K&B 6550
 

Dar:

I have to back Flyboy Dave, and tell you he's not getting full power.

I have more than twice as many K&B 61s as he does, we've probably been running them about the same length of time, but I've probably run a lot more of them.

The engine in the attached picture is a stock 6550 except for the muffler, I don't know the rpm it pulls with a 12x6 MAS three blade, but I can go to full throttle, hold the plane vertical, and let go of it. It goes straight up until I chicken out.

Underpropping??
 

And here is the plane assembled, it's a Hobbico Diablo. Prop in the picture is a Graupner 11x7 three blade, figured since I had far more static thrust than I needed I'd see if I could trade some for flat speed. Haven't flown yet with this prop.

Yes, I know this is making the engine do things you would not expect reading the published numbers.

My conclusion from the variance? Either K&B was extremely conservative in their ratings, the other manufacturers are liars, or the numbers don't mean anything in the real world.

And I also have two K&B 61 model 6560 engines, if the 6550 is 1.2hp, the 6560 is almost 2hp.

Bill.

Underpropping??
 

I have 4 6550's I ran one last week and it did 13,600 with Top Fite 11-7. It's a CF Lee special with the old square K&B carb.

Was 20% with caster added.

w8ye

Underpropping??
 

That's damn good! What is your altitude and what was the temp? It can make a huge differance. Last time I ran mine up it was about 12,500 with a MA 11-7, but it was not a CL special, low nitro, and it was really hot outside. Opps that was a Fox Eagle 1! Same day ran a HP Gold Cup .61 with a Semco muffler and it ran 13,000, but it was about 90 degrees outside.

Underpropping??
 

I don't live 70 mile from you but the elevation is 1174. The temp was 75 degrees and the fuel was Rich's Brew 20% with caster added. I bought the fuel at Toledo.

The performance is fine and dandy but it has a 1/2" exhaust outlet and is incredably loud . The engine is not much bigger than a Tower 46. Throttle response is kinda wingy. It sounds like a circle track car with no flywheel on it.

I bought it on here as a regular 6550 and sent it to Clarence for him to work on it. I have four of them.

Enjoy,

Jim

Underpropping??
 

SportPilot:

When you talk to Clarence Lee about doing your engines he will warn you about the noise.

Bill.

Underpropping??
 

Is it louder than a Semco muffler, or the old Fox Eagle I with the old can muffler with 5/8" outlet? I think the Semco was around 100 Db, and the Fox is a bit louder.

Yo, Jim....
 

:eek: ....1/2" pipe outlet....on what muffler...? :confused:

Why are they so loud....?

Underpropping??
 

He took the old style mufflers that were on the engines which had no baffles and cut the back end off. He shrunk 1/2" aluminum tubes into the cut - off mufflers.

They are nothing more than a exhaust diverter?

I have one of the current mufflers that I gutted out but I havn't tried it.

Enjoy,

Jim

Underpropping??
 

Yo, Sport.....3D flying wasn't around in '72 when I first started
running the K&B's.....

....but you might be onto something....if a 12-4, or a 12-5
works good on a Kadet....I'm gonna switch all my stuff out
right away....

....thanks for the great advise.... :rolleyes:

Underpropping??
 

Dave:

My 6550s spin the pooh out of a 12x6 Three balde prop. Bet you could run a 14x4 two blade comfortably.

Bill.

PS: Here's a picture of a brand new 8560 Perry 40, and a brand new 6560 Perry 61 - and I have more of each. Eat your heart out. wr.

Underpropping??
 

Sure, Bill....maybe someone could run a 16-2, or a 18-1, or
maybe even a yardstick....with a hole driiled in the middle. :eek:

:D

Underpropping??
 

Dave:

You're the one talking about going to a 4" pitch, I'm just saying I think a 14x4 would be better than a 13x4.

The 13x4 wouldn't be enough load, you'd tend to over rev the engine.

Bill.

PS: When you drill the hole in the center of the yard stick please warn me first. Thanks. wr.

Underpropping??
 

....Bill...heh heh heh....I was kidding "pilot"....I don't think
he has ever run a K&B .61 either....

...watch my lips....I run 11-71/2, and 11-8's on my 6550's.
MAS, of course....I use "special" carbs, and 15% Powermaster
type fuels.....

Your quote:....
"I have to back Flyboy Dave, and tell you he's not getting full power.

I have more than twice as many K&B 61s as he does, we've probably been running them about the same length of time, but I've probably run a lot more of them."

I don't think so.... :rolleyes:

Underpropping??
 

Two of my 6550's have Perry carbs but one is a pumper. It's a 6535. I have the original box and all the instructions for the pump and everything. It's a pre '84 model. I havn't run it.

Clarence cuts the stacks off within 1/8" of the fins so you can get to the mounting bolts


Jim