gocart building

[tkwetzel]

Briggs and Stratton and Tecumseh both make strong engines. For a small engine for a go-kart I would go with one of them over a Honda any day. Honda makes reliable stuff, but I believe that the small engines made by these other companies are just as reliable if not more so. We had a Tecumseh 6 HP engine on our chopper for a long time and it had no problems. It spent a year on a go-kart getting the crap beat out of it before we put it on the chopper too, so it can withstand a beating. We recently sold the 6 HP engine to a friend of mine who is also building a go-kart. He has also started from scratch. Though I do think that you will be very limited with a $500 budget and that to make a decent kart would require about $700 and up (depending on how good you want it).

[greencactus3]

hmm. i searched for pocket rockets on ebay and with shipping seems i can get one for a bit over $200. 49cc, dual diskbrakes, chain driven and claims to go over 40 so i was thinking i can take that apart and then build a frame ($50ish), buy spindles, etc and wheels/tires for under $150. is there sumthing im forgetting? clutch(some pocket rockets have a "CVT" which im assuming is the belt type torque converter)... oh axles. bearings, well that cant cost too much, do you think $500s a little tight?

[sanddrag]

Pocket rocket engines are derived from Weedeaters and Chainsaws where gokart engines are derived from lawnmowers and waterpumps. 49cc is a pretty good displacement size for that little engine but one thing for sure is that you are not going to mow your lawn with a weedwhacker and you are not going to whack your weeds with a lawnmower. A pocket rocket engine is never going to put out 5 horsepower without serious expensive modifications where a gokart engine easily will. Gokart engines rev lower but have more torque where pocket rocket engines rev higher and have less torque. For a gokart, you want a big engine. Lawnmower (horizontal) style, not weedwhacker style.

[Matt Attallah]

X2 For what Sanddrag said. Get a larger engine - for 2 reasons.

1. The torque. Remember - Torque is what gets you up to that speed - Horsepower keeps you moving. I'd always go for more torque.

2. I'd personally don't feel very comfortable with an engine at 7,000+ RPMs doing only 30 mph down the road. Again - get the larger engine and you can gear it much better!

I don't know that much about the technicals on smaller engines - but it's still off the principle of a 2/4 stroke Internal Combustion engine...

And anyways - remember the saying - "There's no replacement for displacement"

[greencactus3]

thnx guys, but most lawnmower/waterpump engines rev only up to about 3500. which isnt too pleasing for me. as matt said, id much rather hear it running high rpms. i dont need to burn out or anything. i wouldnt care so much even if i had to push off running next to the cart if i have more top end torque. and high rpms. if i wanna start drifting with it, id like the high rpms. (and a manual clutch would help... is there a way to get a manual clutch rather than a torque converter or a centrifugal for a gocart?)
power to weight ratio with a 2 stroke or a big displacement with a big 4st. dont dirtbikes use anything as small as a 50cc? i dont know too much but say for example, a 5hp b&s lawnmower engine. whats the displacement on those?
oh and a little offtopic but whats the legality or w/e on gocarts? (michigan) anyone know off the top of their heads? save me some time looking it up

[tkwetzel]

Originally Posted by greencactus3

thnx guys, but most lawnmower/waterpump engines rev only up to about 3500. which isnt too pleasing for me. as matt said, id much rather hear it running high rpms....power to weight ratio with a 2 stroke or a big displacement with a big 4st. dont dirtbikes use anything as small as a 50cc? i dont know too much but say for example, a 5hp b&s lawnmower engine. whats the displacement on those?
oh and a little offtopic but whats the legality or w/e on gocarts? (michigan) anyone know off the top of their heads? save me some time looking it up

I know that B&S and Tecumseh engines rev to 3000-3500 rpm stock, but can push out close to 7000 rpm with some modifications. And the 6 HP Tecumseh engine we used on the chopper was like 150 cc...not as small as you would think. I have no idea about the legality in Michigan.

[greencactus3]

Originally Posted by tkwetzel

I know that B&S and Tecumseh engines rev to 3000-3500 rpm stock, but can push out close to 7000 rpm with some modifications. And the 6 HP Tecumseh engine we used on the chopper was like 150 cc...not as small as you would think. I have no idea about the legality in Michigan.

what are those modifications you mention? is it something to be done in a garage? or do i have to take it somewhere and have it professionally done?
so seems everyones against the 50cc engines. how about pricing? is a lawnmower engine worth the money over the small engine?

[tkwetzel]

Originally Posted by greencactus3

what are those modifications you mention? is it something to be done in a garage? or do i have to take it somewhere and have it professionally done?
so seems everyones against the 50cc engines. how about pricing? is a lawnmower engine worth the money over the small engine?

The modifications can get exspensive, but our stock 6 HP Tecumseh 4-stroke engine cost $225 brand new and we did not modify it. I am unsure about how much each modification affects the power and RPM range, but I know that 7,000 RPM can be achieved (it will probably cost you at least $500 to do it though).

Modifications range from putting a high-lift camshaft in, to boring the cylinder out, to changing the timing. Many of these things can be done in a home garage, but boring the cylinder out would require the use of a machine that I doubt anyone has in thier home garage. These small 4-stroke engines are very simple and easy to take apart and could be rebuilt with new parts within a day if you spent the whole day working on it.

Some people that use the 5 HP B&S engines for go-kart racing end up spending up to (if not more than) $1000 on them, but those are all out racing engines, which is more than you are looking for. A stock engine would suit you well for a home-made go-kart just to fool around with (unless you really want to hear the thing wind out several thousand RPM's).

[greencactus3]

yea. thats the prices ive been seeing on ebay for those motors. but ive heard tecumseh is unreliable? how was yours? anyone think different? and the ones on ebay some have alternators. think thats useful? or does it like reduce performance even? headlights sure would be cool but no need for them. if we wanted, we can always stick a battery on.
so prolly no mods are gonna happen other than maybe change the timing a bit if sumone knows what they're doing. i know timing on electric brushes but for valves and such nope.
i have a friend who really races shifter carts and yea, i know how money can get you speed lol. but dont wanna spend too much. BUT i do like high whines.

[Andrew Y.]

got to agree with everyone else, chassis is the first place to start.
then move on the the drive train (steering and motor)
the engin and differentials really depend on wut kind of driving ur ognna be doing so just experiment with that


hope it all comes together good for ya. if u have any questions cantact. glad to help out

[greencactus3]

Originally Posted by Andrew Y.

got to agree with everyone else, chassis is the first place to start.
then move on the the drive train (steering and motor)
the engin and differentials really depend on wut kind of driving ur ognna be doing so just experiment with that


hope it all comes together good for ya. if u have any questions cantact. glad to help out

thanks but how can i design a chassis without knowing what kind of engine i want? and differential? i was planning solid axle. yea i know less steering but whaddya guys think? less weight too. and brakes/drive spur would be easier to mount with a spool. a diff worth it?
and experimenting. oh i wish i could but due to budget, i prolly have one shot to buy the right things,

[tkwetzel]

Originally Posted by greencactus3

thanks but how can i design a chassis without knowing what kind of engine i want? and differential? i was planning solid axle. yea i know less steering but whaddya guys think? less weight too. and brakes/drive spur would be easier to mount with a spool. a diff worth it?
and experimenting. oh i wish i could but due to budget, i prolly have one shot to buy the right things,

Differentials are completely unnecessary for go-karts. A sprocket from the engine to a sprocket on a solid axle. It is easy to mount a brake to a solid axle too. So it sounds like you had the right idea to begin with.

[Not2B]

I know you want to do it non-kit style, but you might be able to get some parts near you.

I see you are on the Farmington Hills team. At the corner of Orchard Lake and Grand River, behind the carwash, next to the Wendy's - is a place that sells parts for motorcycles, snowmobiles and GO-KARTS!!!!

I've never been in, but I see them moving go-karts and such in and out, and I think they sell parts. (Sign says so.)

They should be able to at least supply you with some parts, or at least you can go in and look around and get some ideas.

Good Luck!!

(P.S. - I coach on the Canton/Plymouth/Salem team, but I live in Farmington Hills.)