I found something cool I think Need a k&b expert

The Sportster engines have a high silicon sleeve and the piston has the top chrome plated. These are not high performance engines, they turn low rpm's. I prefer the .20 over the .28. These make excellent diesel conversions once broken in. They're quite heavy for their size but they make up for it swinging larger props. The Fox .19 and .25 are in the same case. The Fox runs quite fast and is a terrific engine and I believe the .25 is one of the lightest ball bearing .25's offered. They tend to vibrate a bit but they do run strong.

davidll1984 wrote:Question new this engine comes with a brass tube in the bag wit the long Exaust header screw what is it for  ????? Tube !!!?????

Looks like Ken sneeked in ahead of me. Written withough having read Ken's comments.

David.  I'm not sure about the brass tube.  The long exhaust screws pass through the back of the port on the engine, through the extension and screw into the side of the muffler.  Be careful not to over tighten the screws as the little die-cast bracket on the inside ot the muffler is not very strong.
I believe the inside if the cylinder is chrome plated, running a plain aluminium piston.  The crankshaft is bushed so you should use fuel with castor.  They are a fairly cheaply built engine and I can't vouch for how long they might last in use, but the couple I have seem to be very will made and run very nicely indeed.  They are no powerhouse, but they run very smoothly and consistently at lower revs using a larger propeller.  Some people say that you should treat them more like a four-stroke of the same size, using a size larger prop.  The muffler is very effective at keeps the engine very quiet.  The carb seems to behave well and is easy to tune.

All parts and complete new engines are still available from MECOA.  Both engines I have, a .20 and a .28, were purchased cheaply off ebay as used engines, but there was no evidence of wear or damage.  Both were missing parts and were easily repaired.

I have difficulty understanding the system the mixture disc? with the Hi jet neadle maximum jet but how do we adjust the slowdown mix range should you screw it? this disc with the hi jet install on it i Find this weird
Is the mixture disc is for idle seting bafle It's just a choke or another needle is hidden in the barrel air blead of som sort ?

The Sportster line of engines are very high quality even though they were marketed towards lower end entry. These engines in my opinion will outlive the user. It takes a long time to break them in but when that happens, they're real sweethearts. I have all displacements and the .65 while weighing a 18 oz's, it's a remarkable piece of machinery.

I think where the problem that lay with the Sportsters is that many modelers didn't understand how to properly treat the technology. It was advanced for its time. However, if mistreated, they didn't last. If one fueled them as they did with the earlier iron piston with steel sleeve engines, with decent oil content (not the 2% Castor and 16% synthetic) and didn't run them lean, plus propped them properly (shooting for torque versus pedal to the metal RPM), they did well.

From what I understand, the high silicon content aluminum cylinder-crankcase with chromed piston was also used in high performance racing automobile engines. (I can't swear to this, because I have not studied the subject, those more intimate with the subject would know).

I am a late comer to this engine, now have several .20's, and the nice thing is that they originally came with an optional rear bulkhead mount. Yes, I have heard that they are basically the poor man's 4 stroke, able to amazingly turn larger diameter props with ease.

Hearing about the little known engine's abilities that I thought very desirable, I bought one on an Internet auction 9 years ago, thinking I was getting a bargain. The description of like new didn't match what I received, a .20 with ruined piston and scorched cylinder.



Fortunately, Dennis who also posted in now gone BOTR and Stuka Stunt, also Stunt Hangar came to my rescue, by offering me 2 parts engines for the price of postage. (He mailed them to me immediately, to which I sent him a check afterwards. The C/L community has many fine friends in it.)

I was able to restore it and cobble another from the parts. Now I have 2 good .20's.


K&B .20 Sportster R/C repaired and prepared for test run.

I did find it interesting that the exterior of the engine is about the same size as my Enya .35-III TV.


Also I find it interesting that powerwise, they aren't too far off from each other as well.

GallopingGhostler Thank you for confirming me for the piston which is chrome plated this is similar To som Yamaha yz 2stroke dirt bike just inverted Somehow the yamaha has a plated cylinder with an aluminum piston we called this plating nikasil I see you don't use pressure on the gas tank on the picturs look like no presure fiting I'm not looking to get the maximum performance, just good advice to get to know it better to treat it appropriately. I already know that this engine loves oil just like the cox engine 22% plus It's knowing how the settings work to have a reliable engine

davidll1984 wrote: I have difficulty understanding the system the mixture disc? with the Hi jet neadle maximum jet but how do we adjust the slowdown mix range should you screw it? this disc with the hi jet install on it i Find this weird
Is the mixture disc is for idle seting bafle It's just a choke or another needle is hidden in the barrel air blead of som sort ?

The mixture disc is simply an air-bleed.  It is rotated slightly left or right by the eccentric screw, with just a couple of degrees being enough to get a really smooth idle and transition.  These carbs work very well and are similar to a Perry.

George, Dennis is a close friend of mine. Dennis unfortunately developed severed neck and back pain which ended his fun in the c/l hobby.I've taken over Dennis's Sportster collection. I value them and I enjoy just running them. His advice was prop it like a 4 stroke and don't skimp on the oil and you will never wear it out. I totally agree.

Ken, sorry to hear that about Dennis, he had a heart of gold. He was one of the faithful posters in BOTR until may be about 3 years ago.

A little prior history not involving Dennis, I don't know what happened there, an earlier falling out with one of the faithful moderators, who was also a heavy contributor. Prior, BOTR was fun. They even had little contests on who could make an interesting Ringmaster variant. I came up with the half-A Gee Bee Z Ringmaster for my Gilbert .074 engine. Also thought of a Gloster Gladiator "Gladys" Ringmaster and a SU-24 Frogfoot "the comb" Ringmaster may be future.

Anyway, enough drifting off topic. Hope to one of these days put my Sportsters to good use.

GallopingGhostler wrote:
Anyway, enough drifting off topic. Hope to one of these days put my Sportsters to good use.

I suspect that this will never happen in my lifetime, but I had always fantasised about building a Cessna Skymaster using my Sportster .28 in the nose and my Sportster .20 in the rear. I love the 337 but a mate of mine who's a licensed aircraft mechanic hates them because they have a tricky control cable system housed within the wing struts.

There are still plans afoot, but more in the 1/2A realm.

Rod, I noticed that Outerzone (now down temporarily with 500 error) and Aerofred have several Cessna Skymaster plans for C/L in the 40" (1000 mm) wingspan range that could be easily adapted to haf-A R/C.

I have a World Engines kit, a 50" Robin Hood 25 that the K&B .20 Sportster with back radial mount would be the right engine for it.

GallopingGhostler i like the World Engines kit, a 50" Robin Hood 25 Seems good for this engine If I use the engine it will be a model to consider precisely I am looking for a biplane or something almost aerobatic that would have a good ability to fly slow but the wing must be completely removable for storage as i have limited space

Perhaps a 42" wingspan Mark's Models fun scale SE-5A?

https://aerofred.com/details.php?image_id=90554


It's wing uses a thinner Jedelsky airfoil, so may be a little quick. There are others, such as the Tidewater Parakeet. Outerzone has been down the past day, so giving links would be useless.

I notice that these days I have more difficulty finding artf models for nitro engines unfortunately
I like to build them from scratch but with a little four year old boy around I really have to work fast and well it's difficult to leave a model on a table it would expose it to sudden death danger He's not that bad just kidding With this motor mount I believe it would be easy to adapt to an existing brushless artf model a 42" wingspan Would be fast I would like a model with a little more lift and ability to fly very slow to spare the engine and the fuel a little on this engine Knowing that he is able to spin a good prop It should be able to fly a pretty big model but not too much. custom built Do you have any other suggestions, especially a model kit to build?

I just can't get enough. Today, this engine came in, a brand new never run K&B .45 Sportster R/C with optional bulkhead mount but without box or instructions. My highest bid of $40 + $13 shipping + sales tax.




K&B .45 Sportster compared with a Cox .049 F4U Corsair product engine.

It is for my Goldberg Falcon III kit.

George, one needs to own one of these and run it to appreciate it. The engine certainly isn't a high rpm barn burner but it is a tractor of a engine as your aware. My .20 Sportster swings a 10x6 quite impressively.  I also like that it's a very quiet smooth running engine. I really do enjoy these engines and I wish I had a Davis Diesel conversion for my .28. These engines run superb on diesel once broken in. They do take a bit to break in but in the end, it's very satisfying. It also amazes me how this technology carried directly into automobiles and larger scale engines. I suppose the same can be said about the Testor's plastic pipe bombs. Seeing that most intakes and other various top end parts nowadays are made out of similar plastics.

         I have a few different mufflers for the Sportster, the backplate mounts as you show. They may not all be stock but a derivative of header pipes cobbled with other K&B mufflers. Rod had mentioned about the screws stripping out in the main muffler body. I've had this happen to some of mine. I was able to place a T-nut inside the muffler to alleviate the stripped hole. By no means a easy task but it's doable and much more reliable.  I also have 2 .65's converted to control line. I have a very large Pat King Combat Streak which the .65 might be going on. I believe the engine is nearing 18 ounces so I might have to do a bit of a balancing act with it but it would be cool. NO ONE flies anything like that on a control line plane. The cylinder is massive but it spells cool factor x2.  This thread is going to make me get all of these engines out and running.

  On another note, I spoke to Dennis this weekend. I mentioned this post and the inquiries in regards to the Sportster engines. He said at one time he posted a lot of info on the Brotherhood of the Ring with many pictures involving many different topics. He said he was glad to know you remembered , all gone now and it was upsetting to him.

George --
What a great find and bargain. Congrats.
a--

I am very impressed with this engine I must say that it is lighter than I thought Especially the very light silencer for its size very well adapted to the rules concerning the sounds with the internal tube which must really very well muffle the engine sounds The .20 a bit between two difficult to compare When I received this package I thought it was something else the big box was so light I see a lot of quality And this is just at first look The engine itself is also light I have few motors of this size A little big compared to a .15 or a .18 bugy engine To see that others like these engines encourages me to find the perfect model for them. Your opinion really matters to me, I learn much more with you than I did alone al Your tips and tricks are precious to me
Compare To a .35 enya

The machining is also done nicely. The only gaskets used on the .20 is a backplate gasket. The .20 doesn't even use a head gasket, the early versions had a o-ring but were found to be problematic. The .28 uses a head gasket. Looking at a .20 and a .28 is difficult to differentiate them apart. Some of the later .28's had .28 on the lug. All .28's have the crankshaft stamped with 28 on the crank web which is visible when the backplate is removed. These engines have no gaskets from cylinder to case. It was a engine designed to be competitive for a lesser dollar amount and it earned it's place serving a double standard. Most users early on used incorrect fuels or expected it too much too quickly. These engines won't tolerate being pushed and can seize. I have a .28 here that someone stripped it's life at a early start. Everything appears in order and but it has little to no compression. Parts for the .20-.28 are still available.

Echo that!

I love the simple integrated muffler attachment, and the machining is excellent.

I weighed some engine for quick comparison Sure it's big but smaller than a .35 bigger than .15 a lot

The engine mount is quite big though seems smaller than a .35 .40 almost the same as my .19 supertiger the .20 The engine mount I believe who is somewhere in between

195g for the .19 without carb
Simple..40k&b torpedo wit no exaust
Just the pipe only

rsv1cox wrote:Echo that!

I love the simple integrated muffler attachment, and the machining is excellent.  

he look like u found a new engine look Good To How much does this one weigh? Nos compare To exact same size from difrent brand made!!?