Hi Guys,
I have an 85 honda GB400, single cylinder, single carb. I recently did an overhaul on my carburetor, due to it leaking everywhere and running too big jets (had #165 main jet, and pilot screw (on fuel side) was only screwed out about 1.5 turns). I replaced the main jet with a #152 and it runs great now, the only issue I have is that when I accelerate over about 90kms and then slow down I get a loud backfire. It is always a single backfire, and it is a loud enough to scare the crap out of a lady that was walking on the side of the road. I don't get any backfiring, or popping any other time, just when decelerating from high speeds.
I'm running stock muffler with the baffle in and stock air box, but new OEM air filter. The jet sizing is stock, and stock settings are 2 1/2 screw turns out.
The bike will run OK, anywhere between 2.5 to 3.5 turns out, with 3 seeming to run the best. But I get the pop at 2.5, 3 and 3.5 turns, when the weather clears up I'm going to try quarter turns (2.75, 3.25 & 3.75 turns).
If this fails, I might try go up 1 size on the main jet.
Anyone got any other suggestions? (I've also adjusted the idle screw, so that it idles at a bit higher RPM as I read this might help - yet to test ride the bike after doing this).
Cheers
Slav
I have an 85 honda GB400, single cylinder, single carb. I recently did an overhaul on my carburetor, due to it leaking everywhere and running too big jets (had #165 main jet, and pilot screw (on fuel side) was only screwed out about 1.5 turns). I replaced the main jet with a #152 and it runs great now, the only issue I have is that when I accelerate over about 90kms and then slow down I get a loud backfire. It is always a single backfire, and it is a loud enough to scare the crap out of a lady that was walking on the side of the road. I don't get any backfiring, or popping any other time, just when decelerating from high speeds.
I'm running stock muffler with the baffle in and stock air box, but new OEM air filter. The jet sizing is stock, and stock settings are 2 1/2 screw turns out.
The bike will run OK, anywhere between 2.5 to 3.5 turns out, with 3 seeming to run the best. But I get the pop at 2.5, 3 and 3.5 turns, when the weather clears up I'm going to try quarter turns (2.75, 3.25 & 3.75 turns).
If this fails, I might try go up 1 size on the main jet.
Anyone got any other suggestions? (I've also adjusted the idle screw, so that it idles at a bit higher RPM as I read this might help - yet to test ride the bike after doing this).
Cheers
Slav