AMB

OK mr UPS showed up at my door today with a box from davis. Mr Davis had picked up the engine and his head with it, The head was
redone by Bob since the original owner lost the locking screw did his "homemade thing"It has very low hrs all intructions and warranty
card still with it in the box along with a radial/Mount backplate unit the price was still on the bag a mighty $3.15 maybe60s??
benched it today ran Davis Plane fuel Zinger 10x5 running 9000-9100 single needle carb not even an air bleed ( none needed)
idle about 2700 and steady This is the one going in my Thunder Tiger Lazy Cub a 25 size plane 14" chord 50" span about 650 sq inchs

My 2nd Kand B my first decades ago in U control good stuff goes forever martin

gcb

I have a couple of the 20's NIB (no conversions though). They came with the radial backplate in the box. My parts list had the backplate as $3.50 retail. Nothing in either box indicates the time of manufacture, but I remember it as early eighties. I think the 20 was short-lived in that they upped the size to 28 and dropped the 20.

These are still being made by K&B/RJL, but I think it is only the 28. They may still make the larger Sportsters also.

Good luck with it.

George

NM2K

My Feedback: (14)

I have a low time .28 that I have thought about converting, but it is the early version that does not have a bushing in the crankcase. Is anyone running one of these? How is the crankcase holding up in diesel use? TIA

FrancisPerson

Please post any K&B Sportster .28 Diesel conversion info as I have one and it is none to powerful. I imagine that a converted .28 could spin a 10x6 at 10K ???

Hobbsy

My Feedback: (102)

I recieved a new head for my Irvine .25 from AJ today and it works and looks great. The top picture is idling at 3,000 rpm, the lower pic. is full throttle at 11,750 rpm. The prop is an APC 10x5, yes I actually used an APC, for the first time ever. The 11,750 rpm is not the max rpm attainable, I got 12,100 at one point but the engine would wander between 11,900 and 12,100, I reduced the compression 1/8 of a turn and it settled at a rock steady 11,750. I think a lower idle is doable with a little tinkering. The thing actually started while I was priming it with my finger over the carb. The fuel was Davis ABC mix and the muffler is a Davis in cowl. The engine is going to be on its side on a Sig LT 25. Thanks again AJ, good job.


Francis, I don't know if this any comparison or not. Here's ma link to the pics.. http://www.rcuniverse.com/forum/m_1748209/tm.htm

NM2K

My Feedback: (14)

I haven't ran my K&B .28 as a Diesel as yet. On glow it doesn't like large props. It runs great with a 9x4 on my wife's Red Zephyr R/C Assist. I haven't tached the engine in over a decade, so I can't remember what it does as a glow, but I'll betcha it is over 13k rpm on glow when running the 9x4 MAS prop with the stock muffler.

With that said, are you stuck using a 10x6 because of space constraints? I would think that a 12x6-7 would probably present the Diesel conversion in its best light.

AMB

Hobbsy sounds great but I think your pix has vanished somewhere in the great electronic black hole martin

AMB

I just jumped to the Davis site and indeed both the 20 and 28 sportster heads are listed not bad for an engine 20+ years old
I think RJL still makes the 28?? martin

FrancisPerson

Ed,

this plane is only recently finished and I do not have a Davis head yet. It is a Tiger 20 and weighs 3 lbs 12 oz. I am worried that it will be wimpy. My Davis diesel converted FOX .15 turns a black MAS at 13,200.

For some reason it turns 11K on the plane and 12K on a test stand??? Could that be because I did not use the usual Dubro black mount and the Goldberg "breakaway" mount is flexable???????????

This Tiger 20 is replacing my "EX" Tiger 60; see the pics and play taps.

Francis

FrancisPerson

Dave,

A 10x5 at 11,700 would be great.

Francis

Hobbsy

My Feedback: (102)

http://www.rcuniverse.com/forum/m_1748209/tm.htm

Here's a link to the pictures, I couldn't move them here for some reason.

NM2K

My Feedback: (14)

I just woke up, FrancisPerson. I'll have to think about your rpm dilemma for a while. <G>

I flew my Florio Stunt Wagon a few times with the K&B .28 on glow in place of the OS .32F-H that normally powered it. It was like flying at half throttle. I quickly put the OS.32F-H back on the 4.5 lbs. Stunt Wagon. I thought the K&B would stack up a lot better against the OS than it did. However, the K&B .28 did run well after break-in, just not as powerfully.

As I said, I have to wake up. I'll think about that rpm difference. You may be right, it could have been due to flexing of the mount.

Hobbsy

My Feedback: (102)

I had the pleasure of flying Francis' green Tiger and that prompted me to get one of my own, his flew like it was on rails, I loved it. What a shame to lose it. I have a Fox .74 conversion in mine with a Sullivan soft mount. The Sullivan is too soft and I'm going to completely re-do the engine install.

AMB

Just surfed to the mecoa/kb site the sportster 20 is is still listed but "requires time" on availabilty the 28 is available both are $69.95
If one was starting from scratch you would want the 28 anyhow but quite happy with my 20 martin