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#Post#: 5577--------------------------------------------------
Water cooled piped Stihl weedeater for RC
By: Chainsawrepair Date: December 16, 2011, 9:06 pm
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Just found this interesting. Water cooled piped 2 stroke weed
eater motor for RC boat.
HTML http://www.youtube.com/watch?v=Y25NFd0vxxw&feature=mfu_in_order&list=UL
#Post#: 5579--------------------------------------------------
Re: Water cooled piped Stihl weedeater for RC
By: 660magnum Date: December 16, 2011, 10:02 pm
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Here is my John Deere weed whacker 30cc. I bought it new as a
short block from the local Homelite dealer. I have no clue as to
the origion of the flywheel. I broke the fins off with pliers
and cut down the stubs with a A11 burr in a small die grinder. I
balanced it with the aide of a model airplane prop balancer. The
carb is from a Red Max. The Plane was a Bridi Old Timer Kit.
HTML http://img.photobucket.com/albums/v11/jamesirl/Auburn/BridiStick1.jpg
The following is a Makita 3.2 saw engine that was converted to
be a model airplane engine. The plane is a Bridi Big Bee Kit.
HTML http://img.photobucket.com/albums/v11/jamesirl/Auburn/100_0840.jpg
#Post#: 5580--------------------------------------------------
Re: Water cooled piped Stihl weedeater for RC
By: Al Smith Date: December 17, 2011, 3:45 am
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Neat stuff .When you get into RC stuff the game changes .
A guy at work has a Sachs saw engine of around 70 ccs to be used
for a giant scale P51 Mustang with an 18" prop .He wanted me to
soup it up .In conversation with a very knowledgable gent at the
Poulan GTG he advised me to set the r's at around 8-9 thousand
RPM .Now that might seem slow .
Here's the deal once the outside prop speed reachs the speed
of sound the prop will cavitate just like a boat prop .Kind of
like spinning your wheels on a burn out,can't get a bite .Now I
knew that but had forgotten all about it until that conversation
came up .
Another thing ,I've picked up more tips from Brit motorcycle
forums and RC sites on engine mods than all the chainsaw forums
combined on info of engine mods .Another source of --how to
.Worth looking into if anyone is interested .
#Post#: 5582--------------------------------------------------
Re: Water cooled piped Stihl weedeater for RC
By: 660magnum Date: December 17, 2011, 6:01 am
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The engines in the pictures are not hopped up for the very
reason you mentioned.
The Homelite 30 runs 7500 rpm with a 18 X 8 prop and the
Sachs/Makita 52cc runs 7,000 with a 22 X 8 prop.
Any more rpm and you get the prop buzz.
#Post#: 5584--------------------------------------------------
Re: Water cooled piped Stihl weedeater for RC
By: Al Smith Date: December 17, 2011, 7:19 am
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I have no idea how fast you could spin a screw on a boat but I
suppose there's formulas some place .Because they sit so close
to the surface and weigh so little it's doubtfull an anti
cavitation plate would work well .
On a weed wacker engine with a pipe and a big carb I'll bet you
could wind that thing up though if you really wanted to .I've
seen those little rascals shoot over a big pond with just the
screw in the water ,Lawdy talk about quick ..Ha As slow as my
reflexs are I'm about certain I would flip one going that speed
. ;D
#Post#: 5586--------------------------------------------------
Re: Water cooled piped Stihl weedeater for RC
By: 660magnum Date: December 17, 2011, 9:00 am
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The boat engines can run high rpm so it is not unusual to see
15,000 with a racing boat engine.
The boat engines also run the single apex cone pipes.
#Post#: 5588--------------------------------------------------
Re: Water cooled piped Stihl weedeater for RC
By: rgclmc Date: December 17, 2011, 9:18 am
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Would'nt that sharp bend right at the engine kinda defeat the
benefit of the expansion pipe?
#Post#: 5589--------------------------------------------------
Re: Water cooled piped Stihl weedeater for RC
By: Chainsawrepair Date: December 17, 2011, 9:45 am
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[quote author=rgclmc link=topic=597.msg5588#msg5588
date=1324135128]
Would'nt that sharp bend right at the engine kinda defeat the
benefit of the expansion pipe?
[/quote]
I dont think so. Becuase the one on the MVP166 piped racesaw.
Bent right and did a U straight back to right side.
#Post#: 5591--------------------------------------------------
Re: Water cooled piped Stihl weedeater for RC
By: Chainsawrepair Date: December 17, 2011, 9:52 am
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I located a piped 166 pic Woooohoooo and I thought they were all
lost.
[IMG]
HTML http://i59.photobucket.com/albums/g289/doemaster789/166/166hotsaw.jpg[/img]
#Post#: 5611--------------------------------------------------
Re: Water cooled piped Stihl weedeater for RC
By: 660magnum Date: December 17, 2011, 4:52 pm
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Here are some pictures of my Brison 3.2 model airplane engine.
It is made using the P&C and rod from a Dolmar 111. They even
use the same Walbro carb that comes on the straight 111, the
WT76A. They have a CNC crankcase and their own cantilever single
ended crankshaft. Mine has a fixed timing ignition module. The
ignition timing sensor is mounted on a nylon ring that is
controlled by an extension of the throttle rod. The timing is 2
degrees BTDC at idle and 28 degrees at full throttle. Some of
them have a automatic electronic advance on the timing. It uses
a 22" diameter prop with 8" pitch. It runs right at 7000 rpm at
full throttle on the ground. I also have a twin one of these
that is a 6.4 size. The carb intake ports have a plate over them
and the crankcase has a vee shaped reed block and single up
draft Walbro.
HTML http://img.photobucket.com/albums/v11/jamesirl/House/Brison32A.jpg
HTML http://img.photobucket.com/albums/v11/jamesirl/House/Brison32B.jpg
HTML http://img.photobucket.com/albums/v11/jamesirl/House/Brison32C.jpg
HTML http://img.photobucket.com/albums/v11/jamesirl/House/Brison32D.jpg
HTML http://img.photobucket.com/albums/v11/jamesirl/House/Brison32E.jpg
Here is a manufacturer's picture of a 6.4 twin. Mine has a blue
anodized case.
HTML http://img.photobucket.com/albums/v11/jamesirl/House/Brison64.jpg
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