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K&B Sportster Club

Old 07-14-2012, 03:41 PM
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AmishWarlord
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Default RE: K&B Sportster Club

Sounds good. Congratulations on the maiden!

What Twin Star do you have? I think there are 4 or so on the market now.

Post some pics of her!
Old 07-14-2012, 04:48 PM
  #202  
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Default RE: K&B Sportster Club

I briefly ran my runner sportster today on one of the new carbs AW sent me, only had time to run a few ounces of fuel as I had errands to run but it mustered 12,840rpm on an MA 11x7 and a 2250rpm idle. I'll run it a little more tomorrow as I have an "RC day" planned. What little it ran today, it throttled better than it used to. I'll post back with further results tomorrow. Fuel was 5/25 and mc59 plug.

It spewed much less from the front bushing on the 5/25 fuel than it did on 5/20. I'm using the stock muffler without the baffle and today I used muffler pressure. Last time I ran it I got better rpm not using muffler pressure and just venting the tank.
Old 07-14-2012, 09:24 PM
  #203  
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Default RE: K&B Sportster Club

A little eye candy for sportster fans. This was from two summers ago shortly after I finished the boat build. 12x8 MA prop and SIG Champion fuel. I'm going to have a rematch sometime before summer is over with the sportster 65 on this boat which the boat was originally built for. http://www.youtube.com/watch?v=pwdsXcMDSMA

Old 07-15-2012, 12:39 AM
  #204  
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Default RE: K&B Sportster Club

ORIGINAL: 1QwkSport2.5r

A little eye candy for sportster fans. This was from two summers ago shortly after I finished the boat build. 12x8 MA prop and SIG Champion fuel. I'm going to have a rematch sometime before summer is over with the sportster 65 on this boat which the boat was originally built for. http://www.youtube.com/watch?v=pwdsXcMDSMA


How about trying an 11x11 or 11x12 prop on the Sportster .65, if you haven't already? That should provide plenty of high speed thrust and very high speeds.

Also, you could mount a weight within a tube and use a string and an electric motor to adjust the weight's position, fore and aft, to help prevent the hopping your boat is experiencing. Just move the weight when at speed for the least hopping.


Ed Cregger
Old 07-15-2012, 03:21 AM
  #205  
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Default RE: K&B Sportster Club

Good tips, Ed. I'll look for those props the next time I'm at the hobby shop. As far as the porpoising, it doesn't really do it at all with the .65. The Enya 4C and SuperTigre S90 are heavier so I have to make mods accordingly to balance it out again, I just haven't found the sweet spot with it yet on those two engines. I'm in the process of rebuilding the radio box, and I'm going to move the engine forward more.

-Tim
Old 07-18-2012, 02:51 AM
  #206  
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Default RE: K&B Sportster Club


Air Age http://www.airagestore.com/plans/rc-planes.html/ had a 50% off everything sale back on the 4th.

I picked up a few plans and one of them was for this de Havilland DHC-2 Beaver. http://www.airagestore.com/de-havill...-2-beaver.html

I chose this plane in light of it's size, wing area, weight, and type of aircraft "slow big" being perfect for the K&B 65 Sportster.

I didn't know at the time but one of our Sportster club members gorish had the same plane with a 65 in it.

When it comes time to paint this plane I'm thinking orange and purple with white trim and a few K&B logos on it.









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Old 07-19-2012, 08:23 AM
  #207  
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Default RE: K&B Sportster Club


Time to play "What's wrong here!"

http://www.youtube.com/watch?v=R6LIJQAE-eU
Old 07-19-2012, 09:13 AM
  #208  
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Default RE: K&B Sportster Club

let's see,
1. running in a closed space
2. loose rags near the prop
3. adjusting the throttle without a pushrod
4. 4.8 volts on a 1.5 volt glow plug
5. was that block of wood even bolted down?

I don't see any problems here
Old 07-23-2012, 09:42 AM
  #209  
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Default RE: K&B Sportster Club

Photo's of Twinstar with .20 Sportsters. oops just realized I have never posted photos. How the heck do you do it?
Old 07-23-2012, 10:26 AM
  #210  
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Default RE: K&B Sportster Club

ORIGINAL: KCLC

Photo's of Twinstar with .20 Sportsters. oops just realized I have never posted photos. How the heck do you do it?
What I do is upload the photos to my account at Photobucket.com (it is free, but any other photo service website would work too).
Then I copy the URL link from the Photobucket site, and paste the URL link to the pic here in the message. There is a picture icon above in the text edit screen that you could use too.


Old 07-24-2012, 05:25 PM
  #211  
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Twin Photos
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Old 07-26-2012, 06:22 AM
  #212  
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Default RE: K&B Sportster Club


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Twin Photos
Nice looking setup. Care if I ask why not flip the cylinder/muffler to the opposite side on one of the engines? I suppose if they were broke in that way they'd have to stay that way. Just curious.

I thought one sportster sounded neat, I can only imagine what two at the same time would sound like.
Old 07-26-2012, 06:46 AM
  #213  
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Default RE: K&B Sportster Club

That is a great setup KCLC, it is looking good on the Twinstar.

Old 07-26-2012, 05:24 PM
  #214  
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Well, you know I never thought of swapping out the exhaust on the left engine. But that would have looked cool. I'm not sure now that I've about got them broke in. These little engines do sound good together. But I discoverd a good/bad thing. They are extremely QUIET. If any one else is flying, I can't here if both engines are running. At any distance, I can't hear them at all. The .20's don't yank it vertically on take off, you have to let it roll-out. But it feels responsive after takeoff, my landings need much practice now. It's low speed maners are different than a single engine plane. It's Basically an over weight .40 sized aircraft and does not float in, you have to fly it down to the runway and flair it with some throttle still in, for touch down.
Old 07-26-2012, 06:21 PM
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Default RE: K&B Sportster Club


ORIGINAL: KCLC

Well, you know I never thought of swapping out the exhaust on the left engine. But that would have looked cool. I'm not sure now that I've about got them broke in. These little engines do sound good together. But I discoverd a good/bad thing. They are extremely QUIET. If any one else is flying, I can't here if both engines are running. At any distance, I can't hear them at all. The .20's don't yank it vertically on take off, you have to let it roll-out. But it feels responsive after takeoff, my landings need much practice now. It's low speed maners are different than a single engine plane. It's Basically an over weight .40 sized aircraft and does not float in, you have to fly it down to the runway and flair it with some throttle still in, for touch down.
I figured you had the engines ran in already. Since thats the case, you shouldn't flip the cylinders now. I'm debating doing this on my second Sportster .65. My runner of the two has the exhaust on the typical side, but sometime I would like to run my pair of .65's on a twin engine something so I may break it in with the cylinder flipped so whatever its on is balanced. We'll see though, as thats a long ways off yet.

Old 07-27-2012, 03:33 AM
  #216  
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Default RE: K&B Sportster Club


ORIGINAL: 1QwkSport2.5r


ORIGINAL: KCLC

Well, you know I never thought of swapping out the exhaust on the left engine. But that would have looked cool. I'm not sure now that I've about got them broke in. These little engines do sound good together. But I discoverd a good/bad thing. They are extremely QUIET. If any one else is flying, I can't here if both engines are running. At any distance, I can't hear them at all. The .20's don't yank it vertically on take off, you have to let it roll-out. But it feels responsive after takeoff, my landings need much practice now. It's low speed maners are different than a single engine plane. It's Basically an over weight .40 sized aircraft and does not float in, you have to fly it down to the runway and flair it with some throttle still in, for touch down.
I figured you had the engines ran in already. Since thats the case, you shouldn't flip the cylinders now. I'm debating doing this on my second Sportster .65. My runner of the two has the exhaust on the typical side, but sometime I would like to run my pair of .65's on a twin engine something so I may break it in with the cylinder flipped so whatever its on is balanced. We'll see though, as thats a long ways off yet.

Although I have one, I have not taken it apart, so this may not work. But, if you turned the piston around when you turned the cylinder around, then the broken in piston and cylinder are still matched, right?
Old 07-27-2012, 03:53 AM
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Default RE: K&B Sportster Club


ORIGINAL: spaceworm


ORIGINAL: 1QwkSport2.5r


ORIGINAL: KCLC

Well, you know I never thought of swapping out the exhaust on the left engine. But that would have looked cool. I'm not sure now that I've about got them broke in. These little engines do sound good together. But I discoverd a good/bad thing. They are extremely QUIET. If any one else is flying, I can't here if both engines are running. At any distance, I can't hear them at all. The .20's don't yank it vertically on take off, you have to let it roll-out. But it feels responsive after takeoff, my landings need much practice now. It's low speed maners are different than a single engine plane. It's Basically an over weight .40 sized aircraft and does not float in, you have to fly it down to the runway and flair it with some throttle still in, for touch down.
I figured you had the engines ran in already. Since thats the case, you shouldn't flip the cylinders now. I'm debating doing this on my second Sportster .65. My runner of the two has the exhaust on the typical side, but sometime I would like to run my pair of .65's on a twin engine something so I may break it in with the cylinder flipped so whatever its on is balanced. We'll see though, as thats a long ways off yet.

Although I have one, I have not taken it apart, so this may not work. But, if you turned the piston around when you turned the cylinder around, then the broken in piston and cylinder are still matched, right?
That sure sounds correct. I am not real sure, but I think there are also some side forces in there acting on the piston. No idea if that would have a bearing on things or not.
????
I have never had mine apart. Are there any areas in the case thatmatch up to the intake port areas in the cylinder? If not the could you turn a cylinder 90 degrees so it was facing aft (not yet ran acourse)?

Ken

Old 07-27-2012, 04:27 AM
  #218  
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I'll have to double check, but I'm pretty sure the piston can go into the liner only one way because of the backplate recess cut in the piston. If you made a relief on the other side of the piston it can be done. The Teflon pad in the piston would ride on the port divider on either side of the liner though.

Ill check my .65 when I get off work.

You cannot run a sportster as "rear exhaust" because the wristpin is retained with a Teflon pad that rides on a port divider in the transfer port on the rear (I believe it's the rear). The Teflon pad would get caught in the exhaust port.
Old 07-27-2012, 06:03 PM
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ORIGINAL: 1QwkSport2.5r

I'll have to double check, but I'm pretty sure the piston can go into the liner only one way because of the backplate recess cut in the piston. If you made a relief on the other side of the piston it can be done. The Teflon pad in the piston would ride on the port divider on either side of the liner though.

Ill check my .65 when I get off work.

You cannot run a sportster as "rear exhaust" because the wristpin is retained with a Teflon pad that rides on a port divider in the transfer port on the rear (I believe it's the rear). The Teflon pad would get caught in the exhaust port.
Thanks1QwkSport2.5r
I knew something had to be screy with run them rear exhaust. My instincks were telling me that but I never had a sportster apart. A ton of other ingines.
What you said makes perfect sense.
I will just go hide and go duhhhhh

Ken


Old 07-27-2012, 06:34 PM
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ORIGINAL: 1QwkSport2.5r

I'll have to double check, but I'm pretty sure the piston can go into the liner only one way because of the backplate recess cut in the piston. If you made a relief on the other side of the piston it can be done. The Teflon pad in the piston would ride on the port divider on either side of the liner though.

Ill check my .65 when I get off work.

You cannot run a sportster as ''rear exhaust'' because the wristpin is retained with a Teflon pad that rides on a port divider in the transfer port on the rear (I believe it's the rear). The Teflon pad would get caught in the exhaust port.
Thanks 1QwkSport2.5r
I knew something had to be screy with run them rear exhaust. My instincks were telling me that but I never had a sportster apart. A ton of other ingines.
What you said makes perfect sense.
I will just go hide and go duhhhhh[img][/img]

Ken


Its one of those things. There aren't many engines that have the cylinder being removable from the crankcase so this doesnt come up in conversation much. I did verify that at least on my .65's there is only one relief in the piston for the backplate, so unless you cut a relief in the piston on the other side, there isnt a way to swap the cylinder without disrupting the pistons fit to the liner. It would probably run, but who knows for how long.
Old 07-30-2012, 06:54 PM
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Default RE: K&B Sportster Club

I don't know if there is enough material left in the piston to cut a couple of grooves for a small wrist pin retainer ring or not. But one could do that to keep the wrist pin from moving. It isn't easy to do it though. But when you rotate the cylinder, you'll need to ensure the ports match up with the piston OK and that the piston skirt doesn't hit the backplate or crankshaft either. Oh yeah, some companies actually drilled a small hole in the piston and wrist pin and pressed in a small roll pin too. One could also cut a groove on one side of the roll pin just on the inside edge of the piston and put on a wire retaining ring there too, I remember seeing that on some old vintage engines before. I have even thought about just using some J&B weld epoxy to lock in the wrist pin too. The cylinder and piston isn't all that expensive to try that on either.

Old 07-30-2012, 07:28 PM
  #222  
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ORIGINAL: earlwb

I don't know if there is enough material left in the piston to cut a couple of grooves for a small wrist pin retainer ring or not. But one could do that to keep the wrist pin from moving. It isn't easy to do it though. But when you rotate the cylinder, you'll need to ensure the ports match up with the piston OK and that the piston skirt doesn't hit the backplate or crankshaft either. Oh yeah, some companies actually drilled a small hole in the piston and wrist pin and pressed in a small roll pin too. One could also cut a groove on one side of the roll pin just on the inside edge of the piston and put on a wire retaining ring there too, I remember seeing that on some old vintage engines before. I have even thought about just using some J&B weld epoxy to lock in the wrist pin too. The cylinder and piston isn't all that expensive to try that on either.

The ports should be okay in a rear exhaust setup if the wristpin issue were out of the way however the engine would have about 2 degrees of sub piston induction as a rear exhaust. The backplate is not machined for the transfer port that would normally be there and the boost port would be shrouded by the crank counterweight somewhat. If one made a new backplate with a recess for the piston it might improve performance some but I wouldnt know unless I tried it.
Old 07-31-2012, 11:48 AM
  #223  
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Default RE: K&B Sportster Club

About the only improvement in performance that one gets with a rear exhaust engine, is that the engine and plane are more streamlined with the muffler hiding more behind the engine. So it may or may not gain you anything unless you needed the extra streamlining effect to reduce drag. Or for a scale model plane where a rear exhaust might be useful to hide the engine and exhaust more.



Old 08-02-2012, 01:14 PM
  #224  
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When the piston goes up and down it rocks slightly due to the side thrust of the rod. The wear pattern of the bore will reflect this, so changing the orientation of the cylinder after it has broken in will reverse the wear pattern. Will require break in again and probably cut life and performance. In other words Not a good Idea! but will work.
Larry
Old 08-05-2012, 10:33 AM
  #225  
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Default RE: K&B Sportster Club

I decided to rebuild my first RC Plane.

It was a 25 size J-3 Cub ARF that I converted into a Super Cub.

The origanal was powered by a .28 Sportster as will this new one.

My goals are to build a more scale PA-18 around the .28 engine.

Here is the power system I'm going to design the plane around.

Master Airscrew 9x5 2-blade.......................$2.19
Dubro Flex Cable 20"................................$2.89
Spinner Adapter Kit...................................$4.49
Hayes 6oz tank.........................................$4.69
Turnergy onboard glow............................$11.56
Great Planes Aluminum Spinner 2"............$17.99
Hitec HS-225BB Mighty Mini Servo.............$17.99
Bission pitts muffler.................................$41.00
Perry Carb.............................................. $43.50
Iorn Bay Regulator...................................$43.95
K&B Sportster .28.....................................$79.99

Total $270.24

I think just this engine set up will cost more than the plane,engine, and ATTACK 4 radio system cost me in 1987

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