Speed
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highfield
- Posts: 12
- Joined: Wed Nov 05, 2014 9:03 pm
- Location: Australia AUSTRALIA
Speed
On my 61G80cs the standard gearing has a 16t gearbox-sprocket which gives an overall ratio of 5.8 to one,mine was getting a bit worn as I couldnt get a 16t I put an 18t which gives a 5.15 ratio.With the original set-up it would manage 75-80mph on my flickering speedo now with an 18t on its struggling to reach 70mph should the ratio change make that much difference? The motor is in good condition new rings,piston,valves,guides but having no tacho I dont know if its managing to rev-out.
g mitchell
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g5wqian
- Member
- Posts: 221
- Joined: Wed Nov 18, 2015 7:43 am
- Location: wiltshire
- Location: near swindon wilts
Re: Speed
although its a twin my model 30 ajs runs a 16t gearbox sprocket and 23 tooth engine sprocket , with a burman gearbox and the std 42 tooth rear sprocket .
that pulls very well and is not high geared , it will go along at 65mph but is revving nicely .
apart from thinking it will blow up if i rev it flat out it will go past 90mph but to be honest i dont take it up there .
those cheap little chinese digital tachos that you wrap a wire around the HT lead will work on the magneto ignition , i have put one on my bike and it is cable tied to the brake and throttle cables that pass over the steering yoke .
the tacho has a cr2032 battery inside and senses the ignition pulse when you start the engine , so you dont have to switch it on when you run the engine , it comes on on its own .
they only cost about $10 au .
cheap and easy way to get a rough idea of revs and are non destructive to the machines wiring because they dont have to have a physical connection to anything on it , except for a couple of small cable ties to hold the readout in place and they can be simply cut off and removed when youve finished .
i wrapped my sense wire around the HT lead just underneath the fuel tank and the kerb side and fed the wire up with all the other cabling at the frame top tube , or rather i fed the wire down from the top and then wrapped it round the HT lead and tied it off with 2 small cable ties .
that pulls very well and is not high geared , it will go along at 65mph but is revving nicely .
apart from thinking it will blow up if i rev it flat out it will go past 90mph but to be honest i dont take it up there .
those cheap little chinese digital tachos that you wrap a wire around the HT lead will work on the magneto ignition , i have put one on my bike and it is cable tied to the brake and throttle cables that pass over the steering yoke .
the tacho has a cr2032 battery inside and senses the ignition pulse when you start the engine , so you dont have to switch it on when you run the engine , it comes on on its own .
they only cost about $10 au .
cheap and easy way to get a rough idea of revs and are non destructive to the machines wiring because they dont have to have a physical connection to anything on it , except for a couple of small cable ties to hold the readout in place and they can be simply cut off and removed when youve finished .
i wrapped my sense wire around the HT lead just underneath the fuel tank and the kerb side and fed the wire up with all the other cabling at the frame top tube , or rather i fed the wire down from the top and then wrapped it round the HT lead and tied it off with 2 small cable ties .
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Mick D
- Posts: 2886
- Joined: Mon Mar 24, 2014 5:44 pm
- Location: Aberdeenshire
Re: Speed
Hi
Without delving too much into the dynamics - you have increased the size of the sprocket by 12.5% - if you reduce the maximum speed, (read power), 80 mph by 12.5% you get 70 mph.
Rough and basic but I'd think the effect you are experiencing is to be expected for the sprocket change.
Regards Mick
Without delving too much into the dynamics - you have increased the size of the sprocket by 12.5% - if you reduce the maximum speed, (read power), 80 mph by 12.5% you get 70 mph.
Rough and basic but I'd think the effect you are experiencing is to be expected for the sprocket change.
Regards Mick