mac on May 02, 2013, 10:59:14 pm

Thanks for all the advice might look for a dt1mx piston 70.5mm in dia.

Title: Re: Piston ring pin relocation
Post by: BETRIC on May 03, 2013, 07:14:12 am

Big Mac I use a DT1 piston in both my Cooper MX and Enduro bikes, I had Greg Ball engineering (in SYDNEY) do the mods to the pistons, DT1 pistons need 4mm cut form the bottom of the skirt for clearance of the crank.
DT1MX pistons were standard fitment in Cooper MX bikes, ISLO made there own copy of the DT1 piston for use in the Enduro model, Big Mac if you need any info on Coopers send me a PM or email me with phone number and I will set you in the right direction. ;)   

Title: Re: Piston ring pin relocation
Post by: big mac on May 04, 2013, 11:36:35 am

Thanks Betric I am about to rebuild the motor so any advice would be great. The model I have is an enduro so I am not quite sure if I will do it as an mx or vinduro rider, how hard is it to get lights & other enduro gear.
Thanks Rory.

Title: Re: Piston ring pin relocation
Post by: BETRIC on May 05, 2013, 05:06:12 pm

Big Mac the standard Cooper lighting and switch gear is hard to find, the standard Cooper tail assembly is the same as used on Rupp minibikes and are avalible.