By 'pick-up' I mean the rpm the engine needs to be doing in order for the clutch to start to engage then...... what is the rpm required to get it fully engaged?

The max rpm for the standard Honda engine is around 3600. I have no idea what rpm is required to get the clutch to start to bite but I know that it bites well before the engine is into its torque curve as it were which makes the acceleration quite 'modest' shall we say. The engine struggles to reach a higher torque. Whilst all this is happening karts with a T/C come zooming past.

The answer lies in two places, the mass of the weight weights in the clutch and the achievable rpm of the engine.
Just removing the governor can allow the engine to rev to 6,000 or 7,000 rpm but under light load so we need to te=weak the engine a bit to enable it to pull hard at these rpm's.

Well, I have tweaked it a bit.
1. Removed Governor
2. Bigger rejetted carb
3.
 

I'm very new to all this, but from what I have found out so far if the governor is removed the engine will rev past the governed speed of 3,600 till it meets the next restriction (air filter, exhaust, choke diameter of the carb and jetting).  If you tweek those then you get up to about 5,200 to 5,500 when valve bounce sets in, but this leads to more expensive mods.

I believe peak torque is about 2,500 RPM, so this could be a good target for your clutch to fully engage.  I believe engagement RPM can be adjusted with different springs, or by chopping coils off springs.

i was originally intending to use just the clutch, but now looking to use a CVT.  Looking at changing the air filter, jetting and exhaust so working my gearing for a theoretical 47 mph top speed and 5,000 rpm to 5,200 rpm.

I have just posted something that you might find interesting
:>)

I'm not sure what type of clutch you are using Adrian, but this may be of help if it's the same internals.



If it's got separate springs the aim is presumably to get them to engage later, so you either need to lighten the weights, or upgrade the springs.

Peter