Engine Conversions Discuss all aspects of engine conversions in this forum

briggs 34cc head gasket

Reply
Old 10-01-2012, 04:48 AM
  #26
flyguyeddy
Thread Starter
 
Join Date: Nov 2006
Location: , IL
Posts: 104
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: briggs 34cc head gasket

Whatever its called I mean the wyk carb similarly to what comes on it from b&s
flyguyeddy is offline  
Reply With Quote
Old 10-01-2012, 04:04 PM
  #27
w8ye
Moderator
 
w8ye's Avatar
 
Join Date: Dec 2001
Location: Shelby, OH
Posts: 37,535
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: briggs 34cc head gasket


Quote:
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?
I know the Walbro WYB has a idle needle inside the barrel that is adjustable.




w8ye is offline  
Reply With Quote
Old 10-02-2012, 02:23 AM
  #28
Nosedragger
 
Join Date: Jun 2006
Location: hartford, CT
Posts: 615
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: briggs 34cc head gasket

Walbro makes two types, butterfly and barrel valve also commonly known as rotary.

The WYK has high and low needles in most cases.
Nosedragger is offline  
Reply With Quote
Old 10-02-2012, 08:55 AM
  #29
flyguyeddy
Thread Starter
 
Join Date: Nov 2006
Location: , IL
Posts: 104
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: briggs 34cc head gasket

Would love to know the already tried mods with this engine and the final result mentioned earlier in the thread.
flyguyeddy is offline  
Reply With Quote
Old 10-02-2012, 11:04 AM
  #30
Scota4570
 
Join Date: Jan 2009
Location: Salinas, CA
Posts: 841
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default 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.
Attached Thumbnails
Click image for larger version

Name:	Zw69621.jpg
Views:	12
Size:	58.6 KB
ID:	1807292   Click image for larger version

Name:	Wr55679.jpg
Views:	12
Size:	28.8 KB
ID:	1807293   Click image for larger version

Name:	Ch95591.jpg
Views:	11
Size:	31.6 KB
ID:	1807294  
Scota4570 is offline  
Reply With Quote
Old 10-02-2012, 02:22 PM
  #31
av8tor1977
 
av8tor1977's Avatar
 
Join Date: May 2003
Location: Tucson, AZ
Posts: 7,100
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: briggs 34cc head gasket

Scota4570 does a lot of work and experimentation with conversion engines and has a good amount of experience. I would take his advice concerning this engine.

AV8TOR
av8tor1977 is offline  
Reply With Quote
Old 10-02-2012, 05:13 PM
  #32
flyguyeddy
Thread Starter
 
Join Date: Nov 2006
Location: , IL
Posts: 104
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default 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
flyguyeddy is offline  
Reply With Quote
Old 10-02-2012, 07:32 PM
  #33
av8tor1977
 
av8tor1977's Avatar
 
Join Date: May 2003
Location: Tucson, AZ
Posts: 7,100
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default RE: briggs 34cc head gasket

Well, ok, have fun with it. But an underpowered, overweight engine is a real disappointment to have invested time in. Been there done that.....

AV8TOR
av8tor1977 is offline  
Reply With Quote
Old 10-05-2012, 01:24 PM
  #34
Scota4570
 
Join Date: Jan 2009
Location: Salinas, CA
Posts: 841
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default 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.
Attached Thumbnails
Click image for larger version

Name:	Hf98162.jpg
Views:	11
Size:	66.7 KB
ID:	1808135  
Scota4570 is offline  
Reply With Quote
Reply


Thread Tools
Search this Thread
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off



All times are GMT -8. The time now is 02:18 AM.