Flat head Briggs mods. Help needed.

#1
Hello I have new project and need some help. Im trying to use what I got and can't figure some things out. First is I have a old Yamaha Chappy frame. I gotta get a set of forks and rear shocks, but the issue is power. My two engines are a 3 hp briggs off a edger. It has no governor. Intake is 3/4 and bolt holes are 1-3/8 inch center to center. I also have a 5 hp off a wizard tiller but its governored. Same hole specs except it has a 3rd hole a little further over. 2. I plan on using a vm20 but Im having trouble finding a intake manifold that will work. I looked at the ET 407 but is $50 and unsure if it will bolt up. Ive read Tecumseh work but no one mentions what part numbers. 3. Id rather the 3 hp but if I use the 5 hp what should I do with the governor?
I appreciate any help.
 

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#6
Its so old I'd rather go with a new carb setup. I might check out the 5 hp too. After doing more research the 79cc predator manifold on Agk looks like it will fit the briggs flat head if I open the hols up. Its off a couple millimeters
 
#7
There should be many performance parts available for 5hp Briggs. They are used in many classes of racing.
I'm sure a billet rod and flywheel would take care of the governor problem.
But that will cost some money.
Lots of times you can find stuff used or an ebay
 
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#8
There should be many performance parts available for 5hp Briggs. They are used in many classes or racing.
I'm sure a billet rod and flywheel would take care of the governor problem.
But that will cost some money.
Lots of times you can find stuff used or an ebay
Alot of the stuff is for newer engines. Both of these are old. The hold up on both is a intake manifold. I found a tecumseh but dont know the bolt hole distance. The one adapter I did find is $50 and it says for 90+ flatheads. These are both pre 90 heck they got points lol. I dont have a welder neither. I like the 3 hp because it has no governor already.
 
#10
Alot of the stuff is for newer engines. Both of these are old. The hold up on both is a intake manifold. I found a tecumseh but dont know the bolt hole distance. The one adapter I did find is $50 and it says for 90+ flatheads. These are both pre 90 heck they got points lol. I dont have a welder neither. I like the 3 hp because it has no governor already.
What are the differences between the newer and older 5hp engines?
Are you worried about over-revving the 3hp with no governor?
 
#16
Part two update. After lots of pounding I got the pressure washer pump off but bad news is it snapped the crank off at the engine. Partially good news though after looking up the part number the stub of the crank was short from the factory so gonna buy a horizontal crank off of ebay with a longer stub. Hopefully in the next couple days Ill get the engine on my bench.
 
#18
what pump was on that? the 3/4 tt9071?
Or did yours have the one inch shaft?

I used the same engine from pressure washer. Very durable.
It was a Cat Pump. Yeah I believe the shaft was 1 inch or 1-1/4. I believe the 407 mikuni adapter will work on this engine because its much newer than the other two flatheads. This one is a 133000 series.
 
#20
Got it apart and gotta order some parts. Gonna check the rings while its there. I gotta to get new valves, a cover for where the gigantic low oil shutoff was, seal and gasket. I think the valve guides are good. Gonna clean it up and maybe paint the block blue or white.
 

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