serious back firing

[timwilks13]

my 413 starts, ticks over and revs just fine, but when I put it in gear its like a bombs going off down there! backfire central, any clues?

[suzukisteve]

running a bit lean perhaps. although in my experience with backfires is usually down to the ignition, check it all out clean and adjust if need be. that's where id start I reckons

[Jordi]

Got the exhaust on it?

[timwilks13]

first half of the exhaust, front section and silencer, no back box .

[suzukisteve]

ah, that probably won't help much mate

[twiss]

Is it only at a certain point in the revs or just all the time when you are driving it?

[timwilks13]

only happening at higher revs. to be honest i really dont mind the sound, if anything i quite like the old "typical disney style generic old banger sound" its just the thought that my fuel consumption is going to be shot if its all just flooding down into the exhaust! ill put my back box on tonight and have a fiddle with ye olde SU, just didnt know if there was anything else i should be checking?

[twiss]

to be honest it probably is just lack of back box! they make a surprising amount of different due to the exhaust pressure

[timwilks13]

fear not, figured it out, the needle on my carb was right out, screwed it in and just came out a turn and problem solved!