spark, fuel, air, compression, no bang

[dudders7]

I am completely stumped with the gpz400r, tried everything I can think of carbs off and easy start in through inlet manifolds, spark timing is right, but no bang, occasionally backfires through the inlets but nothing else. Cam timing seems correct although I'm not 100% on how to check it properly. Any bright sparks out there who can shed some light on this? Thanks[/quote]
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Riding in the sun in Australia on a 04 Worked ZX10R along with a fleet of other crazy toys

[philoldsmobil...]

the old adage is that if it has spark compression fuel and timing it has to run..

by referring to fuel of course it needs to be in the right proportion. There is little capacity for ignition timing to be out, and if cam timing is wrong the engine likely wont turn on something like a GPZ400

I'd be looking closely at the carbs - are they flooding, or alternatively is it far too lean. Might be the choke failing to engage, or a blocked air passage. are those little brass air bleed tubes at the base of the air inlet clear? they are very important. Jets clear?

I'd definitely be looking at carbs..

[N cee thirty]

put a tea spoon of petrol down the plug holes and try and fire,if it goes it should be the carbs
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'00 Aprilia RS50 > '92 Honda CG > '99 Yamaha Fazer > '91 Yamaha RXS > '79 Suzuki X5 > 01' Honda Cg > 07' Honda Cg > 82' Kawasaki Z200 > suzuki gsxr 400 gk73a > honda vfr 400 NC30 Mod 2 Passed 09/06/2011

Jewlio Iglesias wrote: I actually did vote BNP once

[dudders7]

Just stripped and cleaned carbs, possibly inlet valves as its backfiring through the carbs? With carbs on and choke on it splutters and backfires but does not run. And yes obviously it should run, but doesn't. The joys of machines eh! Reminds me of an old 400cc two stroke outboard, same thing, got it to run once after hours of cursing and she ran good for an hour I then turned it off and she never started again...
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Riding in the sun in Australia on a 04 Worked ZX10R along with a fleet of other crazy toys

[dudders7]

Ok I have been a complete idiot, spark, fuel, air, no bloody compression, cylinders 1 and 2 are about 90 psi and are trying to start, 3 and 4 have about 45 PSI. New rings ordered, will strip it down re-grind the valves, hone the barrels etc. Hopefully will be running sometime next week
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Riding in the sun in Australia on a 04 Worked ZX10R along with a fleet of other crazy toys