I've rebuilt carbs I have good spark but still won't start just backfires please help somebody

Was the bike running before you rebuild the carbs??
How long since the bike has run?
More info needed.

Bike ran briefly firstly on three then gradually cleared revved clear of 3000 but nothing below then next day wouldn't fire just back firing out of exhaust hasn't run for a week or so

I would start with all the basics:
- Cold compression above 140 psi
- Working ignition system (LEFT coil leads to 1+4, RH to 2+3)
- Clean/dry plugs
- Fuel levels correct in carb and stay stable (check with clear plastic tubing)
- use a open syringe/remote tank to feed engine whilst testing NOT the fuel tank
- Throttle's correctly snchro'd and the idle angle PERFECTLY set. Start at around 1mm or very slightly less
- New or very good battery fully charged

If it started before it will start again! If all the above fails - treble check the carbs are 100%.

Great thanks will give it a whirl

I know it mind sound silly but did u prime the fuel switch screw.

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