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K&B .61: Changing bearings

Old 04-24-2002, 02:20 AM
  #1  
Razor_Sharp
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Default K&B .61: Changing bearings

I have my K&B .61 stripped down to nothing but crankcase, bearings and crankshaft. The crankshaft turns freely, there is no rust, but the crankshaft will not come out of the bearings. Could it be pressed in there? I there any way to remove the crank? Heating? Pushing it out with my drillpress?
Any suggestions would be appreciated.

Thanks,
Gregg
Old 04-24-2002, 03:01 AM
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w8ye
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Default K&B .61: Changing bearings

Gregg,

Yes, yes, yes, & yes

Warm it up in the oven 200-250 your lowest setting. Let stay in there a while to get the Aluminum case soaked with heat.

At this point, you should be able to push it out by hand.

When going back together, do the same thing. Put the crankcase in the oven. While it is heating up, put the rear bearing on the crank. Do not hammer it on. If the crank was chilled in the freezer and the bearing warmed in the oven, it will drop on. You may be able to push it on by hand anyway.

Slide the crank and the rear bearing together into the hot crankcase.

To put the bearing on the crank first will assure that it goes into the case straight.

Now press the front bearing on with the drill press arbor. Use a socket from your socket set to go over the crank.

If you hammer these little bearings you will make spots on them and they will turn rough.

You may want to warm it up to put the sleeve back in. Be real careful with the ring that you dont chip the edges right where the gap is. Look at it with a 10X lope. If so you will need a new ring from Clarence Lee or from Mecoa who makes the K&B now.

There are others who make rings, maybe one of them will pipe up on here?

I used the Mono Coat gun on mine when I ghanged the bearing to heat up the case.

I put regular bearings in mine from the bearing store up town. At least they were name brand bearings. They were made just like the old ones. The old original bearings were some cheap off-brand made in Korea.

I changed the bearings in an Enya 40 and the old ones had phenoly cages in them which is considered a higher speed more expensive bearing. But the regular bearings have worked just fine in it for 2 years. The bearings used in the K&B 61 are the most common size used in model motors.

Good luck,

Jim
Old 04-24-2002, 03:17 AM
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Default K&B .61: Changing bearings

I simply find a couple of thin chisels and gently tap them between the bearing and the crank journal one on each side. Ninety percent of the time the bearing will slide off without any heat. There is nothing behind the bearing that you can damage very easily this way so don't worry.

OR

On difficult ones I have made up a couple of thin steel plates with notches in them. I open my vice and lay the plates across the vice opening supporting the crank while they are wedged between the bearing and the crank journal one on either side with the threaded end of the crank poking up. Re-install the prop nut and thread it on 'till it's flush with the end of the crank. Grab a chunk of hard wood and place it on the prop nut and whack it with a hammer. If this does not work try it again but heat the bearing with a propane torch first.

I have never had to resort to using a press on this engine.

A note on using heat to remove bearings: The idea is to heat the bearing BEFORE the crank as you want the bearing to expand before the crank does. This is easier than it sounds because the crank has considerably more mass than the bearing and it takes longer to heat a larger mass. Point your torch directly onto the bearing's inner race and rotate the crank while doing this. After about 30 - 45 seconds the bearing should be hot enough to practically fall off.


Re-assembly is a snap. Start the bearing and make sure it's not cocked. Set the crank so it's supported by a couple of pieces of wood and tap the bearing into place. I use a hard plastic hammer for this. If it seems to be stubborn apply heat just to the bearing, get it good and hot and it will fall on.

While these methods might not be what other fellows use they have worked for me on EVERY K&B .61 I have dis-assembled.

BTW: The K&B .61 in one of my all time favorite engines. I have 2 that I bought from the original designer of the .61s Clarence Lee. Both have the PDP mod and were hand fit by CL himself.

Until just recently you could purchase a new one of these engines modified and hand fit by CL directly from him
but apparently the supply of new engines has run dry. CL will modify your engine for under $30.00 and it is well worth the money. His contact info is always in the classified adds in RCM magazine.

The K&B .61 started life as the old Veco .61. Last year I was able to find #73 Veco .61 hand signed by Mr. lee

I use this engine in a Sig Somethin' Extra with an APC 12.25X3.75 prop. It is great for hovering.

Check the pictures I posted here on RC Universe. The Kyosho Super Stearman Bipe in the pictures is powered by a CL modified K&B .61 with a tuned pipe. It performs much better than with the MDS .48 I started with.

GSG
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Old 04-24-2002, 03:03 PM
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Default K&B .61: Changing bearings

GunShip,

Thats good that you came in with some of the details I left out.

I have three Clarence Lee PDP K&B 61's. The oldest has the Perry carb as does yours in the picture. The others have the non finned square K&B carb with the idle needle in the center of the throttle arm. All three run great but the one I use is the one with the oldest serial number and the Perry carb.

They are about the loudest engines I ever owned. Clarence cuts the back of the muffler off and puts a piece of 1/2" aluminum tubing in there. Mine have the old style blunt muffler.

I bought the engines off the net. They were not Clarence Lee engines. All were bench run only and looked new. One, however had bad bearings in it and the piston was spilt about half way down the skirt. It ran but I was afraid of it. This bad engine was the older one with the Perry carb that I use. I was told this engine was bad before I bought it.

I got new parts from MECOA and put in the older one that was bad. The new sleeve was chromed.

Then I got the wild idea to send them to Clarence. He and his wife treated me great and got the three engines back to me right away. He wrote a long letter telling about each engine and just how to break them in.

Jim
Old 04-24-2002, 03:39 PM
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Default K&B .61: Changing bearings

Originally posted by w8ye
GunShip,

Thats good that you came in with some of the details I left out.

Jim
Jim,

Your post was not up when I wrote mine or I would have worded it differently.

I sincerely hope I did not offend you.

Clarence is a great guy and one of the worlds top experts on our simple little engines.

If he says to run some bean oil in all my motors IDO!!

If he says use Cascade dishwasher detergent and hot water to clean my engines I DO!!

You see, I've been building engines of all sorts for over 30 years but I have never wanted to try and re-invent the wheel so having access to an expert on the level that CL resides is a real blessing to say the least..

The K&B .61 is a light weight and powerful engine. Sure most if not all other sixty ones make more power on top but the K&B makes tons of power where I need it - mid range.

Talk about the sound!!

You ought to hear my Stearman with that big old 12X8 or 13X6 prop acting as a brake on down lines. The K&B is barking through a full length tuned pipe and it sure sounds sweet!!

Good luck - have fun - now GO FLY!!!

GSG
Old 04-26-2002, 03:09 AM
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bgi
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Default K&B .61: Changing bearings

Hey, guys,

It looks like I found my experts!

I have a story for you: I used to fly C/L a good bit in the 70's. I did build an RC glider and flew it a few times in the 80's. Then I was out of the hobby until last year. My brother gave me an old NIB K&B .61 with perry carb and pump years ago. I didn't remember that I had it.

About 8 months ago, I discovered this engine and went shopping for a plane for it. I decided to get back into the hobby! I picked up a GP .60 Cub because it was the only kit at the store. I did get smarter and am learning RC powered planes on an Avistar. I've also decided to train myself on tail-draggers on a Sig 4-star 60. I've since kind-of given up on this engine because I can't get it to run well. I've run several tanks through it on a stand to break it in. It idles OK and really screams (REALLY LOUD) at the top end. But it always stumbles a LOT on transition while spewing fuel out the venturi. The perry pump is working just fine. I've tried all sorts of pressure settings on the pump and idle disk, but I can get it to run better on muffler pressure. The pump seems to have no mid-range like it's either on high-pressure or off.

What's the trick to getting this little jewel to run well? I'm attached to it and really want to use it in a Sig four-star 60. But I'll be darned if I'll try to fly a plane with it until I can get it running right. If I can't work it out, I'll put the TT .91S on it.

I never had any trouble getting any other glow engine to run well: Cox .020 pee wee, .049 (various kinds), .09, K&B .19 CL, K&B .35 RC, Enya .19 CL, OS .40 LA, TT .46 Pro, TT .91S, and Saito 180.

What's the trick? :-)
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Old 04-26-2002, 01:18 PM
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Default K&B .61: Changing bearings

bgi,

That's a mighty fine looking K&B you got there. It looks just like my older one except for the pump.

The pumped K&B's had a bigger Perry carb than the non pumped ones. This engine would tend to be troublesome without the pump because the carb is so large.

One alternative is to put the standard Perry carb on it. And just use muffler pressure.

The other alternative is to put a Cline demand regulator on it. This demand regulator is part of a diaphragm carb from a chain saw engine. Those chainsaw carbs have a pump side and a regulator side. This is just the regulator part. The way the instructions read is that you tap crankcase pressure for the tank by using a check valve. (You could just use your backplate pump.)They cast $50 though. Cline is the guy who makes the Perry carbs. Look around with Google a bit and you will find a picture of it.

The regulator only lets the fuel by, that the carb demands. You have to mount it right beside the needle valve outlet. Its made of Nylon or UHMW type plastic.

Some other problems are that this engine is a pure loop scavenged engine. Their characteristic are different from a modern day schnurle ported engine. Some differences are that the loop engine is even more sensitive to muffler back pressure than the schnurle engine. Another is that the intake fuel charge tends to cool the plug off when you go to accelerate the engine and at best it will stumble and will most likely quit. You have to use an idle bar type plug in them. The other thing is that they would like a little more nitro than a schnurle engine.

Another alternative is to send the engine to Clarence Lee and have him make a Clarence Lee modified K&B 61 out of it. It only costs about $30. He will get it back to you right away. If I were you, I would enclose a note as to your experiences with the engine just like you did here on the forum. Clarence doesn't get on the internet.

When you get the engine back, it will be a cross between a loop scavenged engine and a schnurle scavenged engine. It will be called a PDP engine. (Perry directional porting). He will put two small schnurle intake ports up each side of the exhaust port. He will also refresh the engine with a new ring and any other parts it needs. When you get it back, he will tell you how to break it in and how to get it to run right in a letter.

This will take out some of the problems with the engine being loop scavenged. They seem to run pretty good with an OS #8 plug. You will be talking fantastic tales about the engine that the other .61 engines guys will find jhard to believe. Clarence Lee was the original designer of the VECO 61 which became the K&B .61.

There is another thing you will need to know. That is Clarence will want to cut the exhaust stack back to where it is shorter. If you need it to stay as long as it is now, you need to tell him. The new K&B 61's have the stack cutt off even with the fins.

Enjoy,

Jim
Old 04-26-2002, 01:54 PM
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Default K&B .61: Changing bearings

I believe the old pumped version is already PDP ported. So sending it to Clarence Lee would get you nothing but a bored out and loud muffler, oh and blueprinting. You may have a leaky diaphram from age hardening. I doubt you will find a replacement buy you can check out the K&B site. Don't know the link but http://www.mecoa.com will have a link. If not maybe you can buy a plain backplate from them, a new external Perry Pump, and you should have the power this engine originally had. Plus you can use the pump for future projects on differant engines as well.
Old 04-26-2002, 03:06 PM
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Default K&B .61: Changing bearings

Great info, guys.

Sport_Pilot, this thing is already painfully loud!

I've checked out mecoa.com's site. Not much there to help except the really small carb or a replacement perry carb. I can't tell if the replacement carb is the same size.

I may just send it to Clarence with the info and see what he thinks it needs. Sounds like he's the real expert.

thanks!

BTW: Here are some photos (low-res edits) of an Air & Space museum display:
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Old 04-26-2002, 03:07 PM
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bgi
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Default one more

One more...
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Old 04-26-2002, 03:10 PM
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Default And another...

And another...

Hey - looks like Picture-It! put some white dots on my photos. Hmmm... I'll have to look into that.
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Old 04-26-2002, 04:21 PM
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Default K&B .61: Changing bearings

Hey, no guarentiees that an engine from the Air and Space display actually runs. After all it was for display only. Maybe you should put it back?
Old 04-26-2002, 04:37 PM
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Default K&B .61: Changing bearings

LOL Busted!

Ya know, I derived some pleasure from having an engine "just like the one at the Smithsonian" until I looked closer... :disappoin

I noticed that the one in the Air & Space has a huge muffler. Plus, the carb idle adjuster and needle valve end are different materials. I'll bet that one hasn't been broken in.

Can't wait to try out that pulse-jet. :-)

That 5-cyl radial is pretty cool. I wonder how old it is. Did you get a load of that AL prop on it? Looks really nice.

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