RCU Forums - MVVS Twins

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- - MVVS Twins (https://www.rcuniverse.com/forum/mvvs-support-322/6816554-mvvs-twins.html)

Is MVVS still making the 1.44 or 1.20 glow twins anymore? If so where can I get one in Canada?

Rubbie,

MVVS have stopped producing them.

You can only get such engines as pre-owned, from other sources...
Maybe some dealer does have a 1.44, but I cannot know who.

There is a brand new MVVS 1.44 complete with headers & pipes on Ebay right now.

Hope this helps

Mike

I've got a 1.20 twin...test stand run only, so I have yet to put it in a plane.
I'd be willing to sell it, complete w/ canister mufflers...If you're interested, PM me.

I just grabbed it, thanks

another one was just listed as well, it must be my lucky day?!!!

you looking for a really expensive paperweight? The MVVS glow twins have issues with one cylinder going out and they also use a gas type pumper carb. The seals/gaskets in the carb arent compatible with glow fuel either.

Anybody know where I can get a pair of Headers and Pipes for my 1.44? I bought it new and want to use it, but so far no luck with Exhaust Systems.

Steve
[email protected]
979-335-4552 USA Phone

Steve,

Headers and pipes for your engine are available, either from me, or from Pé Reivers.

You can contact these dealers directly by E-mail ( [email protected] , [email protected] ).

Selling and buying directly is disallowed over the forum pages, or in the PM system.

im looking for info on mvvs twins. i picked up a twin cylinder engine . Im not sure how to tell what size it it is. i have no info on it, it also been converted to gas. Anyone have the orignal documenation ?? [email protected]

Bob,

MVVS has made glow twins in the past and is making large displacement, gas fuel, twin-cylinder engines.

The glow engines were made in 20 cc (1.20 cid) and in 23 cc (1.44 later engines) displacements.

I suppose yours is a glow model.

The glow engines were equipped either with a standard carburettor, or (1.44) with a Walbro.

Rosh . the mvvs twin i have doesn't have the walbro carb so i can assume it is a 1.2 ? is there any other way to tell what size it is ? i have the glow mufflers that came with it but it was converted to gas as it has spark lugs steel mufflers and a electronic ignition. it doesn't look like it has ever been started. So the question will the stock glow carb work for the gas conversion ? if not what mods does it need to run on gas. do you know where i can get any of the orignal documentation for it ?

Bob,

Both twins use the .61 engine's stroke of 24 mm.

The 1.20 uses the original .61's bore diameter of 23 mm and the 1.44 uses the .77's 25 mm bore...

Carefully remove one of the cylinder heads (take care that you don't rotate the sleeve out of line with the bypass and the exhaust ports) and just measure the diameter of the sleeve/piston.

Hi Dar. I just bought a mvvs flat twim 1.20. it came without mufflers. do you know where i could pick up some or maybe header pipes. the flanges are predrilled. this eng. has a walbro carb. and the box says it is a 1.20.

i will look tommorw but i believe i have a set of mufflers for the engine i have. ill send pics. the motor i have has the walbro carb. send me the pic of the box it came in if you have it

mr bob thanx for replying. I don't have a way of sending a pict. I'll dig it out tomorrow and try and describe it to you. fujiman

fujiman I looked but I dont have the mufflers for your engine. good luck

mrbob, did some research and found header pipes for a fox,os.60, enya x .60 macs #2850 fit perfectly. the fox tilt up/tilt down (right and left bank) will work for the mufflers. now all I have to sort out is the running problems with this thing. I think the main problem with running probs. is in the reed set up. one fellow here in the forum said he fabed up a different reed set up drilled out the reed boss or flange to match carb base size. wonder what he used for the "new" 4 reed sys. not much room in the reed throt casting in eng block. I'll be lowering the compression also with a couple of extra head shims. maybe a wt-499 alky carb that some guys are using on supertigres.

Hi!
I have those engines available. both the 1.20 and 1.44 came with the Walbro carb. I don't think any came with a standard MVVS R/C carb.

I'm now the owner of a low time 1.20 twin.

I will experiment to see if I can get it to run reliably. If I have an paticular finding that may be of use, I will post again on this thread.

***************

Here is a link to a video showing a twin which appears to run well. Inpiration for the rest of us.

http://www.youtube.com/watch?v=LlLyHpLAKqI

Bill Vail (who posts on RCU occasionally) gave his MVVS 1.20 Twin to the late Jim Cline (Of Cline Fuel Systems) some years ago to sort out. He reports of success with a simple modification, and exchanging the supplied barrel rotor Walbro carb (which seems to be the main problem) to a butterfly Walbro carb suited for flowing suficient glow fuel.

Whilst not set up for all out performance, reliable running and idling was obtained, with Cylinder Head temps within 10 degrees F of each other. Carb Bill used (recommended by Jim) Walbro WA 46 G9.

Here are some pics

Following on from my last post, here are notes Bill Vail sent to another enquirer about sorting the twin, which he kindly made available to me. I post them here for all to read:

************************************************** ************************************************** *******

"It's funny how these threads go. I posted a picture of my collection of toy engines and I've received 3 e-mails asking about the MVVS 1.20!

My 1.20T did NOT run well as shipped. I would not have considered the engine flyable. The carb the engine shipped with would not pump enough fuel and while it would run, it was very close to full goose lean even with the needles back all the way out. Further, one cylinder ran considerably leaner and much hotter than the other. One cylinder ran nearly 100F hotter and of course the colder cylinder was prone to flaming out.

I contacted friend, genius, and hobbyist the late Jim Cline. He recommended the carb pictured. It has proven to be near perfect solution. The carb runs perfectly and the only reason I say near perfect is that the linkage to the throttle is not very handy and will require some work to setup.

As for one cylinder running leaner, he recommended placing a small piece of brass between the carb and reed cage bent such that it deflected some of the incoming fuel charge towards the lean (hot) cylinder. I had NO expectation that such a simple solution would work. It took some tinkering/trial and error but it worked better than I could have dreamed.

At this point I should mention, I've never flown this engine. I did all my tests while it was strapped to the test bench. I removed the engine running extremely well and had every intention of building something that would showcase its looks but the holding pattern over my building bench is large and I haven't gotten around to it - yet (12 years ago)! I did keep notes of my running though.

Dec 1999 - Air temp 70F

Mufflers -Bisson twins

Plugs - Fox IB

Fuel - 8% nitro, Klotz synthetic, and castor.

Prop - APC 15x8, 8,800rpm with solid 1,500rpm idle

RT cylinder 265F, LT cylinder 255F max. (typical - RT210,LT200 at plug)

While it took me several enjoyable days and a fair bit of fuel to get this engine sorted out, all credit goes to Jim. In this ARF/E world, I miss folks like him. Sometimes it's easy to back off sharing what took me days to discover and then I remember Jim who would share everything he'd learned over a lifetime and ask for nothing more than to let 'em know how it went. The bit about modifying the airflow with a bit of brass was genius and he shared it without a second though. I've used it on other twins since and NEVER heard of, or seen reference to, this simple mod anywhere else. If you choose to pass this tip on, please reference Jim.

Let me know how it goes!"

************************************************** ************************************************** **********

Derek,
Thanks for sharing.
I have never had a change to run these twins.<br type="_moz"/>

fiery, could you possibly post some pics. of the fuel diverter that you and jim c. came up with. as posted i too have 1 of these twins, a 1.20cid. thot about a walbro wt-499 alky carb. because of the opened up jetting. the walbro carb. that came with the eng. just is lacking in fuel flow. thought about fabing up a new 90 degree(carb. facing forward) manifold set up with a little greater volume with the reed setup just under the carb. and then putting in a triangle diverter plate down into crank case to direct fuel mix towards both cyls. kind of like a cars manifold does. anyway just a thot.

fiery, guess if i had enlarged the pics. you posted i would have seen the little brass diverter you mentioned. i worry about how long that would last before eng. pluses and vibra. would cause it to break off and the eng. eating it??? i'm also looking at opening up slightly the intake ''slot'' in the reed valve body as it looks very restrictive!!!!! any loose of flow here could cause a ''govenor effect'' and thereby limiting output of the eng. much like restricter plates that nascar engs. are required to use. we used to use restricter plates in the tow tractor engs. when i worked for skywest airlines. we would install an aluminum plate under the carb. with a 3/4'' inch hole in it and this way limit the rpm output of eng. but wouldn't effect the idle at all, just top rpm. mechanical throt. govs. were very expensive, the plates worked and cost was almost 0. i thot i would open up that slot and blend the top of the reed housing to match the carb. base, then taper it down to the base of the slot, much like blending a manifold or cyl. head would be, opened up then blend back into the manifold or head port.