squeezing every hp out of a 5hp briggs?

[zabroluc]

i would like to know every tip, trick, and know facts to get the most out of your 5hp briggs.

i will start off with something i learned. grinding off the thrust casting on the connecting rod will relive stress and help oil flow better.

 

[blownengine]

You need to work off three concepts. Higher compression, more gas, more air.
go buy a head with a larger compression ratio. (or find a 4hp head, Im not sure if the two match up, look into that)
To get more air you need to port the intake and exhaust. Nothing major right away, just smooth out rough edges and casting imperfections.
And with the increase in air you will need more fuel. Which will consist of drilling out/buying larger jets
I know i gave a vauge answer but either google the stuff i have said or wait for others to reply

 

[briggs_boy]

hey man i am going to tell you how to get lots of power out of you briggs.

but the first thing i need to know is are you wanting the engine stock or modified ?

 

[zabroluc]

i want to know the fastest, and cheapest ways to get hp out of a briggs. i have two stock briggs right now. i would like them to have more hp. i dont care if they look stock or not. i would like to mod but money is tight.

i dont really understand your question, wanting stock or mod?

thanks for the replys

 

[briggs_boy]

when i say modified i mean nothing stock at all, fully modified.
but since you are on a budget i can tell you the best way to get the power you want for not alot of $$$.

fist thing you will need is stock length 3.875 arc billet rod part number 6350. 50 bucks for that.

then get a a set of stock class/stock size billet lifter 1.600 about 15 bucks.

then get a dyno 94ss cam this is the only cam you can use in ur situation where you will not need and block work to run the cam. that cost 55 bucks

then you need to buy 21 pound valve springs. and heat treated retainers. witch will be about 10 buck.

then get a copper 0.32 head gasket witch is 6 bucks.

and a 5 degree offset timing key.

to get maximum hp you will need to port your block. if you have a dremel rotary tool you can do this.

you will need to go to your local parts store and order a autolite 292 sparkplug.
also index your spark plug towards the intake valve.

all of this should give you about 9 to 11 hp.

also a good header for the engine.

i have most of the stuff you need.

but some of it you will have to buy new.

just let me know i will help you all the way through you engine build.

 

[zabroluc]

whats way to get hp out of them without buying parts. hillbilly ways. i have a bunch of parts laying around. porting and polishing, will a tec. 4hp head get you more compresion?

 

[blownengine]

You have to spend a little money. You cant get away with nothing. Once the governer is removed you need stronger valve springs at the bare minimum but those are cheap.
And porting is a must.
Get rid of the stock muffler and get a header. If the exhaust has thread(which i believe it does) its as easy as screwing in some thick pipe w/ a small straight through muffler if you want to keep your sound down.
Once both of those are done you need more gas. Im not exactly sure how to do this on a briggs, not my stongest suit. Ask someone else

 

[blownengine]

o and i really doubt the Tecumseh head will fit your briggs. Two different companies, two different ways of doing things. But look into it. Prove me wrong

 

[briggs_boy]

the tec 4hp head wont fit. the briggs 4hp head fits and gives you more compression but you can just get your 5hp head cut down for like 10 bucks. remove the governor get harder valve springs port the block lap your valves in real good. and get a header then a filter adapter and a k&n style filter, and get a 3 degrre timing advancement key,you can do all this for like 40 bucks. this is basically the bare minimum

 

[zabroluc]

thanks a bunch, going hunting now

 

[minidragbike]

A better question is:
How much power do you want?
If you can answer this then a combo can be figured out. Making the most isn't a good thing for riding.

 

[jimh]

A better question is:
How much power do you want?
If you can answer this then a combo can be figured out. Making the most isn't a good thing for riding.

Amen. It's easy to render an engine useless for any thing but racing. If you make 10 or 11hp, that's great, but at what rpm? How will that with my gearing convert to speed? How good a rider am I? Where will I be riding, etc. has to be figured into it. Going fast is fun. Going fast and living to tell your grandchildren about it is priceless.

 

[ruffRider]

briggs boy i need help with my briggs 5hp

 

[ruffRider]

briggs boy i need help with my briggs 5hp

 

[ruffRider]

i dont wanna post here wtf..

 

[cxbra]

Free horsepower? A light port and polish, straight pipe header and make a cheap velocity stack. Thats about the most you can do for free, I'd say a 1-2hp increase (the intake really wakes up the top end pull, the header adds massive torque).

 

[minibikefreak]

Port and polish shave to eye brows stentyen rod i wouldnt go past 4500 rpm with stock flywheel bigger jet header nice flowing air filter. My high school has a machine class so im always bringing my engines their to do stuff

 

[jeep2003]

Do a valve job. make sure your valves open and close at the right time. I throw away the feeler guages because thats never enough. You may get some more valve noise and less opening but the increase in compression more than makes up for it. To do this pull the head and turn the valves with your fingers till you feel them seat. take material off the bottom of the valve stem until you get them to open and close at the bottom and top of the stroke. most of the time youll find they arnt closing until half way up the stroke which cuts compression drasticly. Tecumseh engines actually have a lobe on the back of the cam which intentionaly releases comression to make the rope easier to pull! for that you have to pull the cam and grind that lobe off. this will make your tired old 5hp feel like a brand new 8hp

 

[MikeBear]

As others said, port and polish the intake and exhaust is the easiest, make sure your exhaust doesn't have too much back pressure. Also then replace the original Carb with a Diaphragm carb. The old large chainsaw carbs work wonderful for this.

All that alone, could get you a couple more HP, and you can then see if you like the work, and want to take it farther such as Briggs_boy suggested.

 

[perdue027]

Thanks for this great thread guys! Im trying to redo my ruttman spyder and this sounds within my budget and limited knowledge. My first step would be porting, and I see the exhaust port is threaded. Do I remove all of the threads when porting if I am not using a screw in muffler? Also does anyone know where I can get this recommended 94ss "cheater" cam at a decent price?
I'm looking forward to this restoration, and will post pictures.
And thanks in advanced for any help possible!