Topic: Static timing cb750 help please

[Jaxbchcb]

 Ok so I'm trying to adjust/check my timing on my cb750 sohc with one of those lights with a alligator clip because my bike is only running on cylinders 2 & 4. This is where I'm confused I guess I'm taking the alligator clip and attaching it to one of the fins on the motor and making contact to the points with the light then turning the crank and see the points open but the light never comes on!? I've tried with both set of points but still nothing so I'm stumped... Any help/advice would be awesome thank you! Here's a pic of my light

[evanphi]

When checking 1/4 points, for example, put the clip on the side that opens/closes, and the tip of the light/handle on the side that is stationary.

Make sure your bike is on (key in, and in run position).

Make sure your batter is good.

[Jaxbchcb]

When checking 1/4 points, for example, put the clip on the side that opens/closes, and the tip of the light/handle on the side that is stationary.

Make sure your bike is on (key in, and in run position).

Make sure your batter is good.

Awesome thank you that worked and my timing is perfect! But I guess I have to figure out why cylinders 1 and 3 aren't firing?? They fire when I switch the coils around? Do you have any idea what that could be? I know the coils are good because I test them with a multimeter?

[evanphi]

When checking 1/4 points, for example, put the clip on the side that opens/closes, and the tip of the light/handle on the side that is stationary.

Make sure your bike is on (key in, and in run position).

Make sure your batter is good.

Awesome thank you that worked and my timing is perfect! But I guess I have to figure out why cylinders 1 and 3 aren't firing?? They fire when I switch the coils around? Do you have any idea what that could be? I know the coils are good because I test them with a multimeter?

What do you mean switch the coils? Swap plug caps to other cyls?

1/3 are not a pair. The leads from the cyls should be going to 1/4 and 2/3 (so make sure that is there first!). What about the wires to the coils, the blue/yellow ones. Could they have gotten swapped?

New plugs?

[madmtnmotors]

1/3 are not a pair. The leads from one coil should be going to 1/4 and the leads from the other coil going to 2/3 (so make sure that is there first!).

+1

[Jaxbchcb]

When checking 1/4 points, for example, put the clip on the side that opens/closes, and the tip of the light/handle on the side that is stationary.

Make sure your bike is on (key in, and in run position).

Make sure your batter is good.

Awesome thank you that worked and my timing is perfect! But I guess I have to figure out why cylinders 1 and 3 aren't firing?? They fire when I switch the coils around? Do you have any idea what that could be? I know the coils are good because I test them with a multimeter?

What do you mean switch the coils? Swap plug caps to other cyls?

1/3 are not a pair. The leads from the cyls should be going to 1/4 and 2/3 (so make sure that is there first!). What about the wires to the coils, the blue/yellow ones. Could they have gotten swapped?

New plugs?

That is what's weird I know they are not a pair. But if I take coil cap #2 and put it on 3 it fires

[madmtnmotors]

First of all, what method are you using to determine whether a plug is firing or not? Are the plugs still in the engine and running on two cylinders checking for hot exhaust pipe? Are plugs still in the engine but using an inductive timing light? Are you removing the plugs, grounding the body of the plug, and checking for spark at the tip? Something else?

I would recommend removing each plug, and checking for spark at the tip while grounding the body of the plug and post those results here.

[Jaxbchcb]

Thanks for the replys! I found a wiring diagram and found out what yall were talking about that 1 and 4 are on one coil and 2 and 3 are on another. I guess the guy who had the bike before me put the coil wires on 1234 haha so no wonder it was acting all crazy!! But I corrected it and everything is good now

[madmtnmotors]

Thanks for the replys! I found a wiring diagram and found out what yall were talking about that 1 and 4 are on one coil and 2 and 3 are on another. I guess the guy who had the bike before me put the coil wires on 1234 haha so no wonder it was acting all crazy!! But I corrected it and everything is good now

From what you described many of us believed that to be the case. Hence my suggestion to check each plug one by one to get you to look at every plug and every wire. The "dual fire" coils had me scratching my head way back in the beginning, one just gets a wasted spark.