MZ/MuZ Riders

Hey All

After much lurking on forums and looking at a fair few bikes, I finally found one close enough and nice enough to go for.

Only problem is it now not running right, now that I have it back home.....

Starts fine.

Idles beautifully

As soon as you crack the throttle it stumbles, backfires, chokes. If youre lucky it moves through this and revs up. But you usually dont make it through the choke/stumble/backfiring.

I know this is going to invovle me looking at the carb, Just wanted to post to see if the symptoms point to anything in particular.

Hi.

I would start by draining the carb float bowl and flushing through with petrol in the tank by opening the tap.Gets rid of water/crap that finds its way there.

Cheers

Edit-

The drain screw is at the base of the LH carb.

Tar, will do.

Sigh its such a clean bike.

Funnily enough the ugliest one I saw was also the best running one. Pulled like a train.

Definitely do whatever you can to the carbs. I recommend pulling them and doing a basic cleaning and inspection. The diaphragm on my secondary carb wasn't functional when I purchased my Skorpion. I wouldn't have known that had I not opened it up since it drove home fine. Note what jets you have installed and the needle positions so there won't be any questions in your head if the initial attempts to fix the problem don't work. Check the flow on your petcock by opening the valve while it is disconnected from the carbs. If it is anything like the Skorpion, the stock unit barely keeps up with a bone stock engine and fails to supply enough fuel for a nearly stock engine putting down rwhp numbers in the mid to high 40's. In other words, it sucks. It never hurts to try fresh fuel either.

mine was doing a similar thing the other day strugling to pull then backfiring with flames shooting out from the end can. all it turned out to be was a fraid battery connector.

mine took a fit like this and i got lucky
for some unknown reason i checked the wires plugged into the coil box on the right side
near where my knee is when riding
there was a loose spade wire lug on one of the wires
replaced it and problem was gone
dave

breakwellmz wrote:Hi.

I would start by draining the carb float bowl and flushing through with petrol in the tank by opening the tap.Gets rid of water/crap that finds its way there.

Cheers

Edit-

The drain screw is at the base of the LH carb.

+1

Thanks guys, will be trying all this is a couple of days when my gf lets me have some garage time.

OK So the float bowl screw was rounded out, so had to remove using a grabit extractor and cut a slot in it for next time (can you get spares of these??).

No improvement, so I thought I'd take the carbs off.

Seat off, panels off, tank off.

Hmm

Questions I have relate to the removal of the carbs

I've taken pics of all the hoses so I can put it all back again, but I'd like some advise on removing the -
the choke,
throttle cables

and once all the attachments are off how to get the carbs off the airbox and off the engine carb rubbers.

Do I need to remove the airbox, if so how do I do it without taking the rear subframe off.

I'm looking at it and thinking I'll have to take the rear end off to get to the carbs easily. Do I have to?

Make a measurement of the cables position at the carb and document with a photo. loosen the adjustment on both and rotate to remove one at a time, it's pretty simple. Just that the documentation saves time with assembly.
The air box and subframe don't have to be removed. The carb to airbox rubber should be flexable enough to work it back into the airbox after unclamping them from the carbs.
If you choose to remove the airbox the subframe has to come off.
Be VERY patient when slideing the carbs back and out of the manifold boots. The space is tight but they can be slid back enough for the needed clearance to then be slid to the side and out of the frame.
Note also the vacuum lines and be careful to not damage them, I found out the hard way and chose to replace them with new hose.
I believe that the carbs can be removed either side but on the right side the exhaust has to come off. I'm sorry to add I just don't remember.

Hope this helps some...
Robert

Thanks for the info.

Found out about pushing the air box rubbers in to get the wiggle room from a German site, be trying that on Sunday.

I'm still not sure how to get the throttle cable ending out or how the choke comes out, so any advice there would be top

Before I pull the carbs I'm going to have a quick play with the pilot screw.

Found this post with a guy having the same problem on his xtz 660
www.advrider.com/forums/showthread.php?t=795413

Anyway I'll be back to this on Sunday hopefully.

if you managed to get the drain screw out and cut a slot i would stick with that,mine was replaced under warranty a few years ago for the same reason,i cut a slot in the new one straight away

Hi rodge 70,how you doing?

I buggered mine up the first time i took it out,i think they are put in way too tight.I got a replacement from Grahams.

You may know this one already,switch off the fuel and let the engine empty the float chamber.Mine used to be problematical starting,if left for a while,if i didn`t.

I have always added a bit of 2 smoke oil at each tankfill,i`m sure it helps inhibit internal carb corrosion,and slows up wear to slides etc.

I think i would consider taking the carbs of to be a last resort after squiring carb cleaner down every orifice(On the carbs that is )

Cheers

hi martin,yep things are fine with me,hope you had a good xmas etc.
i agree with how tight the screws are and even tapping the screwdriver before trying to loosen the screw doesn't help either,since i have put a slot in no problems.

i always turn fuel off and run till engine stops if i'm not using the bike for a week or so,it will probably start after 2/3 days if left on but will struggle and you can here the motor turning slower and slower ,but if drained usually fires up straight away thought lately not jumping upto high revs on choke straight away
bike is now on the off road wheels so been playing up the fosse way and around keynsham lately though it doea seem to eat rear knobbly tyres at an alarming rate

@duncmac,very sorry for sort of hi-jacking thread ,got a bit carried away there ,agree with martin on the carb cleaner route,though omc does make it sound fairly easy,you never know it may just clear/unstick something,take the choke plunger is fully retracting at the carb end
good luck with it,rodge.