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Bike won't start!

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ExSpeedTripleOwner
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Bike won't start!

#1 PostAuthor: ExSpeedTripleOwner » Sun Mar 16, 2025 5:08 pm

Hi

I have just rebuilt my Z1B and I cannot get it to start, I think it is a fuel starvation problem! The bike has Dyna S ignition and I have followed the instructions on how to set that up so I am pretty confident the static timing is correct, the test light comes on when the rotor is fully clockwise and the marks all line up!

I overhauled the carbs with the kit from Z Power and followed Allen Millyard's You Tube video on how to set the carbs up and think I have them set up correctly.

All the plugs are sparking, but there does not seem to be any fuel getting into the engine. I can see a small amount of fuel coming out of a couple of the inlet rubbers though! When I press the start button nothing happens and occasionally there is a little bit of a back fire.

Any hints or tips would be greatly appreciated.

Thanks
Dave

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chrisNI
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Re: Bike won't start!

#2 PostAuthor: chrisNI » Sun Mar 16, 2025 8:09 pm

Is your tank vent hole blocked? If you unscrew the float bowl drain screws is there fuel in the float bowls?

ExSpeedTripleOwner
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Re: Bike won't start!

#3 PostAuthor: ExSpeedTripleOwner » Mon Mar 17, 2025 8:32 am

Hi Chris

Thanks for the reply. I am using an open container hanging above the bike to supply fuel, yes there is fuel in the float bowls.

Dave

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wheelysteve
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Re: Bike won't start!

#4 PostAuthor: wheelysteve » Mon Mar 17, 2025 11:27 am

Is the valve timing correct?
1975 Z1B Candy Red/Blue
1975 Dogs Z1B
1976 Z900 A4
1977 Z650B1
1978 Z650B2
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Z1streetfighter71
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Re: Bike won't start!

#5 PostAuthor: Z1streetfighter71 » Mon Mar 17, 2025 1:29 pm

Anytime im ready to start a bike that has had a rebuild for the first time, with the carbs on, throttle slightly open, crank the starter, spray easystart into the carb throats (only a small burst across all 4). You should get a small "run" on the cylinders if the timing is set right and there is spark and compression. Once ive heard that combustion in all 4 then its time to button everything up for for a proper start. Ill probably get crucified for saying that out loud but its what iv always done.
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Re: Bike won't start!

#6 PostAuthor: Z1streetfighter71 » Mon Mar 17, 2025 1:31 pm

Where in Galway are you?
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Re: Bike won't start!

#7 PostAuthor: Z1streetfighter71 » Mon Mar 17, 2025 1:35 pm

Also this has happened to the best of us, have you got the correct plug leads on the correct plugs? Often not starting and a back fire means that 1 and 4 and 2 and 3 are mixed up. It means that you have spark and compression but the spark is happening at the wrong time.
Angus.

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Re: Bike won't start!

#8 PostAuthor: gray » Tue Mar 18, 2025 6:55 pm

I agree with above - if the timing is 180 degrees out, then it won't start and you'll get the occasional backfire.
Easy way to correct it is to trove the tank and swop the feeds to the coils. Each coil has 2 low tension input wires , one is (I think) yellow/ red and the other is some other colour. Both coils share 1 colour ( the red/ yellow) and have 1 that's specific to that coil. Swop the specific colours , not the shared colour ones then fire it up.
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Re: Bike won't start!

#9 PostAuthor: gray » Tue Mar 18, 2025 6:56 pm

trove = to remove. bloody predictive text
gray

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Re: Bike won't start!

#10 PostAuthor: ExSpeedTripleOwner » Sat Mar 22, 2025 9:34 am

Hi all

Thanks for all the replies.

I have double checked everything, all the timing is correct and the coil leads are going to the correct cylinders.

I spoke with Phil at Z Power and he said that the fuel leaking from the inlet rubbers was probably the cause of no fuel getting into the cylinders. I've order a new set, the old ones were covered in silicon sealant which I took off when before I put them back, which has probably caused the issue!

If that does not fix it, I'll take it out to Connemara with a can of petrol and a lighter :shock:

Dave

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Re: Bike won't start!

#11 PostAuthor: Hard Road » Sat Mar 22, 2025 12:32 pm

you might have the plug leads correct but have you got the wires to the right coils ? try swapping them over and see what happens.

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Re: Bike won't start!

#12 PostAuthor: Z1streetfighter71 » Sat Mar 22, 2025 5:01 pm

ExSpeedTripleOwner wrote:Hi all

Thanks for all the replies.

I have double checked everything, all the timing is correct and the coil leads are going to the correct cylinders.

I spoke with Phil at Z Power and he said that the fuel leaking from the inlet rubbers was probably the cause of no fuel getting into the cylinders. I've order a new set, the old ones were covered in silicon sealant which I took off when before I put them back, which has probably caused the issue!

If that does not fix it, I'll take it out to Connemara with a can of petrol and a lighter :shock:

Dave

Or drop it to my house and ill ..." burn" it. :ups I can drop you over a good set of inlets till you get the new ones if you are keen.
Angus.

Too many bikes to list.

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Re: Bike won't start!

#13 PostAuthor: ExSpeedTripleOwner » Sun Mar 23, 2025 10:19 am

The new inlet rubbers should be here tomorrow. Watch this space for an update!

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Re: Bike won't start!

#14 PostAuthor: ExSpeedTripleOwner » Tue Mar 25, 2025 7:23 am

Nothing! Not even back firing now

Rechecked the cables from the Dyna to the coils and they are correct, I even swapped them over to see if that made a difference but it didn't. All plugs sparking but nothing.

As per the Dyna instructions I lined the advance mark on the timing plate with the mark on the crank case and turned the Dyna rotor fully clockwise and the test light came on for 1-4. I repeated for 2-3 and it all worked as per the instructions.

If it is the carbs not supplying fuel what do I need to check??

Thanks
Dave

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Re: Bike won't start!

#15 PostAuthor: Z1streetfighter71 » Tue Mar 25, 2025 7:49 am

Assuming you have good spark.Take the carbs off and while cranking over ( even get someone to do the starter button ) spray easystart across the inlets, not a lot. If everything is timed right and coil wires are correct you should get ignition across all cylinders, even just for one fire. If that happens then its the carbs, if there is no ignition and you are getting spark its the timing, if there is no spark its the either the dyna coils or unit.
Angus.

Too many bikes to list.


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