Be aware that with a stock Bullet
Ace, does that apply to a minimally modified Bullet, classic exhaust, larger carb, k&n? With these tack on upgrades rather than cracking open the engine upgrades could it handle 19T in your opinion?
Thanks,
-Rick
No, I don't think it's the same with a modded Bullet.
I thnk once you uncork the exhaust, it lets alot more heat out of the engine, and I think that helps alot. And runner richer-than-stock jetting is a big help too.
As for "handling a 19T" it's a matter of what you want to accomplish.
For top speed, a mildly modded Bullet isn't going to be able to reach the normal redline rpm with a 19T on it. So in normal terms, that would be considered over-geared.
Now, as CJ points out, that might be a moot point, because you might not care about having it over-geared. The over-gearing might suit your desires for cruising rpms. But it will also make your acceleration slower.
So, I think that if you uncork the Bullet, you can use a little more gearing, and cruise a little faster with probably a decent degree of safety, after break-in.
The key here, IMO, is that if you are going to gear it so that you'll be cruising at a higher speed with lower rpms, you should gear it around the torque peak rpm for your cruising speed, which in our case is around 3500 rpm, typically modded with the exhaust and carb. Or a bit above that.
The uncorked Bullet seems to be real happy at around 3500-3750 rpm for cruising. That's about 55-60mph in real speed terms, with a 17T sprocket. You get about an extra 3.5mph by going from a 17T to an 18T, and probably about 7-8mph by going from a 17T to a 19T. So, that 19T would set you at cruising speed of about 63-68mph, at the same rpms as doing 55-60mph with the 17T.
However, and this is a big however, the load on the engine is still increased by the wind loading at that higher speed. So just because you have the engine turning a lower rpm, doesn't mean that it can't overheat at those speeds. You just get a larger throttle opening at the lower rpm. It still has to produce the same hp to do 68mph, whether you have it geared different, or not.
So the load on the engine is the same at that speed with either gearing, but with the taller gear, you need to produce that same power at a lower rpm. Thus, larger throttle opening.
My recommendations for higher cruising speed would always be to try to reduce the load to some degree, so that the engine isn't working any harder than it was at 55mph.
And the way to do that is to reduce wind loading by improved aerodynamics. A lower set of bars will lower your riding position, and reduce your critical frontal area. This might be enough to get that extra few mph, without stressing the engine any more, and allow you to use that taller gear without additional load on the engine at the cruising speed.
If you don't do anything to reduce the load in some way, the engine will be seeing that 68mph load, regardless of what rpm you are doing, or what gearing you have. And the heating issue could rear its ugly head. Maybe, maybe not.
But, with the bike uncorked, it doesn't hold the heat as badly, and you might be ok with it.
A long winded explanation, I know.
Edited: I just remembered that this is the AVL forum section. I can't remember if the AVL comes stock with an 18T, or not. So, depending on the circumstances, my comments about the 17T sprocket may only apply to the old Bullet.
In any case, the basics that I spoke of are the same. Perhaps the AVL might be a little more forgiving of the heat, and handle the taller gear a little better. Maybe.
Topic: possible issue with rear sprocket. (Read 4811 times)