Bonneville America Forums Forums Technical Forums Accessories Sprocket preferences

I'm thinking about changing out my stock 16T sprocket for a 17 or 18. I only want to change it once, if I get the 17 will it be enough or will I be coveting an 18 later? How much is the response changed by increasing the sprocket size? I'm not unhappy with the 16, I'd just like to try something different, maybe get a little better mpg by not working the engine so hard. I don't look for 6th very often, by the time I hit 5th I'm usually doing 70 already.

I'm the rarity around here. To me 18 was too big of a change and I ended up buying a 17. That's even with interstate speed limits of 75 mph out here. I just felt I was downshifting too much in the twisties, and lost too much torque. I might even go back to a 16 tooth when I need a new chain and sprockets, but then I plan on getting another bike that's more suited to long distances, and keep the Speedmaster as my "around town" bike.

If you just want to try something different then go to a 17. I run a 18 and love it. It is not a big job or expence to change out so go for a 17 and see if that works for you. RIDE SAFE AND GOD BLESS

I went from 17 to 18 and love it. It takes getting used especially if you gonna come from 16. You'll find riding in lower gears more frequently.

I'm quite happy with the 16. I moves my lardish body at a brisk pace and, with my new knobby off-road tire, I'm able to pull pine stumps in the back yard.

Before you guys go running out getting knobbies - I'm just kidding about the second part.

I have the 18 and can't say that I feel like I am missing Any get up and go off the line but it sure is nice to look down and see that I am comfortably doing 60-70 in fourth. Use to look for 6th but no more.

Sebastian

I think the 18T is just right. 3800 RPM's at 65 on my bike. Didn't notice any difference off the line.

If you're still planning on riding up this way in September I would go with the 18 for sure. I never missed out on anything when I went from 16 to 18 either.

I completely agree with CBass139 and FisherCat. I am running the 18 tooth and I love it. When I do shift into 5th, at an indicated 80 mph the tach reads 4000 rpm. I don't feel like I have lost anything off the line at all. I am not a drag racer, but I do get off the line quickly with ease.

Soren

Thanks guys, that's what I needed.

Pat,
I'm still planning on coming up in Sept. and I'm getting ready to order some stuff from Brent so I figured I'd look at a sprocket change as well. Hopefully I'll have it all on and working before the trip with a day or two beforehand to give it a quick road test. Braided brake lines, new rear pads, new plugs, easy brackets, Corbin, sissy bar bag, etc. Man, my wallet hurts just thinking about it.

Greg,
I can bring up the socket for the front sprocket nut and we can change it out Monday evening (Sept 19)if you don't get round to it by then that is! You have to supply the breaker bar and torque wrench!

Me? I run stock. Just ordered a second chain kit too. 42/17.

I have an 18. Some people said they shifted too much when going to the 18, I shift LESS!! Hell I keep it in 3rd or 4th and don't bother to shift to 5th as much cause those gears are much more usable. Keep 5th in the back pocket for the highway.

Sears is going to have a sale this weekend so I'm going to pick up a torque wrench and some sockets. I'll probably order my goodies from Brent in the next day or so and make a checklist of other stuff that I want to pickup (maybe some camping gear or at least a bedroll).

I loved my 16t, and went to the 18t because most of my rides are longer ones. I think I'm in 5th occassionally now, when I'm still in 4th! Don't search for 6th as much anymore, but have. Lost some top-end speed, and gas mileage sucks when running wide open in 5th with the 18t. Mostly from the lack of torque. Overall, I'd recommend it. The 17t probably is the perfect compromise, but maybe not worth the trouble (which it isn't) to change. I still may put my 16t back on one day to compare - I never had a complaint one with it on - even after 400+ mile days. I do like the 18t around town - 2nd and 3rd gears running speeds from 20-50 mph - riding the higher revs. That aspect I had never appreciated with the 16t, but maybe more from lack of opportunity. I had 6-7k miles on my SM before I changed the sprockets, and have put probably 2500 miles on since. It's like learning to ride a new bike all over again.

Change is good, whatever you do. Not much can't be undone.

Greg,
Just my opinion, but I would hold off on doing the brake lines until after yu get back. You never know, if something goes amuck, you ain't going anywhere. The rest of the jobs are easy enough though. But the brake line is a little tricky and you can run into troubles if you're not fully prepared. That's why mine have been sitting in the box until this winter. I didn't want to risk messing with the meat of the brake system until then. I have had them several months too, even before Georgia.

Just to be contrary (not that I ever am!), I had to extend my front brake line with the buckhorns and Jim's Spacers so I didn't have a choice but to dive in. After changing the line and bleeding (combination of vacuum pump and working the lever), I didn't like the position of the line so I did it again. Took me over an hour and two cans of fluid to get ALL the air out each time. What a major PITA!!!

I got SpeedBleeders recently and of course had to bleed the lines again after installing them. Talk about night and day. It took about 15 minutes to bleed each line.

Granted, if you are changing your lines out, it will take a bit more time. But if I ever have to do that, I will vacuum pump until I get some fluid through, and then SpeedBleed the rest!! Definitely worth the money.....

btw, Brent sells them!!

So to completely de-rail the thread....
Phil, do you just pump the lever then? No vacuum pump after you get it started? I haven't installed my speedbleeders yet cause I don't want to intill I see another reason to bleed the lines.

By the way, the brake lines aren't that bad, Pat's a Nancy.

Don't worry about de-railing the thread, I bought the speedbleeders as well since I knew they would make my life a whole lot easier on this project and in the future whenever I do a pad replacement. I remember when Sarge posted the link on the old forum about them. When Brent started carrying them I added them to my list of must-haves.

I should have the parts in a day or two. In fact, I'm surprised that the delivery guy didn't ring the doorbell after I paid for the order I might do them this weekend so that if I f*** anything up I'll have time to get it straight before the rally.

Blackwind: Lower MPG on an 18T sprocket? I've been enying Soren and other's 50+ MPG (I'm around 35-40 right now) and one of the only differences I can see is the sprocket. I guess I'll find out soon enough.

Speedbleeders rock, when I installed them, only took 20 minutes to bleed the lines back down, since then, I've spent a max of 15 minutes bleeding the brakes. Back on the original thread 16T front, 44T rear gives me plenty of grunt, and definitely gives me oomph when 90mph on the highway just ain't enough. With my style of riding, I don't think I'd be happy with the 17T front, so the 16T is great with me.

It took me a while to figure that the America and Speedmaster have different stock sprockets. I guess I was getting a little confused if the writer didn't mention whether they had a BA or SM. I checked with my local dealer and they said all the Americas came with 17 front/ 42 rear. If the Speedmaster has a 16 front stock, is the rear different as well? I was told that changing the front one tooth would make a 500 rpm difference and changing the rear one tooth a 200 rpm difference. So, for us novices, please make it clear what you changed from (front and rear) so your info can be more helpful. I also assume that gearing slightly higher would result in increased mileage. Thanks.

Bob
05 BA

Bob,
I'm pretty sure the rear on an SM is 42 also...

I have an '03 TA, and I went to an 18 front. That was early on before I rejetted and removed the snorkel, installed TBS needles, and TBike pipes. I definitely noticed a difference starting out with the 18 tooth sprocket. You had to get the revs up a bit.
After the other mods, however, the bike runs a lot stronger, even at idle, and the 18t is no longer an issue when I start out.

In all the sprocket discussions on here, it has never been mentioned that the results are quite different between stock and an engine that has been tweaked a bit....

Thanks Grump, for the reply.
My '05 BA has been tweeked to where there is a noticable difference from stock. It did lower my mileage by about 5mpg, but the extra power and sound is worth it. I'll watch the rpms (I do have a tach) and see what a 500 rpm drop would be like. There seems to be plenty of power in the low gear range with the 17T. I may have to try the 18 as I would like a higher gear on the top end and it might bring the mileage back up.

Bob

Quote:

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the results are quite different between stock and an engine that has been tweaked a bit....

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True, but my tweaked engine/air/exhaust didn't quite deliver what I needed, especially when riding two up as I (we) do most of the time. I just recently went back to the 17 tooth (teeth?) sprocket and now everything is the way I want it... (Except of course that it might be even nicer with the big bore, carbs with acc. pumps, KN's etc.)

piper,

Yep, riding 2 up would make a difference, a noticeable difference.

All of these things enter into the equation. That is what needs to be kept in mind when we discuss this "changing of the sprockets" subject....

i'm w/ blackwind here. it's great having the lower rpm for cruising and not searching for 6th gear. but if you're going for top end, i think the 16 is better. yesterday i downshifted to fourth at about 80 and it went quickly up to 98 (indicated) shifted to 5th and couldn't get back up to 98 before a curve slowed me down. it's like there's too much air and no torque.

i've done some mods and have 130 jets/45 pilots, 2 shims on needles, snork removed, drilled airbox, uni filter, so I don't know exactly what's up. i had 135s in w/ this set up (minus the shims w/ stock pilots) but was getting sooty plugs.

the 18 is great for long rides, no doubt, but w/ the 16 the front end gets much lighter.

i think if i was racing someone or doing a dyno, i'd put the 16 on.

i thought about trying a 17...
cat

Ok, I may have to think this out better as I do ride 2 up about 25% of the time. It might get a bit sluggish starting off. I really like the quick performance I've got with the carb mods and the stock 17T. I assume Cat has a SM that came with a 16T. Not only is the torque different (SM vs. BA) the front sprocket is different (16 vs. 17). I was wondering about the differences of changing one tooth up. Possibly, the SM could handle it better than the America due to the increased low rpm torque? It looks like I'll keep the 17 for awhile on my America as it's probably the best for all around riding.

Bob
05 BA

The '05 Speedmaster would take it better, because it's cammed more for low-and mid-range torque than the America is, so it could take a 17T front better and without too much of a loss of pick-up, and maybe gain a little more top end. My riding style dictates that I stay with the 16T front with my '03 Speedmaster, especially since she has cams in her from the dealer, that have undoubtedly taken a little from the bottom to give to the top.

I've had the 18T on my BA for 6K miles now. Love it. No impact on the low end even two up but the relief on the top end is well worth it. Like others have said, I find myself riding in 4th now and thinking I'm in 5th. Also, 3rd gear is now much better around town which cuts DOWN on the shifting in real world riding for me.

Todd, so starting off in first even 2 up is fine? If so, I think I'll have to give the 18T a try. There is about 500 rpm difference between 4th and 5th and the one tooth would also make about 500 rpm difference. I'd LOVE to have that "6th" gear if it didn't mess up 1st too much.

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Bob
05 BA

The RPM difference between the two sprockets will change depending on where in the rev range you compare. At say 2krpm with the 17, the 18 will only be I dunno 100 rpm different, whereas at like 4krpm with the 17t, the 18t would be more signifficantly less, like 500. See what I mean? That being said, I do notice that I have to ride the clutch starting on a hill 2-up a little, but other than that it's all good.

Gear Ratios - Motorcycle Front/Rear Sprocket Combinations

by webBikeWorld.com

Gee. Sitting here counting the points on the front sprocket I took off my America in the spring and it has does have 17. Anyway, I went to an 18T and would never go back. It's great on the highway riding to work each day but I never use 5th tooling around the back streets.

How difficult is it to change the front sprocket? Is there enough play (chain adjustment) on a new bike to fit ok? It sounds like most everyone who has changed from the stock 17T to 18T prefers the 18T better. I spend about 50/50 balance between city and highway riding and currently use 5th quite a bit around town. From about 40 mph up I'm in 5th. Separating the gears a little with a higher top gear seems like it would make a lot of sense.

in which gear?

mert

Ramsound, Cat's SM is one of the pre-05 models, so has the exact same torque curve and horsepower ratings as our Americas.

I replaced the 16 tooth with a 17 on my Speedmaster yesterday. I used 4000rpm in fifth gear as a marker for the change. Where it used to rev 4000rpm it is now 3800rpm, 200rpm difference. Did not notice much difference in town performance wise, but sounded different on the highway, I ride two hundred rpm faster now. I like the way it drives so far.

I have an 05 SM with TBike pipes and am considering a front sprocket. So would the jump to an 18T be too extreme or is the 17T a better choice? I've accidently started off in 2nd gear from the light a couple times and was surprised at how it just took off.

Rich

I love the lazy 18T.

I thought I saw a 19 advertised at ? newspeedmaster or ? Not a single person here mentioned the 19 ... Me either ..