Sportster break-in procedure?
 

Now that I have this K&B .45 running, I was wondering if anyone had definitive procedures for the break in of this engine? The manual for this engine is vague, to say the least, and being a newcomer to the field, I've heard several different comments. I leave it to you, the experts, for further advice. Thanks,

Todd

Sportster break-in procedure?
 

I have two .65 Sportsters. So all I can say is,
these are kind of different engines, you will
notice that the bore is naked aluminum and the
piston is chromed. One of mine was very tight
and the other is loose to begin with.The tight
one tore a little patch of chrome of the
piston trying to break it in. This let me know
that it wants maybe 10% of the fuel to be castor.
I took it apart, it's OK and still runs well.
I run all castor now with these a little bit
rich always, doesn't seem to hurt power much.
Suggest you use some castor in fuel.
If yours is tight run it rich quite a while.
Manual recommends 11x7 but mine handle 12x6
with good rpm.

Good luck

Sportster break-in procedure?
 

JCM,

Thanks for the info! I've been running it so rich, for two tanks now, fuel spray has forced me to cover the garage floor with a drop cloth. I have done this so far: Open the needle valve 2 1/2 turns. Run it for about 30 minutes (in 2 and 3 minute intervals). Close the needle to 2 turns and run it for 3, 4 and 4 minutes, and then twice more at 8 minutes each. With each run, I have only had the throttle at either a fast idle or slightly higher. The engine has quit on its own each time. Is this the correct method, and if so, how do I proceed from here?

Todd

Sportster break-in procedure?
 

If this is a non ringed ABC type engine, running it rich is totaly wrong. By running it rich the engine has been kept cool. This means the engine has been running tight and wearing itself out.

An ABC type of engine must be bought up to operating rpm and temperature during the breakin process. This must be done with a rich setting. To achieve this a smaller than usable propellor is used. This allows the engine to reach it operating temperature and rpm with lots of lubrication. The engine should be allowed to cool completely between each 4-5 minute run.

The running clearances of the engine are correct at temperature, not when it is cold. As the temperature comes up the piston and liner expand to the correct running fits.

By running your engine rich and cool it is very likely you have worn away many usefull hours of engine life.

Ed S

Sportster break-in procedure?
 

From the K&B .45 instruction sheet:
"It is unnecessary to give the engine a prolonged break-in.....It is strongly recommended that fuels containing more than 15% nitromethane be avoided until after the engine has been in operation for about an hour on a mild fuel, and under mixture rich conditions."
I just need to know step by step how I should continue. The K&B instruction sheet just does not go into detail enough.

Thanks,

Todd

Run it Rich
 

The K&B Sportsters are not ABC engines. They don't have rings either. The SOP for ABC type is to run them fairly hot. Don't do this with a Sportster. I have three of them and a rich long break in is required. I put a gallon of fuel through my .65 before I was ready to fly it. Also in practice the reccomended props are too small. I run a 9x4 on my .20 and a 14x6 on my .65. I bought my .45 from a friend but I haven't run it yet. When I do I will probably use an 11x6 or a 12x5. FWIW I found that I got the best runs with Omega or Powermaster.

Sportster break-in procedure?
 

I had a K&B.45 sportster on my trainer. Run it at full throttle and rich enough to be in a four cycle for one tank full(8 ounce). The next couple tanks, squeeze the fuel line enough to get it in a two cycle, hold for a minute and let loose, do this every few minutes. Now it's ready to fly, just keep it on the slightly rich side for awhile(first gallon). This engine does not make a lot of power, and you should not try to run it at peak rpm, ever. I had one that locked up like that, sent it back under the lifetime warranty, they replaced it for the $5 shipping charge.

Sportster break-in procedure?
 

I can only tell you what I do with my .65's,
after I warm it up at 1/3 to 1/2 power with the
needle good and rich I then run it wide open
and quickly screw the needle in to peak it,
and then real quick back it out 1/4 to 1/2
turn. It doesn't seem to lose any rpm and
doesn't get to hot then.I really don't love the
way the K&B carb adjusts wide open, I've got a
Perry on one, it's high speed is better, but
believe it or not the K&B idles better for
me.
I looked at the size of the combustion chamber
in the head, it seems a little small to burn
more than 15%. If anyone has run one on more
I'd like to hear about it.
God luck to all.

Sportster break-in procedure?
 

Alot of good suggestions! I will be setting it up this weekend, after I run a third tank of fuel through it. If anyone else has any other comments, please feel free to leave a post.

Thanks,

Todd

K&B Sportster Engines
 

I can't say about the .45, but the .20 and .28 took an inordinate time to break in, somewhere like 3 gallons of fuel. The people who loved them usually bought them from someone who gave up on the engine before it really started running well.

Sportster break-in procedure?
 

I really like the sportster engines, I flew my 4-star 40 for years with a 45 and a 12-6 prop, yes 12-6, they a real stump pullers. They do however like some caster, although I have known people who have run them for years with total synthetic oil.

Aircat