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« on: February 01, 2019, 08:33:38 AM »
So....being cheap that I am, I did the $$$ on the briggs engine the first year or two and then had an epiphany. Briggs and the Chinese knock off Honda clones were actually exactly like 1955 all over again.
Flat head ford, Poor breathing, 85hp and could be built (with enough $$) to 200hp
sbc, good breathing and came factory with 200hp
Flathead, 3 mains, low rpm
sbc, 5 mains, high rpm
On and on it goes. Well lets compare the briggs;
Briggs, poor breathing flathead, = need to extensively port and relieve,
above 5000 the dipper breaks off the con rod = need billet rod
5000+ the con rod or piston breaks = billet rod and forged piston
5500 the cast fly wheel explodes = billet flywheel
to go above 5500 need cam with more lift so you need to notch the head or go billet = cam/springs/gears/billet head
6000 the side plate flexes and breaks = billet side cover with roller bearing on both ends of crank
7000 the crank breaks so you need a support bearing on the end of the crank by the clutch
8000 (or over boring) the jug blows off = billet jug/head support
Most are "cool bore" which means aluminum cyl which nobody around here can bore/hone
Everything for briggs racing is EXPENSIVE! (Craws in NY "freshens" a friends engine for $5000....FRESHENS!!
Honda clone;
Cast iron liner
Roller bearing on both ends of crank
good breathing overhead valve head
Honda flywheel will take 7000rpm
Karts use the engine so everything is available and CHEAP!!
So, I went to princess auto (Canadian version of harbour freight) and $99 for a 5hp clone.
Karts Canada sold me the "head combo # 3" for $200 or so. SS valves, 26# springs, heavy guide plates, pushrods, some other stuff I forget
Dyno cams sold me a cam for $60 (2500 - 7000)
Made my own intake and bolted the 28mm flat slide alcohol mikuni on and picked up a full second over the previous briggs combo that was WAY more expensive and WAY more "on the edge" (the briggs he blew up which initiated this said 12,200rpm on the data recorder, it normally went through the lights around 9500)
The clone hit 7000 in the 1/8th. We went to a test and tune weekend and were the only junior there, treated like royalty but they were set up for 1/4 mile and didn't want to switch back and forth. The kid held it wide open about 30 runs that weekend, hit 7100 and stayed there the rest of the pass. Poor motor was screaming for 21 seconds or so, not sure if floating valves or just couldn't breath anymore but never hurt it a bit!
Ran that clone engine the last 3 or 4 years and never did anything more that change the oil.
Gas, it slowed a second or so but went through maybe 2- 3 litres a weekend. Oil was fine but changed it at the end of the weekend.
Alcohol (actually I used methyl hydrate, cheaper and available everywhere) Ran Fri night, change the milky oil out. Ran Sat, change the milky oil out. Ran Sunday, change the milky oil and strip the carb and spray it full of wd-40. Total was 8 litres of meth for the weekend.
So, if you're running a briggs and the kids are having fun, fine. Once they get the "I want to go faster like them" then pull the briggs and get a clone. Clutch fits on the same even.
The clone will pick up a bit over the briggs all else equal, but a home made header/mikuni carb (gas or alcohol) and it will be low 13's or high 12's. That will last them for another 2-3 years. If you want more than that, go to "affordable gocarts.com" and get a cheap cam/head package and run 11's. For 1/4 of the price it would be for a briggs.
I kept the kid to low 11's just because I didn't want to spend more to go faster when he was starting to win fairly regularly.
Had a blast, great 7 years and we bonded, race weekend was him and me in the motorhome. Mom and the oldest had no interest so they didn't go. Had a routine of stopping for McDonalds on the trip there and ice cream on the way home. Excellent years and I know he'll remember for the rest of his life.
(still think I should of taken more pictures though, realise now you can't have to many of when you're young...)
Edit: forgot to add, kid thought he was running top fuel the whole time, strutting around after a round win with the arm restrains still on, talking about "whomping the throttle" freaking hilarious! His 2nd last race in the junior was a big weekend with 3 races due to rain outs. He won two of them and runner upped in the third. Left with $600 or so in his pocket. (course it cost me $250 a weekend to get the motorhome there and back....but I digress....lol)
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