briggs flathead

[fastforward]

i would like to build a flathead 5 , do you think i could get 40 mph relatively easy or should i consider something else

 

[07Motorboy]

Not sure, but it sure would be a fun engine to build.

 

[fastforward]

i have like 6 of them and thought it might be neat as opposed cloning

 

[07Motorboy]

Yeah:thumbsup:

 

[bowtiebutler]

Definitely build the flathead! You can get 40mph out of it without to much trouble. :thumbsup:

Matt

 

[Jay727]

You can get 40 out of it stock with a muffler.

 

[Havasu Dave]

I wouldn't say it was "easy" got get 40 on a BS 5 without spending some money to get it to turn faster than 3600 RPM. You need something like 5000 to make those speeds and have any kind of accelleration. (In my opinion) I have a built briggs and I don't have it geared that high, because I like the power on accelleration, and I weigh 225.

Here is a speed calculator you can play with to get an idea of the gearing required, as well as RPM. Speed Calculator For Go Karts and Mini Bikes

 

[Kierw]

You can get 40 out of it stock with a muffler.

Chuckle ......

 

[Jay727]

Chuckle ......

I can :shrug: on a two seat Carter go kart. It does have my own valve springs but otherwise stock.
But then again it is a fun power type engine, they seem more powerful than the older ones.
I was testing a staged racing pipe vs stock muffler--2mph difference. 46--44.

 

[The Restore Kid]

You can get 40 out of it stock with a muffler.

HAHA!! :lol: I WAS gonna say the same thing..

I can :shrug: on a two seat Carter go kart. .

HAHA!! :lol: The rest of the story... :lol:

Ohhh No... 40 is probably a good top speed to aim for if you're not looking to spend a lot of money and are pulling a small car... :facepalm:

There are a lot of things to factor in when trying to go a certain speed in a certain place....

I have a Bicycle with a slightly modded, basically just hopped up Briggs 5 horse, it'll do nearly 60 and actually doesn't pull too bad.. It's pretty slowish getting moving from the dead stop, up to maybe 8 miles per hour, the torque starts adding up, till ya get to like 20, and the clucth really starts to try to grab and and bike shutters each time the fuel detonates and the piston hits, until the clutch really HOOKS UP and it is starting to GO!! because the engine is making 3,000 and just being able to get to come to life some, then from like 20 to hell, 54?? :shrug: It'll try to pull it's ass out from under you... :shrug:

It is geared for 60 MPH and will pull a trailer load of scrap engines to the junkyard... The clutch hates it, but once your rolling, it rolls rite along.. :shrug:

But thats on pavement, in a 75 pound machine, with a motor that runs DAMN good, pushing two 20 inch tires 2 inches wide..

You're talkin like 200 pound vehicle, 4 stubby little tires that thinks 40 miles per hour is 400 miles per hour...

THEN you are probably only driving around the yard, no where to really even get up to 40 miles per hour...

If you are just driving up and down the dirt roads with plenty of wide open smooth driving in front of you, 40 should not be hard with the right gears and some basic hop ups... Just gears really.. But it's hard on clutches and stuff.. SO, if you're trying to do 40 in the yard, and always working the hell out of it, you're just gonna burn up clutches..

A torque converter system for the price, is one way to not only make much more power to work with, end up going faster, but they are more durable than a single speed clutch..

PLUS it is variable speed, literally 8 million different gear ratios... So technically, you can gear the vehicle to go 100 miles per hour, but when you are taking off, not moving very fast, you are in first gear, so although the (gears) are (geared) for 100 miles per hours.... your (transmission) is geared for 35, because you're not moving, and still in first gear...

Know what I mean? :mellow:

 

[WrenchDad]

Makes perfect sense.......one question are those tires street or trail?

 

[The Restore Kid]

What, on the Suicycle? They are moped wheels.. They were on a Tomos Targa.. The best tires I ever had on it were the originals.. Completely bald some stupid ass waffle tread pattern and soooooo rotten they totaly fell apart the first day the bike ran..

BUT!! They were moped tires, with a big old tire, and a heavy side wall..

verything I've had on it since are just whatever bicycle tires I find that look good.. It eats em up fast, but are free compared to 40 bucks each.. :laugh:


The last set were some of the wacky flame looking tread pattern from the cheap K-Mart freestyle bikes.. Mongoose, X-Games, yadayada..

 

[Havasu Dave]

AHA!! :lol: The rest of the story... :lol: :mellow:

I know what you mean. :laugh: The original post asked: "do you think i could get 40 mph relatively easy?" No doubt, we all have our opinions on what that term means.

My 5HP flathead I got from Randi:

New rings, valves, chrome piston (std), Mikuni 22mm, dbl valve springs w/ locks and retainers, ARC rod (3.875), ARC adj flywheel, milled head, nice cam (265 actual lift at the valve)

Smaller frame bike, (Taco) 5" wheels, running a 5.77 final ratio. With me, it "might" do 40, max'd out on the throttle. I don't want to grenade the engine, so I don't.

$400 engine rebuild, a $200 TC, and whatever gearing is required on the frame. (Jack shaft, gears, welding, etc)

Again, relatively easy is a subjective term. (I have been considering a TC so I can gear it down a bit, but still have a decent top end)

 

[chazdaddy]

I have stock 5hp Briggs FH that goes 40mph plus on payment. I took engine down to check, lapped the valves, checked valve lash, and put it back together. Runs very nice. :thumbsup:

Bike is DB30 with pocket tires w/ 40" rollout, gearing is 13 tooth clutch, 60 tooth rear sprocket. At 5,000 rpms, I am going 41mph. It will pull 5,300 pretty easy, feels fast to me.

I think the main mod is the pocket bike tires. With 25psi, the bike rolls like a skate board. Not sure it would pull 40mph with the OEM dirt tires.