MZ won't start

[Mick_J]

I know it's not about a 14 but the knowledge on here may be able to help me out.
My MZ1000sf has been a bitch to start over the years and I generally go through a battery a year on it.  I got so pissed off I bought a LiFePO battery which seemed to work fine but it went the way of the others and died after 4 months, replaced with a new (more powerful) one which couldn't ever turn it over.  Replaced with another with 280CCA and this couldn't turn it over.  I stripped out and cleaned all associated wiring, the solenoid and the starter motor, all were fine, bench tested the starter and it wizzed around, made sure my engine turned and it does, charged the battery and put it all back together and the bastard still wont start, any ideas?

[grog]

Thats a Lot of batteries, a-lot of-frustration. It cranks over ok? Or doesnt crank? Ive just had same with as new whipper snipper. Defies all logic, tried everything. Now thrown in rubbish. Saved my sanity. Bought a new one, again. Maybe MZ in bin? I would.

[gsxbarmy]

Some of the GS1250 BMW's do this, generally it seems to be down to tight valves / cam lifter. Could that be it on your MZ?

[KiwiCol]

Have you thought of actually monitoring the amp draw while trying to start it?   Connect your meter into the circuit and see what she's pulling, also check the voltage drop when starter pressed.
I'd be sus of the starter motor itself, if possible, swap out with a known good one, or buy a replacement & swap out.

Next the battery,
Trying to think what can chew out a battery so fast, head comes up with not being charged sufficiently to replace the draw.

Now, if the starter is crook (that's a technical term btw) and it's basically causing a dead short type scenario, that wouldn't be conducive to battery longevity either, could explain why the batteries die so frequently.  The more I think on it, it points to the starter motor.  It doesn't take much to spin on up on a bench, but with a load to turn, might be different.

Good luck Mick

[Tony Nitrous]

Some Hayabusa's, especially race bikes, have a bit of a reputation for bad starting when hot.

There's an off the shelf kit that never fails to fix them.

A second battery and a small wiring harness.

The bike charges both battery's as 12v, everything on the bike runs 12v as normal, but the starter gets fed 24v which frightens the bike into life!

A mate has one and refers to it as an "Electric Startler".


Out of interest, how does it start with a set of jump leads from a car ?

[Hooli]

Aye my first thought is the starter too. Spinning on the bench is a lot different to under load.

[Mick_J]

Thanks for all your replies.

Grog.     Most time it just seems to stop at full compression.  Can't bin it as it is and when it does run it's a lovely bike to ride.

gsxbarmy.     All valves are within spec, I checked them over the winter.

KiwiCol.     My ammeter cannot handle that much current through it without catching fire.  As for volts it's quite strange, some batteries will start it while showing the load drop to 8 volts, some batteries will not start it when the load drops to 10 volts.  I tested the resistance of the starter at 0.1 ohm which I thought was a bit low but when I asked an auto electrician he said that was about right.

Tony Nitrous.     I have no space to fit another battery so that's out.  When I have failed to start when out on a ride a car battery will always start it up no problem.

Yesterday I started again, stripped everything out in the starter circuit including taking the engine cover off and checking the sprag.  Everything seemed to be fine, put it all back together and replaced the solenoid with a new one, while all this was happening I had the battery sat on the charger (yes it was plugged in) and then tried to start it and it ran.  Put all the plastic back and took it out for a good wash (Water glycol is very sticky stuff and never dries).  Today I will try to start it up again and if its dry go out for a ride. 

[Hooli]

Sounds like it could have been the solenoid then, makes sense if the starter was stalling at max load (just before TDC on the compression strokes).

Fingers crossed.

[KiwiCol]

Can you dis-assemble the old solenoid to assess it's condition prior to removal?  Be inteteresting to see

[Mick_J]

Well the solenoid change made no difference, tried it yesterday afternoon and nothing, starter wouldn't crank it over.  I'm in the process of removing everything electrical that's not in the starting circuit to see if there is a drain on the system.  Might try a long lead straight to the starter to see if it can turn the engine over, just got to find some wire long enough and thick enough.

[Irish in Oz]

Bad earthing!

[grog]

mjgt, try a good jump pack, earthed on motor, pos on starter if available. If it works, then move leads, pos back to batt, see what happens, if ok, then earth back to batt. Elimination process. Starter motor draw should be around 200, clamp meter or inline amp meter required. Only way to solve is with good meters and know good jump pack. Wish i was closer, wouldnt take long.

[Mick_J]

If I had the right gear to hand I would have it sorted by now but I'm having to work around not having the right gear.  No jump leads, no (big) ammeter, no battery pack, no long power leads.  Don't want to buy them unless absolutely necessary as I haven't needed them in 48 years of riding bikes.

[Eric GSX1400K3]

Sorry mjgt, don't know too much about your MZ, but sounds like a common issue with high compression high hp bikes, typically a wiring issue that simply doesn't have the current carrying capacity.  My K1300GT bmw had the same issue, fixed by running a second set of cables from the battery to the solenoid and the starter on both live and earth sides.  On thr bmw it presents as a hot start issue, being that after a run, heat soak into the battery limits the output current on thr next start up (say after refuelling).  I reckon you've got a similar issue but also when cold

The bmw got the double wires plus a HD metal jacketed odyssey battery to give it enough juice to spin it up.

[Hooli]

That's a point, there's a common mod on 1050 Triumphs to fit bigger power cables to the starter as they sometimes refuse to start when hot as if the battery was flat.