Sprocket Upgrade
- Thread starter motojeb
- Start date
dschief
750cc
I changed the counter shaft sprocket on my 790 Bonneville from a 17t to an 18t (same gearing as my Thruxton), it lowered the rev's about 500 rpm in top gear at any given mph. The downside is the 790 doesn't like to be in 5th gear below 60mph, but it makes 4th gear more useable for back roads. Can't say it really made much difference in the mpg.
BlueJ
Blue Haired Freak
I went from 18 to 19t on the front of my 865 Bonnie, made a BIG difference in my commute - I "look for 6th" a lot less often. On the long road trips (MD <--> VT or MD <--> CT), I do still look for 6th on occasion.
With stock igniter, airbox removed, and TOR's, I redline in 4th at about 95 mph...
With stock igniter, airbox removed, and TOR's, I redline in 4th at about 95 mph...
You would have to go as many as four teeth down on the rear to match one tooth up on the front. Cheaper to change the front. There are formulas on the net that will allow you to work out what difference there will be to the revs when you start changing the sprockets. I had a 19T on the front of my 05 Thruxton and changed it back to the 18T. I would really like to try a 17T for slightly quicker take offs. My personal opinion is the 19T drags the arse out the bike at take offs especially on slight inclines needing to ride the clutch a bit more and when you really listen to the motors they really like to sit on 4 - 4500 rpm.
ivar
TT Racer
useful site..:
http://gearingcommander.com/
http://gearingcommander.com/
strokerlmt
Moderator
Thx Ivar.....great interesting site.......
LMT
LMT
BlueJ
Blue Haired Freak
Don't recall exactly, it's been a coupla years. Someone posted the calculator link - it's dead on. My technical brain tells me it should be 18/19th's of 95 mph. And the '95 mph' is an approximation... the speedo bounces around a bit up there and I don't stare at it.
What I know is that I can *just* hit the ton (indicated - damn gps disagrees) in 4th before the rev limiter kicks in.Yeah that: gearing commander.
RumRunner
Street Tracker
I've gone up and down depending on what I was trying to do. I've had 17, 18, & 19 up front, and 41, 42, 43, 45, & 47 on the rear. With the 17/47 combo it would pull the front wheel without even thinking about it. The 19/41 had the best fuel economy... Currently running 18/41 since I primarily ride in the mountains decent fuel economy not too buzzy and fun to play with.
RumRunner
Street Tracker
Yes it is 36mm.
slartybartfarst
Scooter
Went 18 to 19 teeth on front sprocket on 2013 t100 its got the standard 43 teeth rear, like others have said its like all gears move up 1 stops you looking for 6th seems to pull no problem, I much prefer this set up.
Others have said does not change fuel consumption but be aware that speedo takes its signal from the engine out put shaft and it did read4 to 5 mph fast is now spot on! I checked it with sat nav that is dead right. So you now travelling real miles not "short" miles.
Plus owners who have not seen a difference will be getting better consumption its just hidden by the speedo correction.
Will also put less miles on your bike so worth the £9 sprocket from http://tecbikeparts.com/Triumph_parts_7.html
Others have said does not change fuel consumption but be aware that speedo takes its signal from the engine out put shaft and it did read4 to 5 mph fast is now spot on! I checked it with sat nav that is dead right. So you now travelling real miles not "short" miles.
Plus owners who have not seen a difference will be getting better consumption its just hidden by the speedo correction.
Will also put less miles on your bike so worth the £9 sprocket from http://tecbikeparts.com/Triumph_parts_7.html
Last edited:
BlueJ
Blue Haired Freak
Nope. It gets its "signal" from the speedo cable that plugs right into the front hub, with a little lug. Cable spins with hub, turns gears, turns speedo.
Changing wheel size/profile will change the reading on the speedo, but not changing the sprockets.
HUH? Only if you ride it less.