Speed/Torque optimization for 40 series

[Woahgoesdeep]

I have a manco 720l-06(two seater full size)

301 predator
Stage one(intake,exhaust, main jet)
40 series Torque converter
(It's about to get a 2600rpm stall kit)
22" rear tires
I weigh 205lbs
Currently has 9 tooth sprocket on driven pulley and 60 tooth sprocket on the axle.

The Gear ratio Calc I'm using already says I'm in danger of burning up my belt(it's not)

Take off power now seems good to me
Current top speed is 39mph

Trying to push it to 50mph without losing take off power(hense the stall kit coming)

My question is, can I go with a smaller rear sprocket without having to worry about my belt destroying itself every I ride?

If I can't or Shouldn't change the sprockets, what's the next upgrade to get more speed, if ibhave to get into internals in the engine that's fine if that's all I can do but any other suggestions or knowledge would be great!

 

[BrownStainRacing]

I have a manco 720l-06(two seater full size)

301 predator
Stage one(intake,exhaust, main jet)
40 series Torque converter
(It's about to get a 2600rpm stall kit)
22" rear tires
I weigh 205lbs
Currently has 9 tooth sprocket on driven pulley and 60 tooth sprocket on the axle.

The Gear ratio Calc I'm using already says I'm in danger of burning up my belt(it's not)

Take off power now seems good to me
Current top speed is 39mph

Trying to push it to 50mph without losing take off power(hense the stall kit coming)

My question is, can I go with a smaller rear sprocket without having to worry about my belt destroying itself every I ride?

If I can't or Shouldn't change the sprockets, what's the next upgrade to get more speed, if ibhave to get into internals in the engine that's fine if that's all I can do but any other suggestions or knowledge would be great!

What kinda rpm are you seeing at 39 mph????

Have you checked ignition timing??? Stock timing is for tillers engines. 28* is a good starting spot.

Is it electric start???

Can you go to a billet flywheel to get weight off the rotating assembly??? Saving weight here, will ALWAYS make an engine hit max torque quicker, which gets weight moving sooner.

Have you changed to a thinner head gasket??? This bumps up the compression ratio, which again moves weight sooner.
The faster you can get weight moving, the less gear you can run.

Is the plug out of that muffler???

Usually it's easier to change the jackshaft (small) sprocket, then it is the axle sprocket.

Nice kart

 

[Denny]

Go to a 10 tooth sprocket off the driven. Should get you to around 42 mph and be happy with that! Not much fun if it’s burned up or broken all the time!

 

[panchothedog]

I have a Manco Intruder kart. Big two seater. Looks a lot like yours. I am running a moderately built 301 predator. The 2600 rpm stall mods will work great ONLY if you can get more than the 3600 stock rpm. I put the ARC billet rod and flywheel, removed the govoner, cheap twister 250 cam, ported head,
50 b valve springs, header exhaust, re-jetted carb, and free flow air cleaner.
Don't have a tachometer but with a 10 tooth sprocket and a 60 on the axle it feels like to the seat of my pants ( and I own 3 other heavely modified karts )
like it is approaching 6000 rpm and nearing 50 mph. I have a mini bike that was clocked at 44 mph and this kart will smoke it. Also leaves from a dead stop like
a bat out of you know where, since I modified the clutch. I wouldn't worry about the belt, they are pretty robust and you are not pushing that much weight.

 

[panchothedog]

My rear tires are 18" so our gearing ends up different . If you build your engine,
you might want to keep the 9 tooth.

 

[Woahgoesdeep]

Awesome thank you for the responses guys, gives me an idea of what to do next.

Another question tho

All the upgrade parts I see are for 301 HEMI

I see the 212 and 420 have hemi and non-hemi variants but for the life of me can not find anything saying the 301 has or doesn't have a non hemi version, I dont wanna order wrong parts, anyone know?

 

[BrownStainRacing]

Awesome thank you for the responses guys, gives me an idea of what to do next.

Another question tho

All the upgrade parts I see are for 301 HEMI

I see the 212 and 420 have hemi and non-hemi variants but for the life of me can not find anything saying the 301 has or doesn't have a non hemi version, I dont wanna order wrong parts, anyone know?

Look around for parts from a honda gx240 or gx270. They are non hemi's. I'm sure the bore and stroke are different.

 

[panchothedog]

To the best of my knowledge, on the Predator big block engines 301 & 420 the hemi and non hemi will use the same aftermarket parts. Unlike the small 212cc
engines.

 

[Woahgoesdeep]

Look around for parts from a honda gx240 or gx270. They are non hemi's. I'm sure the bore and stroke are different.

On gopowersports,arc, and other kart websites all list a connecting rod for gx240/gx270 and 301 Hemi only, been trying to find one since yesterday with no luck

 

[Woahgoesdeep]

To the best of my knowledge, on the Predator big block engines 301 & 420 the hemi and non hemi will use the same aftermarket parts. Unlike the small 212cc
engines.

Seems like they use the same flywheel and other internals but the connecting rods I've found all say for gx240/gx270 and 301 hemi only