TOPIC:

Hi Everyone,  just joined up since I bought myself an ‘84 KZ750 L4. It’s got 54,000 kilometers on her and not in too bad of shape. 

When I was looking at the bike before I bought it, it was starting fine. I rode it home and over. The next couple of hours took it around the block a few times. Then the next time I went to start it, it cranked and then just stopped. I was able to get it going one more time after that, but now there is nothing. When I hit the start button, all I get is a little bit of a click coming from the relay or whatever that makes sure you have a headlight. 

Im waiting on a factory service manual from eBay, but in the meantime, anyone got any hints on how I can get this thing started again?

If I am understanding what you say is solenoid click with no engine crank over .... first check all major connections at battery, solenoid and starter .... also battery voltage. 
 

Thanks, but I have no idea where the starter or solenoid are or how to get to them. 

Battery is fine. All electrical works, just won’t spin the starter. 

 

If you check out the elec fault finding guide in my signature there is a test plan for starter circuits towards the back

Hahaha!  LOVE Bob & Doug, eh!

Love Rush too!

This is her. 1984 KZ750 L4. Canada only model. The US equivalent, so I’ve learned, is the KZ700a Sports. 

 

I like the look of your machine. Do have a question regarding what sort of exhaust system it has. The pic looks like it exits on the left side (as you sit on the bike) but my old eyes can not tell for sure. As to the starter it by far is the largest drain on the entire electrical system, and requires a fully charged battery to function correctly. Just because lights work does not mean the battery is up to snuff so to speak to run the starter correctly. It makes use of a starter relay to provide full battery voltage to the starter. There are several switches and connections between the battery and the start button, which as stated above makes the relay pass battery voltage to the starter.

I attached a pic of the starter system for a 1981 KZ650 but your machine will, at least as I understand it, be much the same.

I like the look too!  It is reminiscent of my first street bike, which I think was an 82 or 83 Gpz550.

Gd4, you are correct - the exhaust is a four into one exiting on the left side. I’ve had a pretty good look trying to find a stamp or something, but so far nothing to say what kinda it is. 

Thank you for the excellent advice on the battery!  I just hooked up to a battery charger and it read 90%,l.  90% seems like enough, and I’ll try starting it when it gets to 100. 

Regarding the diagram, is there one of those spots that is more likely to be the culprit?

Lenster wrote:

I like the look too!  It is reminiscent of my first street bike, which I think was an 82 or 83 Gpz550.

Gd4, you are correct - the exhaust is a four into one exiting on the left side. I’ve had a pretty good look trying to find a stamp or something, but so far nothing to say what kinda it is. 

Thank you for the excellent advice on the battery!  I just hooked up to a battery charger and it read 90%,l.  90% seems like enough, and I’ll try starting it when it gets to 100. 

Regarding the diagram, is there one of those spots that is more likely to be the culprit?

When it comes to diagnosing electrical faults by far the best approach is start at the consumer and work back in a logical sequence (which is what the test plan I mentioned guides you to do) trust me when I say "trying this" and "trying that" invariably sends you mad and takes 3 times as long and probably costs 3 times as much as well (so many times guys come on here saying I replaced this and replaced that, what do you think it is ?) replacing things that don't need replacing

First I should of welcomed you to KZR, welcome to the fun!  I have a left hand side 4 into 1 Denco system on my 650 and for some reason each time I see another left hand system it peeks my interest. Look none of us here have any real idea of you knowledge level, skills or tools. Not to say which way they lean, I know my own are not as strong as I would like think they are. But there are several very knowledgeable folks here who are willing to assist as they can. I would suggest you take Wookie's suggestion and take a look at the document he has created, as it is, in my opinion, a well thought out approach to troubleshooting electrical issues.

As to the battery see what it does after a charge.  Do you have a VOM for testing the battery and for any troubleshooting of the entire system?

Welcome.

I am not electrical expert but one of the best tools I every bought was a cheap battery load tester at Canadian Tire. Without something like that you will be guessing on the state of your used battery. The wiring on these old bikes depend on a good ground so make sure grounding strap is tight.

If the bike has been sitting for a while there could be some junk that made its way from the tank to the float bowls. If it does not have a inline fuel filter I would get one right away, one with a cleanable screen.