Forum

[MadMike]

Me again. Wallace have you got a tacho fitted? If so what revs were you running at when cruising at 50mph prior to the change, and what revs are you now pulling at the same speed. Beware that the vast majority of bikes are geared for "optimum" performance. Adding a tooth or two to the gearbox end can result in the engime being overgeared, which inevitably makes it run slower than standard gearing, and makes the engine labour on uphill stretches. I will be interested to know the difference in revs at any given speed. the chances ar that you are travelling faster initially at around 50mph........BUT you may also be using more throttle opening to achieve it. Internal combustion engines are only about 28% efficient. That would be for a high performance engine and probably using a turbo. Something like an Enfield or an old British single is probably not much more that 25% eficient. The good old engineers have found ways to burn more fuel faster, but frankly they have failed to make an efficient internal combustion engine. Revs and speeds please Wallace.

[Beezabryan]

I am not an engineer, never have been never will be, but....... I listen to folks and make informed decisions. ............ way back in the last century Alan Hitchcock (who I have grteat respect for) gave me advice on how to improve my Bullet for the type of riding I expected to be doing in the years to come. ..... on his advice I changed the exhaust, upped the final drive sprocket one tooth to 18, fitted a Boyer ignition and a basic carburation tweak. This has served me well on such diverse terrain as the Derbyshire Dales, UK motorways, European "E" roads, the Appalachians (Blue Ridge & Alleghenies) in US. ... Just my 2 drachma for what they are worth

[grunda 12]

if anyone wants to see a bike with a big sprocket look at the photo,s posted on dieselbike.net on face book there you will see a bike called the sprocket at this years big knock rally by the way it has a mercedes sprinter van diesel engine fitted take a look atb paul.

[Alan R]

Oh gawd---this old chestnut---OK, here we go again}---- DENNIS C, get your a-r-s back in here matey !!I agree entirely with your maths....Gentlemen,as any gearing alteration at this level is directly proportional, then for a 1 tooth addition onto a 17t sprocket you have an increase of 1/17th ( or 0.0588.) ..... At 50mph this becomes 0.0588 x 50 = 2.941..Added together we get the new road speed of}---52.941mph.(Actual, NOT what that Enfield "thing" in the casquette says). Similarly for a 19t sprocket fitted we'll get an increase to }-----59.99(60)mph...BUT, the foregoing is based on pure ratios only.......And as MADMIKE rightly says this is "overgearing" for a standard engine..So what's to be done then ?? ............ well, we have to fit all the other free-breathing mods, larger jettings, et al such that the engines' TORQUE is also increased and can pull these higher ratios........ Now when you reach this point you can either a)----carry on cruising at 50 mph ( But now your engine's revs will be 5 to 6% lower ) OR b)---- ride at the higher road speed (because your engine can now do this)------ BUT, at this point your 1950s' rolling-frame and brakes design start to come under scrutiny (I have a disc front brake fitted on No1 bike)....Also at this point you should remember that all this extra power is being transmitted by a piston who loves decapitation moreso than Henry VIII, and a con-rod that thinks it invented the separatist idea !!... In other words-----don't overdo it !!----------- Finally PAUL K }---- I reduced the PRE-LOAD on the rear shocks such that the dampening can start to work earlier ie to balance-up the rears with the front...... And kept especially for last }------ Ducks Disease ?? How did you find out about my GREEN stool ??-----and that coming from a follically-challenged, rotund, Michael of dubious sanity....Remember, there's no such thing as the Sanity Clause at Christmas.....HI MATEY !! WOTSA DATE FOR THE AUTUMN BASH THEN ??????

[sofiaspin]

Scottish deerhound amongst the rabbits gord and bennet why not just reduce the rear sprocket by one tooth rather than the ball ache and expense of a front sprocket change? Alan R?

[Paulk]

Alan, ride height is adjusted by the pre-load I don't understand the connection to damping.

[MadMike]

SS, reducing the rear wheel sprocket by one tooth has much less effect than increasing the gearbox sprocket by 1. As Alan says 1 extra tooth on the gearbox alters the ratio by 1/17th. Altering the rear sprocket by 1 tooth may only alter the ratio by 1/50 if you have 50 teeth, or 1/40 etc etc. You cannot simply sustitute 1 tooth on the front for one on the rear, cos it don't work. Simples.

[Norm]

Sophiaspin, I'd like to see you do that.

[Phil Ashbrook]

I went up 1 tooth on the front sprocket and fitted the close ratio gearbox gears which also changed the kick start ratio a bit , I try not to ride in top gear below 30 mph as it stresses the big end ( floating white metal bush )but all in all the current ratios are good for city and highway riding .

[Beezabryan]

Echoing Norm - Sophiaspin, I'd like to see you do that.