MZ/MuZ Riders

In a side-by-side comparison of a raptor motor and an MZ motor there are differences that become apparent. The outer cases are similar but different. The cylinder in the raptor is noticeably canted forward. The head and cylinder appear to be the same. I hope these photos help with anyone needing to make a comparison.

The 5 valve engines are basically identical. the angle of installation is irrelevant.
What is different:
-the right side covers are different and they are not interchangable. Too bad, too, since the spin-on oil filter of the Raptor is definitely an improvement. This can probably be seen as catering to the US market.
-the crankshaft. The left crankstub has a different taper. The generator rotor used in the raptor is different, smaller. The cranks are interchangable however and the porkchop style crank of the Raptor runs just fine in the XTZ engine. You need the rotor to go with it and, easiest, the left sidecover including generator and starter as well.
-the carb. Te Raptor has a dual CV carb, not the register carb you are familar with. It will work with the XTZ engine of course as well and vice versa.
-CDI. The Raptor has a different ignition. Both ignitions work with both engines as long as they are transplanted entirely.

Otherwise, there are no differences.

The new 4 valve engine is a whole other kettle of fish. The mounting points are the same however.

Thanks for the pictures Fred,

I bought a Raptor 5 valve 102mm piston and cometic gasket set. The vendor assured me they'll fit.

Thanks for posting the info.

Bill

Just looked at the thread and you have obviously tried this out. I thioght the gearbox was a little different as well. I thought the splines for the engine sprocket were different.
It would be interesting to fit the later 4 valve Yamaha motor into the MZ though, especially the version used for the Aprillia Strada that I also ride.
The differences between the Arilia Pegaso Strada and the MZ Baghira are:
The 4 valve motor seems to build up revs a lot quicker
The 4 valve motor seems to make a little more power.
The 5 valve motor seems to give a lot better bottom end response
The 5 valve motor is a lot smoother in operation. The Aprilia and I understand Yamaha seem to have problems with snatchenesss at about 3000rpm.
The MZ handles better than the Aprilia in the twisties
The Aprilia does marginally better gas mileage (on average about 5mpg better)
Both bikes are a lot different to each other, but I still prefer the MZ.

Keith

The things you don't like about the new engine are due to the injection mapping which they still haven't sorted out.

Basically, the 4 valve engine is a better design, some things like the cam and valvetrain are much better. The engine is quite a bit lighter as well because the crank is lighter and because the cylinder does not have a cast iron liner.
The change to 4 valves has, apart from cheaper manufacturing, really only one reason: dual plugs. The engine doesn't have this (yet) but the provisions were made. that and the injection are necessary to meet immission requirements. Performance played no part in development. From that aspect, the 5 valve combustion chamber is much better.
If you stick a good 39 or 40mm carb on your Aprilia and spend some time sorting it out, it should be much better than it is now.
Of course if you stick a better set of carbs on the MZ, it will run circles around the other thing.

Bill

Have to agree on the mapping, but owners on other forums are fitted a Power Commander III, and are claiming that this sorts it out and gives a setting that emulates an accelerator pump sometimes fitted to carbs. At under £200 if you import from the states yourself, its a cheaper option than a big carb.
Mind you I haven't tried a bike with a PCIII fitted, and I always wonder if these fixes really work, or ether spending £200 clouds ones judgment a little

Keith

It's cheaper here....USD $289
http://www.hardracing.com/DIRT&ATV/PowerCommander.htm