Very Strange Starter Problem, KZ750 twin

Beautiful condition. Must have had some really good care.

79MKII wrote:

Damn, I wish my 750 twin were that clean! Nice bike.

bountyhunter wrote: Another problem: most of the US bikes have the lights on all the time which throws an extra big current load on the battery when it's trying to start. I rewired mine to disconnect the lights when the starter cranks, extends battery life makes it start better.

Bountyhunter, you got any info on how to perform this mod?

Topper wrote:

bountyhunter wrote: Another problem: most of the US bikes have the lights on all the time which throws an extra big current load on the battery when it's trying to start. I rewired mine to disconnect the lights when the starter cranks, extends battery life makes it start better.

Bountyhunter, you got any info on how to perform this mod?

I'd be interested in that too. I added RH controls with the headlight switch to my MKII and it was alot more complicated than I thought it would be. It's not as simple as finding a single wire and switching it.

79MKII wrote:

Topper wrote:

bountyhunter wrote: Another problem: most of the US bikes have the lights on all the time which throws an extra big current load on the battery when it's trying to start. I rewired mine to disconnect the lights when the starter cranks, extends battery life makes it start better.

Bountyhunter, you got any info on how to perform this mod?

I'd be interested in that too. I added RH controls with the headlight switch to my MKII and it was alot more complicated than I thought it would be. It's not as simple as finding a single wire and switching it.

On the 79 twin it's plug and play, on the 80 750 twin you have to cut a wire. The hardest part is removing and replacing the switch pod.

My 79 dressed up as a 80 750G



My first 79 750 twin



I have never had a 750 twin with the rear grab handle, I thought maybe the Indiana air caused them to evaporate

Z1 Enterprises sells the chrome headlight bucket and upper and lower chrome gauge covers.

Topper wrote:

bountyhunter wrote: Another problem: most of the US bikes have the lights on all the time which throws an extra big current load on the battery when it's trying to start. I rewired mine to disconnect the lights when the starter cranks, extends battery life makes it start better.

Bountyhunter, you got any info on how to perform this mod?

Yes. On the 79 750 twin, the main battery power comes in through a 20A fuse then feeds the ignition. After that, there are two 10A fuse branches: one feeds the headlight and some little light and the other line feeds brake lights, horn, other stuff.

I inserted a 10A relay right into each of the two 10A branches so that it was connected normally closed. Then I wired the relay coil off the power line to the starter solenoid so when the starter is cranked, the relays energize and open the normally closed contacts removing all the lights and other stuff, but ignition is still alive.

here is the wiring diagram for my 750 twin, you can see the 20A main line and the two 10A lines that I "interrupted" with relay contacts to open under starter crank.

I inserted a 10A relay right into each of the two 10A branches so that it was connected normally closed.

Do you do that with a 5 pin relay?

79mkII, don't worry we'll stop hijacking your thread soon.

Topper wrote:

I inserted a 10A relay right into each of the two 10A branches so that it was connected normally closed.

Do you do that with a 5 pin relay?

79mkII, don't worry we'll stop hijacking your thread soon.

No Problem...I'm interested in this too.

So a normally closed relay....I should have thought of that. The problem I had with the headlight switch was I still needed the brake light, tail light, dash lights, front running lights etc... to work while the headlight is off. My switch is a repro of the Z1 switch...it has "off", "on" and "park". It's fine if all of the lights go off while starting...that's a great idea.

Topper wrote:

I inserted a 10A relay right into each of the two 10A branches so that it was connected normally closed.

Do you do that with a 5 pin relay?
.

yep, takes five pins. One set of pins for the relay coil, and three pins for the high current contacts (center, NO, and NC)

79MKII wrote:

Topper wrote:

I inserted a 10A relay right into each of the two 10A branches so that it was connected normally closed.

Do you do that with a 5 pin relay?

79mkII, don't worry we'll stop hijacking your thread soon.

No Problem...I'm interested in this too.

So a normally closed relay....I should have thought of that. The problem I had with the headlight switch was I still needed the brake light, tail light, dash lights, front running lights etc... to work while the headlight is off. My switch is a repro of the Z1 switch...it has "off", "on" and "park". It's fine if all of the lights go off while starting...that's a great idea.

I should probably explain, I used two relays because I only had 10A relays to work with (freebies) so I had to break each 10A branch. You could also use a single 25A relay and break the main line before it splits into two 10A branches. You just need to make sure the ignition coil remains hot (energized) and everything else is downstream.

If your bike has a headlight switch, it would almost surely be downstream from the fuses so a relay could still open everything up heading into the fusebox and not affect the switch wiring.

On a 5 terminal relay, terminal 87 is NO (Normally Open) and terminal 87A is NC (Normally Closed).