cuwaert

A buddy of mine bought on ebay a ZDZ50 with reed valves in stead of the (for zdz) usual rotating valve.
No big deal, but the engine doesn't exceed 6000 RPM (20m above sea level) with a mesjlik 22x10.
My 50RV puts out 7200 with a APC22x10 on a hobbyking canister.
One should expect at least 6400. Exhaust is a replica (read home made) of a krumscheid (50cc) canister and has served on a ZDZ50ng for 10 years.
Anybody ever encountered such a rare mutation of a ZDZ50? I can't find one.
The back plate is aparently genuin ZDZ (blue colour) with the reed valve in the middle whereas on rotating valve types it is out of centre.

cuwaert

Ok nobody heard of it. Another question, would it be possible that reed valves could influence the characteristics of an engine compared with rotating disc so that a different manifold length would be required for optimum power?

CK1

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cuwaert , If you can post a few photos of the reed valve setup it would help. In general a rotory valve engine has only a marginal rpm gain over a reed induced engine , given that both engines are in proper working condition . The torque curve might be a larger difference then the peak rpm difference.
In either case a 50cc engine at sea level that will only turn a 22x10 at 6k is either not properly tuned or mechanically deficient in some way .

cuwaert

Sorry no foto's available, the engine is not mine . The guy bought it on the internet and I suspect some one installed a genuine zdz backplate with reed block of which I cannot trace the type.
The engines starts very easy but a) hasn't a lot of power b)isn't very much consistent in eigther idle speed and tuning.
Anyway now winter is near, we're gonna pull it and put it on a stand for testing.