Bonneville America Forums Forums Technical Forums General Tech Front Sprocket?

I know the 865cc motor Americas and SM's come with the 18/42 final drive ratio, and I am enamored with the low-end grunt - shifting so early is very different than shifting the 790 motor, which I learned to shift closer to 5K rpm...

But with this 865, I feel like I'm only using 1/2 the motor.

Anybody running a 16t front sprocket on a 865cc America or Speedmaster? I know the 18t front on the 790 really did not help fuel economy (that I could tell), and actually hurt the top end speed and power. Once I went back to the 16t, I knew I was sticking with it from then on.

Thoughts? Anybody?

try a 16 on it you might be able to wheelie

Why would you want to do that on our bikes, OK, I know, I'm a confirmed geezer...

My Speedmaster came standard with a 16 I replaced it with an 18, now only look for another gear some of the time as opposed to all the time.

I recently replaced my 18t with a 16t. I do a daily commute (not long highway rides) and I love the extra torque and acceleration which I use A LOT.

rpm is the only difference you are feeling, and the initial torque off the line, i don't see how you could be shifting earlier, earlier in the rev range maybe because of the different final gear ratio but speed and so forth should be similar.

Hey Keith, My 865 came with a 16 tooth front. I ran it a few years, then switched to a 17 tooth when replaced the chain/sprockets a few years ago, and it's been ok. But I will be going back to a 16 this year when it's time to replace them again. I don't think I would like the 18 tooth on this bike at all, although some do. I say go with the 16 and you'll be happy with it.

Take it easy,
Will

I wonder if you could do something less drastic by using a 40 on the rear.

I had a 16 on mine and went to an 18 when I put a new chain on. I liked the low end of the 16 a lot but felt it was too buzzy at highway speeds. I like the 18 at highway speeds but hate the low end. Do you guys think that a 17 is a good compromise?

It's a balancing act. I'd like a little more grunt but I'm also looking for the sixth gear while cruising. The 17 tooth seems to be the best compromise on my 790.

Running a 19 tooth front on Crantini most of our riding is outside the city on country roads and I like the lower revs for cruising. For fun would like to try 17 or 16 just to experience how much torque these engines have. Will I need a wheelie bar?

In the original stock condition my 865/EFI motor (with 18/42 sprockets) kinda gave up as the revs get to 6,000. Made some mods (904bb & cams) and it came to life. While willing and fun at higher revs it still felt like something was being wasted. I went to a 17T sprocket and the bottom end seemed quicker and nothing was lost on the top end. Just seem to get there a bit quicker now
Wished I had gone to the 17T before the engine mods.

I took it out tonight, and yeah, I can rev it out to 5K and shift, like I do the 790, but it's not the same.

I still looked for another gear often with the 18t, too, on the 790, and liked it anyway, just like I liked the 17t after that. But the 16t is the bomb, even running 85 down the interstate.

I won't do anything until this chain is done, but I do appreciate the comments, and reinforcement of what I wanted to hear.

With a rev limit at 7K+, I'd sure like to use a little more of it.

I was ordering some other bits and pieces, and went on and ordered the 16t front sprocket.

I put a couple hundred miles on it today.

I think I bought the last rocker shifter in the country. British Customs still showed it on their website, and even though one of their parts guys told me it wasn't available, when I ordered it online, I got an order confirmation, and sure enough it shipped from another location. The bag it came in looked 20 years old, too, with a hole or two in it, and no pegs or rubbers for the lever. But my local dealer came through with those, so all is good.

I don't know which I like better though - the 16t front sprocket, or the new Avon Storm Ultra radial front tire. Man! What a difference that makes!

I do like the 16t on the 865 motor though. That'll be a keeper for this bike, too.

Runs like a scalded -*ss ape! I can only run close to 5K rpm when I'm pushing 90 on the speedo - and since I don't have the Garmin wired up yet on this one, I'm assuming that's about 80 mph, as on the '04. But the '04 runs right at 5K rpm at an indicated 80 mph, I think.

Makes me want to check what rear sprocket I'm running now. I assumed it is the stock 42t, but whoever owned his bike before me had already swapped the front for a 17t, too.

But run she does, and quite well, thank you.

Both bikes running great! I'm very happy right now.

On my 790 I just went from an 18 to a 17 and I'm liking it a lot better. Brought back my bottom end and it still keeps the rpms reasonable highway speeds, definitely a good comprimise between the 16 and 18.

i'm liking the 17 too.

Glad it worked out for ya Keith. Which dealership did ya go to?

Good to hear ya supporting an independent shop.