April 20th, 2012 by Jason Giacchino
I have a 1987 Suzuki Quadracer 250 that pings every time I crack the throttle. It has a fresh top end but is still stock spec. The only other mods are a pipe and vented airbox lid. Any ideas?
Pinging is actually the result of pre-ignition of the fuel in your engine’s top end before the piston has returned to the top of its stroke (detonation). There are two potential fixes to the situation, neither of which is particularly expensive or difficult.
The first would be that your pipe and airbox modifications were just enough to lean out your ATV’s fuel/air mixture. In this case try moving your Quadracer’s needle jet (OEM part # 6FP60-3) down one clip position.
If that doesn’t cure the situation, it’s possible that you need to up the octane of the fuel you’re running. Switching to pure race gas may be overkill considering you haven’t increased the compression of your engine so a good starting point would be to try blending one gallon of race fuel (like VP C12) per every five gallons of pump gas. That ratio will likely solve any pre-detonation troubles. If for some reason it does not, increase that ratio of race to pump gas until the pinging disappears.