Rotax 504 crankshaft / flywheel mass

[drog]

Hi. I own a 1997 MuZ 500 Country. I have only one complaint. The lack of crankshaft inertia makes it a pain to ride around town, or when speeds are low. Does anyone have any experience, or knowledge, of how to increase the crankshaft inertia?
Many thanks.

[comanche91]

Hi. I own a 1997 MuZ 500 Country. I have only one complaint. The lack of crankshaft inertia makes it a pain to ride around town, or when speeds are low. Does anyone have any experience, or knowledge, of how to increase the crankshaft inertia?
Many thanks.

What are your symptoms?

[Nozz]

I think the solution is to avoid revs under 4000 or so. Downshift?

[comanche91]

Couple of things I've done to help this:

1. Per Dave's suggestion, I dropped the front sprocket by one tooth. This helped a lot - the gears were too tall from the factory for me. Can still cruise at 75-80 MPH - fast enough!
2. From frequenting the German MZ forum, the Dellorto carb 36mm that came on the earlier Rotax models was switched out to the Bing CV carb around 1995 or so due to the Dellorto's poor low RPM throttle response. The Bing was more forgiving so the factory switched to it.
3. I located and installed a factory A2 muffler, and dropped the needle down one notch (#4 position). The A2 was the "best performance" muffler MZ offered, and supposedly fits all models except the Country. It really helped over the whole power band.
4. I discovered my Bing carb was missing the slider spring under the carb dome (#22 in the below diagram) when I rebuilt it. I called Bing USA and they advised me that it's supposed to be there. Installing this spring gave me a lot better low end grunt and it pulls smoothly now from 2000 RPM on up. Still sucks below 2000 RPM if you lug it, but I think that's just the Rotax. As far as I've been able to find out, some of the Bing carbs had the spring; some did not. Mine runs much better with it in.

[hmmmnz]

you should be able to get a Steahly flywheel weight for the rotax,
it would be fairly easy to get one made up on a lathe as well

[breakwellmz]

Some years ago i fitted an additional flywheel disk to a Saxon Tour(?)i had at the time.I think it was a Rotax kit.Easy enough to fit if you can find one.I seem to remember it didn`t make as much difference as i`d have hoped.The guy i sold it to came down to Bath from Coventry(or near!)He may be contactable thru this forum.