Coloradobanjo

My Feedback: (3)

I have an old K&B .60 that has had two glow plug failures in four flights. Using a normal single nicad-cell to start, so this isn't a voltage problem. Engine runs great at full RPM, rough and rich in the mid-range, and sometimes loads up and stalls at idle. I use muffler pressure. Did I just get two bad plugs? The plugs were both longs with an idle bar. Any ideas?

Chris Bart
Arvada, CO

John Hawkins

My Feedback: (2)

You might check to see if your bearing retainer is coming apart and small pieces of debris are taking out the plug coil. Some of the older K&B bearings were susceptible to this.

John Hawkins

My Feedback: (2)

I should have added that if the retainer goes the bearing will come apart and seriously damage the engine.

Homebrewer

My Feedback: (8)

Rapid glow plug failure is often a result of running your engine too lean and am wondering if you are trying to compensate for the rich low/mid range by leaning out your top end needle instead of your low end.

Personally, I use nothing but OS plugs. The OS 3 plug seems to last forever and is well worth the price. Try one and it should last longer.

John Hawkins

My Feedback: (2)

I'm a fan of OS plugs too, however the K&B being older, may be of the loop scavenged type where a baffle on top of the piston directs the mixture up toward the plug and tends to put it out at idle when atomization is not so good. The idle bar prevents some of the 'large' droplets from cooling the coil. The number 8 may work fine under those circumstances anyway but it is something to keep in mind.

ZB50

I sent my like new Veco 61 to Clarence Lee with a standard plug in the head and he specifically noted in my return note with the modified engine, that I should use a long, idle bar plug due to this engine being of the loop scavenged type.

ZB

Spaceclam

it is probably rich in the midrange because your low end is rich. your low end adjustment works from about 0% all the way up to 80% of rull throttle. try leaning out your low end

big max 1935

My Feedback: (9)

If it is a old K & B 60 it most likely has a Perry carb on it , they don't like dirt & junk in the carb & with age the two "o" rings get hard & effect running. I would run it & put my finger in exhaust & look for shinny particles in the oil , a sure sign that something is coming apart inside. Most likely a connecting rod or bearing. Like C. Lee said a idle bar plug & use a fuel filter before carb. MAX H.

Coloradobanjo

My Feedback: (3)

One way or another I think I can use every post you guys have made. First, I had no idea the idle adjust influenced mixture all the way to 80%. I'll lean the idle out and richen the top end just a tad. I'll go buy an OS idle bar long glow plug or two, and a fuel filter and try that as well. Lastly, I DID notice that the slime on the side of the plane was grayer than I remember from my past gas engine RC days. This is a powerful engine, but it's a really old four head-bolt design, and a K&B is a cheapie. I didn't pay much for it, and I think I'll start looking around for a replacement if the slime doesn't clean up. I looked in the plug hole and saw no damage, but that doesn't tell the story in the crankcase. Thanks for unraveling most if not all of the mystery and adding to my engine knowledge.

Chris

big max 1935

My Feedback: (9)

You have a K & B Sportster 65, no ball bearings, no Perry carb but close,some of same problems. Don't really need idle bar plug but may help in some cases. Possible loose muffler bolts ,noted for stripping out. Only things inside to really go bad are probably connecting rod or piston pin holes. If not these ,like you said ,buy a better engine. MAX H.

Coloradobanjo

My Feedback: (3)

Right you are!

I pulled the owner's manual and parts list off the net based on what you said.

Thanks again

Chris Bart

big max 1935

My Feedback: (9)

I don't think I would call a Sportster series engine cheap . More like innovative & like any thing new & different can sometimes accrue a bad reputation. Another of the misunderstood engines . Run properly with a fuel of 20 to 25% oil content with a larger propeller than you would think it could pull they were a pretty good old beast. I kind of like them! MAX H.

Coloradobanjo

My Feedback: (3)

Your comments intrigue me. I am a often the fan of the underdog, and might give this engine another look.

Reference props:
The manual says start with an 11X7. Being a Denverite, I also got an 11X8, since one size up in pitch is usually the ticket here. Now, I am interested in prop hanging and aerobatics more than speed, so what do you recommend?

My fuel is Cool power 15%. What say there?

So that all said, if I wanted to give the engine a tune-up, what parts would you suggest?

Chris

big max 1935

My Feedback: (9)

Ah ,A man after my own heart. Glad to hear you want to give it a new look. I would pull the rear cover & check the large end of the rod , if it looks ok remove the 4 head bolts that also hold the cylinder to the crank case, slip it up & check the small end of the rod & wrist pin wear in piston . If they look OK you are ahead now. With a prop on it hold the engine upright & push the prop & crank shaft up & down & look for excessive play in crank case . If it looks quite bad may as well stop now as it is kaput. The carb . idle disk is just held in by the two "O" rings , pry it out with a small screw driver & see if the rings are hard or damaged ,look for junk in area between rings & especially in slot & small hole. The small screw is an eccentric & turning lt. & rt. adjust idle mixture, a little bit goes a long way . As for a prop I would go bigger yet ,try a 13 X 5 or 6 . also I like Omega or SIG fuel that has some castor oil in it , you can't beat castor . If all looks pretty good you most likely won't need parts. MAX H.

Coloradobanjo

My Feedback: (3)

Conn rod is shot, some play in the crank to crankcase. Bushing shows wear at front from silver to brass. Piston and wrist pin feel good. Idle bar has hole elongated along its axis. Total for O-rings, bar, conn rod and shipping is 28 bucks. Do you think its worth it?

Spaceclam

no

Sport_Pilot

some play in the crank to crankcase.
Idle bar has hole elongated along its axis.

This is as it should be. I think the bushing may be OK also as I think they used a high silicon case and partial bronze bushing. All you need is the con rod. But how did it wear? Is it bushed? Or plain alluminum.

Other wise it sounds like you did not lean out the idle, you turn the small screw at the top of the disk on the left side in very small increments to adjust.

Sport_Pilot

Also you need fuel with plenty of castor oil. Cool Power does not fill that bill.

Coloradobanjo

My Feedback: (3)

I checked the throw on the crankshaft, and it is a little grooved. I'll take the engine to the swap meet tonight, and sell it as needing a conn rod, and being a good engine for a back-up plane after that is done.

Over and out,

Chris

Sport_Pilot

Small grooves or scratch's on the con rod is also normal. If it doesn't have excessive play, its good.

Coloradobanjo

My Feedback: (3)

...so I didn't either. I tore the engine down again, gave the throw a very light going over with crocus cloth, and it cleaned up beautifully. I mic'ed it with my trusty old Starrett, and it showed no change, and no ovality. Everything else looked good, so I ordered a conn rod for 8 bucks and shipping. Even if it doesn't work, which I bet it will, it is worth it for the education and adventure. I'll post the final results in a week or two.

Thanks to all.

Chris

big max 1935

My Feedback: (9)

Atta boy! I had a feeling you were not a quitter ! Just add some castor oil to your fuel or buy some with it in & the old girl will give you some good service yet ! Good show! MAX HANSEN AMA 14958 AVP AMA & IMAA Dist. IX S.D.