Upgrade HS 142f

[Deleted Member 4613]

I'm going to try this when it warms up on my HS 142F:
drill out the carb jet to 0.026 inches (#71 drill bit) and
install an extra flow air filter from affordable go karts. Will
it work to increase torque and top end? Anyone
done this? What can I expect?

 

[CrazyDan]

You'll also want to install a free flowing exhaust. If you get the jetting correct you will see a noticeable increase.

 

[Chainlube]

You can only get more torque if you add a header too. What goes in must come out.

 

[RB55]

What sprocket are you using? Gearing down is an easy and reliable way to increase speed, these engines usually are geared far too high from the factory (44T).

 

[Deleted Member 4613]

I'm more interested in torque so I will try a 44t and 48T sprocket.
I have a 7/8 inch flex pipe from ezm on the exhaust.

 

[darwin]

No one mentioned doing away w/the rev limited flywheel and pickup coil.

 

[Deleted Member 4613]

I could also try that, remove governor, but I'm
really hoping just rejetting, high flow air filter
and the 7/8 inch exhaust will give me what
I want. We'll see.

 

[CrazyDan]

The flywheel/mag swap doesn't increase torque, it just lets the engine spool higher (potentially unsafe for the engine and your "boys"). I run mine like that and don't advise it. It's a grenade waiting to happen with no cnc flywheel or conrod. The 7/8" flex exhaust with the carb/air filter mods should give you a bit more. The stock carb/exhaust settings intentionally restricts the engine to pass emissions. Another free (or near free if you gotta buy the feeler gauges) upgrade(?) is to set the valve lash properly. Think it's .004" intake .006" exhaust. Set it on a cold engine.

 

[Deleted Member 4613]

OK, so here's the million dollar question:
What if I didn't modify the stock hs 142f
carb and just replace it with the NT carb
using the adaptor? Would that give better
results than rejetting the stock carb and using
a high flow air filter?

 

[mark20]

dont think that will give you much other than better throttle response, i wounder if you could try a gc160/200 carburetor and replace it with the stock one, that should give you much better performance and reliability. but im not sure it would work (dont know how wide the bolt pettern is on one of these, as mine is basically stock) and other than trying to make a throttle for it, it should work just fine.