Drill holes in my piston?

RM250racer
Edited Date/Time 5/9/2016 3:32am
02 cr125. Brand new oem cylinder and a pro x piston kit. There's no holes where the exhaust bridge is, the kit says nothing about drilling holes like how the Weisco kits do. Should it still get two holes? Thanks
|
CrGuy2T
Profile picture for user CrGuy2T
Posts
4183
Joined
3/11/2015
Location
Santa Fe, TX US
Fantasy
3711th
CrGuy2T 5/8/2016 11:32am
5/8/2016 11:32am
No don't drill holes in that piston.
Paw Paw 271
Profile picture for user Paw Paw 271
Posts
3640
Joined
4/3/2013
Location
Benton, LA US
Paw Paw 271 5/8/2016 1:43pm
5/8/2016 1:43pm
If has the exhaust bridge, I would suggest doing the holes for proper cooling and lubrication at the bridge area.
There is no down side to doing them, but there is a big down side possible if they are not done.
Just my 2 cents worth ( based on over 45 years of motorcycle mechanical work experience.)

Paw Paw
CrGuy2T
Profile picture for user CrGuy2T
Posts
4183
Joined
3/11/2015
Location
Santa Fe, TX US
Fantasy
3711th
CrGuy2T 5/8/2016 3:28pm
5/8/2016 3:28pm
Pro x is a cast piston. Only reason I suggested against it.
Paw Paw 271
Profile picture for user Paw Paw 271
Posts
3640
Joined
4/3/2013
Location
Benton, LA US
Paw Paw 271 5/8/2016 5:37pm
5/8/2016 5:37pm
Either way , the bridge needs to be lubricated and cooled no mater what type of piston is run.

Paw Paw

The Shop

See All »
CrGuy2T
Profile picture for user CrGuy2T
Posts
4183
Joined
3/11/2015
Location
Santa Fe, TX US
Fantasy
3711th
CrGuy2T 5/8/2016 6:37pm
5/8/2016 6:37pm
I'd be afraid of it cracking being cast. Totally agree on the lubrication. I personally have a had good luck on all my cr 125's with cast piston not drilled. Cr 250 was notorious for having bridge problems
colintrax
Profile picture for user colintrax
Posts
4704
Joined
8/25/2015
Location
Taylorsville, GA US
Fantasy
2342nd
colintrax 5/8/2016 7:01pm
5/8/2016 7:01pm
CrGuy2T wrote:
I'd be afraid of it cracking being cast. Totally agree on the lubrication. I personally have a had good luck on all my cr 125's with...
I'd be afraid of it cracking being cast. Totally agree on the lubrication. I personally have a had good luck on all my cr 125's with cast piston not drilled. Cr 250 was notorious for having bridge problems
Yeah, a cast piston isn't gonna take well to drilling. OP if you do drill holes, please take a file to it.
Skerby
Profile picture for user Skerby
Posts
1254
Joined
4/9/2013
Location
Mayes County, OK US
Skerby 5/8/2016 7:26pm
5/8/2016 7:26pm
I just put a cast pro x piston in my yz125, it came with two holes drilled for the exhaust bridge.
NHtoWA421
Profile picture for user NHtoWA421
Posts
549
Joined
8/4/2014
Location
Bremerton, WA US
NHtoWA421 5/9/2016 3:32am
5/9/2016 3:32am
CrGuy2T wrote:
I'd be afraid of it cracking being cast. Totally agree on the lubrication. I personally have a had good luck on all my cr 125's with...
I'd be afraid of it cracking being cast. Totally agree on the lubrication. I personally have a had good luck on all my cr 125's with cast piston not drilled. Cr 250 was notorious for having bridge problems
colintrax wrote:
Yeah, a cast piston isn't gonna take well to drilling. OP if you do drill holes, please take a file to it.
put a bit of a chamfer on both sides of the hole if you drill it. it will reduce stress in that area and prevent the chance of a crack propagating from that hole.

Post a reply to: Drill holes in my piston?