Post by loonietic on Mar 3, 2011 10:33:03 GMT -5
It's nice to see a forum for 120 sled racing newbie dads who have reached there limits but their kids haven't. Thanks!
My question is in regard to the 2010 AC120 with the Yamaha 125 cc engine. I have two boys racing in six classes in ovals in Canada. We have a 2006 AC 120 (Improved Stock), a 2007 AC 120 (Super Stock), a 2010 AC 120 (Super Stock) and a 2009 AC 120 (Stock).
We moved the 2010 up to Super Stock and I'm now worried that that was probably the wrong decision. Rec-motors supplied us with their first adj. main jet for these 2010's but unfortunately, the main jet assembly is not fed the same way on the 2010 as previous models. Instead of the main jet threading down into the nozzle, the main jet is threaded into the side of the fuel chamber. Now, the Rec-motors adj. main jet assembly had to be modified (shortened) so that the main jet would not be interfered with as the assembly is threaded down the fuel chamber. With that now completed, I bored the main jet and reinstalled. I changed the pilot jet from a stock 37.5 to a 42.5 and reinstalled carb.
I couldn't get the sled to get full rpm (maybe 3500-4000) with governor by-passed. I ran out of time and will be attacking it today. I'm going to go back to the 37.5 pilot see if that helps. I've already removed air box to get maximum intake (have velocity stack). Obviously, I can't go back to the start since the main jet has now been bored. Any thoughts?
My question is in regard to the 2010 AC120 with the Yamaha 125 cc engine. I have two boys racing in six classes in ovals in Canada. We have a 2006 AC 120 (Improved Stock), a 2007 AC 120 (Super Stock), a 2010 AC 120 (Super Stock) and a 2009 AC 120 (Stock).
We moved the 2010 up to Super Stock and I'm now worried that that was probably the wrong decision. Rec-motors supplied us with their first adj. main jet for these 2010's but unfortunately, the main jet assembly is not fed the same way on the 2010 as previous models. Instead of the main jet threading down into the nozzle, the main jet is threaded into the side of the fuel chamber. Now, the Rec-motors adj. main jet assembly had to be modified (shortened) so that the main jet would not be interfered with as the assembly is threaded down the fuel chamber. With that now completed, I bored the main jet and reinstalled. I changed the pilot jet from a stock 37.5 to a 42.5 and reinstalled carb.
I couldn't get the sled to get full rpm (maybe 3500-4000) with governor by-passed. I ran out of time and will be attacking it today. I'm going to go back to the 37.5 pilot see if that helps. I've already removed air box to get maximum intake (have velocity stack). Obviously, I can't go back to the start since the main jet has now been bored. Any thoughts?
