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Kraft .61 motor

Old 01-17-2010, 12:05 PM
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gene6029
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Default Kraft .61 motor


I constantly see Kraft .61 motors on ebay for bid and they never bring much, even NIB motors. Were they junk motors? I have been toying with buying one for one of my vintage pattern planes, but havent pushed the button. Whats the scoop on them?....Gene
Old 01-17-2010, 12:22 PM
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C185Pilot
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Default RE: Kraft .61 motor

They are very good engines...maybe the most powerful of their time. MECOA sells the RJL engine which is essentially the same Kraft design and is an excellent quality engine...I've had several. Parts are available...so go ahead and bid if the price is right.

Mike
Old 01-17-2010, 12:24 PM
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vpresley
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Default RE: Kraft .61 motor

Hi

the Kraft engines were good. They are a long stroke engine. I had one in a GP Aeromaster and it pulled well. They have a large bore carb and turn a larger prop than most .61s. Get one, you should be happy with it. RJL still has some parts for it.


Vince
Old 01-17-2010, 12:40 PM
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djlyon
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Default RE: Kraft .61 motor

I have both Kraft and RJL. Great motors and parts are available.

Denis
Old 01-17-2010, 01:01 PM
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beppeVRCS
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Default RE: Kraft .61 motor


For what is worth, this has been my experience:
I've been using a Goldberg Tiger 60 to test some .60 size engines, with an APC 12"x6" propeller.

.60-.61 Engines Comparative Tests.
Fuel 10% Nitro. 21% Mixed Synt./Castor Oil

Engine Date Propeller RPM
Supertigre G-60 7 July 2006 APC 12x6 10.900
Supertigre X-60 4 Sept. 2006 APC 12x6 11.250
MDS 61 29 Sept. 2006 APC 12x6 10.800
O.S. FX-61 8 October 2006 APC 12x6 11.750
Supertigre S-61K
Old Muffler 15 October 2006 APC 12x6 11.700
Supertigre S-61K
New Muffler
29 October 2006 APC 12x6 11.700
KRAFT 61 18 March 2007 APC 12x6 11.800
MAGNUM XL .61 29 April 2007 APC 12x6 11.750
Magnum + T.T. Sil.19 May 2007 APC 12x6 11.850
Thund. T. GP-61 15 July 2007 APC 12x6 11.550
Thun. T. PRO-61 21 July 2007 APC 12x6 11.800
HP .61. (1975) 29 July 2007 APC 12x6 9.990

Engines were not tested all under the same atmospheric conditions, and over almost an year; nevertheless the KRAFT 61 is among the strongest of the group. It was consistent in flight, with no bad habits, good idle, smooth transition. In my opinion it is still competitive today, as a sport .60, at a very low price.
Ciao
Beppe
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Old 01-17-2010, 01:50 PM
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gene6029
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Default RE: Kraft .61 motor

Thanks guys, i'll try & pick one up if the price is right......Gene VR/CS 793
Old 01-17-2010, 03:43 PM
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w8ye
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Default RE: Kraft .61 motor

I had a RJL Kraft 61.

It was as good running as my Super Tiger 61's.

Nothing wrong with it. It started and ran and I flew it with a minimum of fuss
Old 01-17-2010, 04:17 PM
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blw
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Default RE: Kraft .61 motor

Jim,

Do you have any suggestions for substitution carbs for the RJL .61 that I have here? Did I get that from you? It looks like it has little or no time on it.
Old 01-17-2010, 04:24 PM
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w8ye
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Default RE: Kraft .61 motor

I sold mine to a guy in Salt lake City

The one you have had a unknown origin and was missing parts when you found it in a junk drawer.

You can get carb parts from RJL
Old 01-17-2010, 04:27 PM
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blw
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Default RE: Kraft .61 motor

Thanks. I remember now that it came from work. That explains the good condition.
Old 01-17-2010, 04:29 PM
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proptop
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Default RE: Kraft .61 motor

The Perry was a common replacement...as was their backplate pump and big bore carb set.

I have 2 of the RJL K.61's and they seem to do ok with the OEM carb.
Old 01-17-2010, 05:01 PM
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blw
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Default RE: Kraft .61 motor

This engine probably never ran. There were 3 engines from an old Army drone contract where I work. There was this one and two new HB .61s. The HBs had castor gunk in them, and they maybe had one tank of fuel run on each. The RJL looks to not have had any fuel ever in it.
Old 01-17-2010, 05:08 PM
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Default RE: Kraft .61 motor

Why all of the tests with only a 12-6 prop? Some of those engines and many older pattern planes they were made for perform better with an 11-7 or 11-8.
Old 01-17-2010, 05:44 PM
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w8ye
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Default RE: Kraft .61 motor

I ran both 12-6 and 11-7 on mine. It did respectable either way.

mine had the original carb and the short muffler
Old 01-17-2010, 06:32 PM
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lfinney
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Default RE: Kraft .61 motor

excellent results, and the thing that is the best part is unless severely abused, they run forever, and a new ring from frank bowman and a new set of bearings and its good for another 100 gallons of fuel
Old 01-17-2010, 09:15 PM
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modeltronics
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Default RE: Kraft .61 motor

I have one of the RJL versions in a pattern plane. I've not run for over a year but when I set it up I had problems getting the carb set while using muffler pressure. So I run mine without muffler pressure without any problem. Anyone else run into this?

Pete
Old 01-18-2010, 05:27 AM
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Harry Lagman
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Default RE: Kraft .61 motor


ORIGINAL: beppeVRCS


For what is worth, this has been my experience:
I've been using a Goldberg Tiger 60 to test some .60 size engines, with an APC 12''x6'' propeller.

.60-.61 Engines Comparative Tests.
Fuel 10% Nitro. 21% Mixed Synt./Castor Oil

Engine Date Propeller RPM
Supertigre G-60 7 July 2006 APC 12x6 10.900
Supertigre X-60 4 Sept. 2006 APC 12x6 11.250
MDS 61 29 Sept. 2006 APC 12x6 10.800
O.S. FX-61 8 October 2006 APC 12x6 11.750
Supertigre S-61K
Old Muffler 15 October 2006 APC 12x6 11.700
Supertigre S-61K
New Muffler
29 October 2006 APC 12x6 11.700
KRAFT 61 18 March 2007 APC 12x6 11.800
MAGNUM XL .61 29 April 2007 APC 12x6 11.750
Magnum + T.T. Sil.19 May 2007 APC 12x6 11.850
Thund. T. GP-61 15 July 2007 APC 12x6 11.550
Thun. T. PRO-61 21 July 2007 APC 12x6 11.800
HP .61. (1975) 29 July 2007 APC 12x6 9.990

Engines were not tested all under the same atmospheric conditions, and over almost an year; nevertheless the KRAFT 61 is among the strongest of the group. It was consistent in flight, with no bad habits, good idle, smooth transition. In my opinion it is still competitive today, as a sport .60, at a very low price.
Ciao
Beppe
Excellent data Beppe. Thanks for posting this.
Old 01-18-2010, 05:40 AM
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Harry Lagman
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Default RE: Kraft .61 motor


ORIGINAL: Sport_Pilot

Why all of the tests with only a 12-6 prop? Some of those engines and many older pattern planes they were made for perform better with an 11-7 or 11-8.
Because the APC 12 x 6 is a very commonly used prop on .61 class engines and it's a standard load. I take it you didn't like some of the numbers (the FX .61 and the HP .61 for example).

This is one of the better tach reading comparos I've seen on the forums. He's used the same prop (indeed, one that is widely used all over the world) and the same fuel on all engines. I wish more people would do this. The next time I see a tach reading on something like a five blade Xero Excalibur 11.342 x 5.56 freewheeling wonderprop I swear I'm going to scream and pull all my hair out!

Old 01-18-2010, 06:30 AM
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Default RE: Kraft .61 motor

There's one on ebay now, will leave that for you Gene, but I think I might like to try one sooner rather than later.

Mike.
Old 01-18-2010, 06:56 AM
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gene6029
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Default RE: Kraft .61 motor

Im going to bid on it. I'm looking for something for one of my vintage pattern planes or my Andrews Aeromaster kit i picked up recently. Sounds like i cant go wrong with it & most come with a muffler i noticed. We'll se how the bidding goes.....Gene
Old 01-18-2010, 10:54 AM
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turbo.gst
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Default RE: Kraft .61 motor

Thanks for the RPM numbers Beppe. Very Useful info for comparing those engines with same prop, fuel, and plug and location. I appreciate all your time and effort, not to mention expensive fuel used to give us the numbers. I don't have all of the engines you listed, so I could not compare them all myself.

Interesting how the newer designed engines run stronger with the 12 x 6 ( long stroke trend??). I wonder if the older 60's were more revvers and shine more with the 11 x 7. I may have to try a few of my own. I can't test the Magnums and Thunder Tigers, but most of the others. I will soon have my Evolution 60 NX ready for some rpm numbers. I am curious to see how it measures up to the revvers of the day.

turbo
Old 01-18-2010, 12:08 PM
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Default RE: Kraft .61 motor

HI OS 61 SF RINGEDA LONG STROKEBLACK MAX MUFFLER- GUTTEDMORGAN OMEGA 10 % (THINK PINK ) - A 12/6 APC-12,600 RPMS - AND MY WEBRA 61 F SPEED 12,900 rpms ARE TWO OF MY STRONGEST ENGINES ON A 12/6 APC PROPS SO WE NEED TO INCLUDE THEM HERE
Old 01-18-2010, 12:30 PM
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Default RE: Kraft .61 motor

I take it you didn't like some of the numbers (the FX .61 and the HP .61 for example).
.

The HP was the original version, it was actually weaker than the Webra cross ported engine at the time. The later one was almost the same engine as a Webra. My HP Gold Cup .61 will turn an 11-7, can't remember which brand right at 14,000 with an old open front Semco muffler. I suspect it would turn a 12-6 at around 12,000 RPM. The OS FX actually did better than I would have thought. Probably not as well with an 11-7.
Old 01-18-2010, 12:33 PM
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Default RE: Kraft .61 motor

Interesting how the newer designed engines run stronger with the 12 x 6 ( long stroke trend??).
I suspect because they are tuned to run better with them and with a muffler. Some of them are long stroke designs simply because the case is made to accommodate a .75 or even .91 displacement.
Old 01-18-2010, 01:46 PM
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Default RE: Kraft .61 motor

My Kraft 61 came has and was originally equipped with a Perry Carb. It will need a pits muffler that is shallow for the plane I want to put it in. I think the Ross 45 are the same size exhaust. It has never been run so I am not sure how much power it will have but I have always had good luck with the Perry's except for keeping them clean.

Thanks for the info on the RJL about part availability.

ORIGINAL: blw

Jim,

Do you have any suggestions for substitution carbs for the RJL .61 that I have here? Did I get that from you? It looks like it has little or no time on it.

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