View Full Version : CB 750, cylinder 2, 3 not firing and gas leak
Jamesdsm
25th November 2015, 22:56
Building a go-kart with a cb-750 engine, its a project so I don't wanna take it to a workshop. Cylinder 2 and 3 aren't firing and gas is pissing out carb 1 overflow at idle. Carbs are clean and plugs are clean and sparking. I don't know what model/year it is and want to get a service manual for it.
http://s72.photobucket.com/user/Fireballracing/library/Mobile%20Uploads?sort=3&page=1
I can take some better pics if you'd like.
Appreciate any help/advice I can get.
Cheers
Akzle
26th November 2015, 04:56
Building a go-kart with a cb-750 engine, its a project so I don't wanna take it to a workshop. Cylinder 2 and 3 aren't firing and gas is pissing out carb 1 overflow at idle. Carbs are clean and plugs are clean and sparking. I don't know what model/year it is and want to get a service manual for it.
http://s72.photobucket.com/user/Fireballracing/library/Mobile%20Uploads?sort=3&page=1
I can take some better pics if you'd like.
Appreciate any help/advice I can get.
Cheers
swap the ht leads? Check teh coils? Check the pickup?
As to fuel pissing out, that sounds like float valve seat fucked...
jellywrestler
26th November 2015, 05:07
looks like a z or a motor 79-80
Jamesdsm
26th November 2015, 09:39
Coils are okay, I'll take the carbie apart and check the seal I guess, argh, they're a bitch to get off and on. Cheers, I'll have a look at the manual for the z and 79-80
husaberg
26th November 2015, 18:39
Coils are okay, I'll take the carbie apart and check the seal I guess, argh, they're a bitch to get off and on. Cheers, I'll have a look at the manual for the z and 79-80
Cylinders 2 and 3 should share a coil and ignition so I don't think its a co-incidence that both are not firing at the same time.
Have you checked to see both are sparking. ie plug out resting on cylinder.
If the bike has been sitting for a bit just a tap (with a blunt object)on the float bowls might sort the carb float valve which are likely just sticking.
ellipsis
26th November 2015, 22:37
...you could hook up with the Honda lovers on here, we would love to show you the ropes...
spanner spinner
6th December 2015, 21:46
did you get this bike to run on the other cylinder's? Check the igniter boxes (square alloy matchbox sized units that connect to the coils) these can fail and as there are two of them they only take out one coil. swap the wiring over and see if the fault moves to the other coil.
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