5 horse parts in an 8 horse ???

#1
I was wondering if 5 horse parts will work in an 8 horse block, I'm talking cam, lifters, valves, valve springs all that stuff thanks. Im going to try to make my own "HOT ROD" style crank and rod by lightening them but dont know what to do for valvetrain except 5horse Comp Cams parts.
 
#3
turn the crank journal down use a 5hp arc rod send out 8hp cam and get ground the lifteer and valves are bigger but you could press in guides and ream for smaller lighter parts
 
#4
Hello and Welcome aboard!

Ill try to help you out the best I can, ask me anything that ya need to know that I didnt cover,

Is this motor for a mini or a kart? Is it going to be raced seriously, or just like a pit bike?

Im going to go out on a limb and say that None of the parts will work, (easily)

The connecting rod has the chance of being too short, (the briggs numbers do not match)

You could have a cam ground but that is going to cost some serious money to have done (100-300 dollars)

Valve springs wouldnt be too big of a deal, as you could find heavier ones, but lifters would be a custom,

Id leave the stock valves, even my raptor has stock valves.

A better carb (True Mikuni, Tillotson, Walbro) would help the most, along with a true header. and loosing the governor, (risk of destroying a motor)

In all honesty if your looking for the most power out of a motor, without busting your bank I would look into the 5 horsepower, (Yes, there is no true substitute for cubic inches) but for the dollar for dollar it may be much cheaper ( briggs 5 horses can easily have 15 horsepower, and as high as 40+) The 8 horse just doesnt have the mass of parts that the 5 does.

Be aware that lightening the crank can have ill effects, and you could possibly severely weaken it, especially under high RPM loads.

Im not sure how much you are willing to spend, but speeds gunna cost cash, Not saying it wouldn't be worth it, or be fun but it WILL be costly.
 
#5
Thanks for the info guys, much appreciated. What is the bore of the 5 horse, been too long since I really messed with them much. Plans are for whatever i build to end up on a mini bike or a small trike.
 
#6
The bore of the 5 horse is 2.565, by 2.438 Stroke, for a total of 13 cubic inches.

The 5 horses are run by karting and are being phased out, but the parts are very easy to come by and there are hundreds out there.

Rieken's Racing: Flathead Parts - OUT2WIN.COM theres a bunch of parts, there are hundreds or more manufactures out there

Id stick with the 5 horse
 
#7
I was wondering if 5 horse parts will work in an 8 horse block, I'm talking cam, lifters, valves, valve springs all that stuff thanks. Im going to try to make my own "HOT ROD" style crank and rod by lightening them but dont know what to do for valvetrain except 5horse Comp Cams parts.
Ditch the fhead and the animal. go for a honda less to buy new and just as many aftermarket parts. will make more power dont get me wrong love the old flatheads probably built over 400 of them. but overhead valve is just more efficient hands down.
 
Top