MZ/MuZ Riders

Finding myself in a bit of a pickle with my ES125/1 and was hoping someone can point me in the right direction.

For the third time now, the engine has died completely after riding for about 5 minutes at about 50MPH (about 80-90% throttle, so fairly high RPMs). The cause being a blown fuse and a melted contact breaker that can no longer make contact. Another problem is the wire wound resistor (part of the charging system) is going very crispy - already replaced once and it looks like it needs doing again.

Luckily, with a new fuse, points, and a very bodge points gap setting I can nurse it back home, but I can't get chucking new points at the thing, there's obviously something up!

I'm using a solid state regulator, other than that my electrics are stock.

Running the bike on the driveway today, when reviving the engine, the voltage over the battery seems to hit about 8.5V (and that wasn't even WOT). Seems a bit high?!?! Does anyone know what the regulator output should be? I'm wondering if my reg is duff and that would nicely explain the melty electrics when at high revs.

Has anyone had a similar problem? What was the solution? Any help/thoughts would be appreciated!

8.5V is a bit high, the regulator should control to 7-7.5V Mine puts out 7.2V.

I've heard (no personal experience on this) that the cheapie generic 6v regs aren't up to much. One thing that can mess with a 6V system is the wiring/connection condition. Go through and make sure every connector in the system is clean and tight - including the switch connections - and that all earth points are clean and making good contact. Once this is done, diagnosis of the failure point is clearer (but your reg. is looking sus to me).

The only overcharging issues I've had on mine were down to a damaged 'variable' resistor - the wire wound one - which was damaged during a clumsy engine refit. But you've changed that already.

Most electronic regulators require the removal of the wire wound resistor to work optimally. Most people either cut the lead or remove it but DON'T BRIDGE THE GAP. However I doubt if this is the reason for the overcharging.

Thanks so much!

I'm thinking the same about the reg - Agree that some require removal of the resistor but the instructions that came with mine said to leave it put, and it's worked perfectly for several months after fitting.

I've got the old mechanical reg knocking about in the garage so I'll fit that and see what voltage it kicks out.

I agree the regulator and wiring need a check but if the points are flashing badly you may need to replace the condenser too.

Andy

You got there before me! Yes, change that condenser!