The Dodger

Hi All,
I'm just starting out and I bought a plane at an auction that I'm fixing up for my first lessons this spring. It has a K&B .45 engine on it. Can anyone tell me anything about this engine...good...bad?
The Dodger

JohnBuckner

My Feedback: (1)

If your engine has four cylinder bolts then it is a Sportster 45. they were made in 20, 28, 45 and 65 sizes. It was an attempt by K&B to moderize and compete with more modern designs in cost. Its a sleeve less AAC design with *****y porting and a bushed crank. Early ones had no bushing just hardened alum for the crank to run in and later a bronze bush was used.

They can be an effective engine but many had trouble with carb design that was differant than most on the market and there were at least two different carbs produced. The muffler system was among the quitest on the market and power is reasonable but far from the most powerfull. Also the muffler has a tendency to shead the tailcone but this can be prevented by normal methods. This engine once you learn to carry a little more prop can become quite friendly and live with the leaking out the crank bushing can be useful.

The .45 was the least popular of the series and the .65 is a superior runner.

I have used numbers of the whole series and I still have a forty five on my cross country airplane which has successfully completed flights of up to eighty miles, two hours long and involveing an elevation increase of twentyfive hundred feet over the course of that trip (a difficult task for any engine).


John

comtech001

My Feedback: (3)

HI there ///
for what is worth i have been in the hobbie for 30+ years i also owend a fulltime hobbie shop for 6 years and i got to tell you i have never seen a good k&b if your just starting out it might be better to pick up a magnum or os the k&b will do nothing but hack you off !!!! when trying to get it running right they are very
picky oh well hope this helps

rob

RLDIII

My Feedback: (1)

Contray to the previous post, not ALL K&B's are problematic. However, with that said, I will agree that the (early) .45 Sportster is probably not one of their finer efforts. As the first reply said, they probably had more problems with the .45 than any of the other Sportster line. One mod not mentioned was that in later versions of the .45, they machined most of the cooling fins off the head to correct an over cooling problem. If yours has VERY short cooling fins on top of the head, yours may run OK. Also, as with the other engines in this line, the engine is NOT set up to be a high RPM engine. However, it WILL turn a much larger load than most .45 sized engines. While it may seem guttless with a 10 x 6/7 prop, try something larger like an 11 x 7. I found they would turn these props about as fast as the smaller props and make a lot more thrust doing so.

Good luck,

Lee

The Dodger

JohnBuckner,
Yes, it has four bolts on the head and....
RLDIII,
Yes, it does have very short fins on the head.

When I bought this plane, it had a lot of fuel "stains" all over the engine and muffler. I cleaned it all off and it looks great but I did wonder about leakage from the looks of it.
I didn't want to buy an expensive engine to learn on and I was just concerned about this one giving me trouble during flying lessons. If it stays running, I'll be happy.

The Dodger

jle

K&B I think it stands for Krash and Burn or thats what we call them where we fly.

MikeL

My Feedback: (3)

A buddy has a .45 Sportster. I thought it was a hunk of junk the first few years he owned it. Now it's as reliable as any engine I've seen. I'm not sure what he's done to it, or if it's just time. Either way, it's a fine engine now.

JohnBuckner

My Feedback: (1)

Hey Dodger that means you,ve probably got a later run. RDL has also given you good info on props, do use an 11x7 or possibly an 11x6 (these engines thrive on longer props). Also MikeL has indavertantly made a good point : Due to the aac tecnology used they do take longer to break in than many engines, this combined with the unusual (but functional) carb arrangement resulted in many failures for even experienced flyers to be successful with them most never completed breakin even. This resulted in many returns to the factory and the LHS's. That no doubt is where Comtech got so soured on them in his store. I did enjoy jle's expression as K&B stood for crash and burn at his field. You see that just means nobody at his field learned anything which is good because although I have never bought a new one but currently have maybe seven sportsters and a bunch more of the old standby fortys and sixties in use, all freebies from those folks. Thats not counting my vintage
Torpedos and Stallions (K&B products).

Lets talk about that Carb on the Sporsters. First the carb midrange adjustment is unusual what it actualy does is rotate the main jet which extends into the carb venturi. The jet is a slit in the tube and it does not function by a needle closing on the main jet as most do. This is done by a tiny concentric slotted bolt head located at the perimeter of a brass disc on the left side of the carb the slotted head is nested in a notch at the edge of this brass disc.
This arrangement is the number one reason Sportsters got such a bad reputation you see early instructions made no reference to its adjustment only to the main needle and an idle stop screw (something most folks just back out any way so the radio can do an idle cutoff). What almost invarably happened is many just merrily adjusted away on the idle stop thinking they were asjusting the mid range and of course the engine never worked right.

Now for that mid range setting. Set that itty bitty screw slot straight up and down which put that little cam dead center of the notch on the disc. Now run the engine if it loads on throttle up at idle just rotate that slot just a few degrees clockwise or counterclockwise. I does not matter I can never remember which way leans it but just tweak it you will know as soon as you try agine. The key is never move it more than a few degrees at a time. If you went the wrong direction just do it agine the other direction and it will soon be throttling up with the best of them.
and the engine will serve you well.

John

WORNBOOTS

My Feedback: (33)

K&B's in general were a good engine, and provided long service.
The carb changes were made to improve user freindlyness. But that was one reason thay were not liked by some.

For racing and lugging power they were great, but tunning them is touchy. And most people did not have the patience.

KW_Counter

This is for John Buckner,
I am relatively new to this hobby. Please explain about cross country flying.
Thanks,
KW_Counter

FLYBOY

My Feedback: (11)

Sounds like you have the Sportser engine. The old .40 was a great engine. The sportster was not as good, but works. They did make a washer that went under the head that made it run better. I don't remember much about what it was. Just remember putting one in and the engine worked better. You might find someone on here that knows about what that was. It was a long time ago. Good luck. You should be able to make it work.

JohnBuckner

My Feedback: (1)

Good morning KW

Cross country flight is just that, a flight from point A to point B. It is typicaly done from the back of a pickup truck or convertable.

In organized events there are two different types one is to acheve the greatest endurence/distance on a given allowence of fuel and the other is a 'Hare and hound' type of event in which a lead cars goes ahead before the start and picks an unknown check point on the preplanned route perhaps five miles down the road and you must land and pickup a poker card at the completion of five stops you have your poker hand and your winner. In this way any sport type airplane can be used with no special tankage. The real winners of course are the finishers who survive the multiple unknown landings and takeoffs not always in the best conditions. I have flown in a number of this type event near Las Vegas and even helicopters and electrics have gone the route.

A few years ago I participated in a flight of six airplanes from Kingman Az. to Seligman AZ a distance of eighty miles along old Route '66'. The purpose was to commemorate the new Public full scale airport at Seligman and most of the town residents of Seligman awaited our arrival with complete with speechs by the town dignataries. The flight was difficult because of the moutains to be traversed and an elevation gain of more than 2500 feet with the resultant richening of the fuel mixture along the way.

In my case I used a forty size trainer with a K&B .45 Sportster fitted with a Perry oscillating pump with a twelve oz tank in the nose, a fourteen oz in the radio compartment and twenty four Ozs. over the CG above the wing. The flight was completed in one hour and fifty six minutes.

And yes, The flight was accomplished with the full cooperation of the tribal council police whch was responsible for most of the route and the FAA for the arrival at the full scale airport.


John

The Dodger

Thanks John for all the advise. I feel a little more confident now especially after that story of the long distance flight. I passed that one on to my brother who is also getting into the RC scene.

The Dodger

JohnBuckner

My Feedback: (1)

Best of luck, John

GreigA-inAus

I have the oportunity to buy 3 month old K&B Sportster45 in Aus at a very reasonable price. My intention was to put it in my near complet Ultimate 40 with a 12.25x3.75 prop. Will this be OK as the other comments in this thread suggest K&B 45's like the bigger prop, but this aerobatic prop has less twist.

William Robison

My Feedback: (3)

GreigA-inAus:

If you are talking about the APC 12.25x3.75 prop I can almost guarantee the K&B Sportster 45 wont like it.

To get reasonable flight performance that prop has to spin around 16K rpm, the Sportster intake is too resricted to pull it that fast. With a 12x6 it will fly well, a 12x7 or 12x8 might be even better.

That 12.25x3.75 is intended for a "3D" plane, the K&B Sportster is not your bet engine choice for that application.

The current K&B 48 would do very well. though.

Bill.

GreigA-inAus

Bill,
Thanks for that feedback, excellent information. But, what if I were to upgrade the carby, such as a Perry carby. Will this provide better performance or am I trying to make a short legged horse jump ?

William Robison

My Feedback: (3)

GreigA-inAus:

I honestly don't know how the K&B Sportster 45 would respond to a larger carb.

The Sportster series was designed for high torque and low rpm, it's a plain bearing engine with a chromed aluminum cylinder.

Almost any model two stroke can be made to give more power, at the expense of incrreased fuel consumption and shorter engine life, as well a usually higher idle speed.

with these warnings behind us, if you have a selection of carbs to try, have at it. Put a larger one on and see what happens.

Bear in mind that there is no such thing a "A Perry Carb," they come in many sizes and configurations. Just for the K&B 40 engines I have three different bore diameters, ranging from 0.265" on a pleasant sport 40, 0.312" for a hot engine with muffler pressure, up to 0.375" for a Q40 full race that wont run without a pump. If 0.312" still sounds small, the K&B model 6550 engine, the 61, only has a 0.328" carb bore. And I have still larger bore Perrys that will fit on the 40 engines, but they are so large that they don't add anything, and the idle is terrible.

You have another limitation - the port size in the crankshaft. You can bore this out a bit to ease the air flow, but there is a limit - strength of the shaft. Go too far, the shaft is too weak.

One place the Sportster is nice for hopping up is the bypass and exhaust timing. You can cut their top edges a little at a time, if you find you've gone too far use two cylinder base gaskets and raise it back up.

So. Order of modifications: First, that will hurt nothing and help with all later: open the crankshaft port. Don't polish it, leave it a matte finish - better air flow than polished due to boundary layer separation. Along with this, cut any rough edges out of the bypass area of the crankcase casting. Again, matte surface. Second, bigger and bigger carbs until the idle goes bad, then down one size. If the engine pleases you at that point, stop. But if you want some adventure, start cutting the ports.

Your limit on max power will be the size of the port in the crankshaft, and possible materials failure if you get the engine screaming up toward 20K rpm.

I have no doubt the Sportster 45 could be made to pull the APC 12.25x3.75 prop at 16K to 17K rpm, but I just can't guess how long it would last.

But it sounds like it would be fun to try. Just think of the surprise on the watcher's faces when your inexpensive Sportster runs away from the other fellows with their OS 46 FX engines.

If you have to buy the carbs you try it will get expensive in a hurry, but if you have a selection to try have at it.

You wont hurt anything trying a different carb, going inside you can ruin the engine with a single slip.

Have fun.

Bill.

Grampaw

Hey Guys, the early K&B engines, were they run with pressure taps off the mufflers? I don't know anything about earlier K&B engines, and later models for that matter, except the smaller .28 Sportsters. A few years ago I got one for a GP Slowpoke and the instructions said not to run the engine on pressure. So I let the air line hang out and had a fine running engine. In fact I picked up a new .28 in a hobby shop at half price. It was sold as used. .
The previous owner said he could never get it to run properly. I saw he had added a muffler tap. So I bought, didn't hook up the tap line and had myself another great little motor. The more they ran the better they got. And they were quiet..several times I was asked if my Slowpoke had an electric motor in it. Glad to hear K&B is back in production.

jettstarblue

K+B

Decent engine, 11X7, or 12X6 Zinger prop.

MAKE SURE YOU USE 22-25% OIL CONTENT IN YOUR FUEL, CASTOR BEING PREFERRED.

Jetts

big max 1935

My Feedback: (9)

Second on the oil ! The Sportster Series engines are mis-understood , over adjusted , under propped good old sport engine, period . MAX H. " I always called them Klatter & Bang as that's what they sound like at idle."

William Robison

My Feedback: (3)

MAX!!!

Good to hear from you again. Total agreement on the castor oil.

Everything of mine runs on castor oiled fuel, including the four strokes. I'd rather clean the oil off the planes than replace an engine after a lean run.

And castor is all but absolutely required for the plain bearing engines.

The K&B engines? In the last four weeks I've bought over a dozen more. All 40 and 61 ball bearing engines, though, no Sportsters.

My only Sportster was a 65, a good reliable engine, but I expected more speed than it gave me, replaced it with a 61 and gave the Sportster to my son. It's still flying on a Tiger 60, and flying very well. With castor oil.

The hot 40s and 61s, the ones with the BIG Perry carbs and pumps built in, are still available, and often available new. Two of the engines I just bought were brand new pumpers. One was an 8360, the Q40 "Pylon" racing engine, the other was a 6560. And the 61, the 6560, cost less than 1/2 the retail price for the 61 without the Perry carb and pump.

Watch for them on the for sale listings.

And most parts are still available with no problem from MECoA.

Bill.

JohnBuckner

My Feedback: (1)

Who could not love the sweeter than four stroke sounding K&B Sportster, Teapot Rattle?


And lets not forget the real contribution of the Dykes ringed K&B's to the coffers of us old cheapos and the fact that everybody thinks they are worn out when still virtually new!

Ya, Ya I love my K&B's

John

William Robison

My Feedback: (3)

John:
I inspect his K&B 40, being sure to turn it slowly, "Man, this engine doesn't have any compresion! I'll give you five bucks, maybe I can use the parts somewhere." Aint it great?

Bill.

big max 1935

My Feedback: (9)

Hi Bill: Seems as if we have a bunch of good old K&B boys here! I have had one some where in easy reach since 1949 & thought they all were runners ,(maybe the Infant was a little weak) . My favorite combo was a Sterling Lancer with a 1969 or 70 Perry carbed .40. Used to run it out of fuel about 1/2 the time & watch it windmill dead stick when landing, a bit un-nerving at first. Used to fill the tank , prime the engine flip it once or twice & put the prop just past TDC & let it set , when it came time to fly just putting the glow heater on it would start about 1/2 the time! Real neat! Have you tried that or had it happen? MAX H.