gsxr400(73a)

[vfrfrank]

recently put engine in bike changed carbs but cant get up and running turns over great but misfires while cranking engine can anybody assist (with advice so i can attempt to sort it cheers would be very much appreciated

[Jaicen]

My guess if it's mis-firing is that you've possibly got the HT leads swapped.
What sort of mis-fire is it?? It could be the valve clearances as well as any number of things like the cam chains.

[Variablevalves suck]

Start with the basics, have you got a spark, is there petrol at the carbs-loosen the float bowl drain on one carb and see if fuel comes out, if these are right check youve got the ht leads on the correct spark plugs-nearside coil feeds 1 and 4- offside coil feeds 2 and 3, check all your connections over, is the battery any good. you have to just take your time and work your way through.

[vfrfrank]

ht leads are as you described 1-4 2-3 have heard before purchase it running there is a clear strong blue spark on all cylinders petrol is getting to carbs ok and all wiring all appears fine battery is around 6mths old works fine this is a real puzzler i have also put new needles in carbs +changed o-rings still same ,thanks for all the help

[Jaicen]

In that case, certainly sounds like a timing issue. I'm assuming it won't idle?

[vfrfrank]

no wont idle at all but dont understand how timing is out as engine came out of running gsxr put straight into mine no adjustments also tried two sets of carbs no change still does the same thing (misfires while cranking)i have noticed that there is a green wire with a yellow stripe on it located above battery i remember there used to be two now theres only one they were identical but one wasnt connectedcan only see one any suggestions where to start looking

[Variablevalves suck]

Hi frank,
The green/yellow wire is from the gear sensor to the cdi, it sends a different resistance from the gear sensor (next to the front sproket) to the cdi and is used by Suzuki to restrict/alter the timing/speed of the bike. Should be some bullet type connectors under the seat. If you want to dersrict the bike you can put a 1.5kohm resistor between the cdi side and earth and the bike will go above 180Kph.

[reggit]

That sounds very similar to the problem I have with my bandit 400 engine swap, the GSXR is a similar engine I beleive.
I had/have a few problems, but found the signal wheel under the left hand casing was different on both motors causing the spark to arrive at the wrong time.

Have a look at the thread in Bandit workshop.

[vfrfrank]

hello all after some investigation on bike have recleaned carbs ,plugs ,checked all wiring apears fine i have adjust carb screw right hand side it fires but wont idle but no back fire (ah progress)if i adjust left hand carb screw any ideas dont want to knock settings out again ?

[Variablevalves suck]

Hi VFR,
Sorry for leaving you hanging! not sure what you mean by adjusting the right and left side of the carbs can you expand or post a photo as i wonder if you may be adjusting the balancer screws.