1998 WR 400 flat spot and backfire when shut off
Posted June 20, 2004 - 11:07 AM
Initially the bike was cutting-out so I cleaned the carbs,
then I took it to a dealer and he found that the slide plate had broken. The dealer replaced the slide plate but now I have a flat spot at the start of the throttle and the bike backfires when I shut it off.
From reading other posts I guess that this is down to the air/fuel mixture but I am unsure how to adjust this (so was the dealer?). Could any of you guys or gals give me an idiots guide. I am not sure which screw is the air/fuel mix either.
Any help greatly appreciated.
Posted June 21, 2004 - 02:53 AM
Under the float bowl (Bottom part of the carb) you will find a small 'hole'. Inside it is a screw. It should be set approx 1.5 turns from closed. Screw it in gently until it seats then back it out 1.5 turns. Further out = more fuel. If you get beyond 2.5-3 turns, you need to probably change your PJ (pilot jet) for a bigger one - this could help reduce the backfire = lean = not enough fuel.
To adjust you will need a very short (1-1.5 inch max) flat bladed screwdrive. Try epoxying a nail to an electrical screwdriver bit and you now have a tool which is small enough and with enough leverage to turn it. Alternatively, loosen you carb and rotate the bottom out so you can get a normal length screwdriver in there.
If your dealer can't help, maybe you shouldnt be taking it to him ?? If you want more help, PM me.
Posted July 15, 2004 - 09:35 PM
On thing I can't get my head around is the fact that my bike was backfiring, which suggests a lean mix. I checked the fuel/air screw and it was 3.5 turns out which would suggest lots of fuel considering stock is 1.5 turns out
Posted July 18, 2004 - 11:42 PM