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Discussion Starter · #1 ·
What's the general feeling about MVVS engines? I've run a .49 that I bought new in March on both an EF edge and a katana P arf. my impressions are that its kind of loud, a little prone to vibration problems, but definitely a very powerful engine.

a) could just be me. but OS .46s on sportflyer type props are at least 6dB quieter.

b) could be the airframes. the EF edge seems to have kind of flimsy mounting rails, and that coulda done it. this is kind of my problem: vibration problems have cut short my flying days numerous times now, and im getting fed up with it. I've lost the low end needle valve, i've killed a servo, and the header bolts backed out several times. I pipe-clamped the header on, and the header broke.

-do i need to support the header or the pipe in another place? at the time it was just bolted on to the motor, and had a mount on the rear of the mini-pipe. perhaps there just was lots of room for the header to vibrate and I should have put another mount on the front of the mini-pipe.

I'm running it on Omega 5% nitro (I forget if thats all-synth or mix) and havent added any head shims to what may already be in there. I do have 2 shims that I ordered from morris so that I can run the .49 on 15% and i wont have to take several different fuels to the field.

-maybe adding a shim for the 5% will calm the vibrating?

any help much appreciated, bros!
 

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I'd have to agree with you on the MVVS... Powerfull little sucker once you get to know it.... The header pipe that comes with that motor is not that strong.... They last maybe a season or two... Morris sell's 'em pretty cheep.

Vibration is an issue too.... I used to go thru motor mount bolts like crazy... Had to start using 6x32 stainless bolts.
 

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If you haven't cut the header at least a little bit (between 1/8-1/2"), it's likely that the pipe is the the culprit to your vibration issues, the stock header is a little too long for the engine to operate properly. My newer blue head 49 shook like crazy when I first got it. Bought a new carb, didn't help. Finally stuck the "tuned" (cut about 1/4") header from one of my older 49 and it completely transformed the engine.

BTW, double check the balance of the prop. If you're using the APC 12.25x3.75, I've found that these props (at least the batch of 6 that I got) were not even close to being balanced.
 

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are you supporting the pipe with anything? or is the header just supporting it?
 

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i see, that sucks :(
 

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I have a little mvvs .21 in my TACO and it works quite nice. With their price they are really good.
 

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I bought an mvvs 15 to put on a funbat and boy was I dissappointed. It would only run on 0% and would not turn an apc 7 x 4 over 10k. I just got tired of fiddling with it and replaced it with a magnum 15.
 

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Discussion Starter · #10 ·
If you haven't cut the header at least a little bit (between 1/8-1/2"), it's likely that the pipe is the the culprit to your vibration issues, the stock header is a little too long for the engine to operate properly.
eeeeenteresting, i had previously blamed the problem on the wimpy rail mounts that the EF edge has in it. when i put the engine on a 1st gen (i.e. ebay) katana P arf, the shaking still happened a little, but it didnt affect reliability - i.e. the header didnt shake off and the low end needle didnt shake off. well, its good to note that I pipe-clamped the header on, and then the header broke off at the header/tube joint, and then the elevator failed before the (edit:) NEXT header could fail again. I've ordered more headers from robert @ mvvs.com and a new muffler, i'll try cutting them down 1/4" or so. also i now have a dave brown vibra damp pipe mount sitting around, it should hold the pipe better than the strap on the rear does.

-barrett[/quote]
 

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I have a MVVS 49 that I have now ran a couple of gallons of fuel thru and I would have to agree. It is a little louder and has a little vibration in it. I too thought it was the airframe I have it on. I do know the engine has the quickest transition of any engine I have (which includes my YS .63) and have more power than any .50 size 2 stroke I have ever owned. So far its never flamed out on me either.
 

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I also have a 49 on my Ucando 46 and while is a little short on power for the size of the plane has been working very nice with fast trasition and tickle idle. The only way to run this power monster is using 5% and enya #3 plug. Cheap gas and expensive plug. This engine is coming out for my MOJO.
Have a nice day.
 

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I have two .49's, they are fussy but run great once you get them dailed in, BUT I havent tried 5% fuel yet (I use 10%) they say that 5% is the ticket.
One has better throttle response and more power than the other but they are both good and plenty powerful.
Overall I like my Webra .50 better.
 

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where is the best place to get a webra 50 and a mvvs 49
are you guys getting 15500RPM on a 12.25x3.75apc with 5% with the .49?
 

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Morris had the MVVS's on sale about 2 years ago $99 that is why I have 2 :!:
I dont remember where I got the My Webra's from, I have 3 (1, .32 1, .35 and 1, .50) I havent tacked anything in years, I just fly :D
 

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Discussion Starter · #16 ·
are you guys getting 15500RPM on a 12.25x3.75apc with 5% with the .49?
closer to 13,5-14k depending on level of tune, but I think my pipe length/vibration was eating a little of my rpm. the real secret to getting mine to run lies in getting the low end needle set just so.

I run morgan 5% pink (what's that, omega? castor blend anyway) and yeah I need some new plugs. enya #3 you say? what about the rossi medium plugs? robert swears by 'em.

I'm thinking about desiging a pattern practice SLASH freestyle aero plane explicitly for piped .50 size side exhaust engines (pipe tunnel on bottom, engine mounted at like 12 degrees below horizontal.) with the mvvs/rossi/webra/irvines in mind. every time I make up my mind to go all electric, i wind up getting another glow motor.

-barrett
 

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capncrunch said:
are you guys getting 15500RPM on a 12.25x3.75apc with 5% with the .49?
closer to 13,5-14k depending on level of tune, but I think my pipe length/vibration was eating a little of my rpm. the real secret to getting mine to run lies in getting the low end needle set just so.
Neither my MVVS 49 or Webra 50 can hit 15500rpm with an APC 12.25x3.75 regardless of nitro content. I'd be really skeptical of anyone whose claiming that high of an rpm using an APC 12.25x3.75 with any 46-53 engine unless they're using a full length tuned pipe (most of us here are probably using the mini-tuned or mouse can pipe which I believe is one reason why the MVVS has such great transition). I tune my 49 for about around 13300-13600 rpm on the ground (the engine can probably hit 14k rpm if fully leaned out), which is a little rich since they tend to lean some if the nose is pointed straight into the sky for 85% of a flight :) My Webra (which has a mouse can pipe) is a couple a hundred rpm less powerful on 5%.
 
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