Backfiring but still fine

[JakeZXR]

Took my L1 ZXR400 on a 50 mile run yesterday hit some traffic getting out of Bristol and was running a bit hot but got out into the countryside towards cheddar after doing decent speeds and stayed at a mates.... The next day it was cool but clear and pretty warm I let the bike warm up using the choke like usual for about 2-3 mins and set of easily sticking to 30 ish at high gears for the first 10 mins and as I got up to some national speed parts I stayed in 6th and as I gradually accelerated to about 50 and it back fired loudly with a sudden loss of power but then straight back on and fine again then it happened about 5 mins later
After this the bike seemed to be running fine and didn't do anything wrong
Any ideas?!? I know it's an old bike and it was still cold I'm also running quite a loud and large MICRON exhaust however although I haven't had it long it's never done it before?

Cheers

[banner001]

only time ive known about that was with a friends car that we were modifying, it was running lean and when hot would backfire and lose power.

you said you are running a micron exhaust, what air filter and main jets you got in there?

could be a coil or plug going, causing unburnt fuel to enter the pipes?

[JakeZXR]

Ah this is frustrating it's literally just had a full service and work over

Um I believe I'm not what sure air filter I'll check