Problems with MZB ignition?

[Rowan]

My bike has been sitting unused for about 2 years so I recently had my cylinder rebored - '87 auto. It ran for a while last Saturday while I gently started to run it in but now it will not start. Even then it was very reluctant to start and took half an hour to come to life. Before the rebore it would start from cold with 3-4 kicks.

Since then I have spent hours checking everything and kicking it but still nothing. I have stripped and cleaned the carb completely. It has a fresh batch of premix. I have tried 6 different plugs - including 2 brand new NGK B8ES set to .020" as per the manual.
'
The engine won't even cough or make any sounds like it is trying to fire. I have checked all the connections on the ignition, run ohm tests as per the MZB instructions and everything is correct. I have even added a cable directly from the head to the coil mounts to ensure a good earth for the spark and still nothing. I have checked the timing twice - perfect. One thing I noticed is that, if I take out the plug and hold it in my hand while giving the kickstart some good hard kicks, I only feel a tingle through my hand. It does not throw my across the room.

Is it possible that my 6 year old ignition has died already or am I missing something obvious. The plugs come out damp after a period of kicking so it seems that fuel is getting through but just not firing.

Any advice or cure would be very welcome

Rowan

 

[justintendo]

when watching the spark, is it blue? this will indicate good voltage. its possible the timing has slipped, but dont discount something other than spark being wrong. is the exhaust plugged? i keep silencer plugs in everything since animals love 2 stroke exhaust for some reason.

 

[Rowan]

I just checked the spark in a darkened garage and it is blue. As I said above I have checked the timing twice and it is at 2 mm btdc. I first had it running last Saturday (after much kicking and swearing) and it ran ok for about 20 minutes. I switched it off to let it cool down, as recommended, and then it refused to restart - and hasn't run since.

 

[grouty]

I would pull the flywheel and check for any corrosion on the stator plate. Putting a tester across the various connections would be a wise move. Power Dynamo (was MZB) should be able to give you the values.

 

[Kartwheel68]

I agree with grouty, you have to make sure you have ground through everything. The ground wire from the head to the coil is an excellent idea, but if you have corrosion and bad contact between the stator base plate and the case that can cause an intermittent ground. You can also get rust/corrosion and bad ground between the frame and cases. Once you go completely through all the possible places to lose ground then you start looking elsewhere.

 

[dukkman]

Flywheel spun ?

 

[rdeford]

My bike has been sitting unused for about 2 years so I recently had my cylinder rebored - '87 auto. It ran for a while last Saturday while I gently started to run it in but now it will not start. Even then it was very reluctant to start and took half an hour to come to life. Before the rebore it would start from cold with 3-4 kicks.

Since then I have spent hours checking everything and kicking it but still nothing. I have stripped and cleaned the carb completely. It has a fresh batch of premix. I have tried 6 different plugs - including 2 brand new NGK B8ES set to .020" as per the manual.
'
The engine won't even cough or make any sounds like it is trying to fire. I have checked all the connections on the ignition, run ohm tests as per the MZB instructions and everything is correct. I have even added a cable directly from the head to the coil mounts to ensure a good earth for the spark and still nothing. I have checked the timing twice - perfect. One thing I noticed is that, if I take out the plug and hold it in my hand while giving the kickstart some good hard kicks, I only feel a tingle through my hand. It does not throw my across the room.

Is it possible that my 6 year old ignition has died already or am I missing something obvious. The plugs come out damp after a period of kicking so it seems that fuel is getting through but just not firing.

Any advice or cure would be very welcome

Rowan

I had somewhat of a similar problem on my 74 mag with a MZB a few years back. Hard to start, ran crappy when I got it started. Pulled the fly wheel to check the timing and noticed one of the magnets on the flywheel wasn't spaced quite the same as the others. It came loose and moved a little.Called the guys at Penton Racing Products, sent it to them. They re attached the magnet. Bike has been running great ever since. That was in 2009.

Good luck,

Rick

 

[Rowan]

I have now had a chance to check all fuel and earth items and all is well. So I decided to pull the ignition out and take a look - just on the chance that something is amiss. Lo and behold I appear to have stator problems. The two stator coils in the photo have rub marks and one is distorted (or maybe badly made). The rotor also has what appear to be rub marks on the inside. There is NO movement of the crank and the seal is fine.

Does anybody think that maybe this is the problem? Are these windings for the lights or do they contribute to the ignition?

Any ideas welcome . . .

 

[dukkman]

One is knocked forward and the other backward [ big one is AGAINST rotation ] ??????????????

 

[Rowan]

It has never run backwards so I can only assume that it was made this way and I never took any notice of it when I got it. It ran OK so, back then, it was not a problem.

 

[Rowan]

I think that I have solved the problem. During this last week I removed the ignition completely and asked a local independent guru to check the various ohm readings - they were all correct. When they saw the small spade connections they suggested that I should use a fine screwdriver to close up the gap inside the female parts - what feels tight might only be snug inside the plastic body and not actually making good contact. I did as they suggested and it started after 4 kicks. I killed it and it started again first kick and idled smoothly.

This must a trick to look out for on these connections. I can only assume that, during the process of removing and replacing various parts for the re-bore, I had nudged something to reduce contact.

As an extra piece of information my guru (ex Husky Husky Imports, OZ mechanic) told me is that increased compression requires more zap to fire an engine - higher compression can overpower a weak spark. It is possible that my bike ran with the 'tired' piston' and did not notice the dodgy spade connections - now it is up to full pressure again the system was not making good enough contact. Just a possibility.

I have it currently timed to 2mm btdc so now I can advance it to 2.3mm as per the manual.

Rowan

 

[justintendo]

I think that I have solved the problem. During this last week I removed the ignition completely and asked a local independent guru to check the various ohm readings - they were all correct. When they saw the small spade connections they suggested that I should use a fine screwdriver to close up the gap inside the female parts - what feels tight might only be snug inside the plastic body and not actually making good contact. I did as they suggested and it started after 4 kicks. I killed it and it started again first kick and idled smoothly.

This must a trick to look out for on these connections. I can only assume that, during the process of removing and replacing various parts for the re-bore, I had nudged something to reduce contact.

As an extra piece of information my guru (ex Husky Husky Imports, OZ mechanic) told me is that increased compression requires more zap to fire an engine - higher compression can overpower a weak spark. It is possible that my bike ran with the 'tired' piston' and did not notice the dodgy spade connections - now it is up to full pressure again the system was not making good enough contact. Just a possibility.

I have it currently timed to 2mm btdc so now I can advance it to 2.3mm as per the manual.

Rowan

it does indeed require more spark as compression goes up..
i would leave the timing retarded..more stress and kickbacks when advancing to factory spec. are you running better than pump gas? im not familiar with how good your gas is tho.

 

[Rowan]

I usually put in 98 octane as I fill the fuel tin when I fill up the car to go to a trail ride. I can only assume that 98 is the same standard in all developed countries - in some other places the true actual octane can vary quite a lot.

Would there be any real power loss by keeping the timing slightly retarded from the manual?

Cheers

 

[justintendo]

I usually put in 98 octane as I fill the fuel tin when I fill up the car to go to a trail ride. I can only assume that 98 is the same standard in all developed countries - in some other places the true actual octane can vary quite a lot.

Would there be any real power loss by keeping the timing slightly retarded from the manual?

Cheers

slight loss in bottom, slight gain in top. easier starting less or eliminated kickback. likely less engine wear, a little less cylinder pressure. these are small differences, except for the kickback..98 octane is about perfect i think..i get that from blending 110 leaded with 91 ethanol free equal parts..

 

[suprize]

as its easy to do the timing, advance it up and see how you like it and see if it kicks on you.
it is better to avoid the kicking back as the potential to do damage to the case, pawl, gears etc outways the loss of a few ponies unless your racing for a sheep station over there

 

[Rowan]

I will give some thought to changing the timing - it shows no signs of kicking back at present. But I will weigh up the options.

I gave up competition years ago - I am getting a little old and so I only go on orgainsed trail rides to raise funds for a local kindergarten or school etc.

Rowan

 

[justintendo]

I will give some thought to changing the timing - it shows no signs of kicking back at present. But I will weigh up the options.

I gave up competition years ago - I am getting a little old and so I only go on orgainsed trail rides to raise funds for a local kindergarten or school etc.

Rowan

if it doesnt kickback you are probably good. there is a lot of variance in the cylinders of these..2mm btdc will start back talking a bit in my 400 and my 87 430..backed to 1.5-1.6 it never happens..

 

[suprize]

leave it then...not worth finding out it gives it a bad habit and have to change it back. I timed the 400 with a zip tie down the plug hole and a ruler so its set back a bit and starts easy, gives the occasional kick if I wimp at the kicker but they are half hearted, never going to cause damage. its pretty much up there with the power.

 

[Rowan]

Well I have re-timed to 2.3mm btdc and took it for a bit more running-in yesterday. I did not have any signs of kicking back but it was very reluctant to start and took more than a few before finally lighting up. After a few minutes of warming it was all go and I got it thoroughly hot while riding for about 15 minutes. Switched off for a few minutes then it needed the choke to restart - even when warm.

This morning I took off the carburettor to check the float height - it had been niggling me since I stripped it down a couple of weeks ago. Yes I had reset the float height a little bit low - it was a little over 19mm instead of 17-19mm. I have now reset it to about 17.5 as I suspect that the extra low float level was the cause of my starting problems yesterday.
Not until I got home did I remember that I didn't have the air filter installed - just the empty air-box. I was riding around the truck parking yard at my work (fully sealed- not shingle) so it will not be a problem.

I reckon that the low float level was making it hard to start but would an air filter be essential to get the correct suction effect in the carby?

Rowan

 

[Kartwheel68]

Yes, having no air filter will also cause a slight lean condition. In addition to the low float height I would imagine that is your problem.