Hi, my mind keeps going back to when Centaurus converted Enfields with a Ruggerini 850, and their website claimed 78mph.
Anyone know how they achieved 78mph? Was this on the road or rolling road?
3600rpm through an Enfield gearbox gets you 60 to 65mph, did they increase the revs, up the sprocket size, monkey with the gear ratios?
Does anyone have a Centaurus? What is pulling away like?
Cheers
Ian
Centaurus mph
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Anorak_ian
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I've no idea regarding the top speed.-
andrewaust
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Hi Ian
I guess they probably upped the front final drive sprocket, and may have even upped the front primary sprocket.
I would guess you can achieve a fairly high top speed with a 22 tooth front sprocket on the final drive.
Your right about top speed with the standard gearing. My Enfield will get to around 95 klm hr, and shows around 3800 rpm on the tacho.
By the spec's that came with my engine = max rpm is 3800. I though it was revving more than that, but a digital tacho was a good purchase to keep an eye on things.
Cheers
Andrew
I guess they probably upped the front final drive sprocket, and may have even upped the front primary sprocket.
I would guess you can achieve a fairly high top speed with a 22 tooth front sprocket on the final drive.
Your right about top speed with the standard gearing. My Enfield will get to around 95 klm hr, and shows around 3800 rpm on the tacho.
By the spec's that came with my engine = max rpm is 3800. I though it was revving more than that, but a digital tacho was a good purchase to keep an eye on things.
Cheers
Andrew
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Anorak_ian
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If all they did was to fit a 22 tooth gearbox sprocket I'll be happy.
Thinking about it, a tooth is regarded as 4 mph, so if they started out using an 18 tooth=62mph, then moved up to 19 tooth=66mph, 20 tooth=70mph, 21 tooth=74mph, ending up at 22tooth=78mph.
I'm going to use Enfield trails gears to lower 1st 2nd & 3rd gear keeping 4th normal, adjust the gearbox sprocket to push the three gears back up to normal, that way 4th becomes an overdrive
I'm hoping the difference between 3600rpm and 4200rpm with overdrive is 12mph cos that will be 90mph which is my goal.
What is gear changing like with the Enfield box? Petrol owners say there is a big jump between 3rd and 4th, I'm just thinking that an over drive may be too tall.
Thinking about it, a tooth is regarded as 4 mph, so if they started out using an 18 tooth=62mph, then moved up to 19 tooth=66mph, 20 tooth=70mph, 21 tooth=74mph, ending up at 22tooth=78mph.
I'm going to use Enfield trails gears to lower 1st 2nd & 3rd gear keeping 4th normal, adjust the gearbox sprocket to push the three gears back up to normal, that way 4th becomes an overdrive
I'm hoping the difference between 3600rpm and 4200rpm with overdrive is 12mph cos that will be 90mph which is my goal.
What is gear changing like with the Enfield box? Petrol owners say there is a big jump between 3rd and 4th, I'm just thinking that an over drive may be too tall.
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Anorak_ian
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Hi, I have looked in to the 5 speed box, but unfortunately 5th gear is 1 to 1 the same as the 4 speed 
, no trails gears or alternative ratios have been made for the 5 speed box or are likely , Dr. Stuart McGuigan who designed the 5 speed box told me that it was designed so alternative gears could be used but none has been made so far.
He went on to say that he could make some for me but the cost would be high. The other problem is the extended main shaft would have to be manufactured specially as Enfield hasn’t used one with a diesel bullet.
As the box costs £600 new, and the gears, plus mainshaft I think we would be looking for little change out of £1000
I have been looking at old Albion boxes from Greeves and Villiers bikes, there was a 1965 5 speed Greeves Silverstone box on ebay not long ago, I lost the auction unfortunately but it would have made a good project to see if I could have mixed some Enfield gears with it and got a decent box from it.
I would prefer a 5 speed Norton Quaff box but they are very rare and expensive.
, no trails gears or alternative ratios have been made for the 5 speed box or are likely , Dr. Stuart McGuigan who designed the 5 speed box told me that it was designed so alternative gears could be used but none has been made so far. He went on to say that he could make some for me but the cost would be high. The other problem is the extended main shaft would have to be manufactured specially as Enfield hasn’t used one with a diesel bullet.
As the box costs £600 new, and the gears, plus mainshaft I think we would be looking for little change out of £1000
I have been looking at old Albion boxes from Greeves and Villiers bikes, there was a 1965 5 speed Greeves Silverstone box on ebay not long ago, I lost the auction unfortunately but it would have made a good project to see if I could have mixed some Enfield gears with it and got a decent box from it.
I would prefer a 5 speed Norton Quaff box but they are very rare and expensive.
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andrewaust
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Hi Ian
Yeah I looked into the 5 speed box also, finding exactly that = 1.1 ratio in fifth gear, and no extended shafts for spacing the clutch out so you can use the primary chain-case etc.
The Enfield 4 speed box has a HUGE gap between 3rd & 4th Ian, and can bit you in the butt if your going up a steep hill with the single cylinder diesel, although a twin would have a better power cycle between bangs of course.
One other thing that surfaced with the 4 speed Enfield boxes, but not sure if this may apply to the 5 speed's - there seems to be a lot of wear evident in boxes that use the lower gears a lot from the two shafts spinning in each other, that's interesting as we know both the 4 and 5 speed boxes have both there top gears as a 1.1 ratio, although I think the Brit boxes may have been different, as there was a rumour of a top gear overdrive gear-set - but never personally came across one
If you decide to go with/and get your hands on the 22-tooth whopper sprocket Ian, I think what you said in regard to changing the ratios of 1,2,3rd a great idea, as you'll need to space them out as best you can.
Cheers
Andrew
Yeah I looked into the 5 speed box also, finding exactly that = 1.1 ratio in fifth gear, and no extended shafts for spacing the clutch out so you can use the primary chain-case etc.
The Enfield 4 speed box has a HUGE gap between 3rd & 4th Ian, and can bit you in the butt if your going up a steep hill with the single cylinder diesel, although a twin would have a better power cycle between bangs of course.
One other thing that surfaced with the 4 speed Enfield boxes, but not sure if this may apply to the 5 speed's - there seems to be a lot of wear evident in boxes that use the lower gears a lot from the two shafts spinning in each other, that's interesting as we know both the 4 and 5 speed boxes have both there top gears as a 1.1 ratio, although I think the Brit boxes may have been different, as there was a rumour of a top gear overdrive gear-set - but never personally came across one
If you decide to go with/and get your hands on the 22-tooth whopper sprocket Ian, I think what you said in regard to changing the ratios of 1,2,3rd a great idea, as you'll need to space them out as best you can.
Cheers
Andrew
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oldbmw
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The 1:1 ratio for top gear is to be expected. final drive should be set using whatever combination of chain sprockets suit. The five ratios means you are more likely to remain within your power band when changing gear.
Not sure about the extended shaft issue. F2 motorcycles import old bikes refurbished ( including a new 5 speed box, disc front brake and 325cc Greaves diesel engine). There is an option for a slightly bigger engine. see here for details
http://www.f2motorcycles.ltd.uk/usedbikes.html
maybe that will help ?
Not sure about the extended shaft issue. F2 motorcycles import old bikes refurbished ( including a new 5 speed box, disc front brake and 325cc Greaves diesel engine). There is an option for a slightly bigger engine. see here for details
http://www.f2motorcycles.ltd.uk/usedbikes.html
maybe that will help ?
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Anorak_ian
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Yes 1:1 is a pain as petrol bikes get to a high speed by revving high, that isn't to say that a petrol bike wouldn't benefit by having an overdrive, my Harley has five gears top was 1:1 until I put on a larger gearbox pulley (sprocket) so it's now slightly in to overdrive, but no way good enough, what it needs is a proper overdrive gear. I took her to 120 by over revving her regretted doing that. One of the things that bugs me is they are still making bikes with 1:1 top gears in this age of expensive fuel and green issues (cars as well).
I agree that the final drive should be set using whatever combination of chain sprockets suit, but after sorting the gears in the box, and correct primary drive ratios first (in my case). I think as long as you can pull away in first gear up a slight hill with out it being too easy, then its set.
The Greaves engine is a lot narrower than my twin, so I think I will need a longer shaft, having said that the 4 speed Enfield sprocket can be modified to move closer in to the gearbox, but the standard shafts that I have are all in bad condition so I may as well get a long one.
Interesting to see a 5 speed used though. Cheers
regretted doing that. One of the things that bugs me is they are still making bikes with 1:1 top gears in this age of expensive fuel and green issues (cars as well). I agree that the final drive should be set using whatever combination of chain sprockets suit, but after sorting the gears in the box, and correct primary drive ratios first (in my case). I think as long as you can pull away in first gear up a slight hill with out it being too easy, then its set.
The Greaves engine is a lot narrower than my twin, so I think I will need a longer shaft, having said that the 4 speed Enfield sprocket can be modified to move closer in to the gearbox, but the standard shafts that I have are all in bad condition so I may as well get a long one.
Interesting to see a 5 speed used though. Cheers