MZ/MuZ Riders

less restrive mufflers actually hurt performance. Also, what is the main jet? should be 105 with the M4 can. --Steve

Steve is the M4 can stock or aftermarket? Too loud for my stealthy life. I had the carb off earlier and looked right at the main jet but can't remember the size. I think it was a 105. I'm
at the age now when I can never remember a name , But I always forget a face.
How do you guys get the carb out? I had to disconnect the air cleaner boot from carb, Then 2 mounting screws carb too intake boot, Then hose clamp on intake manifold to be able to get enough clearance to get it out.
Is there an easier way to do it? Pivot it in it's rubber boots?
Got a 151 oil filter locally Dave so it's going in now W fresh oil.
Coolant leak was up by the crossover hose but I could never really see from where. I took this hose off which had the original foofoo hose clamps and hose looked fairly new with no splits or tares. Replaced all orig hose clamps with regular farmer John hose clamps.
Bought a radiator pressure testing kit from Harbor Frieght and it held 12 lbs for 10 min but would slowly bleeed down to zero cause I think the test cap wasn't sealing completely. I didn't see any coolant coming out of the system any where so I will go ride it again and see if it piddles.
Do the thermostats go out on these bikes? Thanks again ,Rob

"and put a stock pipe back on it if you can find one
trying to get to get them to go faster just screws them up"

Dave , I have found this to be so true

Can someone measure the stock pipe exit diameter on end of muffler?
Mine on the m4 is 1.9".
Maybe I can machine a reducing plug with the right size hole in it and stuff it in the M4.
thanks

try one of the chrome suffers from an older rear engine vw muffler in the m4 muffler

So I made a cap with .812 hole that fit in the end of the muffler that quieted it down considerably and gave it a nice little kick when it comes on the pipe kinda like a 2 stroke hitting the pipe. I didn't notice this hit with just the M4 muffler.
So the bike runs great , brakes are great.
Only thing bothering me now is coolant blowing out the overflow hose.
I put a 3oz. bottle at the end of overflow hose and I notice a few drops on my LH shoe while riding. I rode it steadily for 42 miles and when I got back to the shop and turned it off , It did a one time belch sending a lot of coolant out of the bottle. Probably 2-3 oz.
The temperature light has never come on.
Does this indicate a head gasket leak? Air bubble in system?
Bike was cruising around 55-60 with the occasional zip up to 70 on the speedo.
Is the Odometer and trip meter in miles or kilometers?
Thanks

Is the Odometer and trip meter in miles or kilometers?

miles on my rt
you may have air in the system

To fix air bubble in system do I just keep adding a little more coolant, ride it , keep checking and adding till it doesn't burp any more Dave? Are you guys filling coolant up to bottom of the fill spout or just over the radiator core? I think I won't fill it as much and give it room to expand till I figure it out, thanks again, Rob

M4 was an aftermarket performance can. The stock muffler outlet ID is .7" (7/10ths.) Never had a thermostat problem on any of my MZ's---Steve

So when I crank it over , it is pumping air into the radiator . I put a pressure gage into the radiator filler opening and as it cranks it raises the pressure in the radiator. When I ride it , it will burp out coolant from the over flow hose. This is why I believe it to have a head or base gasket leak ????? I took the head off and reheated the copper gasket, lapped in the head and it still is pumping air into radiator.
Ordering head and base gasket from Graham's.
This bike runs great and is in very good shape otherwise, so I would like to get it figured out.
Has anyone else experience this and how did you fix it.

Did you quench the copper gasket? That makes it soft. --Steve

Steve , I heated it till it changed color good and hot, then let it air cool. Was I suppose to stick it in water to cool / quench it ? thanks, Rob

Gotta quench copper to soften it. Slow cool will be too hard to seal.

Rats, oh well I need to take it apart again anyway.
I've since read online where some people do and some don't quench it in water. Some air cool it.
Isn't the internet great.

Does this corrosion around the combustion chamber look like it could be the cause of leak in cooling system that pressurizes the radiators when cranking the bike over? burping the coolant out the overflo tube?