MZ/MuZ Riders

Right I have a few questions

My bike (ETZ251) is temper-mental at the moment...

When I got it, it lurched badly when the throttle was closed, wouldnt pull properly (5th gear useless as you slowed down), and would flood easily when starting....
now I've stripped the carb, and given it a clean and reset the settings as per haynes manual (old one supplied)

The floats are now perfect height (both up and down)
the bypass air screw and pilot screw were at stock settings anyway.
the needle is on the 4th clip from the top

Now if its starts, it will run nicely if you can keep the revs up, and the float adjustment has cured the lurching.
but its still a bit fussy whether it starts or not...

Its running on premix at the moment (I think its running on around 25:1 due to a slight misreading of the petrol pump litres counter....)
the oil pump has been removed and a plate has been fitted over the hole.
the crankcase pipe stub has a short piece of pipe thats been blocked off....

now I have the oil tank and oil pump, and I was planning on fitting it back on, as it will be a little easier to fill up....
I'll have to get a new throttle twist grip (a genuine one), as its currently got one from a newer bike...



the other issue I have, is the clutch lever isnt the original either.
now if the clutch is adjusted properly, the lever adjuster hasnt got enough travel to actuate the clutch...it drags....

now I'm not sure why, but I dont think the clutch cable is supported properly at the engine end.
it goes into the 'clutch cable spacer block' which screws into the engine, but theres a small, thin slotted washer type object that stops the cable casing being pulled into the engine.
the only way said washer doesnt drop off, is because the rubber grommet pins it into place....

is that original, or a PO bodge?


for the moment, I was going to make a couple more 'washer things' and space the casing off (hopefully in the process improving the clutch)....



but obviously the clutch isnt as important as getting the engine working nicely :p

what settings do you use on your ETZ251s?
(I know every engine is different, but hopefully it will give a better starting point!)


Thanks in advance

anyone?

Have you checked your ignition timing?

lever on the clutch not stroking the cable in a full pull

had a Yamaha ym1 1966 and the lever did not pull far enough on the cable
when it would go in and out of gear
and and shift ok it would slip at speed
took eye on handle of an adjustable wrench and bent the leaver then it worked
but NOT A RECOMMENDED FIX unless nothing else works
dave

Could be an air leak via the blanked off oil pump, or the crankcase feed. Also try Ebay for an original lever, try a world wide search as parts are still readily available from Germany, also are you sure you have the right clutch cable?

Hello everyone

I havent been online for a while due to circumstances

and the poor little MZ hasnt really been touched for a month or two!

I've 'sort of' fixed the clutch though.....

I made a couple of spacers to pull the clutch cable tighter from the engine casing (I seem to be missing a block of some form on the clutch cable entry hole)

it means the clutch will adjust properly and doesnt slip when the lever is out......

however, when the clutch is pulled in, I get a 'grating rattle' sort of noise (thats the best description I can give!)
and its dragging.....
even if I remove the spacers, I still get it....

so I think something in the clutch is broken.....perhaps the clutch plates have broken......

as for the engine ignition timing, its set as accurately as I can....
when the engine is running, and its in the powerband, it runs fairly well to be honest....
its just under 3,000rpm it doesnt.....and its a nightmare to start.....

it still needs a new regulator, because the mechanical one will not adjust properly.....

do you think the high voltage (~18v) could be causing difficult starting and rough running?

I sadly cant afford to buy a MZ-B system........
so I'm stuck with the standard alternator and ignition for the moment.......
so I want to try and get it to work......

although, I have considered a couple of options......

first option I've considered is fitting a v belt pulley onto the crankshaft instead of the rotor, and then modifying the right hand side cover and the generator outer (where the points fit) to allow a V belt to be routed to an external alternator....

I have a small 35amp car alternator sitting in the shed doing nothing.......

the other option (the one I'm most tempted by), is to fit a simple magneto system (like the PVL kart ignition) to the bike.....
then convert most of the lights to LEDs, and run them off a small battery that isnt recharged by the bike.....

the only light I cant really convert to LED for the moment, is the headlight bulb (but you can buy LED H4 bulbs).....

the only thing I'd need to work out, is what battery type to use......

I could use a couple of those 6 volt PP9 batteries in series for 12v....
they are very cheap and should last fairly well driving a few LEDs.....

either that, or some rechargable batteries of some form (not motorcycle battery), and then permanently fit a small solar charger to the bike

the only bulb that would draw a lot of power in comparison is the headlight bulb......

has anyone got an MZ running a PVL style ignition?

if so, does the bike run OK?

is it fairly easy to start?

I've got quite a few magneto ignition engines in my shed, which I can raid parts from for the MZ.....

EDIT:
as for the crankcase feed, I've check it for leaks, but its nice and sealed.....
as for the oil pump, if the casing was leaking slightly, it would just leak the odd bit of gearbox oil.......

but I'm thinking about fitting the oil pump back on anyway.....
I'm planning on buying a standard MZ throttle casing and tube, as I currently have a Kanuni/Saxon plastic one fitted (the kill switch isnt wired in), and I cant see how a second cable would fit for the oil pump control....
I might see about a standard clutch lever as well......

Hi difflock,

On the MZ 250s where the clutch cable goes into the tube in the clutch casing, the outer cable is held in a split plastic bung that's held in place by a waterproof rubber cover, the clutch adjustment is by a coarse and fine process, the coarse adjustment is by the adjuster plate under the rev counter drive, this takes up most of the slack, and the fine by the cable adjuster at the lever end of the cable.

Sorry can't help with the clutch rattle.

If your carb is a BVF, did you make sure the rubber bung that seals the choke was in good order, as this can be the source of bad starting/running,

On my MZ there was only a thin washer with a slot in it (so it fitted over the cable), and then a waterproof rubber cover...

with the clutch adjusted correctly internally (well correct according to the info I can find), the clutch cable was VERY slack.....as in the lever pretty much came to the bar before the clutch mechanism was moved (then there was about 2~3mm of lever travel until the bars)

I made up a couple of spacer blocks to take up that slack.....


when I got the bike, the clutch had been adjusted internally so the lever moved correctly.....
however it slipped a little under load (especially on hills)
and 5th gear caused it to slow down......

it now drags however.....

some of the issue with the clutch could be due to the clutch lever though.........
I notice that I havent got anywhere near the adjustment at the lever that I should have! (I think my bike has a CBR600 lever to match the CBR600 master cylinder)


any chance of a piccy of the bung?







as for the carb, yes its a BVF, but it had a new choke rubber just before I got the bike (and I've double checked that it does)
but I dont think its the carb to be honest.....

when it eventually starts, it seems to run quite nicely.....


I think the troubles are with the ignition

I'm going to rewire the bike eventually, but the first thing I'm going to try, is hotwiring the ignition coil and points to a battery....
if it starts easily then, I know it must be a wiring issue.....

Sorry difflock.

No Pic's of plastic bung but you should be able to get one from Fred Rogers, and any other parts you need.

Fred Rogers
Spares & Repairs
01606 593 638

I'll see about the clutch bung one day.......

more important than that, is to get it running again.......


I'm going to also take the clutch cover off, and see if the clutch plates are ok......

Put MZ ETZ251 into google's video search. There are a few MZ factory video's showing an ETZ251 engine being built. It obviously shows all the parts so will give you a clue what to ask for.

David.

P.S Try here http://www.youtube.com/user/vnandor86#p/u
look for MZ service films 1 to 10 in the video list on the right.

I've seen those videos before

very useful




but its time for a bit of an update.......

I'm pretty sure the carb isnt working correctly.......


it wont always wet the plug if the ignition is off


I've read about other people having similar issues though.....
basically the carb 'seems' to work correctly, and is setup as it should be.....but for some reason it just doesnt want to work




so I think the first stage is to get another carb and see if the bike will start and run a little better.....

the only carb I have in the shed is a Mikuni BSR36 CV carb, which I think may be a little big for the MZ motor :p

I haven't been online for a while.....

Made some....progress?



Decided to take the plunge and strip the engine.

I haven't got a clutch removal tool, so I had to leave the crank in that half of the engine....
but the generator side is off, which revealed a shredded crankseal, and a grinding, notchy crank bearing

so new bearings and seals would be needed.....
plus a few other bits.......



at this moment, I'm not sure I want to replace bearings and seals, as I have little money, and if it still didn't work, I'd be rather annoyed
and the bike isn't really worth much!

"it wont always wet the plug if the ignition is off"

Had this problem myself with sporadic running & idling.

In my case the fuel tap was partially blocked with gunge from the tank and whatever I did seemed to make no difference.

In the end the tank was removed and flushed out properly and a new fuel tap fitted - been fine ever since.

Just a thought............

Andy

I did clean out the tank and fuel tap completely...but there wasn't much dirt in either....

the float bowl did fill up, it was just that the engine didn't seem to pull fuel through the carb....


But since stripping the engine (as mentioned in my last post), I believe the crank seal failure is too blame....


not sure if the bearings are just rough due to dirt or whether they are worn out.....
but both the seals and bearings were replaced just before I got the bike.....

it had new NSK bearings, and the blue single lipped crankseals....