Bonneville America Forums Forums Technical Forums Performance Mods sprocket question???

ok, so i would like to set up my bike (08 america) to run at a lower rpm at highway speeds. should i change the front or the rear more teeth or less? do i need a new chain when i change it? + any other suggestions would be much appreciated.

+1 or +2 on front sprocket.. no need for new chain

TrOjAn

I went from a 16 to 17 and it dropped revs about 500 - 700

I went from a 16 to a 19 on my speedy... Great for highway travelling now... Just a slight noticeable difference off the line.....

I have a 19t front sprocket for the last few years. I am never going back. Stops you from looking for that 6th gear. All gears get a few hundred RPMs taller.

24k on the bike no clutch issues to answer your next concern.

18/42 is the best all round set up, 19/42 is best for long highway ride

I had an 18t front, and liked it, but recently switched to the 19t. I'm not a fan of the 19t. Not enought take off for me. I think the 18 is perfect. I think when I'm going 70, with the 18t it's right in the power band.

+1 for 18t.

decided to go with an 18 front. will order tomorrow. i was on dinqua's site reading on the sprocket instructions and ran across an increment of measure i'm not quite familiar with. it says the torque for the sprocket is 132nm.....what's that in foot pounds???

Torque Converter

Heres one I found....it comes out to 97 ft/lb

Two grunts and a pull is 100 pounds on my seat of the pants torque wrench. Its a gear with a lock nut. Just make it tight.

17t to 18t, I bet you still reach down for 6th gear on the highway

I'll admit every now and then I reach for 6th, not nearly as much as the 17T though. With the 19t I've got now... I'm reaching back for 4th.

I am running a big drive gear, I was thinking it was a 21, but after looking thru this thread, perhaps it is but a 19.

I also have a 42 rear sprocket. I had to get a new chain (DID X-Ring) and I love it. I am usually in 3rd or 4th around town (60 mph and under) and don't even need 5th till I am cruising at Highway speeds!

I don't have a speedometer anymore, but try to stay above 3500 rpm.

I have a basically stock 865 pony (except jets and exhaust) and have had the speedo (when attatched) buried for 20 to 30 minute intervals with both the stock and current gearing.

I am looking to get a big bore kit and Cam for even more MO-JO LOL

If you want more bang for the buck, look into Fast Fred's bored stock carbs. I gained 8hp on the dyno, and he gets at least 4-5 more hp on a bone stock bike. Here is the link to my thread... http://www.bonnevilleamerica.com/forums/...ge=0#Post386230

Definitely go just one step at a time 17 to 18, etc. It makes a big difference. I had a 17 for almost a year and 18 over 3 years. There's times I've thought about going back to the 17 for the quick starts, but have never changed since putting on the 18. The 19 would be too tall and high for me. Sorta like starting off in second gear all the time.

These P-twins like to rev a bit; 18/42 is about perfect for me.

What is the stock front sprocket on a '09 Speedmaster?

17 tooth I believe

Everyone I know that has fiddled with the sprockets are prematurely having clutch problems....leavin mine alone...

I really didn't want to leave mine alone when it was a stock 16 toofer. Went to the 17 and pretty happy with that but I already have an 18 with a new chain for the next. Seems the 18 has the numbers so far

18 was stock on the 07s. Seems strange that they'd downsize to a 17t for the 09s.

my bad

the stock front sprocket on me speedmaster was a 16 tooth not 17

I now have a 19/42 set-up and it ROCKS! I still have a blast from stoplights and haven't had any problems in the hills and such

and occasionally I still look for a 6th gear on the big road!

I felt the 19 worked the engine too hard for every day riding, but maybe that's just me... Anything under 4K RPMs seemed like the engine was slappin' around inside. The fact that I'm a little over (ahem) ideal body weight may be a significant factor in my 19aphobia.

I like the 18 well enough, but somewhere between 17 & 18 would be right where I want it.

I have the stock 16 toofer around here somewhere. If ever I get back to a dyno, I'd like to see what, if any, the difference is as compared to the 18. Not sure how that works.

I run the 18/41 combo and it's perfect when doing a lot of two-up riding. I also use a 530 chain.

After I get my new cams for more torque, I will probably switch to an 18 tooth sprocket. Right now I really like the giddyup off the line with the 17.

I've had 16t (stock), then 18t, now 17t - and liked all three a lot. You get used to what you have and adjust. I never disliked the 16t, even after a lot of 300-400 mile days, but the 18t just made more since. When it was time to replace the chain, I put on the Triumph America Chain and Sprocket set (17t), and debated a lot about it, but I have no complaints with it, either.

I will never go back to the 18t, and certainly never a 19t.

With my 17t now, I'm still running only about 4800 rpm at 80 mph, and have to be doing over 90 mph to be over 5k rpm....and I want so bad to stretch it out because she runs so good and smooth, at the higher rpms.

If I had the 16t back on now, with the pipes and jets, etc., I might be able to see what she feels like over 6000 rpm without risking jail time to do it.

I'll most likely just stick with the 17t I have now though. My old stock 16t only had about 10k on it I think when I went to the 18t, so I may just try it on again before the next chain swap is due.

There isn't another fast cruiser out there that can curl your toes like these can.

I have my new 16 tooth on and I don't think I'll be changing it. Just hit 90 mph in 4th gear today.

HERE is a sprocket ratio chart that can help when deciding...

I changed from my stock 17 to an 18 after about 3,000 miles on the bike. I now have 17,500 on it. I've loved the 18, especially traveling on the highway. I just got back from NC riding the Cherahala Skyway and the Tail of the Dragon. I'm now wondering if the slightly shorter gear ratio might be better in the twisties.

I'm way more used to running higher rpms than when I first got the bike. I also ride 2-up quite a bit and the take off would be better with the 17. I almost went back until I did the 904BB which added considerable torque and eliminated riding the clutch as much starting off. I'm due for a new chain before long. If Triumph doesn't make an 18/42 kit, I'll probably put the 17/42 back on and try it.

It is going to effect your gas mileage but I have nothing for comparison since I have always had a 16 tooth sprocket on my bike.

I've always had the 16 too. I get about 42 mpg. Most of my riding is half freeway at 80-85 indicated, and half city streets.

I find that my mileage greatly improves riding the twisties, keeping the engine in the 5,000-7,000 rpm range up to 55mpg, so I'm thinking it's more a factor of (lack of) aerodynamics.

I get from 50 / 54 every time I fill up. I really am looking forward to trying the 16... I travel at speeds up to 60 most of the time.. If I don't think it will be good on long trips I'll just change back to the 17 for the trip.. But I don't think it will be a problem. V.

If you're getting 50-54 mpg, I don't think any sprocket you can fit would make a huge difference or be any problem. I get 35-40 and have an 18T. I might have gotten a mile or so worse with the 17T. Use what you like the best. One tooth does make a difference but not a HUGE difference. Certainly not enough to change one tooth for city vs. hwy.

Cool. I just went out and broke the 8mm bolts free... I heard that someone on this site broke one... All is good to go.. I'm waiting for the sprocket, going to borrow a 38mm socket.. Does the 8mm bolts on the axle move it forward and backward???? Or do I loosen the 24mm bolt and kick like heck out of it to move it?? V.

hmmm mine has a 15/16" axle nut and 5/16" adjustment bolts

I use a chain adj. bracket that attatches to sprocket to align chain up (I used to eyeball/count notches and or threads, but wasted a sprocket that way)

I also got around 32mpg to 36mpg with 16 tooth and I get around 34mpg to 38mpg with the 19 I have now.


course it might have more to do with riding style



ride it like ya STOLE IT

OK.... Here's a good one... I talked to the trump dealer and asked about a 16T sprokect.. He danced around for a bit then said, I don't have a listing for one.... Hmmmmm. Then he told me my 09 comes with a --------------------------------------pause------------------------- Are you ready... A "18T"... WHAT!!!!!!!!!!!!!!!!!! I went home a popped the cover............ Yup ! It's an 18 alright... No wonder it feels like crap taking off... So now I'm going with a 17T. So forget all the nice things I said about the 16T... V.