New 1977 Kawa 750B owner problem

Hello everyone.

Im from Page Arizona, and I found a beautiful 1977 KZ750B for $600. 7k miles and in really great shape.

I have one problem with this bike. The previous owner put a lithium ion battery in the bike. Its the only thing he changed. I dont know if this caused the problem, but in the two weeks since Ive had the bike, I noticed the rear running light part of the 1157 bulb keeps blowing. The brake light is fine, just the running light that keeps getting fried.

Ive also noticed a very slight burning smell. So i took out my multimeter and checked that battery at idle. Its a healthy 13.5 v at idle, and never goes above 14.5 no matter how wide the throttle.

However, while idling, i noticed the voltage will drop randomly, and for a split second only to the following: 9v - 0.20v 7v etc, but never for an extended time. Ive also noticed the bike shudders a bit at 3k rpm (carbs are fine. they were rebuilt to spec and function properly).

The battery is being charged, but could this still be the reg/rec?

Great looking bike! Because of the burning smell I suggest you carefully inspect all the wiring. It's possible there is a loose connection or maybe a wire that the insulation has somewhat rubbed through. Wiring that is still wrapped should be fine, but single wires and connectors should be looked at to make sure they are sound. Ed

Thank you Ed.

Would exposed or frayed wiring result in the voltage drop Im seeing at the battery?
The rectifier appears to be charging properly, but some of my mates have said there could be something internally wrong with the recitfier though it appears to be operating properly via the multimeter.

KawaKrazy wrote:
Ive also noticed the bike shudders a bit at 3k rpm

Do you have checked the ignition points (dwell/timing) and the ignition advancer is moving free (lubed)?

I have not, but can you explain to me the possible relationship between the voltage drop Im seeing at the battery and the check you describe regarding the points? Seems unrelated from my limited knowledge perspective, but im happy to learn if Im wrong.

It was more pointed into your shudders a bit at 3k rpm Problem.

Get a Service Manual that covered the 76 - 78 models.

kzrider.com/modules/ServiceManuals/Kawas...l%20KZ750%20Twin.pdf

Get a Service Manual that covered the 78 - 81 models.

ufile.io/p63hplfl