3 hp briggs cam

minidragbike

Supporting Speed Nut!
#3
I wouldn't fool around with it. The motor will blow up. Simply because you need a billet rod, extended lifters, springs etc. If you don't have these you might as well leave it stock.

You can buy a 5hp version and bolt on all the upgrades you need to go faster. The question is how much power do you want?
 
#4
I've never seen any parts upgrades for the 3hp...the blue wazoom and raptor series of performance engines were both based on the 5hp.

You could try a header, and shave a few thousandths off the head to bring the compression up a little. I have one I made a little intake manifold for and put an adjustable Tecumseh carb and a K&N air filter on it. These three things will pump up the power a little.
 
#5
yea, Ive been planning on shaving the head, first upgrade that came to my mind actually. Even stock, this motor pulls me around good. How much did that increse power for you?
 
#7
It perked it up a little bit. I'm not a big fan of that inch-thick dense foam air filter that comes stock on those engines. I think they were intended for use on lawn equipment in really dirty environments. If the engine is going on a minibike, I always put on a little K&N type filter...you'll be able to tell it's breathing better because you'll probably need to readjust the carb after the new filter is installed.

I just read the FAQ on how to add a photo, so here's a pic of one of my Briggs 3hp with a little header and air filter upgrade...
 
#10
Yeah, I have to be careful to measure the clearance with a straight edge and a dial caliper or a lump of modeling clay before I start shaving. I mark the head also, so I don't put a higher lift cam in that block.
 
#12
I cheated a little bit...I made an adaptor on a lathe. I also have one that has one of those small four-inch chrome Mr. Gasket air cleaner assemblies. They seem to work well, and look fairly decent.

I just finished an engine this evening that has a copper and brass velocity stack on it...I made it from a flea market bugle. You can see it at...

http://pictures.aol.com/galleries/yellowhand1961

I'd put the pic here in the post, but I need to tag the photos first so I can link to them from here.
 

kbs8ball

Active Member
#16
go to auto zone..look at the breathers for car motors..I bought one and modified it so it would bolt up to the carb...costs 8 bucks or so
 

65ShelbyClone

Well-Known Member
#18
I have one of the 3hp enines with a plasic cam. I got the engine dirt cheap and used it for experimentation. I milled the head as far as possible with the estimated lift I was after. I took the plastic cam and reduced the base circle on it for more lift. I also happened to have some 4hp Tecumseh long lifters that I could shorten to ultimately have "extended" Briggs lifters for the big cam. I think lift measured out to somewhere around .320". I rant he engine on propane because the carb and tank were junk.

Yeah, not much of that stuff can be done by the average DIYer, but it gives you an idea.
 
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