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#Post#: 6300--------------------------------------------------
Changing the 'Pick-up' rpm on a centrifugal clutch
DIR By: Adrian
Date: April 11, 2022, 9:51 am
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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.
#Post#: 6301--------------------------------------------------
Re: Changing the 'Pick-up' rpm on a centrifugal clutch
DIR By: TheGiantTribble
Date: April 11, 2022, 10:05 am
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6000 RPM!!!
7000 RPM!!!!!!
Wow sounds like a right 'Beast' of an engine you are building
:-)
(did you see what I did there)
Can't wait to see and hear this here build of yours.
#Post#: 6303--------------------------------------------------
Re: Changing the 'Pick-up' rpm on a centrifugal clutch
DIR By: Ian F
Date: April 11, 2022, 1:00 pm
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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.
#Post#: 6305--------------------------------------------------
Re: Changing the 'Pick-up' rpm on a centrifugal clutch
DIR By: David F-R
Date: April 11, 2022, 1:25 pm
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--- Quote from: Ian F link ---
>
> so working my gearing for a theoretical 47 mph top speed and
5,000 rpm to 5,200 rpm.
>
--- End Quote ---
Personally I shall be aiming at 35mph with a tailwind down hill.
After that I think it may be double underpants.
But we shall see!
#Post#: 6312--------------------------------------------------
Re: Changing the 'Pick-up' rpm on a centrifugal clutch
DIR By: Adrian
Date: April 11, 2022, 2:41 pm
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I have just posted something that you might find interesting
:>)
#Post#: 6315--------------------------------------------------
Re: Changing the 'Pick-up' rpm on a centrifugal clutch
DIR By: StefanN
Date: April 11, 2022, 5:36 pm
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--- Quote from: Adrian link ---
>
> 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?
>
--- End Quote ---
If you’re using a Comet TAV Adrian, the engagement RPM for
various spring/weight combinations is in the Comet
documentation. This post on the US site has a discussion about
it and shows the info.
HTML https://www.cyclekartclub.com/forum/cyclekart-tech-forum.2/how-to-tune-your-tav2-and-a-little-comet.42744/
It’s also possible to machine the weights to get intermediate
weights. I’ve posted a couple of photos of this in the Bugatti
build journal.
#Post#: 6316--------------------------------------------------
Re: Changing the 'Pick-up' rpm on a centrifugal clutch
DIR By: peterL
Date: April 12, 2022, 1:39 am
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I'm not sure what type of clutch you are using Adrian, but this
may be of help if it's the same internals.
HTML https://youtu.be/gpo7GGSS8ZY
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
#Post#: 6329--------------------------------------------------
Re: Changing the 'Pick-up' rpm on a centrifugal clutch
DIR By: Adrian
Date: April 12, 2022, 2:46 pm
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Yes, onto that. Thanks Peter
:>)
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