ROOSTERLEW

Can anyone tell me how to ID my Stihl...it has no markings of any kind.

Also, anybody done a conversion on one of these?
Planing on going gas/glow

tstotts

where are those numbers you gave me to look up[?

ROOSTERLEW

I DUNNNO...GAVE EM TO YOU

Rcpilot

My Feedback: (78)

Pull the muffler off.

Pull the spark plug.

Measure the bore through the muffler port.

Measure the stroke through the plug hole.

Volume = Area of piston x stroke.

Taa Daaaaaaa!!!

av8tor1977

My Feedback: (6)

Formula is:

(Bore x Bore x stroke) x .7854 = displacement

Measured in inches, that will give you cubic inches. To get cc, divide by .061.

KI8FR

bore x strok x 3.14 = displacement. But the post before will all work too.. Just wanted to put mine in lol

buck1856

My Feedback: (49)

heres an example poulan/30mm bore,30mm stroke.
round pie to 3.14-divide bore by 2 or squared
15x15x3.14=706.57
706.57mmx30mm stroke=21195 cubic mms
theres 10mm in 1 cm.
this engine would be 21.195cc"s.
i just completed a 28cc (27.2)actual stihl with ch ign but will run it this weekend when my hub arrives.im also doing the 26cc wich is( 25.9)actual.
the 28cc came from a FS-46.
the 26cc came from a BG-75
ill post a pic of the 28 when hub arrives

KI8FR

I did mine like I would a v8.. Like a 351
bore 4" stroke 3.50"
4x3.50x3.14=43.9x8 selenders give you. 351.68

Sorry about that. lol

Rcpilot

My Feedback: (78)

Any of you guys ever heard of Pie R squared?

Volume of a cylinder is Area x height.

Area of a circle is as follows:

Area = Radius squared x pie

Radius x Radius x 3.14 = area

Radius is 1/2 diameter.

If you had a 3.25" bore and a 5" stroke:

Radius = 1.625

1.625 x 1.625 = 2.640625

Now take that and multiply it by 3.14

2.640625 x 3.14 = 8.294916 <<<<<<<thats the area of the piston

Now multiply that by the stroke:

8.294916 x 5 = 41.47 cubic inches

____________________________________________

350 Chevy

3.5 bore

1.75 x 1.75 = 3.0625

3.0625 x 3.14 = 9.61625 <<<<<area of the piston

9.61625 x 4 = 38.465

38.465 x 8 cylinders = 307.72

Your 350 doesn't have a 4" stroke. In fact, it has a 4" bore and a 3.5" stroke

Let's do the math on that

2 x 2 = 4

4 x 3.14 = 12.56

12.56 x 3.5 = 43.96 cubic inches per cylinder

43.96 x 8 = 351.68

You go the same number as me, but you skipped the step about radius squared. It just happens that 1/2 the diameter of the 4" bore is 2 and when you take 2 (radius) x 2 you end up with 4 again. [:-] The rest of your math is correct.

But, it's still only a 3.5" stroke. 4" bore.

KI8FR

Mhhhhhhhh.... I see that.. I forgot that part.. It has been to long that I had to do that.. lol

but I did say that the bore was 4" and the stroke is 3.50... In fact the stroke is 3.498+or-002
lol

Thanks for the info.

Paul

av8tor1977

My Feedback: (6)

YEP...

AV8TOR

davewallace

My Feedback: (29)

Upload a picture and maybe someone will recognize it.

Dave

ROOSTERLEW

thanks guys, will put pic up when get a chance

foamcut

My Feedback: (40)

Isn't that "Pi" R squared?

Ralphbf

My Feedback: (27)

Pie are round, sheet cakes are square.

davewallace

My Feedback: (29)

Entered in error.

ROOSTERLEW

Its a stihl 44fs, 30.6 cc thanks guys...pass the pie ralph

tstotts

Hey Rooster Set the plug at .030, mix the fuel at 50:1 and prop it to turn 7500 an stick it in a 120 size plane and no not big enough for your yak 54. you want at least a 46 for that bird.