earlwb

I think that the Twinstar with three K&B .20 Sportster engines would be super fabulous. But using .28's would be a good one too.

SRQFlyer

My Feedback: (17)

Hmmmm - I've got two idle K&B 20s. Maybe they could do it with help from a 28 in the nose? Where's my box of spare motor mounts?

earlwb

Yeah I have four K&B 20 sportsters left over from a ill fated B17 project I had done years ago. It is giving me ideas as to what to do with the engines.

1QwkSport2.5r

Twin engine aircraft sound so cool, I could only imagine what 4 engines would sound like. Music.

earlwb

Yeah four engines are really great sounding. I have three twins in use at this time. A F82 Twin Mustang with two Saito FA40a engines, a Twinstar with two OS FS26 engines, and a Combat Airmadillo twin with two OS 40 FP engines. I also have a Cessna Skymaster kit for 25 size engines and a P-38 for .10-.15 engines. I had built and flown two B17's built from Royal kits years ago and I sold them off. I had started building a third B17 and it was mostly framed up and built needing filling in and sanding before covering and painting, etc. But it got destroyed when I was moving from one home to another. I had started a little .049 B17 years ago but it never got finished and I gave it to someone else who wanted it really bad at the time.

So making up a three engine Twinstar using three of my K&B .20 engines does look quite fascinating to me. I might do it later.

ThunderBoat42

My Feedback: (1)

Subscribed! Fist RC engine was the 20 sportster 30 yes ago best running engine best idle. Still a sportster junkie

jeffie8696

You gots one of these boat guy? Yea, I know it aint a Sportster, but its a K&B.

1QwkSport2.5r

I've wanted one of the .67's for a long time. I was gonna scratch build a mono hull out of wood for it. Some day...

flyingagin

I am in the early design phase of a tri motor Biplane. I posted else where on this site. and also on the Brotherhood of the Ring
http://www.rcuniverse.com/forum/scra...raftsight.html
Not decided on motors but around .25 cid. K&B Sportster .28s would work. I don't think .20s would be enough.

Ken

ThunderBoat42

My Feedback: (1)

Found an old 20 Sportster and it's on the way! Feel like a kid at Christmas. LOL. (Probably because it was my first RC engine LOL). But they?e always run flawless for me.

jeffie8696

Can we get some weights posted with mufflers. Might be surprising.

GallopingGhostler

My .20 Sportster with muffler less propeller weighs 9.5 ounces. This is with the internal muffler baffle removed.

jeffie8696

There is my first surprise, my Thunder Tiger GP25 only weighs 8.9oz. With the Sportsters lack of heavy brass liner I would have thought it much lighter.

GallopingGhostler

I have TT's earlier Magnum .25GP and it's exterior is smaller, about the same size as my Enya .19-VI TV. The K&B Sportster .20 is about the same size as my Enya .35-III TV. I guess that in order to have the same strength to support the chrome plated piston, they thickened the aluminum cylinder walls. The control line guys like them, because they can swing a 10x5 prop all day.

1QwkSport2.5r

Keep in mind the sportster uses a high silicon aluminum cylinder and crankcase. This adds a lot of weight. Also, the sportster is an open port design; No removable liner per sé but the whole cylinder/jug assembly comes off. This requires the cylinder casting to be somewhat beefier.

Side note: I thought TT and Magnum are made by different companies? Never heard of them bring the same.

GallopingGhostler

See http://www.rcmplans.com/issues/reque...051989-1-1.pdf

ThunderBoat42

My Feedback: (1)

Just picked up a newold Sportster 20 and another old CG eaglet kit. One happy camper here

dakoris73

Hello everyone....
I have a K&B Sportster .65 motor and I'm really liking this motor, however, apparently I just blew out the back end of the muffler, which means that I'm in need of a replacement muffler. I was doing some reading and read that it would be possible to use a muffler from a K&B 61 muffler, which is similar to what an OS Muffler looks like. I happened to have an unusable k&b 61 motor sitting in my engine drawer, I was wondering if this muffler would actually work for my 65 Sportster engine, or would I be causing other issues to the motor. .

Here is an image of the muffler that I'm hoping to use.

.

Here is an image of a 65 motor with muffler that I had before I blew out the backend of the muffler.

I'm hoping someone can let me know if using the k&b61 muffler is a workable option or if I will need to order a new muffler from the MECOA website.

jeffie8696

If it bolts on , try it.

ThunderBoat42

My Feedback: (1)

Also. Check ebay.... May be able to pick up one there cheap.

dakoris73

I've been looking on ebay for another muffler, but the only ones I keep finding are the ones from the k&b 61 or buying a whole nother engine...... I'm just wondering if this will muffler will work without damaging this motor so that I can get back in the air again with this plane. Budget's kinda tight and don't really want to spend the extra if I don't need to.......

GallopingGhostler

Stock K&B Sportster muffler is more restrictive IMO due to the internal baffle. A good Muffler is nothing more than an adiabatic expansion device. I've used mufflers from other engines with good success on a limited number of engines without. Key is adequate chamber volume for exhaust gas expansion to minimize loss of power, which also helps prevent overheating. The K&B .61 muffler appears to have at least the same expansion volume as the Sportster's. It's worth giving it a shot.

flyingagin

As long as the muffler has sufficient volume you should have no problem. And since both engines are very close in displacement the 61 muffler should be fine. Might even work better as the .65 has a bunch of internal baffling.

Ken

SRQFlyer

My Feedback: (17)

I had a 65 Sportster without a muffler. I found a muffler for a HP (maybe HB) 61 that fit perfectly and worked great. As others have said, a 61-size muffler that fits should work just fine.
Good luck,
Jim

Twin_Flyer

My Feedback: (4)

Also don't forget the parts are available form MECOA.

The front and rear caps with the stud is $12.

http://www.mecoa.com/kb/58/58-parts.htm

https://mecoa.biz/shopdisplayproducts.asp?id=158

Bill S.