more power on a budget

[foster2484]

im looking to boost my 5hp briggs but defintly on a budget. any tricks i should know?

 

[BAMBY]

i have a 5hp briggs on my minibike too.
oscaryu1's guide on this engine is awesome!

http://www.diygokarts.com/vb/showthread.php?t=1583
he also has lots of videos on youtube that are helpful.
thanks, oscaryu1

i lapped my valves, ported the in and ex, and shaved the eyebrows, all in one swoop, and believe me, there IS a NOTICEABLE difference once you are done. for me, it let me rev a lot higher, but now my problem is valve float...(need heavier valve springs)... and a new cam for more power.

i think a cam is the best power adder, but it can be costly though (60-70 green ones)

if you have a dremel, you can port it and shave the brows, its pretty easy, just go easy on the ports. specially the exhaust... ONLY remove casting imperfections like little bumps and ridges.

BAMBY

 

[foster2484]

sounds pretty easy. i just got another 5 horse and ill do all that to it and swap em out and see the differance hopefully. do u un hook the governor??

 

[Kenny_McCormic]

Sell it and buy a sled motor.

 

[modelengineer]

Buy a complete motorbike and sell all the parts except the engine.
Believe it or not you can actually earn money on it.

 

[BAMBY]

yesss, thats the first thing i did when i got the engine...
definitely remove the governor. otherwise all the work you do will have been useless because the gov. will limit the rpm's.
well, it might still have more low end if you keep the gov. but i would take it off.
BAMBY

HOWEVER, now that you have the governor off, DO NOT rev the engine while its on a stand or bench, without a load on the engine, overrevving can completely ruin the engine. the high rpms are fine when your driving along though!
BAMBY

 

[Raywelder]

Port and polish, Straight pipe, Mill the head down, or, get a head off of a smaller motor.
Like bamby said, Lap the valves!
Stronger valve springs?

Well after reading that thread posted above, I dont know whether you would want to switch heads or not, I just know that the Racing mower guys do that.

 

[BAMBY]

Stronger valve springs?

just wanted to clarify why i put stronger valve springs.
you only need them if you get a new cam, and it has more lift than stock, then you need stronger springs.

i have heard in multiple places that milling the head or getting a 4hp one increases compression a little, but makes the flow horrible. my vote is against it.

maybe oscaryu1 knows for sure...