Just wondering what engagement speed to set the cvt at for a 14hp single cylinder project, I'm guessing it'll pull from around 1200RPM but not sure, what's everyone else running?
Cheers
Lex
Engagement speed for CVT
Moderators: Dan J, Diesel Dave, Crazymanneil, Stuart
Engagement speed for CVT
Hey there
Just wondering what engagement speed to set the cvt at for a 14hp single cylinder project, I'm guessing it'll pull from around 1200RPM but not sure, what's everyone else running?
Cheers
Lex
Just wondering what engagement speed to set the cvt at for a 14hp single cylinder project, I'm guessing it'll pull from around 1200RPM but not sure, what's everyone else running?
Cheers
Lex
Lex,
You dont so much set the engagement as they dont come calibrated as such, instead you sort of work it out by trial and error.
There are so many variables such as belt tension, final ratio, wheel size, weight, engine used etc that pretty much each machine is unique.
The first thing to get right is the belt slack. Pinch the belt together in the middle of its run and you want about 5mm of gap at the clutch. Much more than this and the engagement will be high and any less and it will drag.
Then spend a bit of time getting your idle speed correct. Although its tempting to set it really low to reduce noise and knocking etc you may find that it causes the engine to stall when you shut the throttle smartly, another 100rpm or so will solve it.
Assuming you spent the time getting the pulley offset correct you can now test the machine.
It is most likely that the engagement will be too high for your liking as these units are designed for higher revving machines such as go-karts and snow mobiles. To bring it down, pull the clutch cover off and add extra pucks/bob weights also see what tension spring you have been supplied.
Test machine again and repeat the above until you bring the engagement down to where you like it. As a general rule of thumb a set up with maximum weights and lowest spring tension works best.
Bear in mind if your engine likes a few hundred rpm when starting that the engagement isnt this low.
This all sounds more complicated than it is. It is really worth the investment in an hour or two tuning the cvt, it vastly improves your enjoyment of the bike.
Hope this helps, good luck.
You dont so much set the engagement as they dont come calibrated as such, instead you sort of work it out by trial and error.
There are so many variables such as belt tension, final ratio, wheel size, weight, engine used etc that pretty much each machine is unique.
The first thing to get right is the belt slack. Pinch the belt together in the middle of its run and you want about 5mm of gap at the clutch. Much more than this and the engagement will be high and any less and it will drag.
Then spend a bit of time getting your idle speed correct. Although its tempting to set it really low to reduce noise and knocking etc you may find that it causes the engine to stall when you shut the throttle smartly, another 100rpm or so will solve it.
Assuming you spent the time getting the pulley offset correct you can now test the machine.
It is most likely that the engagement will be too high for your liking as these units are designed for higher revving machines such as go-karts and snow mobiles. To bring it down, pull the clutch cover off and add extra pucks/bob weights also see what tension spring you have been supplied.
Test machine again and repeat the above until you bring the engagement down to where you like it. As a general rule of thumb a set up with maximum weights and lowest spring tension works best.
Bear in mind if your engine likes a few hundred rpm when starting that the engagement isnt this low.
This all sounds more complicated than it is. It is really worth the investment in an hour or two tuning the cvt, it vastly improves your enjoyment of the bike.
Hope this helps, good luck.
Hi Mark
Thanks for the info - I'm going the cvt route with this bike and just about to order the transmission from combidrive in wales. They said that their standard drives engage at 1600 rpm, so If I go with that and play with it from there - I remember your other threads when you were setting yours up so I shall re read those.
Cheers
Alex
Thanks for the info - I'm going the cvt route with this bike and just about to order the transmission from combidrive in wales. They said that their standard drives engage at 1600 rpm, so If I go with that and play with it from there - I remember your other threads when you were setting yours up so I shall re read those.
Cheers
Alex
Hi Lex,
Smart choice to order from Combidrive, they have been faultless with me as far as advice and after sales service. Im sure you wont be disappointed.
Just for the benefit of others who are doing CVT builds I'd like to reiterate a couple of points that might save some time in the long run.
The figure you have been quoted for engagement is a nominal figure, presumably for an optimum set-up.
Get the final drive ratio too tall and more force is required to turn the wheel. This means more friction is required to over come belt slip. More friction means more revs and before you know it your clutching is engaging far higher than the manufacturer states.
Likewise if the belt is too slack, more revs are required to take up this slack before engagement, then as the belt has had to travel further up the cone, it is trying to engage at ratio higher than is necessary. Again higher ratios require more force and suddenly your quoted 1600rpm figure can easily become 2200rpm.
Apologies if Im repeating earlier stuff, I just want others to understand the importance of getting the basic set up right. Whilst I knew the theory of how they worked, I only really understood it when I started playing about with it.
Look forward to hearing how you get on, good luck
Mark
Smart choice to order from Combidrive, they have been faultless with me as far as advice and after sales service. Im sure you wont be disappointed.
Just for the benefit of others who are doing CVT builds I'd like to reiterate a couple of points that might save some time in the long run.
The figure you have been quoted for engagement is a nominal figure, presumably for an optimum set-up.
Get the final drive ratio too tall and more force is required to turn the wheel. This means more friction is required to over come belt slip. More friction means more revs and before you know it your clutching is engaging far higher than the manufacturer states.
Likewise if the belt is too slack, more revs are required to take up this slack before engagement, then as the belt has had to travel further up the cone, it is trying to engage at ratio higher than is necessary. Again higher ratios require more force and suddenly your quoted 1600rpm figure can easily become 2200rpm.
Apologies if Im repeating earlier stuff, I just want others to understand the importance of getting the basic set up right. Whilst I knew the theory of how they worked, I only really understood it when I started playing about with it.
Look forward to hearing how you get on, good luck
Mark
Timppax,
I couldn't tell you if Combidrive deal with a full range of Suco products, why not email them your requirements?
I did a quick google search though and found a press release from them on EngineeringTalks site. They are certainly supplying a new Suko clutch which is claimed to have a very positive engagement and reduce slip. Due to this it is said to be ideal for high torque, low revving applications. Therefore Im a little confused by the info that your distributor supplied.
The clutch Im using is a Comet Duster. Comet recommend it for high torque and v-twin applications. From an engineering point of view its near perfect. It has a broader range of ratios than the 40 series and a bigger belt, so helps to minimise slippage. It is not however the Holy Grail of Diesel Bike transmissions as its quite bulky and unsightly when in a large cover so you have to make sure you can make the ergonomics fit and can face looking at it.
Cheers, Mark
I couldn't tell you if Combidrive deal with a full range of Suco products, why not email them your requirements?
I did a quick google search though and found a press release from them on EngineeringTalks site. They are certainly supplying a new Suko clutch which is claimed to have a very positive engagement and reduce slip. Due to this it is said to be ideal for high torque, low revving applications. Therefore Im a little confused by the info that your distributor supplied.
The clutch Im using is a Comet Duster. Comet recommend it for high torque and v-twin applications. From an engineering point of view its near perfect. It has a broader range of ratios than the 40 series and a bigger belt, so helps to minimise slippage. It is not however the Holy Grail of Diesel Bike transmissions as its quite bulky and unsightly when in a large cover so you have to make sure you can make the ergonomics fit and can face looking at it.
Cheers, Mark
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TimppaX
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Local/national/bureaucratic tendency is to deny all if one is unsure. Perhaps Suco´s local distributors are more into customer service than importer.
I haven´t found importer for Comets but go-kart-kits.
Looks are secondary in my project
the uglier the better - makes me shine even more 
One route is to use transmission package from suitable ATV. New gearbox, with reverse is around 300€. That´s for 4x4 system. 2wd even less.
At this point my project is stalled since engine haven´t yet arrived form China + slight shortage of cash.
I haven´t found importer for Comets but go-kart-kits.
Looks are secondary in my project
the uglier the better - makes me shine even more One route is to use transmission package from suitable ATV. New gearbox, with reverse is around 300€. That´s for 4x4 system. 2wd even less.
At this point my project is stalled since engine haven´t yet arrived form China + slight shortage of cash.
that should do it