Posts
29
Joined
6/14/2018
Location
Houston, TX
US
Edited Date/Time
8/7/2018 8:54am
2003 rm 125, the spark plug arm is bending up and completely closing the gap after about 3 laps (6 minutes), happened twice in a row after a long wide open straight. replace the plug and it runs perfect until this happens again. Previous to this the whole engine was rebuilt with new everything except transmission. Cylinder was replated and bored with the head matched to it and a new piston. everything was installed correctly. Powervalve assembly was taken apart and cleaned with the exhaust valves replaced and trimmed down for the cylinder bore. Everything on the bike is new and at spec. I am at a loss for what is causing this? and yes I did the heat cycles before opening it up. Any help or ideas would be GREATLY appreciated!
Check you squish to make sure you are in spec.
Paw Paw
You might be able to use the depth bar on a set of dial calipers to figure out how close the piston is getting to the plug at TDC.
The Shop
SPARK PLUG (NGK,R6918B-8)
Mfg. #09482-00509
$25 each on rocky mountain
Post a reply to: spark plug gap is closing?