1.26 Glow Twin?
 

Picked this up at a swap meet and WOW! Talk about compression! Even with the plugs out it has one good pinch fit at TDC. Guy at the meet told me it was a 1.20 but if the stamping on the case is correct then its a 1.26(?) Info id limited at best on the web for MVVS twins and I can't find out if the stamping on the case would be the dis. or not. Anyone with first hand knowledge on this engine out there? Thanks, Mike.

RE: 1.26 Glow Twin?
 

It is a serial number, Mike.

Nothing else.


If anything, the displacement would appear in metric units, i.e. cubic centimeters (cc).

It says 126I (not 1.26), which is neither Imperial units, nor metric.

RE: 1.26 Glow Twin?
 

Ah-ha. Thanks Dar. BTW, I'm going to blend up some fuel to run it up, while I wont use any nitro, about what % oil should should use? Thanks again.

RE: 1.26 Glow Twin?
 

Mike,


That would be 20% oil, at least half of which is castor.

And you can use 5% nitro.

RE: 1.26 Glow Twin?
 

This is a super engine, to bad I bought it to re-sell. It'll be on fee-bay this weekend, Here's a short video of it run up. http://www.youtube.com/watch?v=LlLyHpLAKqI

RE: 1.26 Glow Twin?
 

Too bad indeed, Mike.

It seems to be running much better and more consistently than other engines of this type that I have seen.

RE: 1.26 Glow Twin?
 

Well after reading all I could find on the web and reading all the negative feedback, It seemed to me that the biggest problem was likely too much nitro and/or not enough oil. Thats a big reason euro engines do so poorly over here in the states. I talk to too many people that just want to stuff 30% nitro and only 12% oil thru all the engines they handle regardless of its requirements thinking thats the only way any engine builds power.

RE: 1.26 Glow Twin?
 

Quote:

---

ORIGINAL: AutoMike

Well after reading all I could find on the web and reading all the negative feedback; it seemed to me that the biggest problem was likely too much nitro and/or not enough oil. That's a big reason Euro engines do so poorly over here in the States. I talk to too many people that just want to stuff 30% nitro and only 12% oil through all the engines they handle, regardless of its requirements thinking that's the only way any engine builds power.

---

Mike,


That may be a part of the reason in North America... But in Europe they are not usually considered too smooth running, for reasons of mixture balance in the cylinders.

Perhaps Pé will care to add a few words, once he returns from Egypt.

RE: 1.26 Glow Twin?
 

HELP guys and/or Dar. Just bought a mvvs 1.20 flat twin. anyone know what mufflers or header pipes could I use to exhaust out the bottom of aircraft. the flanges are drilled and tapped already. how about head shims? maybe from another eng. manufacturer??? I run 15% nitro and I hate to think that I have to buy several diff. nitro %s for several diff. engs.

RE: 1.26 Glow Twin?
 

FM,


The manufacturer's recommendation is that you do buy the right fuel for the right engine.

If I am to quote only what the manufacturer's say, this is it.


But MVVS' head engineer says that 15% nitro can be used, if you add head shims (a total of two under each head is usually enough).

The internal diameter is 23 mm; just like the OS.61SF and other 'Long Stroke' era engines.


You would have to buy from an overseas dealer, or maybe David Moen in Canada; if you want the original MVVS items (they come in sets of three).

RE: 1.26 Glow Twin?
 

thanks dar. I'll try to locate os shims.

RE: 1.26 Glow Twin?
 

The muffler sets for the twins are no longer available. However, the 10cc #3255A mufflers still are, as well as Exhaust manifolds #3251 and tuned pipes #3250.
This opens up a score of fitting possibilities.

The twin engines have issues with fuel mixture, which are partly due to the Walbro carb, and partly twin design related.
The walbro is in fact a gas carb with gas jetting, and will not regulate the intermediate mixtures with glow fuel all that well. Changing the carb to the glow 1.60 carb will cure a lot of half-throttle issues.
The twin design (any boxer twin!) issues can be lessened using a lot of Nitromethane in the fuel and a shim or two under the head, like Dar already suggested.

With these changes, the engine runs like a champ!

RE: 1.26 Glow Twin?
 

thanks Pe. I have come across an alky carb from walbro, a wt-499 I'll try that along with the head gasket added. Maybe that will tame the beast!!!!!!! If the 499 doesn't cure the twin woes I'll try the os 1.60 or maybe the 1.08 7d carb as I have several of those then again there is always a Perry HP carb. too. Some years ago a friend had a twin Tartan with a walbro on it and it gave him fits. but it could have been the pressure prob. because of the diaphram vent hole being pressurized in the air stream at high aircraft speeds. I don't think he ever did get it sorted out and lost a 1 of a kind prototype plane. I'm a small engine specialist by trade so I'll get'er done. Thanks again Pe for info!!! The pool of knowledge here on rcu is priceless. Remember: Fly in the middle of the air, danger lurks out at the edges!!!!!!;) PS. Guys have had some good success with the wt-499 on their Supertigres. I think Zenhoa has a glow engine that runs the 499. I got mine from a scooter shop that specializes in little racing engines, also someone posted in the forum on gas to glow that Zama japenese carbs have a carb kit for alky but the carb still may need the jets opened up a bit to flow glow fuel.

RE: 1.26 Glow Twin?
 

I think the biggest worries with the Walbro, (if the main jet will handle the alky flow), is the idle and intermediate jets (not the needle). At part throttle they let air enter the idle fuel plenum, and thus also provide brake air that mixes with the fuel that exits the jets downstream of the throttle valve. Location and size of these brake air jets can be very critical.

PS,
Do you still want me to answer the mail you sent me?

RE: 1.26 Glow Twin?
 

might have to go to the OS 1.60 or perry HP carb. i'll have to fab an adapter to fit reed base to OS/perry. Or better yet.......... OS BGX type carb, has a flat 2 screw affair to mount on eng. case. that mite be the easiest :D HEAD GASKETS FROM OS .55ax 23mm or the OS .61fx 24mm. also Jan says he has shims and mufflers/headers for the twin. i'll tame this critter or it will kill me tryn'

RE: 1.26 Glow Twin?
 

triumphman, i'm unable to send you a PM thru rcu. a window comes up that says error page not found. so rcu is messed up somehow with this.[:@] i'd like to help you so if u get this message e-mail me at [email protected]

RE: 1.26 Glow Twin?
 

Any news?

3255A mufflers are no longer produced by MVVS. They now introduce the 3255N side muffler.
The MVVS 3219 glow carb is as good as any two needle carb on the market. However, some have found good results with the Walbro.

RE: 1.26 Glow Twin?
 

Hi!
Being the Swedish MVVS distributer I'm sorry to say that the those twin engines were a total failure for MVVS!
They did not run well! Ten years ago I sold one of those and the later I run one myself. Both of these engines were extremely unreliable on idle and they were both imposible to set rich at full power which made them run very hot. But being ABC engines they could stand it though! But it made me think that something was not the way it should be...
Then there was the problem with fitting silencers without having problem reaching the fuelneedles. Got the thought that MVVS had stopped thinking here ... Badly constructed is just the beginning!

I have tried both the walbro carb which is mounted as standard and ordinary R/C carbs from MVVS (7and 8mm) and all carbs has worked as bad as the walbro!
So! Sorry to say. The MVVS twin is not an engine which you would put in an expensive airplane! No wonder MVVS stopped making them after just a couple of years!

RE: 1.26 Glow Twin?
 

a fellow over in Australia and i have been in contact with each other about getting our twins running correctly. one thing i did was to add a head shim, and add a wt-499 alky carb. i'm also looking at the intake block and reed assy. i'll will be running on board glow ign. from 1/3 thrott. down to full idle. i will be running enya #3 glow plugs and 15% nitro fuel (reason for lowing compression). i'm a small eng. tech. by trade and i refuse to give up on the eng. it is a challenge i'm sure, but i refuse to give up.

i' haven't herd from my friend in assy land lately but he is trying some things too. we'll keep everyone posted.

ALWAYS REMEMBER: fly in the middle of the air, danger lurks out at the edges!!!!!![X(]

RE: 1.26 Glow Twin?
 

Engine is on bench .. need to redirect pressure pulse to suit WY 449 carb. Will get to it ....

RE: 1.26 Glow Twin?
 

hi fiery, good to hear from you again!!!!!!!!! you can tap into case anywhere below the reed pack should work. then run a line to the pulse fitting on carb. you will have to drill and tap pulse chamber lid on that 499. oops you are using the wy-449. is that carb. bored for alky use and how about the diaphram and rubber parts are the alky safe??????

i gotta get motivated to start on mine, this winter maybe.

RE: 1.26 Glow Twin?
 

Point to ponder:
Because of the two stroke boxer twin's inherent unbalanced mixture L/R, the engine probably will like different plugs l/r.

RE: 1.26 Glow Twin?
 

i'll be using a temp. meter to read head temp and then i'll be able to see which may be running hotter and then i can exper. with plugs of diff. heat ranges, there by adjust the combustion timing. we'll see what becomes of that.

RE: 1.26 Glow Twin?
 

Good point Pe

In the original instruction sheet shielded ("idle bar") plugs are recommended for best results.

That suggestion is not made on any other MVVS engine. Novarossi C5S or C6S seem to be the usual recommendation. They are excellent plugs. I suspect the engineers who designed the engine knew there would be an issue with mixture balance. Use of shielded plugs would help broaden range of acceptable tuning.

I have not forgotten your suggestion to substitute a carb from the larger glow engines. That will be my fallback if the Walbro WT-499 proves unsuitable. I understand the modern tan coloured woven diaphragms are much better at handling methanol than the old "black" diaphragms. They would have to be, with ethanol being added to petrol in many parts of the world.

Some pics from Mr Bill Vail who has used a "deflector" to even intake distribution between culinders follows. Also, aftermarket walbro carb intallation (adaptor for rerouting pulse) is shown. Bill reports great results and even running temperatures for each cylinder. The set up was "fettled" by the late Jin Cline of Cline Fuel Systems. My thanks to Bill for sharing this information. Carb orientation places throttle lever in wrong position though.

RE: 1.26 Glow Twin?
 

Is this an Mvvs 126I that your talking about it has an OS carb on it...
I purchased this plane and i have no idea about the motor...
need a little help figuring this one out...
i can send you a pic of it...
HELP !