Engine trouble 660

[Fredrik]

Hi,
My first try in this forum! I have a Mastiff 660, 1998 model with engine trouble. Was on a trip yesterday and had been driving for 4-5 hours, and stopped for 1/2-hour. When going off again the battery was flat. Just before I stopped a recognized that the RPM indicator just worked between 0-1800 rpm. When over 1800 it dropped dead to 0 but the engine was still running perfect. OK, flat battery. Managed to start it by pushing, running good. Hit the road and after one minute it just did work extremly bad over 1800 rpm. Idle at 1400 rpm = perfect. Checked the battery = bad things, 5Volt. Put in a new battery, checked charging, 14 volts = OK? Still running bad over 1800 rpm but sometimes it's possible to cheat it and get it work fine for 5-10 seconds. A friend stated that the CDI-box have three ranges : low, medium and high and it can work fine in low and high range. True ?
Could the low voltage on the battery result in a too high charging voltage that have damaged the CDI-box the way my friend stated? Maybe something else is damaged ?
I would really appriciate help on this!

[phlat65]

yes the cdi could have been damaged. most common problem we have seen is corrosion in connectors, esp ones that carry current like charging system. if you have a DVOM, check for excessive AC voltage at the battery.

I would disconnect every connector you can get to, and clean and apply some waterproofer, or contact grease. removal of the fuel tank will make it much easier.

good luck!!

[Wonky]

Yes the CDI box can be damaged if run with a faulty battery! Also as just suggested above, use contact cleaner on your terminals if they look dark in colour, or rusty. You may have a problem in your wiring loom thats causing your problem, do you have a friend with a Mastiff/Baghira? Try using their CDI box and see if that cures it, if not then check relays,etc on loom. Or talk to David T, hes a bit of a wizz with the old electrics!!!!

[DAVID THOMPSON]

there are diodes in the wire looms of the mz bikes that i have not seen in other makes these are to control spikes in the voltage from relays and the spark coil they can cause funny readings if you do not know there there
when checking with a voltmeter

several riders have said they have found some blown out.. one is under the gastank in the loom if blown or shorted they can cause funny things to happen

electrical drawing are avabile i can forward them if needed

these bikes are bad about corrison in the connector plugs
and DO keep a close inspection of the battery condition as it is the sorce
of many problems due to its small size

[Wonky]

Wiring diagram here:

http://www.teamslipstream.co.uk/mzbaghirawiringdiagram.html

[Chris Hunsicker]

This from a previous post:

[Nils D]

[DAVID THOMPSON]

relay 19 (cutout relay) part of side stand interlock wireing and supplys cdi box with power....

look close at this relay it is to small and it failed the other day on my rt125

i have been having funny tach readings most of the summer....

from time to time bike would not start with kick stand down..

then last Thursday it just died

i jumped pin 3 to pin 5 and rode it home

replaced relay and no trouble for 6 days now
ar dave

ps on my rt125 it is mounted beside the battery and it is gray in color

the contacts carry a lot of current and supply's the cdi box on my rt125
so funny tach reading from funny voltage supply to cdi box ????
cdi box drives tach on most bikes


SEE ALSO HERE FOR REPLACEMENT RELAY DRAWING
http://www.mzriders.com/mz/viewtopic.php?p=12180#12180

[Chris Hunsicker]

[Bill Jurgenson]

Yes the MBB tachs are worse than bad and even even working after a fashion, the values shown are from a different planet. Rest assured that the Denso CDI cuts the engine at precisely 7200rpm, regardless of what you see - or don't as the case may be.

As far as ill effects are concerned, it is really quite simple; the tach gets its signal directly from the coil, so if the circuitboard of the tach goes bad it can short out the ignition circuit and bingo - misfiring or totally dead.

[Chris Hunsicker]

For the record, here's the MFG's web site:

http://www.nova-mmb.com/

[Nils D]

Hmmm....

The tachometer has been strange for over a year. (It started with a electric black-out. It turned out to be the horn that had shortcuted. Just to get home, I got help to jumper. But during that 200km journey, the tachometer was far over the scale, just going down a bit if i used the indicators. Since then there has always been something strange with my traveller.)

The engine runs OK, apart from some missfireing at low speed. It has become worse this summer. I can sometimes provoke short, but total, loss of current by fidling around with the ignition-lock or its loom. I have opend and cleaned the ignition-switch, but the problem remains.

I realize this will cost. Time and money.
I have started to work me throug the conectors.
I have bought a new battery. (Had to be done soner or later.)
The tachometer is so expensive I might just unplugg it.
Since the ignition-lock is bad I have ordered a lock-kit wich also contains a fresch switch.

The screws holding the ignition-lock, do you think they can be drilled out? Or are they made of hardend steel?

Still serching, Nils

[hb7]

They are one way hardened screws...and yes they can be drilled if you use very high quality drills, then tap in your easy out.
You have to remove the top triple to do it. The switch at the bottom is replaceable without having to change the lock.

ps: I used a drill press and recommend you do too.

The tach is repairable...open it up and resoldering the board worked for me.

[Nils D]

[hb7]

Good to hear it worked for you. Once the the tach bezel is gone....You can seal with silicone and tape it up.....or use a hose clamp to hold the glass/o ring in place.