garch 22

My Feedback: (7)

Fellows,
I have a NIB 6550 which was purchased 20 years ago, but never got around to using. Am now thinking it may be a good choice for my Goldberg Extreme 330 Profile. I know this is an old-tech, loop scavenged engine which will not wind up like the newer fire-breathing schunurle ported fx's etc, but for this application I am primarily interested in a dependabe, well mannered, light .61 which would swing a 12x4 to 13x4 APC or maybe Zinger. ( The actual weight of my engine is 15
oz. and 3.5 oz. for the muffler, which has no baffle )

I have tried to research this engine in these forums and there is scant info regarding this engine, or tach readings. The only thing I found was a user review of the the K&B R.C which is supposedly the same 6550, with a remote needle valve.

I know there are a number of "experienced" modelers out there who have a lot of respect for these older engines, and ask the following:

- How well does the Carb adjust and perform? ( It's the original metal metering box w/ the K/B
stamped on it).

- Spec's show H.P. of 1.3 @ 12,000. ( I know it's a lousy way to evaluate power, but it's the
only number available). Anyone have any tach readings with a 12 or 13x4 ? How would this
engine compare with say a Supertigre .51 or OS 50 sx?

- How is the fuel consumption rate compared to the above ST or OS? Was thinking it should be
less, due to lower rpm's. Are the loop scavenged engines considered more fuel efficient? Not
trying to save money, just flying weight.

Any and all comments welcome, Thanks in advance


Blue Skies, Green Lights

William Robison

My Feedback: (3)

Garch:

I have a bunch of the K&B ringed 61 engines, my favorite use is to replace a 40-52 engine. More power and no more weight, often the K&B is lighter.

For an example, my Diablo 40 has the same engine you describe, carb and all. I have absolutely no complaint about it. The engine will pull the plane in a vertical take off out of my hand.

The fuel rate is miserly, if you add a Bru-Line fine mesh air filter (BRU-202 from Horizon) you’ll find the fuel rate even better, and the plane will stay clean by eliminating the fuel spray out of the carb.

I am currently assembling a new twin with a pair of K&B 6560 engines, these are the same as yours with the addition of a built in Perry pump and a very large bore carb. The 6560 will keep up with most modern Schneurle ported 60-65 engines.

You can also send yours to Clarence Lee, he’ll add the PDP modification for about $30 and you’ll also have an engine that will keep up with the later designs. It will be louder though.

Your “Block” carb engine is the middle version, the earlier ones had a standard Perry carb, the later ones have what is called the “Ribbed” carb. The ribbed carb was originally supplied with the needle valve at the carb, latest version uses the remote needle.

Choices, choices. Take your pick.

Enjoy it, it’s a great engine.

Bill.

RaceCity

I'd bet cash money that'll be a fine engine for your model...

Enjoy!

oldtimer2

My Feedback: (19)

Go to Mecoa.com, They have info. abour anything you would want to know about this engine. Manual, parts list,exploded view, etc.

garch 22

My Feedback: (7)

Guys, thanks for the replies. I know the 6550 puts out some power and is supposed to be a pretty mellow engine, was just trying to get some actual performance readings using various props.

Oldtimer: I had talked to Randy at Mecoa and he could not give me any tach readings or real world H.P. but thought it was more powerful than a schenurle ported Super Tiger .51. Said to use a medium / hot glow plug with an idle bar and a wood Zinger 11x 8 for speed and a 12x6 for sport.

Bill: Sounds like this engine pulls your Diablo 40 just fine. Couple of questions, what does the plane weigh? Were you using the 3-blade when you hand launched it? Also, I see part of a gold colored muffler, is it the stock one, or something else? Have any other muffler recommendations?I have Tower .75 muffler (no baffle), which fits up. Don't know if it will have enough back pressure for the tank, and don't know if the engine timing will like it, any thoughts? Can you elaborate on Clarance Lee's PDP modification. Does he rework the porting or is this something to do with the Perry Pump ?

I've decided to just bolt mine on and see what it will do. Plan to start with a Fox miracle plug, and break in with 10% PM with some added Castor oil. I can post some tach readings if anyone is interested. In the meantime, I'm still looking for more comments about the engine.

Blue Skies, Green Lights !

William Robison

My Feedback: (3)

Joe:

The Diablo weighs about 5½ pounds, plus a few repairs that have added weight. Actual weight now I don’t know. The vertical take off was with a MAS 12x6 three blade prop. At the moment I have a Graupner 11x7 three blade on it, it’s faster with the Graupner but all round I like the MAS three blade better.

The muffler is special, sorry but I don’t remember the brand. The company is out of business anyway. I do have a pair for the K&B 40 engines, I like them �specially because they can be easily reversed, just as the K&B 40 engines can, for use on a twin.

The last picture shows how much larger the bore is on the "Pumper" carb, the one on the left.

Great engines. Given reasonable care your great-grandchildren will still be using them.

Bill.

Harry Lagman

Joe,

Check out this thread. There is a lot of the typical sentimentality that ensues during discussions on K&B engines but amongst this is some testing done by TimC on a couple of K&Bs versus an OS .61 FX.

http://www.rcuniverse.com/forum/m_43...tm.htm#4364296

Kweasel

My Feedback: (29)

If your carb has a low speed screw in the barrel then its a pretty good carb. At lower rpms they run with modern engines, but not with small props. The mufflers are a little noisy and it will need the K&B idle bar plug. If weight is important then its a great choice.

garch 22

My Feedback: (7)

Harry
Thanks for the heads up. It appears there is a Parallel Universe thread already going which is full of good information. It didn't come up when I searched the engine forums for some reason.

Blue Skies Green Lights !

rcuser002

My Feedback: (12)

Hey Bill..... and all the K&B fans that have contributed to this friendly thread,

Thanks for the tip about the Bru-Line fine mesh air filter (BRU-202 from Horizon) in order to keep the "spray" down. I was wondering where the mess was coming from. At 1st I thought it was the old Tatone "pitts style" muffler that replaced the stock K&B muffler until I noticed just today that the leak was coming from somewhere else.

I just got a never been flown Carl Goldberg Super Chipmunk with a never been run K&B 61 mounted sideways. The plane is on the lighter side of 7lbs. I'm using a Zinger 11x7.5 prop and running the engine rich w/15% synth fuel and I can't seem to get the low end to come down without conking out. Could it be because I'm using a OS#8 plug? Should I be using an idle bar plug instead and if so, what brand is best?

If this isn't why the low end is running correctly please advise me - I'm leaning the high end little by little and richening the low end screw accordingly. It's out kind of far from the "flush" factory setting at this point. I can not seem to get the idle below 2800rpm and being "reliable".

root

p.s. I really love flying this plane - what a great match up - it's definatley got "ENOUGH power Captain".

William Robison

My Feedback: (3)

Root:

I think you probably don’t have enough prop on your K&B to get a good idle. Sounds strange? I mean in weight. The Zingers are light, and specially if it’s a Zinger wood, there’s just not enough “Flywheel” to get a low idle.

Going rich on the LS as you lean the HS can also be wrong, the LS, once set, is mostly independent of the HS.

Go back and try a MAS 12x6 or other heavier prop, lean the LS for good idle and transition, see what happens.

I have excellent results with the K&B 6550 and the MAS 12x6 three blade prop. Think I’ve already said that.

Bill.

rcuser002

My Feedback: (12)

I've tried the heavier 11x7 APC and it helped lower the idle to 2200 but still it's fluctuating from 3000 down to 2200 over a minute or so - what gives??

My local hobby shop isn't open till Monday for the MAS 11x7.5 or the 12x6 swap yet.

I don't think that's gonna change the fluctuating idle though.

The coarse in line mesh filter over the venturi sure solves the "spray" problem.

root

Sport_Pilot

Was that with or without the idle bar plug? Sometimes the idle acts that way if it needs the idle bar plug. Not that it couldn't be something else.

Kweasel

My Feedback: (29)

The K&B 61 is one of the few engines that really need an idle bar plug. A K&B long idle bar plug will absolutely work well in this engine. I tried a couple of different standard plugs and none would idle down without quiting.