Prop Nut

My Feedback: (3)

Sears sells the BS (now that just sounds funny to say) 34cc four stroke on thier weed trimmers.

rcbilly

My Feedback: (9)

Hi Dave, How's the BS conversion going? what's your impression of the power?

Prop Nut

My Feedback: (3)

The BS Conversion is Done!! Runs great. Very easy to convert. I used a prop spacer by Wacker Engines for 18.00 and another club member made me a 1/4 inch plate aluminum engine mount (its just a flat plate the slaps on the back in place of the original) I am using the stock carb, muffler etc. We bench tested two of them this week. Mine (off a well used Craftsman weedeater) and another new in the box from BS. Mine ticked over at 1790 then throttled up to a respectable 7500. I bench I had it mounted to has locking wheels on it, good thing they were locked, the table pulled a couple of inches.
Bill, I am going to send your Newport 28 plans with Jim some wensday morning as I never seem to get down around your house anymore.
Getting back to the BS 34cc Four stroke. I am going to mount it on a 100" stick I am building (bobs old one) and will use it to test out the motor. I have no doubt that it will be a great flyer. The engine casing is shaped in such as way as to keep the oil out of the piston while inverted. This does not mean that I can mount it inverted but short flights should be ok. I will post some pictures of it one of these days. It really was very simple to convert. The total cost (for me) was 145.00 that was 125 (ebay 100.00 plus shipping for the wacker) 18.00 (plus 2.00 for shipping on the prop spacer (thanks again Peter) and the plate was scrap alumium. If all works well I will mount it on the Balsa USA Fokker DVII I bought this winter. (after I get it built, still havent finished the Albatros DIII, almost though.) Bill, get in touch.

rcbilly

My Feedback: (9)

What size prop did you use for your testing?

Prop Nut

My Feedback: (3)

I was using an 18-10 for the test. I think I will try out a 20-10 for the flight though.

rcbilly

My Feedback: (9)

Dave , Wacker engines? do they havw a web site? or how did you get a hold of them? 7200 on a 18-10 prop sounds like a lot of power. What's the weight?

Prop Nut

My Feedback: (3)

Not sure of the wieght, Robb Quick probably has wieghed his though. Its heavier than a G26 but sounds sooo much nicer. I almost have that old Eindecker of Bob Altmans ready to go, it will hold the BS engine. You can find Wacker engines by doing a search on Ebay, that is where he does most of his sales. or go to Wackerengines.com and look around. He seems like a really nice guy. This spring Nick Traub will be back and he can whip up anything you need in his machine shop also. He made most of our parts before he ran off to florida for the winter.

Prop Nut

My Feedback: (3)

Its on the plane, ready for its first flight. Turning 1600-7500 on the ground. I will post some photos after tuesday (I hope the weather clears by then)

Prop Nut

My Feedback: (3)

By the way, the 1600 to 7500 is with a Master Airscrew 18-10 prop. Unleaded gas. I wonder what it would do with a higher octane, or maybe octane booster poured in. Any ideas?

Prop Nut

My Feedback: (3)

Here are some pictures of the finished product (almost finished, one of these days I want to have the flywheel machined down.) Its a little dusty from sitting in my shop during working hours. I have mounted this on a 100 inch stick and its ready to go. I do not however have a weight on the plane and engine combo. I do not yet have a scale to use.

Prop Nut

My Feedback: (3)

Here are the flight pictures, I used an 18-10 prop. It flew great!! The sound was unbelievable. So scale and quiet. This is a huge plane and it had no problems at all flying with the Briggs and Stratton. I will get a scale this weekend. It came out very very heavy though. Its a really old fuselage with a new wing. The engine hangs out 14inches from the CG so it took 24oz of wieght in the tail (which you can see in the picture) this engine is destined for a BalsaUSA Fokker DVII where the engine sits very near the wing. I do not think I will have much of a problem with balancing on that.

Flypaper 2

Propnut:
If I was me, I'd test run it without the muffler and tach it and check how much noise. Then take that crimped flange around the centreline of the muffler and grind it off and eliminate the outer half. weld a suitable plate over the end with a pipe in it, or whatever it needs to cover the end. Looses a bit of weight and gains a few RPM. and makes it a little more compact.

Prop Nut

My Feedback: (3)

This thing aint done yet by half. I will have the flywheel ground down this spring, a new muffler made for it, and a few more odds and ends. I did run it without the muffler the other day, it was louder (with the muffler it is very very quiet) but I didnt see an appreciable increase in RPM. I am going to put a straight pipe muffler on it, they sound good and are supposed to help with performance.

captinjohn

Propnut: Good job so far. Maybe with further weight reductions...ect.... it will be even more fun. I bet its good on fuel. Take Care.....Capt,n

tango28charlie

I'd run in on 100LL avgas. You won't get any difference in power, but it sure will smell full scale.

Charlie

Spychalla Aircraft

My Feedback: (34)

I was considering a converted version of the B&S 4-Stroke as a product for my company to sell. As a B&S employee (Day Job) I had a better chance of obtaining them at a reasonable price and maybe even short blocks, but yesterday I got the official word regarding the potential use as a model airplane engine. The product manager of this engine was open and supportive of my idea to convert and sell some of these engines. He thought it was cool, but the legal team said NO. Briggs & Stratton calls this an "Unapproved Use" of the engine. They get many request for unusual applications and other hobby uses including cars and boats. The company evaluated the cost of expanding their insurance policy to cover these uses. It turned out to be prohibitive. So if an individual modifies a B&S engine for airplane use their is little or nothing B&S would ever do about it, but if a company was to modify engines in quantity and sell them to the market they would likely step in and shut them down because they don't want the exposure. Consequently to stay out of trouble and to protect my day job, "Spychalla Aircraft LLC" is no longer considering this as a marketable product. I think this goes a long way to explaining why see engines similar to this on the market for $800 and not the price of a weed wacker.

Check out the photos of the B&S modified for me by Ralph Cunningham of RC Ignitions.

Leo

Prop Nut

My Feedback: (3)

What did you do to modify the carburator spacer to get it so short? Can you just chop it down or is there something else I should do? Mine sticks way out there. What else was done (besides the electronic ign) for performace? I have been using mine on a giant stick (96"wing) and it is doing great. The engine is going into my Balsa USA Fokker DVII so I would really like to shorten the carb mount. What carb are you using on that? It looks nothing like the stock carb I have.

Spychalla Aircraft

My Feedback: (34)

Prop Nut,

That is the stock carb. Ralph C. cut a new spacer that is only about 3/8" thick and re-mounted it. I would recommend a new spacer versus cutting the production one down. For performance Ralph tried every Walbro adjustable needle carb he had. The production Walbro that comes with the B&S outperformed them. It has fixed jets and it is finely tuned for this engine. It really seems to work. I just never liked the spring on the throttle plate. I destroyed several carbs seing if I could pull it out. Spring removal is just not an option. For performance Ralph played with the timing, carb, pulse line to the carb, and even ground the head clearance. If he reads this he may chime in with the specifics, but the net result was that the timing was the only thing worth working on. Carb, pulse line, and head changes just screwed the engine up.

Leo

Antique

My Feedback: (4)

Problem was, the carbs I tried were only made for two strokes...the one for the 4 stroke, WT456 with the helper spring would work better, I just didn't have one here...If one of these engines will turn an 18-10 at 7200 stock, I made it worse by milling the head for more compression...I could only get about 7500 with an 18-6....Flathead 4 strokes are a different breed....Too bad Briggs won't go along, but I found the same thing with Homelite and McCulloch many years ago....Only company that was willing to sell engines for RC applications was Tecumseh, and that was a long time ago...I converted a 50cc 2 stroke but was not impressed with the power to weight ratio..
Kudos to Prop Nut, great job....

Prop Nut

My Feedback: (3)

Thanks for the information, I am no longer getting the performance I was, after running the engine in the air for a while it is down to 7200 with a 18-8 (I broke the 18-10 on a bad landing) I am still very happy with the output. Where can I find a carb spacer that small? Thanks for the cudo's RCIGN, we have had a great time with the engines so far (A buddy still has not flown his, the Spad XIII that it is going on is not finished.....still).

oslim

What is the purpose of the white plastic cover plate below the carb? Looks like a crankcase vent with an orange rubber duck-bill check-valve. Does it have 2 camshafts to drive the intake & exhaust valves? Thank-you

Flypaper 2

I believe the duckbill valve is used for the same purpose that a flapper valve is used on the lawn mower motors in the valve cover. Keeps negative pressure in the crankcase to keep the oil from being pushed up past the rings with pos. pressure. When the valve failed on the push mowers you couldn't see for smoke out the muffler.

Prop Nut

My Feedback: (3)

I have no idea, should that be plugged up or left open?

Flypaper 2

I would leave it open. Has one cam lobe for both valves.

Prop Nut

My Feedback: (3)

Thanks, I will open it back up. I am going to pull it out of the hanger in the next few weeks and do some work on the flywheel.