Posts
2156
Joined
1/11/2012
Location
USA
Edited Date/Time
3/4/2013 11:07am
Anyone have any info on grinding powervavles, particularly for an 01 CR125. I read some info from Gorr and some other folks that you can shape the valves to different profiles which in turn alters the powerband a bit. From what I hear if you grind them down a little you lose a little bottom but gain some on top.
Any help would be appreciated. Thanks.
Any help would be appreciated. Thanks.
made the transfers too tall to come off the bottom end strong. Profiling the power
valve outer edges was the main portion of the work, not sure if I can scan the 00
pics but can probably upload a crappy cell phone picof the 00 mod....if that helps.
No top end to be gained as long as the power valve opens fully without any mis-
match causing flow or timing restrictions.
alignment dowels), there is a poor match then that makes for an easy pattern. Matching
is pretty easy, it really depends a lot on the tools you have. Patience and some nice rat
tail files should be able to accomplish your needs. Just remember, your not so much
trying to enlarge the port..........as to eliminate the turbulence.
Instead of grinding the power valve, an installed a pin stop into the power valve assembly so it didn't closed that much, it helped the bottom end quite a bit.
I opened some holes in the air box side and installed a net yo not allow too much dirt into the air box
That about the cylinder not getting the cases is true. After some research I found the CR125 case volume is bigger than it should, and that is the main reason to the poor bottom end. So instead grinding the transfers to align them with the calendars an epoxy filled the cases to align them with the calendars, this way I reduced a little bit the cases volumen, gaining some more bottom end and mid range.
With these mods the bike got much better, not telling that it will drag race with a KTM 125 but sure it helped, and helped much more than the HGS pipe that it already had fitted.
I sold the bike and it eventually ended in a local tunner. One day I was in a track and due to a common friend we found that he had just done the bike motor and told me that I was stupid for stuffing the cases, that if you want power you grind material, never add. He told me that when he was mechanic in Argentina he prepared the fastest CR125 in their nationals (I don't trust people from argentina, not racist, they just talk too much), an that he removed all epoxi.... Whatever, he could say all he wanted, I am not a pro and those mods did the bike much easier to use, I was faster in it, I dont know if it gained max power but it definetly had a much better delivery
The Shop
DeCal Works Huge Plastic Inventory of UFO and Polisport kits.
Luxon 4-Post Bar Mounts
$189.95 - $239.95
^ Ha ha! Agreed.
After riding this weekend I think I need to send my shock to get rebuilt, Its kicking my ass (literally) on accel. bumps. I found the high speed compression to be adjusted all the way soft from the PO. Think its time for a rebuild to make that power a little easier to use.
Post a reply to: shaping power valves