I'm building a B&S 5hp engine for a go-cart. I want to get as much power out of it as possible. What is highest compression this motor can safely handle? If I have the head shaved and bore the cylinder .020 over, what kind of problems might I run into? It is a 130202 model, type is 0198-04, it was made in 1974. Will changing the valves make a difference? Can I put a different carb on it? Are there any aftermarket camshafts and crankshafts for this particular motor? I want to build it right and do any and everything short of buying a new motor to get the best performance out this thing. Where's the fun in buying something new and settle for stock, anybody can do that, plus I'm not scared of a little work and want something "one-of-a kind". Any info and or advice would be greatly appreciated. Thanks!

Hi,

There are a number of things you can do to increase the power of a 5HP engine. Increased compression and cam work are just a few. If you do these things you'll want to be sure to replace the connecting rod with a billet rod. If you're interested send me an email and I can give you some more pointers. :thumbsup:

Dave
MileHighPowerSupply.com

Hi Jon,

Just curious, what are you looking to do with this motor? There are numerous different things you can do to increase the hp of the 5HP. It is essentially the building block for the Raptor and Blockzilla racing engines.

First, what is the model & type number of the engine you are working with? This will help identifying if the block is built well enough to withstand the extra ponies.

Just a few things to think about to increase the HP are:

1) A stroker rod as you mentioned. This will help as well as provide a rod that will not snap on you when the engine hits the higher RPM's.

2) Mill the block and head and install a copper head gasket. Same gasket used for the JR. Drag engines.

3) Port and polish the valve cavities to provide a better flow.

4) Bore the carb and jet it. This has a huge effect on the engine when all else has been modified with it.

5) Install a light weight billet flywheel to help engine acceleration.

6) Get rid of that stock cam!

These are just a few things you can do. Depending on what you want to do with it depends on how much you spend. As I mentioned before it all starts with the block.

I hope this helps.

Dave
MHPS (http://www.milehighpowersupply.com)

The model number is 130202 and the type is 0198-04, it was made in 1974. I believe it's an aluminum block, without a cast iron sleeve. So I guess I don't want it to get too hot. I'm not really going to be racing it, just something to pull out of the garage and show off on. Thanks for the info.

Jon

That engine has only one crank ball bearing on the PTO side. Although not a prefered block for a builder it shouldn't give you grief if you're looking to just have fun with it. I wouldn't build it so big that the crank is stressed too much or the block could crack. I've learned that one the hard way a few years ago.
Because you're looking to have some fun with it, rather than racing it, you should be able to get a pretty decent boost for a lot less money. I suggest a larger carb (jetted), modified cam, lighter flywheel and strip it down to the basics. No gov. etc. I can help you out with this stuff if you need it. Let me know.
Dave
MHPS

I found a kit that converts a single bearing block to a dual, would this make the enging stronger considering it was designed to be a single. Also someone told me that I could put a 3hp flywheel on it, is the shaft the same diameter on 3's and 5's? Also I was told that a carb off a 100cc dirtbike would give me more power, don't know if it will work. Any suggestions on the cam? Any certain brand, or type? Thanks.

Jon

That will make it stronger and even out stess. Specifically if you want to get "torqy" with it. You can install a 3HP flywheel but it will advance the timing to 6+ degrees. To adjust this you'll have to install a bracket. I have these and are pretty inexpensive.

As far as the carb goes, you're better off honing and jetting your existing carb.

The cam is another topic. It really depends on what kind of power you are looking for. I can work up a cam profile if you would like and let you know what the $ is. Do you want a torque motor, high speed motor? Any info like that will help.

One other thing to look at is a straight or trumpet pipe. Exhaust mods help greatly.

Dave
MHPS

briggs makes racing engines info is available on www.briggsandstratton.com raptor
racing engines good luck

Hey big ed,
Brigg's actually makes a Raptor engine kit. They no longer sale this engine complete because of the numerous modifications available to the consumer.

This kit is designed to be a base for a full blown racing engine with a price reflecting that! For more info here is a link to the racing site Brigg's Racing (http://www.briggsracing.com)

Dave
MHPS