3hp Briggs and strat. Enough for gokarts?

[slaps]

Hello all.

I recently got an old 3hp Briggs and Stratton engine going that was laid up for years. It's going great. I was thinking of making a gokarts for my sons to use in years to come, however the engine has a splined drive which runs a reduction gear. The reduction gear can come of no problem leaving just the engine and splined drive etc. Can the spline drive be used with any clutches available? Would it be even worth the bother trying to convert the splined drive to standard straight shaft drive? Is a 3hp even enough for kids gokarts?

Thanks in advance! Pics attached.

 

[Russ2251]

Is a 3hp even enough for kids gokarts?

I have used 1½hp engines with no difficulties. With governor disabled I can reach speeds of 18 to 20mph.
I have a vid of it somewhere...
If I can locate it I will post to YOUTUBE.

---------- Post added at 03:31 PM ---------- Previous post was at 02:35 PM ----------

Here it is:
1953 Briggs & Stratton model 6S 1½HP

 

[Zombient]

Depends.

How big is the rider, how big is the kart, what's the gearing, what's the wheel size?

 

[slaps]

Firstly, is what I've show workable? Splined drive in the engine etc?

---------- Post added at 10:25 PM ---------- Previous post was at 10:24 PM ----------

I have used 1½hp engines with no difficulties. With governor disabled I can reach speeds of 18 to 20mph.
I have a vid of it somewhere...
If I can locate it I will post to YOUTUBE.

---------- Post added at 03:31 PM ---------- Previous post was at 02:35 PM ----------

Here it is:
1953 Briggs & Stratton model 6S 1½HP

Very helpful, thank you.

 

[Russ2251]

Firstly, is what I've show workable? Splined drive in the engine etc?

Anything is possible.
I have not worked with anything other than straight, keyed shafts.
Perhaps someone else will chime in.

 

[landuse]

There are no clutches for your engine that I can think of that would work with a splined drive. You might be able to swap out your crank with a straight keyed one, or machine yours down to a size that a clutch might fit. I don't think the latter would work though, cos a 3HP already has the smallest diameter crank that I think a clutch would fit on.

 

[slaps]

There are no clutches for your engine that I can think of that would work with a splined drive. You might be able to swap out your crank with a straight keyed one, or machine yours down to a size that a clutch might fit. I don't think the latter would work though, cos a 3HP already has the smallest diameter crank that I think a clutch would fit on.

Just as I suspected. Very helpful reply. Might just sell the engine instead I think

 

[porsche930dude]

you will need to swap the crank and side cover. I think you might be able to just get a new seal to press in the old splined cover but im not 100% sure. another thing you can do is just make a belt tensioner clutch off the gear reduction. i beleive they are 6:1 so you can run 1:1 pulleys and be good. 3hp is enough for kids but wont be able to do much hilly terrain just stick to flat ground and itll work.

 

[slaps]

Picture showing reduction gear.

 

[OzFab]

Now, that's more like it Is there a clutch involved in that setup? If so, you're good to go; if not... not so much...

 

[slaps]

Now, that's more like it Is there a clutch involved in that setup? If so, you're good to go; if not... not so much...

There's no clutch ATM. That is the gear that was always on the reduction box. This unit came in off an old hay bale elevator. The gear is very much seized on there so I'll have to get a little heat on it the get it off. I am guessing a clutch could then be fitted?

 

[landuse]

There's no clutch ATM. That is the gear that was always on the reduction box. This unit came in off an old hay bale elevator. The gear is very much seized on there so I'll have to get a little heat on it the get it off. I am guessing a clutch could then be fitted?

What Fabroman is trying to say is that some of these reduction boxes have clutches build into them. I don't think yours does though

 

[slaps]

What Fabroman is trying to say is that some of these reduction boxes have clutches build into them. I don't think yours does though

Ah right, this does not have a clutch built in that's for sure.

 

[OzFab]

What Fabroman is trying to say is that some of these reduction boxes have clutches build into them. I don't think yours does though

That's only half of it; the other half is you may have trouble finding a clutch that will actually work; most centrifugal clutches engage at around 1800rpm & fully lock at around 2200rpm; even with 2:1 redux gears, that means the engine will be at 3600rpm (governed speed) before the clutch even engages, 4400rpm before it locks...

Yes, you can get a clutch with a lower engagement speed but, I'm unsure if you will find one that engages close to 1000rpm...

 

[supermanotorious]

as I found with trying to convert a vertical shaft Briggs to horizontal that if you have to replace the crank, the engine is totaled, meaning its easier and more cost effective to buy an engine that will work off Craigslist rather than ordering the replacement shaft

 

[porsche930dude]

this isnt vertical shaft. everything else is normal except the crank and sidecover. its a 6:1 box there is no putting a clutch on that. It just wont work.

 

[supermanotorious]

I know that, he's talking about replacing the crank, see the connection now?

 

[slaps]

Thank you all for your time, replies and advice. I think I'll sell her on. It's just not cost effective to start changing the crank. Again thank you all. Laters.

 

[slidewayz]

Slaps, I know its easy for me to say, just shell out some $....but if there is a Harbor Freight anywhere close to you, do yourself a favor and just get yourself one of these. They are less than a hundred bucks, and work like a champ, and for about 20 bucks more, you can upgrade to the 212cc (6.5hp) version if your kart needs it and if your driver is up to it.

 

[supermanotorious]

I would absolutely suggest going with the 212cc from Harbor Freight, the difference in price between that and the 79cc is negligible, esp after a 20% coupon that can be found in the back of any mechanic, home improvement, manly type of magazine, plus we get gobs of them in our "junk" mail