CB77 Points and Ignition Timing

mcconnellfrance · Post by **mcconnellfrance** » Sun Dec 22, 2013 4:07 pm

I purchased a partially restored CB77 earlier in the year. On checking the ignition timing, I was surprised to find the the points were labelled left and right in white paint, in contradiction to the stamped markings on the points back plate.

I have confirmed that the paint markings are indeed correct and necessary to get the timing right and the motor to run. However, I am not comfortable to leave it that way.

Does anyone have any idea why the engine has been built thus way? I suspect that the Points shaft has been inserted incorrectly or the wrong part no has been used.

Thanks for any advice.

Gordon

LOUD MOUSE · Post by **LOUD MOUSE** » Sun Dec 22, 2013 4:59 pm

Check the wires at both coils and plugs. ............lm

mcconnellfrance wrote:I purchased a partially restored CB77 earlier in the year. On checking the ignition timing, I was surprised to find the the points were labelled left and right in white paint, in contradiction to the stamped markings on the points back plate.

I have confirmed that the paint markings are indeed correct and necessary to get the timing right and the motor to run. However, I am not comfortable to leave it that way.

Does anyone have any idea why the engine has been built thus way? I suspect that the Points shaft has been inserted incorrectly or the wrong part no has been used.

Thanks for any advice.

Gordon

mcconnellfrance · Post by **mcconnellfrance** » Mon Dec 23, 2013 2:25 am

Thanks for the answer. I had checked all the wiring and it is correct except that the points are transposed to make it run. I concluded that it must be something wrong in the mechanical timing of the points cam.

I will double check again.

Gordon

Rickytic · Post by **Rickytic** » Mon Dec 23, 2013 1:54 pm

I try to remember that the yellow wire is left (yellow line in the road), green wire right (grass growing on the side of the road). I know you said you checked the wires, but you are right, a recheck could lead you to the answer. From the left coil Yellow wire to the left points, green wire right coil to the right points. If you are sitting on the bike, the left coil is on the left side etc. I am sure you know what you are doing, but sometimes I overlook the obvious, and thought this might trigger the overlooked.

Rickytic

mcconnellfrance · Post by **mcconnellfrance** » Tue Dec 31, 2013 11:29 am

Dear all,

I have double checked the wording and it is definitely switched from between the points and the condenser and the coils. The engine will only run in this configuration. When I connect the yellow wire from left point to left coil and vice versa for the green, the engine will not run.

I notice that the line on the end of the points shaft is pointing down when the right piston is at TDC on the compression stroke. Is this normal? I suspect that the points shaft is indexed around by 180 deg. Is this the possible reason for the need for the wires switch.

Regards,

Gordon

cknight · Post by **cknight** » Tue Dec 31, 2013 11:39 am

Are the points upside-down? The wires should attach at the bottom, with the contacts upward. If they are inverted, this usually indicated the points cam being 180 degrees out. Regards, Chase

mcconnellfrance · Post by **mcconnellfrance** » Tue Dec 31, 2013 11:56 am

Afraid that is not the case, the points are the correct way up.

Thanks for the reply.

Gordon

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CB77 Points and Ignition Timing

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