K&B .45 Sportster
09-28-2011, 05:07 PM
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K&B .45 Sportster
Hey, i have a ole' K&B .45 Sportster that was given to me and i wanna put in a sport/scale airplane. Any ARFs come to mind for this motor?
09-30-2011, 10:41 PM
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RE: K&B .45 Sportster
I have one of these. Quiet, easy to tune, excellent manners, easy one or two flick starting, a most enjoyable engine. But don't expect .46 size power. In fact , I suspect a modern .40 would put it in the shade.
Choose an ARF that is rated for a .40, and you should be OK.
I flew mine in a scratch built Stik, that at 6lb 8oz, and a wing loading of 16.5 oz/sq ft, flew "on the wing," and I reckon a .35 would have flown it OK, so the K&B 45 Sportster was quite adequate. But it wouldn't allow me to prop hang (on any prop), whereas an OS 46FX would.
Some notes from my logbook at the time (all on a K&B 1L plug):
Run in on 22% castor, 5% nitro, then peaked on ground at 10,000 on APC 12.75x3.75, flew at 9000rpm
Tried 9% Coolpower, 14% castor, 5% nitronot as happy on this. Reverted to 22% castor.
Used muffler pressure to fuel tank (K&B note this is not necessary). Retuned main needle slightly richer, noted better transition.
Tried the following props: APC 11x4, 10,000rpm, no improvement in flying characteristics. 11x6 APC, 9700, ditto. 12x5 APC, 9200rpm, as good as APC 12.75x3.75 in the air.
Changed fuel to 10%Coolpower, 10% castor, 5% nitro.
12x5 APC 9200rpm. 12.75x3.75 APC 8900rpmOK in air. 12x6 APC 8000rpmsame as 12.75x3.75 APC in air, but slower aircraft acceleration.
I continued with the APC 12.75x3.75 prop and 10% Coolpower, 10% castor, 5 % nitro fuel, and muffler pressure to fuel tank.
Hope this is of help. It's a lovely engine, but not very powerful. Mine's currently in storage, awaiting a plane that suits it. I am currently using an old OS61 fourstroke on the Stik.
All the above rpms were as measured on the ground after setting the main needle to give sag-free high throttle nose up, and sag free flying vertical.
Also, too: Mine tends to leak oil from the front. Not surprising, as it is a plain bearing engine, and the 'leak' is evidence the bearing is getting lubed. Make sure your firewall area is well fuelproofed. Use at least 20% oil, and at least half of this castor.
Good flying.
Jock
Choose an ARF that is rated for a .40, and you should be OK.
I flew mine in a scratch built Stik, that at 6lb 8oz, and a wing loading of 16.5 oz/sq ft, flew "on the wing," and I reckon a .35 would have flown it OK, so the K&B 45 Sportster was quite adequate. But it wouldn't allow me to prop hang (on any prop), whereas an OS 46FX would.
Some notes from my logbook at the time (all on a K&B 1L plug):
Run in on 22% castor, 5% nitro, then peaked on ground at 10,000 on APC 12.75x3.75, flew at 9000rpm
Tried 9% Coolpower, 14% castor, 5% nitronot as happy on this. Reverted to 22% castor.
Used muffler pressure to fuel tank (K&B note this is not necessary). Retuned main needle slightly richer, noted better transition.
Tried the following props: APC 11x4, 10,000rpm, no improvement in flying characteristics. 11x6 APC, 9700, ditto. 12x5 APC, 9200rpm, as good as APC 12.75x3.75 in the air.
Changed fuel to 10%Coolpower, 10% castor, 5% nitro.
12x5 APC 9200rpm. 12.75x3.75 APC 8900rpmOK in air. 12x6 APC 8000rpmsame as 12.75x3.75 APC in air, but slower aircraft acceleration.
I continued with the APC 12.75x3.75 prop and 10% Coolpower, 10% castor, 5 % nitro fuel, and muffler pressure to fuel tank.
Hope this is of help. It's a lovely engine, but not very powerful. Mine's currently in storage, awaiting a plane that suits it. I am currently using an old OS61 fourstroke on the Stik.
All the above rpms were as measured on the ground after setting the main needle to give sag-free high throttle nose up, and sag free flying vertical.
Also, too: Mine tends to leak oil from the front. Not surprising, as it is a plain bearing engine, and the 'leak' is evidence the bearing is getting lubed. Make sure your firewall area is well fuelproofed. Use at least 20% oil, and at least half of this castor.
Good flying.
Jock
10-01-2011, 03:39 AM
#7
RE: K&B .45 Sportster
I have tried using a castor/synthetic blend in my sportsters originally but found they ran a lot better on 100% castor. Mine do not have the bronze bushing like the more modern ones do. Mine overheated on 10% nitro 20% blended oil 50/50 but ran better and gave a higher top rpm on my all castor fuel. I think the .65 gave up 12,200 on an 11x7 MA prop on 5% nitro 20% castor.
10-01-2011, 08:09 AM
#8
Senior Member
RE: K&B .45 Sportster
Ifound this from an old post of mine the tach readings forum.
" I used my Sig 15% nitro 20% castor and an 11X6 Master Airscrew prop. It will run 12,200 AND idle down to 2300 . It even hand flip starts at idle. I believe the plug was an OS #8."
This was a well used engine that Ihad repaired the stripped head bolts with studs. The muffler was an aftermarket one and very free flowing.
" I used my Sig 15% nitro 20% castor and an 11X6 Master Airscrew prop. It will run 12,200 AND idle down to 2300 . It even hand flip starts at idle. I believe the plug was an OS #8."
This was a well used engine that Ihad repaired the stripped head bolts with studs. The muffler was an aftermarket one and very free flowing.
10-01-2011, 08:18 AM
#9
RE: K&B .45 Sportster
ORIGINAL: jeffie8696
I found this from an old post of mine the tach readings forum.
'' I used my Sig 15% nitro 20% castor and an 11X6 Master Airscrew prop. It will run 12,200 AND idle down to 2300 . It even hand flip starts at idle. I believe the plug was an OS #8.''
This was a well used engine that I had repaired the stripped head bolts with studs. The muffler was an aftermarket one and very free flowing.
I found this from an old post of mine the tach readings forum.
'' I used my Sig 15% nitro 20% castor and an 11X6 Master Airscrew prop. It will run 12,200 AND idle down to 2300 . It even hand flip starts at idle. I believe the plug was an OS #8.''
This was a well used engine that I had repaired the stripped head bolts with studs. The muffler was an aftermarket one and very free flowing.
10-01-2011, 02:30 PM
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RE: K&B .45 Sportster
Very informative posts. I didn't realise there was this much interest in the humble K&B 45 Sportster!
I also tried removing the muffler baffle, and gained about 300rpm on 20% castor, 5% nitro, but I didn't like the extra noise, so re-fitted it (one of the 'charms' of this engine is its low noise levels.)
I also tried an ASP twin needle carb that I had spare, and which was a drop in fit. The ASP venturi was 8mm bore, which is ample for a good .45, and probably enough for most .60s. The K&B carb was, by my crude measurement, about 6.5mm through the venturi. I was interested to check if the small carb was limiting the power. The bigger carb gave about 500rpm improvement on 20% castor, 5% nitro, but was fiddlier to tune, and I replaced the K&B carb.
When K&B brought the Sportster series out, I think they were aiming for the same 'inexpensive,' plain bearing, easy to tune, entry level market that OS were supplying with their FP series, and I imagine the porting, timing, and carb size were all designed to give an easy handling engine, which it is. The 65 Sportster, which I don't have expereience of, reportedly has all of the above, plus users report an almost fourstroke-like ability to swing big props at lower speeds. I didn't get round to exploring this with the 45 Sportster.
JockC
I also tried removing the muffler baffle, and gained about 300rpm on 20% castor, 5% nitro, but I didn't like the extra noise, so re-fitted it (one of the 'charms' of this engine is its low noise levels.)
I also tried an ASP twin needle carb that I had spare, and which was a drop in fit. The ASP venturi was 8mm bore, which is ample for a good .45, and probably enough for most .60s. The K&B carb was, by my crude measurement, about 6.5mm through the venturi. I was interested to check if the small carb was limiting the power. The bigger carb gave about 500rpm improvement on 20% castor, 5% nitro, but was fiddlier to tune, and I replaced the K&B carb.
When K&B brought the Sportster series out, I think they were aiming for the same 'inexpensive,' plain bearing, easy to tune, entry level market that OS were supplying with their FP series, and I imagine the porting, timing, and carb size were all designed to give an easy handling engine, which it is. The 65 Sportster, which I don't have expereience of, reportedly has all of the above, plus users report an almost fourstroke-like ability to swing big props at lower speeds. I didn't get round to exploring this with the 45 Sportster.
JockC
10-01-2011, 03:18 PM
#11
RE: K&B .45 Sportster
ORIGINAL: JockC
Very informative posts. I didn't realise there was this much interest in the humble K&B 45 Sportster!
I also tried removing the muffler baffle, and gained about 300rpm on 20% castor, 5% nitro, but I didn't like the extra noise, so re-fitted it (one of the 'charms' of this engine is its low noise levels.)
I also tried an ASP twin needle carb that I had spare, and which was a drop in fit. The ASP venturi was 8mm bore, which is ample for a good .45, and probably enough for most .60s. The K&B carb was, by my crude measurement, about 6.5mm through the venturi. I was interested to check if the small carb was limiting the power. The bigger carb gave about 500rpm improvement on 20% castor, 5% nitro, but was fiddlier to tune, and I replaced the K&B carb.
When K&B brought the Sportster series out, I think they were aiming for the same 'inexpensive,' plain bearing, easy to tune, entry level market that OS were supplying with their FP series, and I imagine the porting, timing, and carb size were all designed to give an easy handling engine, which it is. The 65 Sportster, which I don't have expereience of, reportedly has all of the above, plus users report an almost fourstroke-like ability to swing big props at lower speeds. I didn't get round to exploring this with the 45 Sportster.
JockC
Very informative posts. I didn't realise there was this much interest in the humble K&B 45 Sportster!
I also tried removing the muffler baffle, and gained about 300rpm on 20% castor, 5% nitro, but I didn't like the extra noise, so re-fitted it (one of the 'charms' of this engine is its low noise levels.)
I also tried an ASP twin needle carb that I had spare, and which was a drop in fit. The ASP venturi was 8mm bore, which is ample for a good .45, and probably enough for most .60s. The K&B carb was, by my crude measurement, about 6.5mm through the venturi. I was interested to check if the small carb was limiting the power. The bigger carb gave about 500rpm improvement on 20% castor, 5% nitro, but was fiddlier to tune, and I replaced the K&B carb.
When K&B brought the Sportster series out, I think they were aiming for the same 'inexpensive,' plain bearing, easy to tune, entry level market that OS were supplying with their FP series, and I imagine the porting, timing, and carb size were all designed to give an easy handling engine, which it is. The 65 Sportster, which I don't have expereience of, reportedly has all of the above, plus users report an almost fourstroke-like ability to swing big props at lower speeds. I didn't get round to exploring this with the 45 Sportster.
JockC
I wouldnt be surprised to see that .45 turn a 12x6 at 9500 or better. Keep the nitro low, and load 'em up a little. You'll be surprised what they can do.
