briggs 34cc head gasket
10-01-2012, 04:04 PM
#27
RE: briggs 34cc head gasket
ORIGINAL: Sport_Pilot
Rotary carbs do not have low speed needles, instead a disk is used with a slot that widens as the throttle is opened. Perhaps you mean't a barrel throttle carb?
Rotary carbs do not have low speed needles, instead a disk is used with a slot that widens as the throttle is opened. Perhaps you mean't a barrel throttle carb?
10-02-2012, 11:04 AM
#30
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RE: briggs 34cc head gasket
The main issue I had with a regular walbro was that the pulse was not correct for a 4-stroke. I got a 7, 8 or 9mm one ( I forget which), to work, after a fashion. IT was a little butterfly type. I installed a tiny spring to push the diaphram back. The 4-strokes only have half a pulse, negative pressure, so a return spring is needed. Even so the needles did not work as expected. Basically you have no way to get a positive and negative pulse because there is oil in the crankcase. These carbs are pricy so once you mess it up you are sunk. It might be easiest to leave the OEM air cleaner on it and be happy.
I have a BUSA 1/4 scale D-7 on the bench right now. You do need extra weight in the nose, lots of it. I have a G-38 in it right now. IT is about right powerwise and very reliable. The little Briggs only turned a 22x6 at about 5600 rpm. I doubt it would fly very well if at all. I know it has been done. I just don't like every take off and climbout to be a harrowing experience.
Search this forum for my wranglings with this engine.
The yellow arrow on the Poulan is where the idle jet is adjusted. The yellow arrow on the Briggs is where the pulse is diverted into the carb.
I have a BUSA 1/4 scale D-7 on the bench right now. You do need extra weight in the nose, lots of it. I have a G-38 in it right now. IT is about right powerwise and very reliable. The little Briggs only turned a 22x6 at about 5600 rpm. I doubt it would fly very well if at all. I know it has been done. I just don't like every take off and climbout to be a harrowing experience.
Search this forum for my wranglings with this engine.
The yellow arrow on the Poulan is where the idle jet is adjusted. The yellow arrow on the Briggs is where the pulse is diverted into the carb.
10-02-2012, 05:13 PM
#32
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RE: briggs 34cc head gasket
I just want to know what he has done just in case I have ideas that he perhaps hasn't tried. This engine was free and so is my time so a little experimentation never hurt anyone 
10-05-2012, 01:24 PM
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RE: briggs 34cc head gasket
I pulled mine out and played with it. It gets 5200 rpm with a 22x6 and 6400 with and 18x8. That equates to about 1.5 HP. The static thrust is about 12-pounds. That is about like a 90 4-stroke or a 60 2-stroke glow motor. It runs real smooth and starts easy. It idles really slow, 1200-ish. It is fun to watch and listen to. Sort of like the stationaly motors that used to run pumps and farm equipment. It sounds like an old gas engine powered washing machine. I wish I could post AVI files to give the full experience. It might be OK in a 1/5 scale biplane, something like a Sopwith Pup. It would be way to feeble for my 1/4 scale Fokker D-7.
