running great but surprised by carb settings
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running great but surprised by carb settings
Hi - Just been out on my '54 G80 after doing a final tune of the carb, as the last plug chop from 60 mph things looked a little lean. The Carb is brand new mono block supplied and jetted etc by club spares (as standard on '55 I think). Anyhow I ended up with the needle on its highest setting (lowest groove). Engine runs really well, low tone exhaust note, picks up beautifully, cruises effortlessly at 6o - 65mph on pretty small throttle opening once up to speed. Little bit of vib at 50mph but clears at higher speed and nothing to worry about. On throttling off lots of engine breaking and no hint of any popping. So, not intending changing anything as I am a happy bunny now, but I am surprised at where my needle has ended up. Is anyone else running their needle on the highest setting (ie lowest groove)?
- Harry44
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Re: running great but surprised by carb settings
As in another thread I've adjusted the fuel level on mine and gone up two main jet sizes. Modern fuel has Ethanol in it which contains an oxygen atom in its molecule so it makes sense to run a richer mixture.
si is does non opportunus vos postulo a maior pango
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Re: running great but surprised by carb settings
Am having to run a 389 on the richest needle setting on my Model 31. Which surprises me too. And that's having upped the pilot jet a size too. Plugs about right and pick-up etc like your G80. Float level correct, no air leaks, so no faults that the settings are trying to compensate for as far as I can see. I've been happy running it this way, but have wondered about it from time to time.
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Re: running great but surprised by carb settings
Oh well, learn something new re the ethanol and extra O2 being available, thanks for that insight Harry. As everything seems running so well, first gear is not really engaged for any length of time at all - I am sure she could handle a bit more gearing without much depreciation in acceleration - so starts another journey!
Am I correct that standard engine sprocket is 21 teeth? - has anyone tried a 23 tooth one?
Am I correct that standard engine sprocket is 21 teeth? - has anyone tried a 23 tooth one?
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Re: running great but surprised by carb settings
You wont find a 23 tooth sprocket unless you have one made. Try going up one tooth on the final drive sprocket
Tony
Tony
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Re: running great but surprised by carb settings
Tony - would I not need to go down in number on final drive sprocket i.e. on the rear wheel or were you referring to the gearbox output sprocket?
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Re: running great but surprised by carb settings
Stephen G80 wrote:Tony - would I not need to go down in number on final drive sprocket i.e. on the rear wheel or were you referring to the gearbox output sprocket?
Yes. To be pedantic, the gearbox sprocket is generally described as the final drive sprocket since the one on the rear wheel is a 'driven' sprocket.
Although the gearbox sprocket is a driven sprocket relative to th'engine sprocket........
(Now, where did I put that anorak? ).
'There is a tide in the affairs of men
Which taken at the flood............'
Which taken at the flood............'
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Re: running great but surprised by carb settings
love it - a pedant within the pedant - OK so if one wants to up the gearing is the general consensus to change the most hard to get at sprocket then ie the gear box output sprocket? by a tooth or two teeth? - or do some folk take the route of reducing the final "driven " sprocket on the wheel by say 2 teeth? (I was thinking with the latter it would be relatively easy to get a sprocket made up or adapted and then put onto the hub (obviously old sprocket would be machined off).
Anyone "knowledge" gratefully received.
Anyone "knowledge" gratefully received.
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Re: running great but surprised by carb settings
(It's o.k. I've found my anorak under a box of the wrong type of rivets).Stephen G80 wrote:love it - a pedant within the pedant - OK so if one wants to up the gearing is the general consensus to change the most hard to get at sprocket then ie the gear box output sprocket? by a tooth or two teeth? - or do some folk take the route of reducing the final "driven " sprocket on the wheel by say 2 teeth? (I was thinking with the latter it would be relatively easy to get a sprocket made up or adapted and then put onto the hub (obviously old sprocket would be machined off).
Anyone "knowledge" gratefully received.
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If a finished rear sprocket sprocket isn't available this company will supply blanks for others to machine..........maybe give them a call?
http://www.sprocketsunlimited.com/
'There is a tide in the affairs of men
Which taken at the flood............'
Which taken at the flood............'
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Re: running great but surprised by carb settings
thanks Spriddler -that link may prove useful. However, I have sussed out that modern equivalent size of chain is 530 (I think) and 40 tooth sprocket for that chain size is used on a duke - so should be quite simple and I don't have to strip down the primary drive (again). Dropping two teeth at the rear is about 4.8% increase in gearing. Which means plodding though town in 3rd as opposed to 4th but slightly less frantic at 60mph when cruising. I am sure others on here have tried similar changes but can't find anything on the forums