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Briggs and Stratton 34cc Fource?

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Old 06-07-2006, 01:02 AM
  #76
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Default RE: Briggs and Stratton 34cc Fource?

Thanks for the replies Maninder and Prop Nut. I wasn't able to get the video on this thread to download, but found another thread with another video which I was able to see and hear. That DVII sounds great Prop Nut. I see that your DVII is 18-19lbs., and the BS hauls it it around pretty well. I think I'll email Bryan Loftis and see what he has. While looking on Ebay I noticed some 40cc BS 4strokes on Craftsman trimmers, but I don't see them on the BS site. I wonder if they are the same Fource style. I'd like to build an SR Batteries Eindecker or similar for one of these engines.[sm=cool.gif]

Rod S
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Old 06-07-2006, 08:33 AM
  #77
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Default RE: Briggs and Stratton 34cc Fource?

The 40cc is a Fource but I have no other data about them. There are mentioned on Briggs and Strattons web site as being the same as the 34cc, just bigger.
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Old 06-07-2006, 02:23 PM
  #78
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Default RE: Briggs and Stratton 34cc Fource?

My 34cc Fource will ultimately end up on a Flair Hannibal.

The kit is manufactured in the UK by Flair:

http://www.flairmodels.co.uk/Aircraf...coutframes.htm

It's a sort of an Eindecker look alike but relatively simple to build. It is 72 inches long and at the standard wingspan of 91 inches the wing area is 1500 Square inches. I intend to increase the wingspan to 100 inches and build the wing in two pieces. This will give a 1700sq inch wing area and a target weight of around 15 - 16 lb.

Should fly very slow!

I already have the kit and all the other parts- it's just a matter of finding the time to build.

Maninder.
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Old 06-07-2006, 04:38 PM
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Default RE: Briggs and Stratton 34cc Fource?

That sounds like a perfect match. Here is a picture of a huge stick I tested the Briggs on a couple of years ago. It was really heavy 25 ish pounds.
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Old 06-07-2006, 05:41 PM
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Default RE: Briggs and Stratton 34cc Fource?

Well, I just ordered a BS Fource from Bryan Loftis at BsVWRabit@aol.com. I excited about this project. I like the idea of a flathead on a vintage plane. Kinda like a Model T engine. That Hannibal looks like a good one for that engine. I'm going to the LHS and see what they have and probably end up ordering something. [X(]

Rod S
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Old 06-11-2006, 03:16 AM
  #81
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Default RE: Briggs and Stratton 34cc Fource?

Just curious, what about mounting one of the B&S fource on an older model ultra stick, not the lite? I know I would have to mount the servos in the rear of the stick to help with the balance. My stick weighs in at 13 pounds with a Saito 180 now. Ideas? Wouldn't mind a relaxing easy flyer. Or I have a Lanier Giant Stinger just built, no engine yet.
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Old 06-12-2006, 06:55 PM
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Default RE: Briggs and Stratton 34cc Fource?

Friday I received the 2 B/S engines that I ordered from BsVWRabit@aol.com. These are brand new power heads. I started stripping one of them down last night. The complete unit as received weighed 8 lbs. After removing the plastic shrouds with recoil starter and tank, the weight was 6 lbs. Then, since I am going to run this engine as gas/glow, I remove the coil, flywheel/mag, air filter, spark plug, and muffler. The weight has dropped to 4 lb 3 oz. There is still a good bit of casting that I will remove from the front of the case, so it is possible to get the weight under 4 lbs. I did run the other engine on the gas/glow mixture and it cranked easily with the recoil starter, but was a bit too lean with the methanol in the mix. I may drill out the main jet (it is fixed), but will probably put a 2 needle carburetor on it to allow for changing conditions. It is extremely quiet with the stock muffler on it.

Gary
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Old 06-12-2006, 09:07 PM
  #83
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Default RE: Briggs and Stratton 34cc Fource?

Prop Nut; What kind of R.P.M's are you getting with the B&S? I'm running an 18-8 on my Honda 31 and i'm only getting about 6600. That's enough to fly my plane ,but I would like to get 7,000 to 7,500. Do you think the B&S would do that with the same prop?
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Old 06-12-2006, 09:37 PM
  #84
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Default RE: Briggs and Stratton 34cc Fource?

I just got my BS today from Bryan Loftis. I thought I would start it before stripping it down. Put the 3oz. of oil in the crank, a splash of gas, pumped the bulb a few times, set choke, started first pull on idle and I imediately open the choke. Nice running engine. I'm amaized at the recommended 3oz. of oil. Almost like a dry sump as most of that oil will probably be coating the innards. The manual says that the engine loses 3.5% power for each 1000ft. above sea level, so that .75hp goes to .6 for me at 6000ft.. I'll definately need to keep the weight of my plane down to 12-13lbs. max.

Rod S
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Old 06-13-2006, 06:06 AM
  #85
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Default RE: Briggs and Stratton 34cc Fource?

RCSport, that is exactly what I am getting with the Briggs and Stratton. This engine is really weak compared to a two stroke, it is only for the sound that I built it.
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Old 06-15-2006, 06:16 PM
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Default RE: Briggs and Stratton 34cc Fource?

Hi Rod,
The briggs is a flathead motor, just like most of their lawn mowers. The best running flatheads I know of were the 750cc Harley roadracer motorcycles of the late sixties. They used streight exhust and a air horn carb stack. The secret was that they were allowed 50% more displacement then the overhead valve bikes. Just think of your 34cc as a heavy 25cc gasser.

Dave
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Old 06-17-2006, 07:00 PM
  #87
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Default RE: Briggs and Stratton 34cc Fource?

I remember those 750 Harley's. Didn't know they were flatheads.

I'm dink'n with my BS. Ground down the flywheel, and excess chunks on the engine. Decided not to mess with the carb spacer for now. I think I could take off about a half inch, without destroying it. Should be easy to braze an exhaust pipe to lose an ounce or so, and give it that sound of power.

Rod
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Old 06-17-2006, 08:18 PM
  #88
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Default RE: Briggs and Stratton 34cc Fource?

You can lose half the carb spacer by swapping the one on a Ryobi 4-stroke, it will bolt right on and work fine. They are around 3.00 at small engine parts stores.
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Old 06-22-2006, 12:28 AM
  #89
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Default RE: Briggs and Stratton 34cc Fource?

P. Nut, I may have to get one of those Ryobi carb spacers. I ground down mine about 1/2 inch and am a bit worried if I got the bleed channel carved in it OK. Attached are some pictures. The first shows the 360 degree oil sump. Very simple idea, with splash lube. The other photos show it running with the prop spacer, ground flywheel, shortened carb spacer, and exhaust pipe. The original muffler was 8 oz, this pipe is 4 oz now and I will eventually trim off a bit more.

Rod S
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Old 06-22-2006, 07:32 AM
  #90
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Default RE: Briggs and Stratton 34cc Fource?

Boy that looks familiar I am wondering what the 40cc will do for RPMs.......
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Old 07-18-2006, 10:57 AM
  #91
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Default RE: Briggs and Stratton 34cc Fource?

Is there any trick to getting the flywheel off the engine? I've never had any problems with my other two-stroke weed whacker engines, but this one doesn't seem to want to come off, and I don't want to break it.

Thanks

J
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Old 07-18-2006, 11:10 AM
  #92
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Default RE: Briggs and Stratton 34cc Fource?

Use a gear puller. Place grippers at magnet and counter weight. You can break off the thin areas easily. Been there, done that.

Dave
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Old 07-18-2006, 03:17 PM
  #93
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Default RE: Briggs and Stratton 34cc Fource?

I just pried mine up with a flat headed screwdriver. I put pressure with the screwdriver and tapped on the shaft (Put the nut back on flush with the end of the shaft) and it popped off.
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Old 07-18-2006, 05:46 PM
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Default RE: Briggs and Stratton 34cc Fource?

Hi,
If you pry it off. Do it away from the weak web area.

Dave
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Old 01-19-2009, 09:06 PM
  #95
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Default RE: Briggs and Stratton 34cc Fource?

hi guys, I see this forum has been dead for a while but i need to know the dimensions of the bs 34cc motor. I am building a 1/5 waco and i want to put the motor IN the cowl (get the idea)?? the cowl is 8inches in diameter and i have 6 inces firewall to the back of the prop flange. i want to keep cutting to a minimum

also can these motors run inverted? ideally i would like an inverted install

thanks
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Old 01-19-2009, 11:24 PM
  #96
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Default RE: Briggs and Stratton 34cc Fource?

Mine runs inverted in my Fokker DVIII, no problems. I dont have the sizes right in front of me but I believe your setup will work. You can do a search for Fokker DVII and look for my nickname as the starter, I have the dimensions listed on that thread. I put this engine in my DVII, DVIII, 1/4 scale Bud Nosen Aeronca, and have flown a eight foot stick (home brew) with it. Have fun.

David
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Old 01-19-2009, 11:26 PM
  #97
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Default RE: Briggs and Stratton 34cc Fource?

I was shocked to find a new B&S posting!

About 5.25" across the crankcase, 7.25 high minus the spark-plug, and 5.25 back to front depending on how you shave the flywheel. I have no experience inverted, but prop-nut you see posting above did it with no problems, last I heard. I still have mine ready to go for when I get a plane built, hopefully by summer.

Rod S
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Old 01-20-2009, 12:56 PM
  #98
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Default RE: Briggs and Stratton 34cc Fource?

It is not going to fit in an 8" cowl.
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Old 01-20-2009, 12:59 PM
  #99
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Default RE: Briggs and Stratton 34cc Fource?

Not completely but if you invert it it should look ok. If you were hoping to completly hide it you are out of luck. Jstisch is very much correct there.
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Old 04-18-2009, 05:13 AM
  #100
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Default RE: Briggs and Stratton 34cc Fource?

Does anyone have any details of the Honda GX31 conversion? I'm doing one right now, I have changed the carb to an adjustable WYK which has improved the revving no end but I would need a retract servo to move the throttle! I believe there is someone using one in a DR1, any details/vid etc? I would like to change my carb to a normal Walbro rather than the WYK type which would eliminate the return spring problem.
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