Conference vmszoo::rc

As I reported earlier in another note, my K&B .20 broke a head
bolt during running in.  The bolt broke from fatigue failure, as
the crack had the characteristic form of that type of failure.  I
just received it back from K&B yesterday; they replaced the
cylinder and piston assembly.  It puzzles me that they did this,
since they also sent along a couple of head bolts, implying that
I could replace them myself.  I suspect that I scored the
piston/cylinder in my ignorance of proper break-in procedures.
The repair was done under warranty, with no charge except the $5
for postage and handling. 

I haven't run the engine yet, it looks like I will be going
through the whole break-in procedure again.  Glad its a fun
engine to play with. 

Anyway, to help with your question.  I noticed that mine ran hot
during run-in.  I think that the material used for the engine is
not as good at heat dissapation as metal.  For this next run-in I
will add castor to my fuel; should have done this anyway, but I
didn't know the first time.  As to the engine quitting suddenly,
if its running hot, it may be freezing up.  Not a pretty thought.

The muffler worked perfectly, and I have not had any failure as
you mention.  I'd send away to K&B for a new unit.  Just my brief
dealing with them made me confident that they would back their
product. 

As it turned out, it was a fortunate happening.  Not only did I
get pardoned for my rough break-in procedure, but I wound up
using an OS .25 in the Eaglet.  At this altitude, the OS barely
pulls the plane; I don't think the K&B would have cut the
mustard. 

The lower crankcase, and I believe part of the cylinder head and
piston is made of a "high tech" plastic composite.  Stu Richmond
tested the engine some time back in Model Builder, but I dont
have the article (can someone send me a copy???, or anyone else's
test, for that matter).  Stu also mentioned that this material is
used in some European engines; I think he specifically mentioned
one that is manufactured behind the Iron Curtain.  Back when I
read the descriptions of this material I wasn't interested in
buying an engine.

A characteristic of this engine is that it is quite large.  My
.20 is about the size of an old McCoy .35 that I have laying
around.   It dwarfs the OS .25, and is significantly heavier; the
Eaglet was nose heavy with the .20 and balances perfectly with
the .25.  But, in its favor, it is one of the quietest engines
ever made, and it has a very smooth and pleasant sound while
running. 

Yuck on those metal chips in the .20!  How did you clean them
out?  I suppose you pulled the back plate and flushed the
area...? I did notice that as the engine ran in it became cooler
and picked up considerably in RPMs. 

I know next to nothing about engines, except 1/2A.  The K&B .20
and the OS .25 are the two largest engines I've ever owned.  This
is all new stuff to me.   Of the two, I guess I gotta agree that
the OS is better quality.  But I bought the K&B cheaply, for the
express purpose of training.  It is a good beginner's engine, as
its quietness makes it seem smaller.  I felt confident enough
after playing with it to go on to the OS without a second
thought. 

As it turned out, the K&B didn't go on my primary trainer, but it
will be on the next one.  If I bury it, I will not cry...However
if I buried the OS, I might feel worse.  I've felt from the start
that the K&B was expendable; I just underestimated how expendable
it really was!

I think that the biggest limitation on the .20 is its size, it is
after all a sport engine.  I don't think it would cowl very
easily for a scale application.  Is the .40 also large (for a
.40)?  

Along those lines, I notice that K&B makes another engine with
its muffler running behind the cylinder.  I think its a .21??
This is for scale applications.  Fred Reese used it in the
Miles-Atwood special. Any experience with this one?  I think that
the problems with the K&B are more due to the uniqueness of the
.20 than with the product line itself.   In other words, I would
buy another K&B without prejudice.

    The 10 minutes of flight time on a 4oz. tank is about right.  At
    least thats what I get on my 4oz. tank.  I recently bought a 6oz.
    which now gives me about 15 min. per flight.
    

    Dan,
    The first thing I would do with a hot running engine would be to
    remove any restrictions to the exhaust.  Many of our model engines
    will not tolerate the added backpressure and the result is overheating.
    I had an OS 40 that was in my chopper and I couldn't even have a
    the 90 degree adapter on the muffler without the engine overheating.
    Other than that, the engine ran fine.  I tried an exhaust extention
    on a Supertiger 40, and I had to take that off due to overheating.
    I have seen some people run with exhaust extentions, but I have
    never had any luck when I have tried it.  
    
    Ken 
   

    Hi Dan,,,
    
    Something must be very wrong with the 40.... I ran it on 12% (from
    Tom's) and never ever had a problem.. It was incredibly dependable.
    I never ran it at high throttle settings for long periods though,
    due to lack of skill.... It might be worth a teardown to check for
    blockage in the fuel flow that might be leaning it out...
    
    
    				Brian...

A couple of evenings ago, I finally got around to being able to
face my K&B .20 again.  The last thing I did to it was to put
some form-a-gasket on the cylinder head to try to stop a leak.
It didn't work; in fact the engine sounded worse running with the
form a gasket.  I wanted to take it apart and clean it before
sending it back, since it just didn't seem nice to complain about
the engine not working with an "unauthorized substance" gooked
all over the head.

Well, I got some news; the form-a-gasket doesn't get along with
model fuel.  The stuff was just as runny as can be; I cleaned it
off in just a few seconds with acetone.

But the reason for this note; I noticed when running the engine
through TDC that as it hit there it had a sloppy spot, about 1/8
inch on either side as you turn the prop shaft gland.  I could
watch the connecting rod on the crank pin and it wasn't moving as
the engine went through TDC.  I checked this with a brand new
engine at the hobby shop; that one was tight, though the shop
owner said that it was normal for them to develop a little slop
at TDC when broken in.  I know that the engine has one heck of a
squeak as it passes TDC.

So...other Sportster owners out there; could you please turn your
engine through TDC with the prop shaft and tell me if your K&B
has slop there too?  If this is normal, I'll try to run the
engine once more, otherwise I'll send it back.

I hear through the grapevine that once these engines are
overheated, and mine was, they are simply scrap metal.

        Re:< Note 771.232 by CLOSUS::TAVARES "John -- Stay low, keep moving" >

        John,
        
                I'll answer  here  anyway.    The problem with the K&B 20
        Sportster  is  that    its   leaky.    That's  actually  a  gross
        understatement.  Air sucks  in  and  fuel squirts out of the most
        incredible places.  I saw  one  where you actually could put your
        finger on top of the venturi and it would keep running!
        
                So what do you do about  it?   Step one is to put a piece
        of  fuel tubing between the carb and  the  needle  valve.    This
        prevents the carb from sucking air in and  spluttering  fuel  out
        that  way.   The enxt step is to totally  diassemble  the  beast,
        clean  all  metal  to metal joints and then VERY CAREFULLY  apply
        liquid  gasket  to  them  and  then  reassemble.    This  applies
        EVERYWHERE, cylinder to  crankcase, cylinder to head, culinder to
        manifold, manifold to muffler, muffler to front plate, muffler to
        back plate, and anywhere else  a leak may happen.  The only place
        it would be nice to plug  and  you can't is the leak at the front
        of the crank shaft.  It will continue to pull air in and splutter
        fuel out around the sleeve.
        
                Once you have done this you will discover  that  it  real
        tight and runs much better.
        
                      _ 
                     / |
        |  _====____/==|
        |-/____________|
        |    |        o \
             O           \ 
                          O
         Hang in there! o_|_
                          |
             Anker      \_|_/

    I need some help getting my K&B .45 to run OK.  First of all, I've been
    tuning OS engines for a while, and I don't have any trouble at all
    getting them to behave.
    
    I can get the K&B to peak out nice at high speed, but at low speeds,
    it tends to "load up".  I'm not real familiar with the K&B carb, so I
    probably haven't set the idle mixture properly.  Any suggestions?
    Is that what that "funnie" screw is near the hi-speed needle on the
    brass disk?
    
    From speaking with a few folks "in the know", the concensus seems to
    be that K&B engines take a looong time to break in. I've run at least
    10 tanks through, so I'd guess it was on it's way to becoming stable.
    Starts great, but isn't reliable enough to fly yet.
    
    
    ANY help is appreciated,
    ....bill_who_should_have_bought_an_OS

    Spend about 35 bucks for an OS Type 4D carb that will fit in place
    of that thing K&B calls a carb. This works great.
    
    
    						Dave
    

Re:      <<< Note 1007.0 by TALLIS::SAMARAS "Advanced Vax Engineering LTN" >>>
                            -< Help tuning K&B .45 >-


Bill,

Do not despair. I do not personally like K & B but they are a good engine. Your 
"in the know" people are definitely correct, they do take time to bed in, that 
is not a catastrophic "feature" only an annoyance.

Try reading my note 289.0 and stick with it.    
    
John

Well, it seems like I got bit by K&B. I got a K&B 20 Sportster a couple
weeks ago for my Scooter. It's the only engine allowed if I want to race
it in the Charles River Club.

I hadn't run the engine yet, or even played around with it much. Then the
CRRC newsletter came last night, and reproduced in it was a letter from 
an RC publication to John Nilsson about problems encountered with the K&B 
engine. In the letter, the writer suggested sealing all metal to metal 
interfaces with RTV gasket material and using K&B 500 fuel rather than
Red Max (something about incompatibility with the silicon aluminum some-
thing or other). The writer also mentioned that he had to send several 
engines back to K&B because the piston/cylinder was out of round. 

Anyway, this got me interested in checking the seals in my new engine, so
I went to hand crank it through a cycle and couldn't do it (no prop). Good
compression, thinks I. So I put a prop on and try again, and STILL can't
turn through TDC. I removed the glow plug and tried again. The piston
definitely binds just before it reaches TDC. This is an engine that will
never run, and now I'm wondering how it could possibly have gotten through
any kind of quality control.

I'm going to take it back to Bob Fish tonight. If I can't get an exchange
I won't be able to test fly the scooter this weekend. I'm bummin'.

Dave

Ah, my favorite subject! :-)

The engine is purposely made to be tight at tdc.  What you're
seeing is normal, and they should all do this.  The engine takes
an especially long time to break in for this reason.  It also
gets very hot.

Woe betide thee if you let it get lean and hot.  My engine has
been so hot you couldn't touch the top of the venturi after a
short run.

My engine squeaked at tdc when it was new.  It squeaked again
after I sent it back to the factory for a new piston and
cylinder.  This last time it came back it was just tight, so I
think they've done an ECO on the part.

K&B owners talk about the times they're sent their engine back in
the same way that Seniors talk about their latest operation, or
commuters talk about their last heart attack.

The first few runs should be for no more than a minute or so.
Then be sure to run it blubbering for the first 20 minutes to
half hour.  After that lean it up slowly --- my experience is
showing that it needs at least 45 minutes to an hour before you
can lean it up to two cycle (if you don't know what this term
means, please ask someone, its easier demonstrated than said),
and some time longer before  you can tweak it for max revs, if
ever.

I've found that the engine needs at least 10% nitro to run right,
and possibly 15%, though I've haven't tried it.  It is extremely
finicky about the setting of the needle valve, and especially
fussy about the balance between the idle mixture screw and the
main needle valve.  You have to alternate between the two
constantly and the final setting is +/- one click, maybe two if
you're lucky.  Also the fuel tank position is very critical for a
full tank run -- it must be set at the classic position in line
with the engine inlet.

I've not spewed much K&B venom here lately, mostly because I'm
still trying to decide if the engine is a piece of junk or not.
Some days I love it, others I'd like to send it to hell.  You
sure can't beat it for starting quickly.

Interesting about it needing the overpriced K&B fuel.  I've added
extra castor to my CoolPower to try to ease its pains.

Rotsa Ruck.

Well, I'm going to show it to Fish anyway, maybe compare it to another (if
he has another). I just can't imagine flip-starting this thing. "Snug" doesn't
properly convey the fit at TDC; more like "welded".

Dave

Well, now that I've gone and slandered K&B, I figure I should give an update.

I took my new .20 back to Bob Fish. He immediately tried to hand turn it, and
even with the plug removed, it was very difficult. "Yep", he says, "this is
pretty tight." Then we compared it with another new .20, and found it was only a
little looser. He then pulled a .40 off the shelf and it was damn near 
impossible to turn through TDC. 

There were a couple other guys in the shop, and they swapped stories on tight
fitting new engines, and how some people actually hand turn all the engines and
buy the tightest one. Now, while we were talking, each one was taking a turn
at sort of absently turning the shaft on my engine (with a prop attached) and
I'll be damned if it didn't slowly start to loosen up! 

So, the upshot is I took it back home and installed it in the Scooter. This
weekend, I tried to start the engine without an electric starter and had no
luck. It sounded like it wanted to go but just couldn't overcome the resistance.
I gave up after getting cramps in my starting arm. I think it'll go with an
electric starter.

But... boy this engine is tight...

Dave

I don't know if I've mentioned it here before, but by .20 has the
nasty habit of firing when the glo battery is not attached.  In
the past its been one or two pops; just enough to make it
important to get the finger out of the way when flipping it for
the prestart prime.

This weekend it started on its own, and actually ran several
seconds without the battery!  Amazing thing was that the engine
was cool, not hot.

Be careful.

I am Inspector Colombo, still trying to trap the criminal
Sportster .20.  So far he has covered his tracks and had an
airtight alibi -- but I know he's guilty, and I watch his every
move.  He will make the fatal mistake sooner or later.

    
    Could this engine possibly have been in a fatal crash at some
    point in the past???????? I was just wondering if some spirit
    of some past plane may be haunting your engine.
    
    Steve

    Re: last-2, John, Steve,
    
    What you're experiencing is _NOT_ that uncommon.  Our 2-cycle engines
    are little more than diesels at best in that they are just on the verge
    of firing the fuel mixture through nothing more than compression...all
    that's needed to complete ignition is just a leeetle help from the
    glow-plug.  As John notes, this phenomenon normally occurs when the
    engine is warm/hot but this condition is _not_ required to have the
    engine fire if all the other conditions are just right.
    
    I've seen/heard/read of many such instances occurring when flipping an
    engine over after blowing it full of WD-40 so it can be seen that the
    presence of glo-fuel is not even a requisite.
    
    The point is that one should ALWAYS treat an engine as though it
    "could" fire cause, when yer' least expecting it, it just might!  I
    value my hands/fingers enough to treat my engines much like a
    loaded-gun and exercise all safety precautions when handling them in
    _any_ circumstance.    

      |
      | |      00	 Adios,      Al
    |_|_|      ( >o
      |    Z__(O_\_	(The Desert Rat)

    I just bought a K&B .28 that has a hole (and plug) for a pressure tap,
    but no tap was included.  The hole is threaded for a 6-40 tap, not the
    6-32 threads that would match the DuBro #241 pressure tap.

    I can drill the muffler for the DuBro or make a new tap from scratch or
    carefully braze in the DuBro or do without or maybe buy a different tap.
    K&B wants six dollars for their tap which they didn't include with the
    motor; grump!  Is there an aftermarket tap for 6-40 threads?
    
    The threads could possibly be a metric 3.5-.6, essentially identical to
    6-40, but I wouldn't expect a US manufacturer to needlessly use a very
    odd metric size, and I'm pretty sure it is 40 tpi, not 42.

    I just put my K&B 28 into the frozen ground hard enough to push the
    carb back, breaking the crankcase and various carb parts.  I haven't
    been happy with the engine's characteristics in starting or tweaking,
    even after adding a pressure tap to the muffler, but the crash was my
    fault with no blame on the engine.  However, it gave me my first
    occasion to take the engine apart.  I was *not* favorably impressed.

    The head-to-cylinder and cylinder-to-crankcase joints are bare metal to
    metal joints with no gaskets.  Moreover, the machining of the crankcase
    surface at the latter joint is rough, not smooth, so this fit could
    never be tight.

    The holes in the crankcase for the pass-down-through head bolts are not
    where they should be.  They are sufficiently off center that the
    threads for one hole are too close to the inside; the crankcase has a
    fine crack at that hole --- almost certainly unrelated to my crash, but
    not indicative of good quality control.

    The piston is worn at the top front and less so at the bottom rear.  I
    suspect that the piston-cylinder fit was too loose.  I had broken the
    engine in at low speed for an hour and then put another 2 to 5 hours of
    use on it.  I did not expect such wear.  I am meticulous about keeping
    the engine clean and using after-run oil after each day's flying, and I
    do not tweak for absolutely maximum power.


    It will cost me about $25 to repair the engine myself or about $35 to
    send it back to K&B, a reasonable charge considering what I did, but is
    this pouring good money after bad?  It had more power than my plane
    required, and I was pleased with the muffler quieting, but my one and
    only delight with the engine was the built-in spider mount.  My OS
    engines are delights to start and run --- every time, every day.

Sounds like a typical K&B engine to me! My .20 shows many of the same quality 
problems as yours (mine has big holes in the casting inside the carb). And I
have never been able to get the needle valve assembly to stay tight, so when it
loosens it leaks and the engine runs lean. 

BUT, if you seal up all the orifices and interfaces with high temp RTV, it 
turns into a real screamer, and a quiet one at that. But I have yet to find an
RTV compound that won't come apart with prolonged contact with fuel.

Dave

    I always bought o.s and H.B engines.The k&B has been nothing but
    problums.After two gallons of fuel and many dead stick landings
    it started spitting out little chips of metal.The most fun i had
    with this engine was throwing it into the woods behind my house!
    What you save in money,you pay for in aggravation.
    
                                                     PM
    

No, the K&B .20 is the worst engine ever made.  Nothing could
possibly be a bigger piece of junk than that.  At least you got
your engine to fly by throwing it; I didn't try that, but I have
it in a box to remind me to never buy anything but a OS, Fox, or
Enya.  Maybe I'll have it bronzed and buried with me to remind
the world that Here Lies A Fool Who Was Easily Parted With His
Money.

>         <<< Note 163.34 by CLOSUS::TAVARES "Stay low, keep moving" >>>
>                                   -< Bah! >-
>
>No, the K&B .20 is the worst engine ever made.  Nothing could
>possibly be a bigger piece of junk than that.  At least you got
...

What about 6 K&B .20 all geared together in a radial
configuration from Radial Engine Technologies Inc.

Someone at the WRAM show said - putting 6 together is the only
way to be certain one is running!

I have no personal complaints of K&B and I have a K&B .60
that runs just fine.

Bye          --+--
Kay R. Fisher  |
---------------O---------------
################################################################################

	We've been through this one many times, but I'll repeat: you have to
	seal up the K&B .20 for it run reliably! I use hi-temp RTV at the 
	interface between the body and the head, and where the muffler attaches.
	I also have a persistant leak where the needle valve screws into the
	carb, so I have to occasionally retighten the hold down nut. My problem
	is that the fuel seems to attack all the RTV compounds I've tried, so
	periodically I have to re-seal it. 

	No doubt about it, a lot of work for a simple little engine, but when
	it's running good, it really screams! I think it holds its own against
	the OS 25.

	Of course, in hot weather it seems to overheat pretty easily. Come to
	think of it, it IS a crummy engine! But for unexplainable reasons, I
	stick with it.

	Dave

    Just for the record,  I can't stand K&B.  Cheaply built, cheap
    quality, poor design, heavy.  Definitely a throw away engine.  My .61
    lasted about 2 seasons (Spring and Summer).  Good engine if you like
    creating alot of oily mess on your airplane.
    
    Just my opinion,
    
    John C

    I'll stop waaaaaaaaay short of recommending K&B, much to my chagrin. 
    We really need a "competitive" U.S. engine manufacturer!  However, Bob
    Frey has a K&B .61 which he won in a scale contest a few years ago and
    it's been in an Ugly-Stik, an Aeromaster and, now, his tired old
    Stagspitoon (cosmetically altered Kaos) and has always performed well
    (at a sport-engine level).  It's always been a bit fussy on the needle
    setting but, otherwise, has been dependable and reasonably powerful.
    
    K&B racing .40's, especially the Clarence Lee customs, are still a
    quantity to be dealt with in Formula-I and quickie-500 racing.  And,
    K&B ducted-fan engines, particularly the special Violett KBV .81,
    remain the most common seen in that field.
    
    I believe K&B _does_ have the ability to build good engines but,
    somehow, that ability doesn't seem to filter down to their sport and
    entry-level engines.  If K&B (and Fox) would upgrade their designs and
    tighten up their quality control, I can see no reason why they
    _couldn't_ compete with the foreign mfgr's.  Perhaps it's merely a
    question of desire, although I strongly suspect it's more a matter of
    economics. 
						 __
				|      |        / |\	   	       
      	         \|/		|______|__(o/--/  | \	   	       
      | |        00	       <|  ~~~  ____ 04 ---- | --------------------
    |_|_|        (O>o		|\)____/___|\_____|_/	   Adios amigos, Al
      |     \__(O_\_	        |	  |___/	 o	   (The Desert Rat)

    Hey, 
       wait a minute,
    		    there are some of us who have K&B 20's (albeit on a 
                     boat), and have had good luck with them. 
    
    
    					Steve M...

    Every boat needs and anchor!

Well, I *do* get upset whenever I think of that beast.  Its
really strange, the engine starts on a flip and runs perfectly.
It just has two faults: it gets very very hot, and it has no
power.  I don't need it pointed out that these are probably
related.  I've never seen an engine get so hot down on the
crankcase, to where you couldn't even touch the carb without
getting a nasty burn.

After the 2nd rebuild from the factory, I ran it for a
summer in Son of Quik Stik, with absolutely wonderful results.

I really felt bad for knocking the engine and I then began to
prepare for my pilgrimage to the K&B factory. I would shave off
my eyebrows, coat myself with ashes and wear a sackcloth, and I
would go to the factory like this: I would pause after each step and
whip myself once in attonement, and after every three steps I
would kneel and beg forgiveness for cursing their wonderful
engine, while crying and beating my chest.  I would do this all
the way from Coleraddy to California (where the factory was at
the time).

I was ready to do this, I even shaved off my eyebrows and started
saving ashes from my fireplace (only the most fragrant cedar
logs).  Then the engine started losing power. Each flight it got
worse, until it wasn't even up to the snuff of an old .15 I have.
Finally after dead sticking Son of Quik Stik into the field for the
umpteenth time, I realized that I was right all along, and that
made me feel better.  Though I felt much better when my eyebrows
grew back.

To be honest, I was thinking recently of digging it out of the
box and trying it once more on the test jig -- I just can't
believe it was that bad, and my selective memory remembers some
wonderful flights with that engine.