TOPIC:

Hi All,
I'm rebuilding/restoring an '82 KZ750M1 CSR twin, with electronic ignition, from a pile of rust. The bike worked fine when I parked it (11yrs ago) I've pretty much got it put back together(80-90%), so I thought I'd try to start it. I believe I have everything wired back where it belongs except the rear break switch and I do not have the clutch hooked up. I've rebuilt the carbs and am at least getting gas to the float bowls. I'm getting power to all the fuses and all lights work and up until yesterday the starter was working. Yesterday when I was cranking it after a few seconds of cranking the starter it would sound like something was running loose and clatter. After a few times of doing this it just stopped working(the chain did seem a little loose when I had the engine side cover off). It didn't seem as if I was getting spark when it was turning over. Same result when I use the kick start. The battery has a full charge. I'm hoping someone will see something obvious I've done/not done or some quick things to check, otherwise I've got a long electrical/carb trouble shooting process to go through. Which will have to wait until I come back from vacation, it would be real nice if I could at least get it to cough before going away.
Thanks
Ron

twin 750's are known for the starter clutch failure.
power to ign box?
power at coils?
starter interlock circut complete?

Post edited by: trippivot, at: 2006/06/21 17:03

Thanks for the reply, trippivot. Yeah, those look like the things I have to check out, although I'm not sure of what/where the starter interlock circuit is. I'm going to be leaving for vacation tomorrow, so I guess the diagnostics are going to have to wait until I get back. So you think it's in the clutch/starter-lockout system? Kinda what I was thinking also. One thing I did notice last nite and am going to have to fix is that all the balls from the ball-bearing clutch are missing. Must be somewhere on my garage floor...I hope they didn't get sweept up during the mid-rebuild clean-up.
Thanks again, for the tips.
Ron

Ron, I don't know what your skill level is nor anything about you so I will pretend this bike just rolled off a trailer at my shop and the owner handed me the keys and asked me to get it running.

1. I would check compression with throttle open - If compression seemed low, I would check valve clearances. If they were GOOD I would call the customer and ask whether he wanted to look at rebuilding the top end.
2. If compression is OK and valve clearances are OK, I would pull one of the two plugs and put it near the engine case and turn the bike over with the kicker. IF I saw spark, I would measure the voltage at the coils. IF I had 12VDC or so with bike not running; just had igntion switch on, I would start looking at the timing (points), condition of the points and condensor, etc. Also would be looking at the plugs, plug wires and caps and how the wires seated in the coils.
--- IF I found no spark, I would fix whatever the problem was. Could be any of the things mentioned in the first part of #2 that are not right.
3. IF I had compression and spark, I would look to see if the carbs were getting gas. With the bike on side stand, I would measure the fuel level in the bowls. Your Mikunis have a drain nipple on the bottom. Hook a hose up and hold the hose steady to the side of the carb body. Open the drain screw and let the hose fill with gas with the petcock in PRI (prime). When gas stops creeping up, tap the hose to remove any air bubbles and note the level of the gas relative to the gasket mating surface on the bowl. Gas should be 1/8" or so below this line. If it isn't, open float bowl and bend the tang above the spring loaded bit on the float needle.


If you have compression, spark and fuel, and the bike is timed properly, I suspect it will start.

wiredgeorge said:

With the bike on side stand, I would measure the fuel level in the bowls.

Not to be nitpicky, but I think you meant to say/type "centerstand" so the bike's on the level?

neilage66 wrote:

wiredgeorge said:

With the bike on side stand, I would measure the fuel level in the bowls.

Not to be nitpicky, but I think you meant to say/type "centerstand" so the bike's on the level?

No centerstand on a KZ750M1

Starter interlock on the clutch lever only on that model, seems like the starter drive chains on the 750 twins are always loose (no adjustment).
At least it is fairly easy to work on the starter clutch on a 750 twin, just take off the left side engine cover and the starter, then pop off the stator and you are holding the starter clutch in your hand

Could be either an electrical or a mechanical problem, quick way to see if it is electrical is to hook jumper cables to a car, ground the negative cable to the motor, and put the positive cable on the starter power stud. That eliminates all the bike wiring, so if the starter works you know the problem is electrical, if it don't work then you know the problem is mechanical.

Ahh so...no centerstando...

Thanks for the replys and thoughts and sorry for the lateness of reply. I've found that the starter chain is streached, which is why I was getting such a god-awful noise when I tried to use the electric start. Used parts guy is looking for a replacement. Good compression. Pickup, igniter and Coil test out but found the plug wires had corrosion and fixed. After putting oil in found several seals leaking. Had to take bike apart again to replace and am waiting for new seals/gaskets. I'm not going to try starting again until I have all the above fixed. Right now the gas level is about 1mm below the float-bowl juncture. Of the 2 wires going to the coil, one of them gives the battery voltage but the other only gives a reading of about 1 volt. Is this correct? I painted the carbs, are there any external vents I need to be aware of that might have been painted over?
And yes, this bike does not have a centerstand which causes all sorts of problems w/wheel maintainance.