Modding an older briggs 5hp

[13angryB's]

I'm interested in modding my mini-bike to make more power,
It has a Briggs 5hp
130202 0862 03 79072007

What can you tell me about this motor?

Does it have a governor? Where?


-Will this Aluminum Flywheel & hi top coil work on my motor?

http://cgi.ebay.com/ws/eBayISAPI.dl...MEWA:IT&viewitem=&item=170126504817&rd=1&rd=1


I put a gas pipe exhaust on,
sounds pretty good,
but I havn't test driven it yet,
since i'm waiting for some new shocks & a disc brake caliper.


what kind of porting can I do?
..I have some carbide burrs & grinding bits.

 

[13angryB's]

Also, What is the secondary linkage on the carb for?
-goes from the carb to a lever on the back of the motor,
under the fuel tank.
..Mine was unhooked.
should I hook this back up?
or tie it up?

 

[GTO]

The linkage that goes to the motor is your Gov and it sounds like it's disconnected (and flopping around?) How does it run as is when under load?

 

[13angryB's]

Yeah the arm was just floppin.
should I tie it up or down to un-govern it?



I only had a chance to ride it around the block a couple of times,
before realizing I needed to replace the shocks & wheel bearings.
i'm trying to get it tuned up while waiting for parts get here.

So far,
I've put some hose clamps on the vac tube to the carb, because the rubber joints seemed loose.
I tightened the loop on the plug wire because the ignition was cutting out on bumps.
I shimmed up the loose headset with fender washers.
the new wheel bearings are installed.

 

[5hpbriggs]

pretty much if you are looking into dropping about $280 inperformance parts for this briggs. that is a light build up. thats with a dyno cm briggs motorsport carb rod and a few other goodies.

 

[minidragbike]

It's best to open the engine up to totally remove all the governor moving parts. All 5hp briggs have governors, the Raptor doesn't have it.

The stock rod is the first thing to break. So it's best to get a billet rod before you do anything.

 

[13angryB's]

What size billit rod would I need?

and, Will the Aluminum flywheel work?

 

[minidragbike]

3.875" billet rod will do.
Don't by that flywheel it's dangerous and it will explode. It's for a vertical shaft motor, and it's unbalanced. Use the stock flywheel, or a 3hp briggs flywheel.

 

[Backyard Builder]

Don't buy that flywheel it's dangerous and it will explode.

I completely agree! Stay away from this flywheel, it's a grenade waiting for a victim!

On a side note, when removing a flywheel, NEVER hit it with a hammer or any other object. Not even a rubber mallet. Hitting a flywheel will create tiny invisible cracks that will eventually make it explode, and that ain't pretty. 5 pounds of cast iron coming apart at 5000 rpm is enough to kill someone.

Buy the appropriate flywheel puller from Briggs. Oh and, when tightening/loosening the starter clutch, NEVER put an object in the flywheel fins to prevent it from moving (for the same reason as above).

Ok, that being said...

Happy modding :001_smile:

 

[javimanic]

i noticed you didnt have an aircleaner...really need one onless your motor is a throw away only used on perfectly clean maybe even wet streets. OK, you want more motor power...but some fun can be had in your clutch too- if it engages at a better rpm it will give more take off grunt. I had a motor like yours as a kid ona kart and never changed oil and ran without governor all its ife. never threw the rod. But, my valve springs I am sure(like yours) couldnt really keep the valves in line anyway above 4500/5000 rpm I suppose. You can leave your motor as is...or go crazybut just remember your side cover behind the clutch is a standard non-bearing type and doesnt like high horsepower work. It will melt to the crank...trust me I KNOW all too well. with the price of motors these days it almost seems better to upgrade to a bigger motor or a better motor sometimes. Like RIck Siemons says..."the best way to rebuild YOUR motor is to take your sparkplug and screw it into a New _______________________" fill in the blank with your choice of new motor with better features.