3hp engine upgrade?

[Abchoppers]

This kart pictured has a Briggs and Stratton 3 hp engine, it’s kind of a pig to say the least. The problem is I don’t really want to put a 212 on, it’ll be too much for my youngest. It has no low end power at all, like any incline and it won’t move. I know that’s partly because of the clutch set up and partly the engine size. Are there any ways to upgrade the power of the 3hp? Does anyone make a 5hp engine? I haven’t found one anywhere after searching.
Thanks in advance

 

[Denny]

The Predator will be your best option and cheapest also. Atleast with the Predator you can upgrade later with a CVT.

 

[Abchoppers]

The Predator will be your best option and cheapest also. Atleast with the Predator you can upgrade later with a CVT.

Do you think a predator 3hp would be any better than the old Briggs 3hp?

 

[Denny]

No, not at all! Plus due to the small shaft size you would need a new clutch. While a predator will have more power it does not translate to more speed. RPM controls that. By the way what are your gear ratios? Can we see a picture of the working side of the engine and sprockets?

 

[madprofessor]

Gear ratio is almost everything, but chopping off top end does make for more quick-reactions-needed acceleration for a little kid. A way to tamp down both top speed and acceleration together is by adjusting the throttle limiter, the simple screw that stops the throttle from being pressed too far. Denny's right about the Predator. The 212 comes out of the box at only 6.5hp., can be throttled back as stated, and is very easy to return to average and then to even hotrod it up later.

 

[JimD]

Give us the teeth count on both the clutch sprocket and the axle sprocket. Make sure the brake isn't giving you the problem by dragging in the drum or constant pressure on the disk. Is it a stub axle kart or live axle? The built lots of 3 and 4 hp karts and they were plenty peppy. Brister Thunder karts had one with 2:1 gear reduction unit to help slow them down for a new driver. The side picture showing the clutch and rear sprocket sure would help for giving you good advice. A 3hp and 6hp both go 3,600rpm but the 6 will get you going to top speed faster but eventually the 3hp will be doing the SAME top end speed.

 

[Abchoppers]

Thanks for the replies. The clutch sprocket is 10 teeth, axle sprocket is 60 teeth. It’s not a live axle, it’s stub axle I believe

 

[pearl111]

It does appear to be a live axle to me I could be wrong,I see a key way on the axle. And the Sprocket is not attached to the wheel.

 

[JimD]

Thanks you for the pictures. Gear ratio is correct. Looks to be a live axle- put the rear end on a box and turn the wheel closest to the sprocket and see if the other wheel turns at the same time, if so you have a live axle. The end of the crank looks blue from heat or maybe not but if so what is causing the heat? Chain looks to be too tight. Should be around 1/2" to 3/4" lift in the middle between the two sprockets.

When you have it up on the box start the engine and run it without touching the brake. Make sure you put the front end of the kart against something stationary like a tree if you are in a warm area or the front of the garage if you are freezing like myself. Run the engine so the clutch engages for several minutes then turn it off and feel the brake drum, if it is real hot then the brake is dragging to much. You will have to adjust it if that is the case.

 

[Abchoppers]

We finally had time today to get to check out the go kart, only one wheel spins which I thought was not a live axle but maybe I’m wrong? I did the brake test and no heat, it is a brand new band so it does look very close to the hub but doesn’t seem to be rubbing.

After watching my girls ride around today it does seem that the 3hp has a decent top end speed like you guys said. I think the problem is that we’re also on dirt, which isn’t ideal with a clutch.

I think if I do any upgrading it’ll be the predator 212 like suggested, but for now my little one seems content with the power so I guess I should be too lol I just wasn’t sure if my gear ratio or something else was way off. Thanks everyone

 

[JimD]

Riding on dirt will not hurt the clutch. As for the axle, if only the one tire spins free (the one on the right hand side of the kart) because there is a bushing in the wheel just like the front wheels then you do have a stub axle. If only the left tire moves the chain when you turn the wheel then it is a stub axle drive. Oil the clutch bushing when you are done riding and put a little oil on the chain at the same time and give it all night to penetrate around the pins. Drip 3 or 4 drops of oil right on the snap ring of the clutch when it is warm and it will suck in the oil like a sponge when it is warm when you are done riding for the day. Oiling it before you go riding you haven't accomplished a thing because it will throw the oil off instantly and you just gave yourself some false security thinking you did something.

 

[ezcome-ezgo]

Only one wheel is being powered? In the 1st picture you posted here, there is very clearly a bearing hanging the axle opposite the motor. If only one wheel is being powered, there is some kind of voodoo going on.

 

[Abchoppers]

Riding on dirt will not hurt the clutch. As for the axle, if only the one tire spins free (the one on the right hand side of the kart) because there is a bushing in the wheel just like the front wheels then you do have a stub axle. If only the left tire moves the chain when you turn the wheel then it is a stub axle drive. Oil the clutch bushing when you are done riding and put a little oil on the chain at the same time and give it all night to penetrate around the pins. Drip 3 or 4 drops of oil right on the snap ring of the clutch when it is warm and it will suck in the oil like a sponge when it is warm when you are done riding for the day. Oiling it before you go riding you haven't accomplished a thing because it will throw the oil off instantly and you just gave yourself some false security thinking you did something.

It’s definitely a stub axle, right tire spins independent, and when riding the left will spin when it loses traction. I’ll definitely try the oil trick, I also need to loosen the chain as was suggested. Thank you

 

[Abchoppers]

Only one wheel is being powered? In the 1st picture you posted here, there is very clearly a bearing hanging the axle opposite the motor. If only one wheel is being powered, there is some kind of voodoo going on.

I’ll investigate more, I think it would help if it was a live axle, maybe something broke
Thank you

 

[madprofessor]

Many folks recommend using aerosol Brake-Kleen to remove all old grease and oil from chains and etc., but I've never seen anybody recommend electrical contact cleaner, like from LPS. I love the stuff, it has almost no viscosity, so it runs right into the tightest places, like purple PVC cleaner does, and very quickly evaporates away completely. I'd use some of the LPS to completely renew your chain and sprockets, then start over with a thin spray lube like Liquid Wrench Chain and Cable Lube (I use it for cables). It will quickly sling off any excess as soon as you wind up the rpms a bit. Leaves a great thin layer that won't hold dirt. Used to use similar stuff for motocross on my thumper bikes.
Lps LPS 16 oz. Aerosol Can, Contact Cleaner 03116 | Zoro
Chain & Cable Lube – Liquid Wrench

 

[jmaack]

you have a live axle. the other side is probably missing or broken key.

 

[Abchoppers]

Many folks recommend using aerosol Brake-Kleen to remove all old grease and oil from chains and etc., but I've never seen anybody recommend electrical contact cleaner, like from LPS. I love the stuff, it has almost no viscosity, so it runs right into the tightest places, like purple PVC cleaner does, and very quickly evaporates away completely. I'd use some of the LPS to completely renew your chain and sprockets, then start over with a thin spray lube like Liquid Wrench Chain and Cable Lube (I use it for cables). It will quickly sling off any excess as soon as you wind up the rpms a bit. Leaves a great thin layer that won't hold dirt. Used to use similar stuff for motocross on my thumper bikes.
Lps LPS 16 oz. Aerosol Can, Contact Cleaner 03116 | Zoro
Chain & Cable Lube – Liquid Wrench

My cousin who does motocross gave me something similar, he uses it on everything

 

[Abchoppers]

you have a live axle. the other side is probably missing or broken key.

That’s actually good news, I’ll look it over and report back. Thank you

 

[Abchoppers]

Update - so after examining the axle today, I discovered there was no key channel for the non drive tire side, but axle definitely spins, soooooo it was a loose axle nut on the right side . We now have a live axle go kart, thanks all! Yesterday with 3 girls and 3 karts I played pit crew. Had everything from stuck TC, brake linkage falling off, and dirty carbs. They had a great time
Thanks again!

 

[Denny]

That makes it all worth wile don’t it! To see the kids laughing and enjoying themselves!