TRX250R.ORG
Workshop => Engine and Bottom End => Topic started by: Tyler 54 on August 05, 2013, 01:33:46 AM
-
Is this doable? My 88 Cylinder is at 69MM I need a piston for it. Its a ported LRD.
-
To put an 85-86 cylinder on a long rod motor you need to be +5mm. So a 3mm spacer and two 1mm gaskets. Not sure if you can put an 86 piston in an 87-89 cylinder, port windows may be different. Seems like it should work though, maybe someone with more knowledge can shed some light.
-
It will work & as noted you'll need a 3mm spacer plate.
That is an old school big bore build, they did for years until the big bore cylinders came out.
The next size piston in the 85/86 TRX style after the 69.00mm, is a 69.50mm & is the last size you can get in that style, so measure the cylinder bore good to see if theres enough meat left that you can get a good clear bore & hone out of it.
If not, then all you can do is use a 70.00mm YZ250 Yamaha piston & a 2.5mm spacer plate.
You'll need to check the cylinder porting if the YZ piston is used, to make sure the port windows not widened to much, because if they are, the end of the ring could get hung in a port opening because on the ring pin locators in the YZ piston.
Neil
-
It will work & as noted you'll need a 3mm spacer plate.
That is an old school big bore build, they did for years until the big bore cylinders came out.
The next size piston in the 85/86 TRX style after the 69.00mm, is a 69.50mm & is the last size you can get in that style, so measure the cylinder bore good to see if theres enough meat left that you can get a good clear bore & hone out of it.
If not, then all you can do is use a 70.00mm YZ250 Yamaha piston & a 2.5mm spacer plate.
You'll need to check the cylinder porting if the YZ piston is used, to make sure the port windows not widened to much, because if they are, the end of the ring could get hung in a port opening because on the ring pin locators in the YZ piston.
Neil
Thanks! I've had it measured and theres enough to get the 69 or 68.5 out of it.
Good place to order the spacer? probably be a few months before I'm even ready to build my engine...
-
http://www.youtube.com/watch?v=l3kYLJajA2o
http://www.youtube.com/watch?v=ydCQkJsO_cU
-
Good place to order the spacer?
Ordered mine from TLR Online. Pumashine makes 'em. You will need extended base studs also.