woodburner

For that price I can get a property on the dark side of the moon, taxes included....

earlwb

I had acquired a K&B Sportster 65 engine a while back. What made it unique was someone had made a new crankcase for it using a big chunk of aluminum barstock material. After getting the engine, I found that it wasn't quite ready yet to run, it still needed some work. It looks useable, but it wasn't quite finished yet. The original owner had machined out a crankcase from a large chunk of aluminum barstock. But I suspect the person may have passed away before they finished it or something. So then it was up to me to fix it up.

I first had to use a 5-40 bottoming tap on the backplate screws as they weren't going in deep enough to lock the backplate on. I then also needed a rear gasket too, so I fabricated one out of some cardstock paper. The carburetor is held on with a draw bar clamp, but he had drilled the hole for it too far into the carb hole. So I had to relieve the hole and move it back about a tenth of a inch before the draw bar would fit. Since the carb does fit pretty tight, I decided to use some high temperature gasket sealant to seal it up the excess gas a little. I really don't think I need to deal it but you never know where air leaks can develop. The next problem was when I was assembling the engine, I found that the front of the crankcase is just a few thousandths of a inch too long and I couldn't put on the steel shim washer between the drive washer and the crankcase nose. When I tighten up the prop, the drive washer just barely touches and binds against the crankcase front, So I had to leave the shim washer off for now. If the engine runs, that will loosen up a little more and I can slip it on later. Then the carb had a broken needle carrier, so I needed to make a new one to fit the needle onto and I also used a Fox ratchet clip so the needle won't move when the engine is running. Hopefully the repaired carb will work OK now. It feels a little rough but everything seems Ok with it, unless the internal O-rings have gone bad on it.

The original owner did pretty good machining out all that metal. I only have a mini-lathe and a mini-milling machine. So I can't take large deep cuts when machining stuff. I have to shave off a few thousandths at a time. So it would take me a long time to hog out a crankcase from barstock aluminum. Plus the guy had also pressed in a piece of bronze bearing material for the crankshaft too. The original crankcase and crankshaft shows significant galling where the metals had touched and worn in on the two parts. I think he decided it needed a bronze bushing instead of going with aluminum like the factory did. Now the factory used a high silicon content aluminum and they may have also added more silicon to the wear surfaces too, making it more like a ceramic coating there. I don't know.

I also did other minor things like replace the threaded crankshaft stud. The one that was on the engine had buggered up threads and was bent too.

Anyway here are a couple of pics after getting it fixed up and put back together.




The homemade crankcase after stripping the engine down.






I didn't like the way he had machined out the intake port on the front. But anything I do to clean it up will result in it being more wide and that would change the port timing a lot. So I left it as is.


Here is where the hole to clamp the carb in using a draw bar was bored to close in, it really needed to be about a tenth of a inch farther out or back from the hole for the carb.




You can see here where the screws weren't threaded deep enough to lock the backplate on good. I used a bottoming 5-40 tap to fix the problem.


But after threading the holes more deeply, corrects the problem and I can mount the backplate on OK.


You can see here where there is a gap after I moved the draw bar hole back about a tenth of a inch to clear the carb better, so it could be locked in place.




But applying a little gasket sealant to the slight gap should fix an airleak if it happens.




Here is a pic of the bronze bushing insert put into the crankcase.


Someone had tried to use a short glow plug in the head, so just in case I chased the threads with a 1/4x32 tap to insure the threads weren't buggered up too much.


After fixing the carb. Watch out for the needle, that sucker has a super sharp needle point and you can easily stick yourself with it.


I fabricated a motor mount out of some 1/4 inch plywood to allow me to test run the engine on my test stand.


I got it all setup on my test stand only to find that the 12v starter battery needed recharging. So I will try test running the engine tomorrow if time permits. I had accidentally cut one of my fingers with a drill bit when I was drilling the holes in the wood motor mount, so I wasn't able to flip the prop by hand well enough to hand start the engine. So close and so far, I hate the suspense too.

earlwb

Here is a pic of the old crankshaft that has the galling on it where the crankshaft at touched the aluminum crankcase front on the broken crashed crankcase and crankshaft, The anti-oiling grooves are deeper than the other crankshafts I have seen, so maybe K&B changed it to allow for more oil to ooze in up front.


and the related galling on the crankcase too.


you can see the much more shallow anti-oiling spirla grooves on this crankshaft here.

1QwkSport2.5r

What prop did you put on, Earl?

earlwb

I am going to try a 12x8 APC prop at first here and see how it does with it.

earlwb

Here are some more pics of the .65 Sportster cylinder and head, etc.







I am hoping that what appears as a scratch in the top of the cylinder doesn't result in a leak when the engine is running. You can't really see it, but it shows up in the flash picture from the camera.


This pic shows the inside of the cylinder from the inside of the crankcase

AmishWarlord

My Feedback: (5)

Well it looks like that motor found the right owner.

"I had acquired a K&B Sportster 65 engine a while back."

Nice writing style! Sounds so distant and full of mystery and intrigue as if you bought this engine from some shady character in the back room of a pub 20 years ago who had found it in an abandoned factory, rather than you buying it off ebay three weeks ago. LOL

AmishWarlord

My Feedback: (5)

Earl pot some machining photos!

I'm trying to save up the funds for this Shop Fox 9x19 bench lathe.

There is so much I want to do in this hobby that requires a lathe and milling machine.

earlwb

I don't have much in the way of machining photos. I have a Taig Mini_lathe and a Harbor Freight mini-Milling machine. I also have a larger milling machine as well, but the drill head got stuck in the arbor and I can't get it out. It uses what they call a MT-2 taper, so it tends to almost weld itself into place. Since it weighs too much to get off the bench, I haven't removed it yet. I hope to get the old part out so I can put in a new one eventually. I used the older larger milling machine to make parts for stuff too. The first job it had was to make new hinges for the front screen door at home. The screen door hinges were a odd offset design that no one sells of course, and the orignal ones wore out after a few years. The hinges I made from better aluminum alloy are still going strong after 15 years of use.

But here is a photo from when I was making a crankshaft for a Marz 2.5cc model diesel engine.







Here is a pic from when I was modifying the exhaust inlet on a muffler to match the exhaust outlet on a .60 engine better.

earlwb

I could have probably saved and reused the old broken crankcase on the K&B 65 Sportster engine. But the crankshaft had worn into the crankcase in the front a lot, maybe too much to make it reuseable. I assume the original owner had crashed a plane with the engine on it. Thus the carb was forced out and off the engine breaking the carb inlet off as shown in the pic. But that could be kludged where one could use JB Epoxy and glue it back in, or use high temperature gasket sealant even. If the broken pieces were still available, it might have been possible to weld them back on or use aluminum solder to put them back on with too. Of course both of those solutions are ugly, but if the engine was being used to teach a beginner how to fly then it isn't a big deal for the short term.

Here are some more pics of the broken crankcase.










Here is a example of a old MDS 61 engine that I salvaged by using aluminum solder to put the broken pieces back in so it could hold the carb on once again.

joebahl

My Feedback: (2)

My K+B sportster 20 on my 70's tidewater pronto surpreme i scratch built last winter. I have 6 or 7 other K+B motors for vintage aircraft . joe

jeffp51

I will be mounting a .65 sportster on a scratch-built biplane soon. That is, as soon as I get it built. The engine is definitely from an army drone, and has never been run. the head fins are the short ones, and does not have the same markings that others are saying come from the drone engines. I acquired this one when my national guard unit transitioned from armor to air defense artillery. We inherited dozens of the drones, but had no way of using them (no transmitters) I saved this one, but had no space for the airframe. This was about 2004. I don't know when the engine was built, but I hope it doesn't have the carb problems some of you mention. I haven't started it yet, but any suggestions are welcome. My first engine in 1984 was a K&B .40BB. It ran great until I landed it in a river. Less well after that.

1QwkSport2.5r

I have two drone .65's with one I broke in and the other unrun still. Some drone engines don't have carb problems. A friend of mine has one thats got some time on it and his carb throttles perfectly on my engine.

Rich carburetion isnt a bad thing with these engines anyway. I highly recommend running a full castor diet and not one of those synthetic blends. Mine sprays a lot less oil from the front bushing with full castor than it does on a blend and it gives better rpm too. I run 20-25% castor in mine. Dont bother trying to get it to throttle good until you have a gallon through it. When the compression (cold) feels crazy strong, its probably got enough time on it to get a decent transition from it.

Good Luck with your sportster.

jeffp51

I really don't know what percentage of my lube is castor, although I know it has some, but I have some castor oil that I could add to my fuel? or do you know which fuel brands only use castor? My biplane project is [link=http://www.rcuniverse.com/forum/m_11004737/tm.htm]here[/link]

1QwkSport2.5r

I think break-in is hyper-critical in engines like these. For this reason I would use full castor fuel, of which you can get from SIG at www.sigmfg.com . They use top notch ingredients and are great to work with. After 4-6 quarts, you could switch to a blend if you want but I'd keep it at least 50/50 cas/syn at 20% total content.

This is just my opinion... Its your engine so run what you like.

Most blends on the shelf like Omega or Byrons are usually 80%synthetic/20%castor or 70%S/30%C at 17-18% content. Modern fuels like this are great for the typical ABC/ABN engines but these old design (and unique) engines need lots of oil; the thicker the better. The crankcase bushing and conrod will thank you. They dont like lots of nitro either. 10% Max.

I am going to follow your build progress. I'd like to build a Biplane sometime, perhaps something with twin engines. Good luck and happy building.

earlwb

Actually several brands sell a all castor oil fuel. Powermaster has at least two, FAI fuel and a special fuel for breaking in engines too.
Sig sells one, and Fox manufacturing sells several types with all castor oil in it. There are some others too.

earlwb

I was successful at bench running the K&B engine with the homemade crankcase. The bronze bushing fit is still a little tight though, but it has loosened up some now. I had to stop running the engine, let it cool off and take it apart. I found a high spot, possibly two high spots that I worked on using some super fine abrasive compound and a drill to spin the crank inside the bushed crankcase. Then i clean it up and reassembled it and that helped a lot but it is still a bit too tight. very little oil comes out of the front of the engine. So I might have to hone it some more still. I also needed to take a few thousandths off the back of the prop driver washer, as when you tightened up the prop good, it tended to rub up aganst the front of the crankcase.

Also when it was first run, I noticed a little fuel and oil coming out around the cylinder to crankcase joint. So when I reassembled it, I put on a little bit of K&W Copper Coat gasket compound to help seal it up, and that did the trick. the head didn't leak at all. But it does concern me that it isn't oozing much if any oil out of the front of the engine though. I'll have to work on that to open it up a little more between the bushing and the crankshaft.

The engine idles pretty good and the rebuilt carb transisitons well too. I can't lean it out as much as I would like yet, but it did get a 12x8 APC prop up to around 8600 rpms so far, I think it'll do better as soon as the crankshaft loosens up more in the bushed front end.








Here is a video of me hand flipping it to start it running and fiddling around with the carb and engine speed.
[youtube]http://www.youtube.com/watch?v=qLnNthdSW7g[/youtube]

earlwb

I also test ran one of my other K&B 65 engines to get a comparison as to how well the 65 engine with the DIY crankcase was doing.
This engine turned the same APC 12x8 prop at a little over 10,000 rpms and didn't have any problems doing it either. Although it didn't look like it, it was oozing oil out of the front of the crankcase around the crankshaft, as when I stopped the engine I could see the oil on the propeller. I did get the engine to idle as low as 1900 RPMs too, but although it didn't stall out, it sure felt like it was thinking about stopping.

earlwb

While tinkering with the K&B Sportster .65 engines, I noticed that there were at least three different head styles or designs on the different engines
The early engine that I have I arbitrarily named it the first head style. it has a more tall head, with deeper and higher cast in cooling fins. The second head that I have on a engine has shorter cooling cast in fins that tend to be more thin with a more wide gap in between. The third head design has really short or minimal cooling fins that are machined into the head, they aren't cast into the head to start with.







The second head design or style:




The third head design or style:

AmishWarlord

My Feedback: (5)

WOW congats Earl.

You got .74 HP out of the block engine and 1.1 HP out of your good engine so you'n not far off from peak power with that block engine.


Block engine

APC 12x8
8,600 RPM
.759 HP
4.35 Static Thrust
65.1 MPH flight Speed

Standard engine

APC 12x8
10,000 RPM
1.194 HP
5.89 Static Thrust
75.7 MPH flght speed

Looks like the APC 12x8 is to much prop for the .65 though

earlwb

Thanks,
    I think the block engine will do better when I get the front bushing a little more loose as it is still a little too tight though.
The standard .65 engine I ran later is outputting 1.1 HP as advertised by K&B.  The online instructions suggest a 11x7 prop as the prop to use.
ref http://www.mecoa.com/kb/58/5800.htm
I don't know what I was reading before I chose the 12x8 prop, but I thought it was in the prop range suggested by K&B, so I might be in error there.
But the K&B information at MECOA was showing the K&B Twister engine with a 12x8 prop thus I might have mixed up the information in my mind.

When I was running my K&B Twister .61 engine, it was turning 10,100 RPMs with the stock muffler and 12x8 Master Airscrew prop.
My old Saito FA-80 engine was turning a 12x8 prop at about 10,500 RPMs when I bench ran it after replacing the bearings. It sort of turned into my reference engine for test running engines in this size range.

iAlex

I have a question concerning the .65 engines. Is the only difference between the Drone engines and the others the idle disk? I have a .65 that was purchased from Tower prior to Christmas in 1991. My flight instructor and I had no end of problems with the engine at the time (I was 15 years old then). It got to the point that I asked for an OS .60 FP for Christmas in 1993 and mostly forgot about the K&B. Well looking at the engine now I find that the backplate does have the 91 on it. So somehow Tower sold an engine that should have never been on the retail market. This would explain the problems we had with trying to dial in this engine.

A new idle disk is just under $14 from MECOA. Not a bad price if it is truly what this engine needs to run like it should.

Thoughts?

iAlex

1QwkSport2.5r

The idle disk *may* be the problem, but in my case, the barrel/spraybar is at fault too. Swapping in a known good idle disk got mine to throttle 50% better. Swapping the barrel and idle disk made all the difference.

To get the barrel you have to buy the carb body. After you get that and the idle disk you're better off buying a whole new good carb.

I'm putting Perry's on my pair.

earlwb

It is hard to say about the carb, but it is possible the carb was defective or assembled incorrectly or something, such as using the wrong parts. If possible one would need to try a different carb with it to see how it behaves. Unfortunately that means you have to buy the a different or new carb though. At present MECOA is sold out of the regular carbs and only has the remote needle carbs in stock, and that carb sells for $27 plus you need a remote needle assembly that costs $27 too. But a 2600 Perry carb sells for $43.00 retail.

No matter how I keep looking at it the K&B carb sure looks like a metal version of a Perry carb, inside and out. So I suspect the design was derived from the Perry carb design at some time in the past. K&B for a number of years used Perry carbs on their engines too. Then they started selling them with their K&B carb that had Perry carb similarities.

SRQFlyer

My Feedback: (17)

Folks,

I have a pair of Sportster .20s that are going in an existing Profile 38 (now has OS 25 FXs). One of the .20s has the older o-ring head and will only get within 1000-1200 RPM of the other one at top end. I assume the engines are identical other than the heads ??? Does anyone have a new or used head that they don't need and could part with for a few coins of the realm?

Thanks,

Jim