un even motor run

[bob whitney]

ok this should be fun .i am running an OS baffled 30 no muff, running a 10/6  with 10/22 fuel on one a Japanese arf kits. it has a 2 oz profile tank .
 the problem is that it goes from too rich to too lean  in maneuvers..starts out rich at the beginning of a lazy 8 ,leans out in the middle and go`s rich again when finished  .does the same uprright and inverted
 where do i start RAD

[Dan McEntee]

  If it is going rich inverted, and doing the same in outsides, you need to raise the tank. If it's doing the opposite, you need to lower the tank. See if you can kick the back of the tank outwards a bit also.

   Type at you later,
    Dan McEntee

[Dave_Trible]

Bob it sounds like it is trying to cycle like you might want stunt engine to do.  If it is one of the older engines then be happy!  It may be breaking too hard for you if the plane is light or smaller.  You might want to let it do it's thing but use a 10-5 prop to slow the airspeed down when it breaks.  Also a 10" prop may be a little much for your .30.  .29s-30s are usually better suited to 9" props.   Too much prop can cause the engine to heat up too much when they do break and then be slow to come back to a four cycle.
On the other hand,  if it is a more modern engine and Schnerle ported they are never very happy trying to run in a cycle/break mode-only high rpms and flat pitch props..with a few exceptions like the late model Tigre 51 which actually cycles pretty well.  You say baffle piston which makes me think it's more like the  Max S 30 and S35. 

Dave

An additional thought-  22% oil might be a little light for this kind of engine.   I use 5-25 all castor in my Max and Enya engines of this vintage.  In fact the Enya .35s refuse to run correctly on anything else,   which is basically what the manufacturer said in the day...Castor and plenty of it.

[Dave Hull]

Bobber,

I have run the OS .30 Max-S on my Super Combat Streak (a huge misnomer....) with nice results. The plane is light, uses the regular Flite Streak wing and tail, and just has a box fuselage. I put the landing gear design from the Peacemaker in it which came out really well. Typical setup was a 10x5 wood prop, .015x52 lines, .261 venturi and a OS 3.5mm spraybar, on typically 10/25 or 10/29 all castor fuel for a happy 4-2 break. A custom uniflow tank, but don't recall the ounces--probably around 3ish. I have run it open-faced with just the forward-facing tank vent, or with the OS-703 muffler and pressure. Works fine both ways. I don't try to run these hard, but my .30 Max-S was pretty tired when I got it, so I swapped it for a fresher .35-S and get about the same results. Just easy pleasant runs. It isn't great in the wind because there isn't the surplus power and the plane just doesn't like hard outsides, but....

All old-school and works fine.

I'd switch fuel, check your venturi size, drop down an inch of prop pitch and if you are running a fuel filter, try it without that. If you still get too much break, then try going down nitro. If still too much break, try slightly smaller venturi. If the plane is too big/heavy or on too long of lines and you are pushing the engine hard, expect the sweet spot to be lot smaller and a bit harder to find. With my Streak setup the sweet spot is mile wide. If your engine isn't too worn out to hand start it should run a nice 4-2 in the air. You just gotta get the setup tweaked in. This is waaaaay easier than running one of your racing diesel jobs....

McDivot

[Dennis Toth]

Bob,
Before you go crazy with all kinds of other mods check where the tank (I assume uniflow) vent is located relative to the fuse profile. I had the same issue when I was running an OS Max 25 (baffled) in a Ringmaster. For years I fought with the engine run. Then I remembered that at one of the  old GSCB forums one of the stunt pro's explained how the tank vents should be inboard of the fuse side about 3/16" off the side and in the free airflow stream. I had been running a uniflow profile style tank (with the vent off the outside top of the tank) not giving any thought to the vent location. I modified the vent to a small piece of copper tube on a clip off the rear engine mount bolt and up above the fuse profile about 3/16" and BAM no more erratic engine runs. Here's a pic of the nose mount. One other thought is to run fuel with at least 25% total oil, I run 50/50.

Best,   DennisT

[Colin McRae]

Bob it sounds like it is trying to cycle like you might want stunt engine to do.  If it is one of the older engines then be happy!  It may be breaking too hard for you if the plane is light or smaller.  You might want to let it do it's thing but use a 10-5 prop to slow the airspeed down when it breaks.  Also a 10" prop may be a little much for your .30.  .29s-30s are usually better suited to 9" props.   Too much prop can cause the engine to heat up too much when they do break and then be slow to come back to a four cycle.
On the other hand,  if it is a more modern engine and Schnerle ported they are never very happy trying to run in a cycle/break mode-only high rpms and flat pitch props..with a few exceptions like the late model Tigre 51 which actually cycles pretty well.  You say baffle piston which makes me think it's more like the  Max S 30 and S35. 

Dave

An additional thought-  22% oil might be a little light for this kind of engine.   I use 5-25 all castor in my Max and Enya engines of this vintage.  In fact the Enya .35s refuse to run correctly on anything else,   which is basically what the manufacturer said in the day...Castor and plenty of it.

I have a Max-s 30 and run a 10-5 MAS prop on a Goldberg Shoestring. I also run the OS stock muffler. A 10" prop should not be too much for the engine as the OS manual for the 30 actually mentions a 10" (4-5 pitch) prop as a starting point go-by. A 10-6 prop might be too much. Try a 4-5 pitch to see of things improve and doesn't slow down your model too much.

My engine was new at the time took a significant amount of run time before it started to run consistent. And I run 28% oil (50/50 castor/syn blend). The engine definitely needs lots of oil. Also, going lean in maneuvers might also be caused by an engine not being fully broken in.

I would definitely increase the fuel oil amount closer to 28-30% until it is fully broken in. Then maybe try to go lower, but, not less than 25%.

[Brett Buck]

There are a myriad of potential problems, but you are getting good advice across the board. In particular, my Uncle Donny and I found long, long ago (in a Jacuzzi plant parking far far away) that the 30S did not like a 10-6 and ran better with more oil. I would suggest both solution from the Daves above. I would suggest a 9-6 to keep the revs down, see how it runs, then add oil up to about 28 percent. We use the same sorts of solutions even on current engines, I run a far less than max prop on the RO-Jett, and adjust the power variation by altering the oil content in small amounts. Less prop = less load feedback = less engine reaction. More oil = less engine reaction. Changing from 18% oil to 20% oil is a pretty big change on the RO-Jett, go to 22 and it's very "flat", with nearly no reaction.

    One thing you didn't state - are you running the "big" venturi, or the "small" venturi? These typically came with two venturis, and at least on the 30 and 35, the "large" was generally not great for stunt on a stock engine. Unfortunately, many people started with the "large" to Get More Power, and then the small one was lost. Randy probably knows the diameter, other people too. You can check it visually, the outside profile of the  "large" was just a cylinder, the outside profile of the small was necked down slightly, so you could tell them apart.

    As mentioned, this was a very long time ago so I don't have the details, it was close to 50 years ago and while my memory is generally pretty good, my attention to detail at the time was about what you would expect from a enthusiastic 12-year-old.

      Brett

[bob whitney]

thanks for all the good ideas. i am usually adamite about running my vent tube 1/2 in from the inside of the fuse on all my race planes .that will be first with some more oil and than a smaller prop .this plane is very light and am flying on 60 ft spider wires(60 lbs).

[Steve Helmick]

Rad, please post a picture of the front end of this device. It'd help a lot to know what sort of tank you're using, how it's
plumbed, etc. If it's a tin tank, it could be as simple as incorrect uniflow tube location, or a flake of solder doing bad things. And what brand of propeller you're using. A 10-6 APC is a LOT more load than a 10-6 Master Airscrew, for starters.

I wasn't aware of any Japanese ARF CL models, so that's also interesting. Did the tank come with this ARF?  Steve 

[Ken Culbertson]

I wasn't aware of any Japanese ARF CL models

https://stunthanger.com/smf/open-forum/xebec-19-35-from-craftline-japan/

Ken

[John Carrodus]

Hiya Bob
I'd like to back up what has already been said . I run a bunch of older OS motors and I can say they seem to get better with more use. I have always run 28% oil , 50, 50 approx synthetic and caster and they seem as happy as pigs in mud.They like to run cool so do not overload with big props. Some of mine have RC carbs which are great as I turn them back so they don't bust off in a prang. They seem to rev just as good too no probs.

[Air Ministry .]

 Reading the other night one of the Big Aces article on engines . And VARNISH . i see your all castor .

What he said was if the sides of the piston were brown , half way up or more , getting to black toward the crown .
Youd better listen to Pappy de Bolt , as he says it needs DE VARNISHING . As you get wonky settings and it goes lean .

So , out with the Lava Soap ( pummice ) . Dismantle it first ! .

Youll need a toothbrush to .

If theres any difficulty , whip over here . we can probly spare you some . gratis .
Lake Taupo is a crater lake, formed during the Oruanui eruption some 26,500 years ago when the crater of Taupo Volcano collapsed inward, simultaneously piling ignimbrite (pumice and ash) debris up to 200 meters (656 feet) deep.
And YOU thought Krakatoa was BAD .  apparently it was a bit of a dwarf , in comparison to this .

--------------------------------------------------
Ran a OS 30 years ago , 10 x 6 Tornado in a 50 inch stunter . 43 ounce . muffled . or a 9 x 6 in a demon . Still got the scars . NEVER hold your lauch hand on the INNER wing in case some pilock yerks the plane & your hand into the prop , with the lines . We run 20 % Castor back then . Usually NO Nitor in the O S es . as they were good without it . in summer anyway . Maybe a touch cranier to start in winter , with our rudimentry  equipment . A telephone battery & wires ( What is a Aliigator Clip  ) ends twisted round appropriate bits . a squeeze bottle , and a rag . One or two snobs later had alligator clips , but they were indicative of snobbery ! . The height of decadance , alligator clips .

Ran the Os 20's on the same fuel , and the G 15 . Till nitro came on the market . Comercial fuel was $ 10 for 250 mills . with a dropof nitro . and usually junk . Methanol was $ 2.50 then $ 4 for four gallons .
Usually used medicinal castor from the chemist . Whatever it was it was clean & oily . As the medical profession had some standards , in theory at least .

The usual ' Nose Up ' vertical , lean till it sags . Out two or three clicks . Then , shake the snot out of it . ( nose Vertical ) to get the ' Combat ' setting . maybe a click or two richer for stunt .
Ive tried it a time or two on F2B stuff . V close to perfect neddle setting for 4 - 2  . Incidently the 30 S has the H 29 R piston liner & rod , so you CAN run it like stink , if that takes your fancy .

[Gary Dowler]

Brett said   "and while my memory is generally pretty good..."   Pretty good?  If Id only forgotten 10X the stuff you've forgotten in your life, my memory would be about 20X better than it is....

Gary

[Ognyan Kumchev]

About uneven motor run. A possible reason . In case you try the following. While the glow plug is still suppied with elctric current, lean the engine to full speed. Then  deprive the glow plug from electric power. The engine should not change its rpm speed. At this point, needle valve may be opened to richen the mixture as needed. But in case , after stopping the electric current from the glow plug, the engine speed changes to lower, very similar to richening by opening the needle valve but actually without touchig it - then you may expect very uneven run up in air.  I have recently experienced this with  a Merco 61 engine. The event/situation did not became clear at once;  with massage castor oil in my fuel  this was not clear enough. This became clear enough  with Benol castor oil used in the fuel. The cure in such a case is said in many places on the net; usually it is  recommended  either a hotter glow plug, or to remove a shim from under the cylinder head, or adding ntromethane to the fuel. In the case of Merco 61 engine, another way is to change the cylinder head - in case it has one glow plug, to mount a cylinder head with two glow plugs, same volume of combustion chamber. Or a combination of the said remedies.
The said above does not exclude any of the other opinions in this forum; the said above  is  another  possibility only.

[Dennis Toth]

Bob,
Have you had a chance to fly the ship with any of the suggested mods and how did it work?

Best,    DennisT