Bang! Bang! Someone was shooted? No, this is the muffler!!!

I went to my dealer last week-end to see my futur bike. we had some problem starting it because it start well but after a secind or two, it dies with or without throttle or choke. After 15 minutes or trying, we finally get the machine hot. I tried it for the first time in just the first gear. RREEAALLY impressed by the quickness of the engine, was on the rear wheel more fast than expected!!! However, the bike is doing backfire. I means real loud and spaced (gun like sound) back fire every 2-4 seconds when closing the throttle.

Philosophal question: Is backfiring a lean or rich conditions. Do we solve it with a needle, main jet or air screw adjustment??

The canadian bike is stock. The funny thing is that I asked to the mechanic if the airbox cover is still there, he answered: Is there an air cover on the wr??? I suspect that the previous owner removed the airbox cover and did not rejet. This could be the cause isn't it??


When I bought mine new, it didn't want to keep running at first. Who knows what someone did to a used bike. The only way to find out is to take it apart. Backfires could be caused by messed up cam timing and all sorts of things.

They all backfire on closed throttle deceleration. It's too lean, you have to re-jet, see the technical section.


'99 WR400

'92 GSXR 7/11

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