hblester

My Feedback: (3)

Been searching for the mini four strokes out there that might be good for converting for rc and picked up a Stihl catalog at my local dealer to see the info on their 4 mix four strokes the 31cc & 36cc trimmers & found a backpack blower with a 4 mix four stroke at 65 cc and 4 hp. model number br 550 here is a link I hope.
http://www.stihlusa.com/blowers/BR550.html

Thanks Hubert

Antique

My Feedback: (4)

Might be OK except for the weight, 22 lbs...The case and blower shouldn't be over half the weight.....[&o]

hblester

My Feedback: (3)

May try the 36cc stihl and I have someone working on getting a gx-35 honda will also put the briggs 34 cc in the mix just to have a cheap engine in the mix just to see. May have a question or two for you after getting a base weight, running rpm & thrust on several props out of each of them put each on a diet which would mean losing the mag ect.

Hubert

BillS

I have a converted BR 400 (57cc two stroke) engine and like it.

The 65 cc engine sounds interesting. Please keep us informed. The 57cc two-stroke blower is only 2.6 pounds lighter and the weight difference might not be in the engine. Is the engine wet or dry sump? It looks like mounting would be easy with a plate behind the pull starter.

Bill

hblester

My Feedback: (3)

Maybe Tripp3d can give us some more info on this 65 cc blower 4mix motor.

Thanks Hubert

Captain Ramius

not to get off track but:

hblester where did you find a GX35?

The four mix of any size is still somewhat of a problem with the gas/oil mixture is runs.The tortuous intake tract makes it quite a challenge to modify for more performance. But in stock configuration they get the job done.A 65cc blower engine probably has the power your looking for in the rpm range you want without mods anyway.
Let us know what you find out

hblester

My Feedback: (3)

I do not have a gx35 yet, know someone in the service posted overseas seeing if he can get me one, also there was a post about a copy cat or clone honda a superior 36 check their web site Ithink it was about 275.00 and was for a scooter.

Thanks Hubert

Captain Ramius

Yeah , you can get them in England and Europe, about $600 usd.
Theres guy on English ebay sells them on occasion but he refuses to ship to the US.

tripp3d

Sorry guys I don't have any more specs on Stihl's new blowers yet, although I've heard rumor about an even larger backpack blower on the way...BR600!! Our service rep is about 165 lbs and he says he has to lean into it when it revs...not even in their 2005 literature yet but might be interesting when it arrives. I'll tear a br550 down and weigh the engine and post my results in a couple of days.

BillS

tripp3d,

It there any more information on the Stihl 4 stroke blowers? I was told yesterday that it was a dry sump and oil/fuel was returned to the tank which sounds like an innovative concept. A picture of the engine would be good. How is the CDI mounted? Is the package compact enough to use in an airplane?

Thanks.

Bill

Captain Ramius

Four mix runs on premix.
All the premix entering engine through carb gets burned.
This should explain it well enough.

[link=http://www.stihl.ca/4mix/english/stihl4mix/service.htm]Stihl Four mix[/link]

BillS

Captain the link was very informative. Thanks.

The Stihl dealer indicated that excess crankcase oil was returned to the fuel tank. Do you know if or how excess oil is returned?

Bill

hblester

My Feedback: (3)

I do not think oil is returned to the gas tank it is a waste oil system meaning that the oil is burnt or put out the exhaust. The oiling system is just like the ones on a two stroke glow or gas in that it rides with the fuel all the way to the combustion chamber and out the exhaust. The only difference on the Stihl is that it pulls it in the lower end through a reed valve as the engine piston moves up then the reed valve closes and as the piston moves down it push or compress the fuel oil mix when when the intake valve opens (on a 4 stroke every over revolution) it is forced into the compression chamber. This is done under a positive pressure, where as on most 4 strokes when the piston moves down & the intake valve opens negative pressure or vacuum pulls or sucks in if not turbo or super charged. The ys glow 4 strokes, the stihl and the shindaiwa hybrid engines use this super charging effect by letting the bottom of the piston compress the fuel oil charge before the valve opens.

HTH Hubert

BillS

Thanks. Knowing that a reed valve exists makes the system understandable.

Bill

Captain Ramius

Yes it goes into cylinder and gets burned, its a total loss system.

tripp3d

After tearing into a br550 I'm thinking the fs130 Stihl trimmer would make a better (easier) conversion since it does not use a rubber isolator boot between the carb and engine like the new blowers do.

Lug-nut

From what I have read, the Stihl br600 owners are happy by far with the power. http://www.lawncafe.com/t12155-what-...dmax-8000.html Some are also happy with the redmax 8000. I can't believe you guys convert them. Couldn't you order the motor from the distributor, just like a mower shop? Maybe even just order the motor from the mower shop?

Antique

My Feedback: (4)

I have converted 4 of the Stihls and one Redmax 8000....All worked well, about like a G62 for power...The carbs are a pain.....Mounting the Stihl is a bit of a challenge...Mounting using the strongest lugs has the engine running backwards..If you use the other side the lugs are fairly weak, but so far as I know, no one has broken one....
Unless you're a 4 stroke freak a 2 stroke is better, IMHO

subarubrat

My Feedback: (1)

That is true. But we are just now seeing the second generation of 4 strokes in this size. Right now there is not a solution for many models. I like the TopFlite giant scale mustang I have, there is no 4 stroke out for it. But I would not be surprised if in the next 5 years there are a few that are large and light enough.