So when riding my kx500 to the next hill to dominate haha, I'll click into 3rd and 4th to get there quicker. When riding in third at around 1/2 to 3/4 throttle is fine WHEN ON THE GAS, when I cut the throttle to coast it hangs up in the rpms and then starts surging. Bike actually lunges back and fourth, as if the top end is super short. I had a 162 main in and bumped it up to a 165, same problem tho. Am I on the right track with my thinking of needing a fatter main or is it something completely different? Any thoughts? Motor was built by pro circuit for race gas. I'm running around 106 octane. Premium gas with Torco Accelerator octane booster
500 Kx500 surging?
- Thread starter AdamRides87
- Start date
Also I pulled a 172 main out when I purchased the bike
Maybe idle speed? Or slide hanging up on decel?
The plug actually looks pretty great. Mocha colored. Air leak, so maybe the air boot or boot to carb? I put the 172 main back in and it seems much better, there's a bunch of assholes in my neighborhood so I really couldn't get on it very long so I'm not sure
the air boot from your air cleaner to the carb is the last one to look at. sounds like carb out including the reed valve and even the base gasket. Don't count out the crankshaft seal(s), most likely the dry side. Is the description of the plug from just shutting it off when you were done, or did you do a chop while it was surging? (still sounds like a leak.)
Damn you guys are smart! Pulled the rubber coupler from between the reed valve and the carb, sure enough a giant gash was in it.
surging is usually a lean condition so the air leak is a possibility. The other is that what ever part of the throttle you are in it could be lean on the jetting. You are probly on the needle as you ride from one spot to the next so raising the needle may be the fix too.
It does have a boyesen rad valve.
This is what the coupler looks like, the tear is in between the two clamps. I'm guessing it was caused from age and over tightening?
This is what the coupler looks like, the tear is in between the two clamps. I'm guessing it was caused from age and over tightening?
GOOD!! it is why i like the rad. Those things are like 8 dollars to replace as opposed to not even being able to get other parts. A silicone hose will work just fine too, and those can be had in colors by the foot!! Good find.