Needing help with Flathead Briggs build.

[Andrew05]

So a buddy of mine gave me a old Briggs 5 horse that he had sitting under his porch, and I decided to put it in a minibike frame I had. However, I found out that at some point the governor got deleted. I plan on building this thing to be something of a cruiser, so the rpm's would sit around 4k to 5k tops. I found a post on here about using a raptor 3 connecting rod and dipper (I have it linked below), so I feel pretty comfortable about swapping one in for the insurance. While I'm at it, is there anything else I'd need to upgrade? I don't want to float the valves so I thought about upgrading the springs, and I'm not sure about the factory flywheel. I'm just trying to add some insurance so if I'm out riding it somewhere it won't blow up on me. Any ideas or advice would be greatly appreciated.

Link to raptor rod thread:

Raptor Con Rod Question

I'm still looking into a better con rod for my flathead so I can remove the governor safely, but I've also noticed that there are some Briggs Raptor racing rods on Ebay for about 1/3 the price of an ARC rod(see pics) The first one is a 555179 part number, and the second one is a 555208. Could...

www.diygokarts.com

Links to the rods I found:

Briggs & Stratton Racing 555179 Connecting Rod 5hp Go Kart Go Cart 130202 | 0024847887327 | USA | Briggs Stratton

BRIGGS & STRATTON 130200, 130400, 131200, 132200, 132400, 133200, 135200, 135232 and 136200 5 HP Horizontal Engines. Also Have Many New Raptor Racing Parts Including Blocks, Pistons, Cranks, Carbs, Etc.

www.ebay.com

Briggs & Stratton Connecting Rod .020 555208 for sale online | eBay

Find many great new & used options and get the best deals for Briggs & Stratton Connecting Rod .020 555208 at the best online prices at eBay! Free shipping for many products!

www.ebay.com

 

[Denny]

You also might want to look for a billet flywheel. Flywheel explosions can be a real drag.

 

[Andrew05]

I've thought about it, it's just a big chunk of change. That being said though I'm pretty partial to my leg. I also thought about selling what I've got and switching to a Predator 212. I know you can get cast aluminum flywheels for those around 40 bucks, and the rest of the part prices are roughly the same or less than the Briggs parts. I'm a big Briggs fan, but since this was supposed to be a budget build I don't know if I could afford a built Briggs. Plus those 212's sound nasty when they're tuned up right. You think that might be a better idea?

 

[Hellion]

You think that might be a better idea?

Yes! Best way to upgrade an engine like that would be take the spark plug out....... and put it into another brand new engine.

I'm a big Briggs fan too but I am somehow less inclined to throw lots of money into them. They are fine, ungoverned, up to the RPM where the valves flutter/float but I am not interested in 9000 RPM.. They first started racing with the basic Model 13 (and Raptor I, II, III) with the stock flywheels for years without an issue until someone had an accident with one so a high-rpm-rated aftermarket flywheel is a good idea at the very minimum. The connecting rod historically gives out before the flywheel, but building a model 13 up is an exercise in evening everything out.

 

[Andrew05]

I've seen some of the crazy things folks have done with flatheads (especially in the dirt oval world), but I agree, I'm not trying to build some 9k rpm race motor. I kept the factory governor gear and whatnot so I may just put it back together and sell it. Thankfully where I live Predators are cheap and easy to find. I appreciate the help!