hello guys.

I have been looking at a range of .61 engines (with rear needles) . I was very close to buying an Irvine .61 mk11 but it does not have a rear needle.. so the search goes on, i am now looking at a magnum .61 or a SC .61 with rear needle....

can anyone reccomend me a reasonably priced .61 engine...
thanks

Adam

Adam,

Why would you bother with the problems introduced by rear mounted needle valves?

Any high quality, non-corporate-lawyer managed engine company, like Webra, YS, MVVS, Rossi and others, have the main needle mounted on the carburettor, where it belongs.

Even those 'politically correct' companies, that have the main needle mounted at the rear, still require you to get close to the spinning propeller, to adjust the idle needle, or worse yet, the idle air-bleed screw.

So what is the use of this rear needle?
Just exercise the utmost caution when adjusting the needles, or buy an engine with a rear mounted carburettor... F1 QM...58cc gas...

If you cannot keep your fingers away from the spinning prop, I would suggest knitting as an alternative hobby.

I'd say MVVS .61 or Irvine .61

Yeah, but if you are smart you do this when the engine isn't running!

If you insist on a rear needle it is easy to convert any engine to a rear needle. Find a screw the same size as your needle valve, replace the needle with the screw (be sure it is short enough that it doesn't go into the spraybar), buy a remote needle from K&B or Fox, or where ever. Mount the needle to the backplate, firewall, or motor mount. Now you have a remote needle. Oh when you plug the spray bar, it's a good idea to use some locktite or gasket sealer to prevent fuel and air from leaking past it.

The real question is why would you bother with a .61 when there are .75s and .91s in the same crankcase, weighing the same, but putting out more power. You can turn a 14-6 on a .91 or go to a 12-8 for a lot of speed.

I run all my MDS and several other engines with rear needles and any problem with a remote mounted needle valve is imaginary, I even run Cline regulators at the carb and have the needle mounted at the rear of the engine. There is no problem. Also, as Sport suggests, you can purchase an add on remote needle, Horizon still has MDS remote needles, I use them because they do not leak when exposed to the 6 to ? lbs pressure when using crankcase pressure with the aforementioned Cline system. The Irvine and MVVS are both great engines especially the MVVS .77, same mounting as the MVVS .61.

Believe it or not, there are a few competitions venues where the maximum size is a .61. SPA pattern competition for example.

some of you have come up with very valid points.

I forgot to mention in my first post.
i have a flair lark that was fitted with an OS61 fx until the sleeve died (famous liner flaking).
I spent hours cutting the cowl carefully so it would be as clean as possible. (OS 61 fx has a rear needle)


And as for going with a .61... i have a tuned pipe on my plane and i have been told by many members here that a .61 w/tuned pipe acts like a .72,
i do not want to rip my firewall off from overpowering the plane and even then with a .61 it is still allot of power for this plane....

Here are the engine recommendations from manual....

Engine 0.63 - 0.70 4 stroke
0.46 2 stroke



As you can see a .61 is BIG compared to a .46! but to be honest i don't see how a .46 could lift this thing off the floor.

Adam

The K&B .61 has a remote needle. Lighter than the FX also.

Adam,

Without being a speed freak myself, you can try an MVVS .49, or an Irvine .53.
An MVVS with the tuned silencer, could spin an 11.5x6 Bolly Clubman prop, at 13,600 RPM (5% nitro), which is more than enough to yank your model off the ground. Most muffler equipped .60s do not have such power, spinning an 11x7 (equal load) at 13,000 or less.

The Irvine with a Genesis tuned silencer will probably be close.

An engine of the .40-.53 size will most likely be much lighter than a .60, so no tail weight is needed.

[link=http://www.justengines.unseen.org/]Just Engines[/link] has both engines. The MVVS has an optional rear mounted needle, if you are so keen on using one.

im a speed freak with my WOT 4 ... with an irvine .53 w/tuned pipe

with this lark im wanting more thrust than speed. i want to maintain control and have plenty of thrust to pull vertical.

Speed Freek. Since nitro is expensive out there I would recommend the Fox .61 modified with remote needle if you like. It was the strongest engine for torque reviewed by MAN a year or so ago, yet the second strongest for horsepower. The K&B screw head wasn't reviewed, but it is strong and much lighter, it comes with a remote needle. There is also the LA .65 which is torqie and actually has more power than that paperweight you have, but I get the impression you want to avoid OS.

I agree with the respondent that recommended the K&B. They are running a discount on the twist head .61 that makes it very reasonable. It is very light an it quite handily out powers the OSFX.61. It does fine with variations in Nitro both high and low.
My son just flew identical planes with the FX & the K&B at the SAE Aerodesign competetion. There was no comparison in power. Both these engines were legal in the competition last year. Last years winner used the K&B and my son wished it was still legal.

I have a Thunder Tiger 61 with the needle mounted where it should be...and it works great. Good engine for the money. Bill in Pa.

I have a Thunder Tiger .61 which powered the maiden flight of my 4*60 today. It ran fine in flight and idled OK as well (finally). It was extremely tempermental on the low-end mixture adjustment, though. My instructor and I worked on it for well over an hour before we got it to idle reliably. We switched to a idle-bar type plug, which made it slightly better, but ultimately it was just a matter of getting the tuning right. Has anyone had any experiences (good or bad) with getting this engine to idle reliably? Thanks.

I like the way the high speed needle is situated- at an angle, back and away from the propeller. Maybe it's not quite as safe as the rear needle adjustments, but I think it's a good combination of safety and performance since you don't have that extra piece of fuel tubing to worry about.

For the Thunder Tiger .61Pro, how much fuel have you run through your engine? If it is new, I think you are beating your head against a wall trying to get a good adjustment.

The running surfaces on a new engine, although they may look smooth to you, are very irregular. This causes a lot of friction which tends to make your engine stop at a low idle. For the first gallon or so, as the engine runs, these irregularities wear down and the piston and sleeve or ring and sleeve mate together very closely. Compression seal, especially in a ringed engine, will become greater. After a gallon or so, you can tweak your engine to a nice low idle.

I never worry about a good idle needle setting at first. Even if I have to have someone carry the plane out, I get some flying time on it before I waste any time tweaking.

As for buying a .61: Senior Pattern Association! Get outta here. Of course certain competitions require engine sizes, but don't they run old ST Blue Heads. Quickies run .40s, but does anyone else buy a ball bearing .40? No way, you get a .46, so why get a .61 when there are .75s and .91s available at the same weight.

A friend has a Big Stick 60 with an OS .61FX in it for a knock around plane when he isn't flying scale. The rest of the guys have Stick 40s with .46s in them. His 60 size tops out of climb while the .46 powered planes keep going. He could just as easily have a .91FX in the plane, no CG change, slightly larger prop 12-8 or 13-6 vs 12-7, if you can't clear a 14-6. The plane would take off and land the same, but have more climb and speed. If you don't like the extra speed, you throttle back.

As for the medium (.46) size engines: The .50-.53 engines are here. Ask anyone who has an OS .50 about power. Try an Irvine .53 or a Magnum .52. It's like comparing a ball bearing .40 to a .46. Cubic inches count. I see Just Engines now is offering a .56 in a .40 case and Tiger Shark also has one listed. A .56! The .61 size is being beat on from both sides. The power-to-weight ratio of a small case .56 must be something. We're talking 17 ounces vs. 25+ ounces for a .61. That's a half pound!

No, they run modern .60 engines or non supercharged .91 four strokes. A few run the older engines but they are only competitive in the lower classes.

Well the FX .60 and it's clones are heavy low powered clunkers. Not much faster than my old loop scavenged K&B .61. My old HP .61 would run circles around it and many of the .75 sized engines. Now the old K&B is perfect for a .40 Big Stick. Not much heavier than a FX .46 but with more power.

A good .61 should not weigh much more than 20 ounces. In fact the K&B weighs less than 20 ounces. The problem with many of the modern .61's is that they are actually destroked, underbored, 75's.

I finally got the idle mix set right on my Thunder Tiger .61 Pro. I seems to run great! I think my assumption from the beginning (incorrect) that the low end mix would be set slightly rich by default from the factory. It was too lean! And when I did the "pinch test" at idle (per TT's engine manual), I wasn't waiting long enough to see what would happen (engine speed up before dying OR just die) and wrongly concluded that that method of tuning was somehow not as useful as other methods. Anyway, I'm much happier with the .61 TT Pro! I can hardly wait to get out there and learn to fly my second plane!

Ed, I think you're right, it will be awhile before the idle setting is perfect until the engine has seen a lot more fuel through it. Thanks.

How about a Jett....

maker of the "Real Men Have All Of Their Fingers!" remove needle valve:

http://www.jettengineering.com/accy/remote.html

According to Clarence Lee the unusual part of the twist is that not only does it turn the std size props as fast as the stronger .61 schnurle engines but also turns a 14x6 zinger at 10,200 on only 12%. Light weight and cheap are only the bonus. Comes with muffler & plug and is made here (as if any one seems to care anymore).

Yeah, but $25 is a bit steep. The K&B needle is less than $20 and a quality unit.