JollyPopper

My Feedback: (6)

I picked up a K&B .65 Sportster for next to nothing. It was new, never mounted or run. I have been attempting for several months now, off and on, to break this turkey in. It runs well for awhile and then quits very suddenly, as if someone were turning off the ignition in a car. It does not slow and die, stutter, gurgle or anything. It just quits. It is running at 3/4 to full throttle one second and dead the next. It has not been run lean at any time. Too rich if anything. I have been using 15% nitro--maybe that is the problem. I am not very impressed with this engine and have been tempted to simply discard it, but thought I'd ask you folks before I deep sixed it. Oh, Completely changed all fuel lines, tank, stopper, etc. It is not a problem getting fuel to the carb. anyone????

w8ye

My Feedback: (16)

You need to run more oil in this engine than what normally comes in todays fuel.

Also the engine is not a high rpm engine so a little bit larger prop at a slower rpm is in order once you get it broken in.

Some people that learned the engine's idiosyncrasies enjoy them. Other's think they are junk.

rcdude7

My Feedback: (264)

That engine is unlike any other, it has a chromed piston running in a bare aluminum bore, also the con rod has no bushings. The alloy they are made from is supposedly a very good bearing material in itself, hence the bare bore. They take a long time to break-in and a very oily fuel mix is preferred, mostly castor. The sportsters are good engines once they are broken-in properly, and prefer to swing props that are on the large side.

FrancisPerson

On the large side!!! My Sportster .65 turns a 13x6 APC at 10,700 RPM, a 13x8 or 14x6 is a better choice. BUT I had lots of sudden stops. I did a few things: one installed a pressure tap in the round part of the muffler, two used large fuel and muffler presure lines, three you must not have the spray bar ANY MORE THAN 1/4" above the center of the tank and I installed a spray bar with two outlets that I got from MECOA. I then had a great running engine, two flights later I crashed the plane???

Francis

TimC

I was having much the same problem with a .45 Sportster. I even had a backfire blow the carb apart. When I switched to 5% nitro, the problem went away.

FrancisPerson

I use 10% Omega with 3~4 oz of extra castor oil added

Francis

Gizmo-RCU

My Feedback: (27)

I got one from a friend in a trade thing. This engine was doing exactly as you discribed. It actually squeeked when running, just before stopping (hot). I gave him some 5% with Castor, the problem was gone never to return as loong as the Castor is used.
These engines will perform nearly as well as larger 4 strokes when using an MAS 14x6 prop and are real easy to use and maintain.

old propnut

The muffler on the 65 will not allow the engine to breath and will cause over heating. Open up the center hole on the internal muffler pipe and drill a few more holes in the internal pipe .this will relieve some of the back pressure,sound will not increase very much.

JollyPopper

My Feedback: (6)

Sounds like adding oil is the first thing to try. I have some Klotz Super TechniPlate (isn't that impressive?), but you guys are stressing castor. Is this the same stuff my momma used to give me for everthing from appendicitis to a cut foot? And when you say 3-4 oz., I assume that is per gallon. Thanks for the replies, folk. Sounds like it may be a decent runner with a little TLC.

Highlights

I Have the same thing going on here. I really only fly large aerobatic planes for 3D and precision, however I have had this little mustang just waiting for flight now for 18 years. I have finally had to put this K&B sportster on a break in stand. I have been running it in for a couple of days now. 5 tank fulls. Just when I think it is too lean , it's too rich. When I think it is too rich it gets too lean. Damn this thing has a complex. I cannot seem to get it to more than just over half throttle. It seems to lean out but then mass amounts of wet smoke comes out, starts to choke so I cut the throttle , recover and try again . I lean it out get a little higher but then can't bring her back down without the low end seeming to have the incorrect mixture. Just rescently I have mounted several engines on airframes and was 3Ding them the same day. YS and OS to name a few. Will I ever trust this K&B to fly this plane???????????????


I have researched everywhere as to what this motor likes. Everything has been checked and double checked. This is a brand new 20 year old motor.

Opinions

PS. the tank was at the correct height in relation to the carb while running. The pic below was just at the time of being set up.

Highlights

By the way I thought I should say.................. I can tune it to a really clean sounding pleasantly smoky mix. I can run it at what ever rpm I choose. It will run until the tank goes dry. No hesitations. The minute I try to transition , it's all over the place

TimC

Highlights, maybe the carb 0-rings have dried and cracked over 20 years. What % nitro are you using? My Sportster didn't like over 5%.

Highlights

I took the carb off and gave it a thourough once over. The o-rings are in good shape. The elasticity is as if they were just out of the box. I am using 15 % nitro. A mix of synthetic and castor. I have tried med /cold plugs and hot plugs. No real big diiferance to note

What seems odd is the low idle mixture. It is a screw that only turns 1/4 right or left. When I try to fine tune it the vibration does not allow for it to hold it's position. It always seems to creep back to neutral. Kind of like it is falling off a lobe. As for the idle set screw, well I just ignore it and use my tx to sort that out. This motor just seems to puke out so much oil. Everything is soaked by the time the tank is empty. The bushing at the front of the crank case allows for excess to leak as well. Unless it is running it really is a messy system. Man I can't imagine it in my nice clean fuse.

I am realy close to ordering up an OS 55 ax. 4oz lighter and .7 more horse at 2000 more rpm.

I just want to see this thing fly. It has had such a long history. The motor too. That is why I am really trying to get it sorted out.

Once it has flown I will probably sell the motor and hang the plane up.

turbo.gst

My Feedback: (8)

My Sportster 65 is also 20 years old. I have used it for the whole time. It takes lots of oil to break it in. I use 22% oil and more than that for the actual break-in. It loves the big props. I use it like a 4 stroke. I have never had one dead stick in actual use. The break-in was an entirely different situation. It squeaked so bad when new, that it was worse than fingernails on a chaulk board. I really like the engine and now have 4 of them.

Good luck,
turbo

Highlights

Hey Turbo, that is good to hear. I guess I will just keep working on her. Anything out of the norm like these other guys are talking about? ie. extra holes in the muffler,larger fuel tubing, pressure taps, low nitro, more oil , hotter plugs, cooler plugs, bigger props, sledge hammer(lol).

Thanks,

Mark

Hey by the way, seeing as you said yours is 20 years old as well; is it the same.62 #5800 sportster like I have. MIne does not have the remote needle like the newer .65 Apparently K&B also recognized that the cooling fins were too aggresive in the earlier models like mine. The later models were machined down so the head could reach a higher temp. I guess this model engine would be considered an AAC ringed motor???? The Mecoa site explains the differances between the types of rings ,cylinders and materials used in the motors, but neglects to clasify any of the motors for the customer.

Gizmo-RCU

My Feedback: (27)

The cold does not help evaluate or accelarate break-in. Wrong time of year for that, especially outside. Went thru that with a Saito 100 twin today.........finally got it dialed. 24 degrees.

NM2K

My Feedback: (14)

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When all is as it should be, the Sportster mufflers (all sizes) were designed to be quiet and to provide a boost when compared to K&B's muffler for the .61 ball bearing engine.

The engine's carb was designed to run without muffler pressure. Doing so on some samples will aggravate tuning issues. On others there is no effect. Don't know why.

There wasn't/isn't a ball bearing in these engines. The originals didn't even have a single plain bearing (bushing).

Break-in (actually self machining in many cases) is a barbaric and brutal process with the Sportster line. When they first came out, folks were throwing these engines away after two or three tank fulls of fuel through them (used to OS instant break-in). You must use a fuel with lots of oil and it is wise to add some castor oil to the mix if the mix consists of all synthetic oil. We used to call the .65 Sportster, "the poor man's four-stroke". Once broken-in, it will easily handle a 14x6 prop as well as most .91 four-strokes.

One last thing - if you want to try a Diesel, but want to go with a conversion head instead of an expensive factory Diesel, these are great engines for that purpose. The smaller ones are notably better Diesels than the large ones. Try to get one with the crankshaft bearing in the crankcase.


Ed Cregger

turbo.gst

My Feedback: (8)

Highlights,

I do run a larger volume muffler on my setup for my Sportster .65 We have the same original version PN #5800. I actually prefer the needle on the carb instead of the remote setup, but they both work fine. I use a BCM 'Sport' muffler # 11062. The muffler fits the ST 45- 60BB, Webra Blackhead/ Silverline .61, HB .40-.61, and K&B .61 & .65, so I have several engines to use it on. I use 22% oil ( the GMA / powermaster stunt blend) with a 13 x 5, 6 or 14 x 6 depending on application.

I set it rich-- in fact, it looks like I have a smoker on the plane. It is very quiet! I have had people come up and ask what engine is in the plane. Most don't believe that it is a Sportster .65 I really like the engine in that use. I was very unhappy with it trying to use standard .60 props with it. I read about using it as a 'poor mans' 4 stroke in RC Report and decided to try it. I have since bought several more and look forward to using them the same way. It is a first flip starter, idles perfectly with excellent transition. It just makes a different type of power than most 2 stroke .60's I hope you enjoy yours as much as I have.

turbo

madman75

I've got one that was given to me years ago when K&B was in AZ. It was about wore out. Sent it to them for warranty repair(remember when the Sportsters had a lifetime warranty for almost everything but crash damage) because it was about wore out. They sent it back at no cost and replaced everything but the muffler, carb and drive collet. I still have it and I fly it in a Sig Kougar. I removed the baffle in the muffler and added muffler pressure. It runs like a champ on Wildcat 10% fuel with 18% castor and 2% synthetic. It swings a 13x5 Zinger prop which pulls the Kougar like a stripped *****ed ape. Almost unlimited vertical and unbelievable level flight speed.
Heck, I even had a Sportster 45 and a Sportster 20 on planes that I still fly. The 45 and 20 were bought before K&B moved to AZ. The 20 has an o-ring for the head gasket so this is how old it is. All engines run like a top and all have the muffler baffles removed and have muffler pressure.

NM2K

My Feedback: (14)

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All of the Sportsters go through a torturous break-in period. I mean, it sounds inhuman to run the engine with all of those weird sounds emanating from the crankcase, but it must be done - and with plenty of oil, with castor oil preferred.

With all of that said, they turn into really great/unique style engines.

Sudden quitting is a sign of insufficient break-in time or too much prop for the state of break-in. You can acclimatize the engine to running larger props by creeping up in prop load as you break the engine in. The Sportster .28 on my wife's Red Zephyr does not like a prop with more load than a MAS 9x4, regardless of how long I run it.


Ed Cregger

submikester

My Feedback: (6)

I'm surprised nobody has said anything about the nitro content. I recall my old sportsters all ran better on lower nitro content and higher oil. All of the advise has been good and all I would add would be to do one thing at a time and try a lower nitro fuel.

Kruzer

Hi everyone. Vey informative thread. This engine sure seems to like things a particular way. Have one question, if handled properly, what would this engine do for a Goldberg .40 Wild Stick? Any hope for 3D with this combo?

huck1199

I have a bunch of K&B engines. They are great values, I get em on Ebay NIB cheap. Most recent is a .45 Sportster with machined head fins. 1 gallon break-in with 15% Omega with an extra 4 oz. of Klotz Castor per gallon. I replaced the o-rings on the idle disk low speed needle before I started break-in. No problems all summer, pulls like a tractor on a heavy S.P.A.D. with an 11x5 prop. Starts easily and transitions fine. It is messy but not much more than most glow engines.

NM2K

My Feedback: (14)

Turbo.gst hit it right on the head, as far as I'm concerned.

If you're looking for an OS type of engine, believe me, this isn't the one. But if you are looking for a "poor man's four-stroke", it is a perfect match.

I have two Sportster .28 engiens and one .65 Sportster. I cursed the .28 engines at first. Why? Because I was expecting them to run similarly to my old K&B .40 and .61 engines of years previous. They do not. At least, they do not right out of the box. These engines are crudely built and they take some babying to get them just right. Lots of oil and it should be castor oil, or one hell of a lot more synthetic oil than you are used to using.

My first experience with the Sportster .65 was when I flew a friend's kit built Sig Kadet Senior. I forget the size of prop on the nose, but it was much larger than the traditional 11x7-8 prop that a sixty would normally spin. The engine had been flown quite extensively on this Kadet Senior and was well seated. It was a *****cat to hand start, idled and transitioned without stumbling at all, and once running, did not quit until it ran out of fuel. Who could ask for more? Well, it was also quieter than the average sport engine too.

The Sportsters were designed with a muffler that was effective and which provided a bit of boost when compared to other design mufflers of the period.

The carbs were designed to run without muffler pressure initially. Later, K&B caved in and fitted the engines with muffler nipples. Didn't make any difference, but it did keep the modelers from complaining about it.

Early versions (many years of production) did not have bronze bushings fitted to any part of the engine. K&B had a lifetime warranty on these engines. When the crankcases or connecting rods wore out, they would replace them for free. Later iterations of the engines were fitted with bronze bushings. Again, this may have been an attempt to quell the complaints of some folks. None of my bushingless Sportsters have needed new crankcases or connecting rods as yet - so go figure. There was one fellow at my Salem County R/C Club field (Ray Hubshmitt), who seemed to take delight in seeing how many times he could get K&B to replace his thoroughly worn-out .45 Sportster crankcase for free. Ray used to fly A LOT, but he always used fuel with at least some castor oil in it - maybe all castor oil.

So, if you are looking for an engine that will pop into your model and run just like the OS, Enya, Webra, YS or Irvine that you took out of there, look elsewhere. The K&B Sportster series is not for you.

If, however, you like exploring new territory in how differently engines can behave (engine freak - like Hobbsy, Jim and me) due to metallurgy and basic design philosophy, the K&B Sportster Series engines can be loads of fun. Just don't be in a big hurry and buy some fuel with at least half castor oil lube, preferably all castor lube.

And remember to have plenty of patience. This IS a hobby my friend. The journey is far more fun than actually getting there.


Ed Cregger

dennis

My Feedback: (90)

Ed,
That Sportster should be doing much better on a larger prop then that. I broke in a 28 as a diesel without ever running it as a glow and flew it for years ,even had it on a Florio Butterfly. The V tailed one. Just for laughs I used to fly it against the Webra 32 with mousse can mufflers. I'd use an 11/7 prop and turn so tight I'd swear that I hit the carbon fibre tube.
It was last on a Sig ARF C/L Primary Force with an 11/5 and easily kept up with much larger and of course higher powered models.
Had a senior moment and crashed the model so the motor is now back in the box after more then 15 years
Incidentally a Sportster 65 dieselized thrives on an 18/5 or 6 prop.
Dennis

Oh and everyone who says that it takes awhile to get that motor run in is absolutely correct, and use good fuel, not that cheap soda pop pink stuff,