I’m having an intermittent problem with my 2008 KFX450R and I’m hoping someone might recognize the symptoms.
A lot of the time it happens right after I shift into the next gear and start getting back on the throttle. It goes dead for a brief moment, almost like the fuel is being cut, and then picks back up. The engine doesn’t shut off completely. I’ve also felt it while slowly rolling on the throttle.
It seems to happen around the same throttle position, roughly ⅛–¼ throttle. I’m not sure if it’s always at the same RPM, but I mainly notice it in the higher gears, not the lower ones.
The problem varies from ride to ride. One day it was really bad and happened repeatedly. Other days it might only happen once, and sometimes the quad feels great.
It didn’t do this when I first got it. The issue started sometime after I installed the FCI intake and put the dynatek coil on, but it wasn’t immediately noticeable after the installation.
The quad has an FCI intake, HMF exhaust, HMF/Dobeck Optimizer
Here’s what I’ve done or checked:
● Replaced the injector with a new OEM injector
● Replaced the spark plug
● Checked valve clearances and the TPS setting
● Tried a Dynatek coil and later went back to the stock coil
● Cleaned the fuel pump area and replaced the fuel filter and pump strainer
● Checked fuel pressure: around 44 psi running in neutral. It drops to around 38–39 psi after the pump stops and holds around 30 psi after 15 minutes.
● Tried running it with the piggyback disconnected, however, that is not smart with my intake setup.
Has anyone experienced something similar on a KFX450R or another fuel-injected Kawasaki? I’d appreciate hearing what symptoms you had and what you found.