MZ SilverStar Modifications

[comanche91]

Got several things done on the 95 (mostly cosmetic) while waiting for the carb rebuild kit from Bing. It's running well, but the carb has never been overhauled since new, and it will do better once that's done. Installed new aftermarket mirrors (didn't have any when I got it, original all-metal look-alikes), new signal lights front and rear (stems and lenses broken), new Smith full waffle grips, and a new Flyscreen from National Cycle. It's a headlamp mount model, fits very well, and actually cuts down the helmet buffeting nicely. Will post pics tomorrow if anyone's interested. I'm really likin' this little thumper.

[95SaxonTour]

Yup, just did the carb rebuild a coupla weeks ago. It runs 100% better now.
If you haven't rebuilt a cv type carb before, I'd suggest getting on the BMW
airhead sites and find all the tricks that are often overlooked in a rebuild. Definitely
make sure you replace the diaphram and float.

I just got back from a 1100 mile ride up to New Hampshire and back last weekend,
got 65mpg and didn't have to add any oil when I got home. They hold 70 mph okay.
But, Its not a road burner.

Ryan

[DAVID THOMPSON]

i must need a carb rebuild mine does about 50mpg
dave

[95SaxonTour]

Dave,

I think the reason you are only getting 50 mpg is that you changed the
final drive gearing. You went down a tooth on the front sprocket, right?
This would have an impact on MPG figures. Also, you are running a
different size tires from stock. This would cut into mpgs too.

The 65 mpg quoted was taken from calculations from gps recorded miles
(not the km based speedo that is totally innacurate. At least on my bike
it is) Also, I am running stock final drive gearing and the recommended
tire size.

Ryan

[DAVID THOMPSON]

120/70x16 rear for buell blast
110/80x16 is stock and Unobtainium in the usa

motofino scooter uses one but not findable yet in usa

but i do think the carb needs a rebuild
had 2 different bmw's with this carb and i just do not like it ...
dave
any one with a source for 110/80x16 in usa e mail me

[comanche91]

I agree w. Dave on the seemingly tall gearing, but since I have zero experience w. MZs and Rotax, I really can't comment intelligently. But I have had my share of both singles and twins w. similar displacement over the years, and getting off in first gear w. the MZ requires a lot more throttle and gentle clutch than any other bike I've had. I do have a new 16T (stock is 17T) front sprocket in hand for my SilverStar, but will hold off on that install until I replace all the o-rings and diaphrams in the Bing. Did this many moons ago on a pair of BMW similar Bings, and it did make a world of difference.

And of course, the smaller sprocket changes the final drive ratio, so actual fuel mileage will have to be recalculated using the new ratio.

[95SaxonTour]

That's the beauty of the Rotax bikes, pretty dang easy to work on. Ive
twisted wrenches on a slew of bikes in my day (these would include old triumph,
benelli, moto guzzi, and the japanese makes) I have found that this bike is
way more easy to work on and delivers the whole "whats that thing" factor
in scores.

Everything on that motor is still available from Woods Rotax. They put these
engines in everything from can ams to harley davidsons. The british military
used em in their bikes, too. Cost is the primary concern. But keep up with
the routine stuff and it should last a while.

As far as the the carb rebuild, make sure everything is clean. It took me a
weekend and a case of beer to get it relatively clean. I found that it helps to
set aside time and do the research on these carbs. In my opinion, they are
nothing to be scared of. I have a bunch of motorcycle buds that run bmws, so
that was a help too.

Final drive gearing depends on the style of riding that you do most. I do alot
of what one would consider Iron butt riding. So the tall stock gearing works out
pretty well for me. If you are doing alot of in town or sport riding, going down a
tooth makes sense.

That Silver Star of yours is pretty cool. It looks just like an old classic. I'd like
to find a nice Saxox Fun. It has the Country's faring and larger tank plus a lower
engine cover. Never seen one offered for sale, though.

Ryan

[95SaxonTour]

David,

You say that 110/80-16 is stock for your bike? I have 120/90-16 on the
rear just like the sticker on the head tube on the bike says.

The recommended sizes on the sticker for build date 12/94 says:

100/90-18 for front
120/90-16 for rear

that size tire can be had. If I were to guess, I would say your bike has
an earlier build date than mine. They changed the sizes to make it easier
for owners to find "stock-size" tires. Just a guess.

Ryan

[DAVID THOMPSON]

mine had 130/90x16 on rear when i got it = it was rubbing the chain cover
and had the rear jacked up so high that the steering was not defined as quick but deadly sudden
it was scary and front was wrong size not helping things
frame label says same as yours
info i saw on internet only said 110/80x16

but beware this is a tube type alloy rim and do not run tubeless
on the alloy rim it is not shaped correct for tubeless tire use
you can run a tubeless tire but you must run a tube in it
dave
i am referring to Saxon Tour with rotax and alloy rims

[comanche91]

As far as the the carb rebuild, make sure everything is clean. It took me a weekend and a case of beer to get it relatively clean. I found that it helps to
set aside time and do the research on these carbs. In my opinion, they are
nothing to be scared of. I have a bunch of motorcycle buds that run bmws, so
that was a help too.

Final drive gearing depends on the style of riding that you do most. I do alot
of what one would consider Iron butt riding. So the tall stock gearing works out
pretty well for me. If you are doing alot of in town or sport riding, going down a
tooth makes sense.

That Silver Star of yours is pretty cool. It looks just like an old classic. I'd like
to find a nice Saxox Fun. It has the Country's faring and larger tank plus a lower
engine cover. Never seen one offered for sale, though. Ryan

Thanks Ryan. Refurbished the carb today - lugging at low RPM and popping thru the intake problem solved. But a lousy 8 o-rings, 4 screws, a couple of gaskets and a diaphram from Bing for $45! What a rip. But, she pulls steadily from idle to redline now so I'm happy. These carbs are pretty simple as compared to a Rochester Quadrajet or Holley 650, piece of cake really. Found some good online procedures that helped a lot. The only thing close to a problem I had was removing the two screws from the dome to get to the diaphram but I had a small impact screwdriver and they tapped right out. The thing was relatively clean inside and I could not see anything obviously wrong, but cleaned everything up w. Berrymans and compressed air anyhow. The mixture adjustment actually works now, and adjusted out exactly as in the procedure which it would not do before. Also put in an inline fuel filter that I guess MZ never put on the Silver Stars. I'm not sure if I'll change the front sprocket out now. I'll ride it awhile and decide. -Don

[comanche91]

EDIT on this thead: After I installed the kit, it ran decently, but was very hard to start. In looking over the parts list that Bing sent me for the Bing 64/33/304 carb when I ordered their manual, I noticed that the large damper spring (p/n 60 306) that sits between diaphram and the top cover was included for this carb. I called Bing and verified that it should be installed - it was not and never had been since I got it. I ordered the spring and installed it. I also pulled start valve back out and discovered I had installed it 180 degrees out when I replaced the o-ring on the shaft. Corrected that and put it all back together, and it finally runs like it should. Man, there lots of ways to make mistakes on these carbs unless you really take your time and double/triple check everything.