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A Reed Valve on an ETZ251

PostPosted: Sat May 15, 2021 4:07 am
by Puffs
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Re: Reeds on a 251

PostPosted: Sat May 15, 2021 4:20 am
by Puffs
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Re: Reeds on an ETZ251

PostPosted: Sat May 15, 2021 4:42 am
by Puffs
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Re: A Reed Valve on an ETZ251

PostPosted: Mon May 17, 2021 8:52 am
by Blurredman
Now I have nothing to add- but I am entruiged as to the long term use this will have esspecially compared with the old stuff..


Does it feel like it used to?

Re: A Reed Valve on an ETZ251

PostPosted: Tue May 18, 2021 3:57 am
by Puffs
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Re: A Reed Valve on an ETZ251

PostPosted: Wed May 19, 2021 10:19 am
by Puffs
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Re: A Reed Valve on an ETZ251

PostPosted: Wed May 19, 2021 9:26 pm
by DAVID THOMPSON
did some pulse jet engine stuff in the early 1960 with them we had a NO MANS LAND SAFETY AREA
behind the exhaust when the metal reeds blew it was very dangerous out there in the back yard

also tested go kart motors at very high rpm no one allowed in room with motor running

dave

Re: A Reed Valve on an ETZ251

PostPosted: Thu May 20, 2021 3:20 am
by Kruh
Pretty cool. But to take full advantage of the reeds, you would need to have windows in the piston or at least, a shorter piston skirt. So that the intake is controlled by the crankcase pressures, not the piston. Otherwise its the same thing, but with less blowback at the carb.

Re: A Reed Valve on an ETZ251

PostPosted: Thu May 20, 2021 4:34 am
by Puffs
Removed

Re: A Reed Valve on an ETZ251

PostPosted: Thu May 20, 2021 4:52 am
by Kruh
True, that does increase piston wear, l hence the windows. Although the concerne there is the strenght of the skirt. MZs have pretty high pistons as is, so I don't think it would increase wear by much.

Yes, most modern bikes with reeds feed directly into the crankcase. Which offers the bet filling potentional. I guess, thats not something that matters much in a low revving machine like the MZ.

Raising the barrel, and shortening the skirt is good for achiveing higher rpms. But, unless you shaved the top of the barrel or head, you deacrease the compression and more imporatantly increase the squish gap. So you loose more than you gained with more port timing.

In any case, seems like something that could work pretty well for street use. Since blowback is most noticable below 4000 rpm. Which is where these engines spend most of there time

Re: A Reed Valve on an ETZ251

PostPosted: Fri May 21, 2021 3:43 am
by Puffs
Removed