PDA

View Full Version : Sprockets: what do you guys think?



NOMIS
23rd October 2008, 14:30
Hi Guys, Hornet needs new sprockets and chain.

Looking at x-ring renthal chain, and 14 front 45 rear, Has any one got any better gearing recomendations for the 250 Hornet, Justin ( gijoe ) you may have something to say here? I'm not to sure what I want to be honest I want a faster bike full stop lol, but this needs doing so now is a good a time as any ( long weekend )

Advice apreciated

EJK
23rd October 2008, 14:34
Bigger front sprocket for higher top speed perhaps? The rumor is that only 2-3 more tooth can make a big difference.

nodrog
23rd October 2008, 14:37
do you want faster top end speed, or faster low down speed (ie accleration)?

you cannot have both.

vifferman
23rd October 2008, 14:38
If you're gearing up, you may find your bike can't pull the higher gearing in top.
Conversely, if you're gearing down, the bike may be too "short-legged" taking off. One of the problems of a 250 - limited torque for varying the gearing much.
You may find you're largely limited by what front/rear sprockets are available to fit your bike. Changing the front (countershaft) sprocket is cheaper, but you're limited how small you can go without accelerating chain wear (chain wears faster having to whizz around a small-diameter sprocket). Similarly, you're constrained with how big you can go at either end by what will fit under the countershaft sprocket cover and chain guard.

Hitcher
23rd October 2008, 14:39
What are these "sprockets" and "chains" of which you speak?

Bonez
23rd October 2008, 14:44
What are these "sprockets" and "chains" of which you speak?They're fitted to 650 bandits. Have a gander sometime ;)

NOMIS
23rd October 2008, 15:37
thanks guys, I dont really know what I want to be honest lol. there just worn and have to be done, Was hoping somone has changed gearing on there 250 could tell me the affects

MSTRS
23rd October 2008, 15:46
thanks guys, I dont really know what I want to be honest lol. there just worn and have to be done, Was hoping somone has changed gearing on there 250 could tell me the affects

Couldn't tell you really. But apply the 3:1 rule...3 teeth on the rear is same as 1 tooth on the front. But they work opposite to each other...up on front = down on rear = slower acceleration/higher top speed

vifferman
23rd October 2008, 15:49
Whelp, generally, a 250 probably won't pull higher gearing (unless you've done substantial changes to the engine to make it more powerful). However (but!), if you find when riding it on the open road that you're often trying to put it in top gear, and finding it already IS in top, then it may need to be geared up. But (however!) if it takes some clutch slipping to get off the line cleanly without stalling, then it won't pull higher gearing anyway.

As for lower gearing, it will generally give it the feeling of more 'guts' when riding, but you'll run the risk of it being too buzzy on the open road, and first may end up being too low when taking off (although you can always start in second and slip the clutch a bit).

I've lowered the gearing by one tooth on the countershaft sprocket (about 6%) on my last three bikes (VFR750, VTR1000, VFR800), because most of my riding is commuting, and I found the lower first gear better. Also, the VTR was pulling only 2600 rpm at 100km/h, which was below the torque dollop, and a bit ridiculous. If most of my riding was weekend stuff, then I would've left the gearing alone, apart from on the VTR.

If you have no real reason to change the gearing, leave it alone. And if you have an electronic speedo that drives off the gearbox rather than the front wheel, it end up being inaccurate.

MSTRS
23rd October 2008, 16:36
Whelp, generally, a 250 probably won't pull higher gearing (unless you've done substantial changes to the engine to make it more powerful).
....And if you have an electronic speedo that drives off the gearbox rather than the front wheel, it end up being inaccurate.

Of course a 250 can cope. I carried 2 front sprockets way back in the early 70s for my TS125. Standard was 14 tooth. I carried a 13 for getting off-road better since the TS was not great in the grunt stakes. And a 15 if I was going on a road trip. That little bike could do 80mph with the bigger front sprocket, but 50mph was about it with the smaller one.
Of course, speedo was cable driven off the front hub, so that wasn't an issue.

oldskool
23rd October 2008, 17:37
I've just changed mine from 13:51 to 13:53, but that's only because I want to keep it in 3rd more in the dirt. Higher revving, more power, more wheelies, less gear changing, better engine braking.