Bonneville America Forums Forums Technical Forums Accessories 17 tooth sprocket on the SM

I have heard the 17 tooth sprocket really helps the performance of the SM and does not have any impact on acceleration. Has anyone tried out this mod and your opinions would be greatly appreciated before I attempt this. Thanks in advance!

I think you read Dazco's post over at Triumphratnet. He is very enthusiatic and in truth I am thinking of trying the seventeen toother.

It has to add something on the high end but in terms of strict torque it has to take just a little bit off the low end. But I bet it is not all that noticeable for a one up rider. Add a pillion and first gear may seem a little bit lacking .....but I bet not much. May not be noticeable at all.

Most of the posts I have read in this here August forum are enthusiastic as to the use of the one tooth up sprocket.

If gas prices keep going up, we'll all be lookin' for 30 tooth sprockets

Skip the 17 tooth and just go for the 18 tooth. It works out great. You don't loose much of anything off the line (even when riding two up) and you can run faster at lower rpms on the freeway. Not to mention you won't feel that need to try and find that missing 6th gear anymore.

Soren

I ran the 17 tooth sprocket for 5 months when i first bought it and didnt really notice much of a performance drop. I then went to a 18 tooth sprocket for about a year. At the time i thought it felt like quite a drop in lower performance but i perservered as most of my riding is on the freeway. I now have the 17 tooth sprocket back feel that its the best compromise. The increase in lower performance was very noticable compared to the 18 tooth, more than i originally thought and the higher revs on the freeway at the limit put it in a better torque zone. Before it used to be doing 120ks ( 80 miles ) an hour, before it really come into itself. Now its more at 105ks ( 65 miles ).

Yup, I put the 17 tooth on. Dropped the revs about 250 on the highway. Same gearing as the America, and the America guys say you should to go to a 18 tooth. Do a search and you will find lots of discussion on this one.

I changed from 17 to 18 on my America about 1500 miles ago. I like the highway and solo, but don't like riding 2-up near as much. The gears start getting a bit tall. I plan to go back to the 17 next month. I think there is a BIG difference each front sprocket tooth you go up. If you're running a stock 16/42 SM, you might find the 17/42 combo like the Americas have stock, just what you're looking for.

I am amazed that anybody that does a lot of highway driving has the 16t primary. Way to many RPMs for a cruise.

My 19t was too tall for around town, my 18t is perfect for all power bands. If you are not drag racing, I don't find the gears too tall at all. Then again I came from much larger bikes so it could just be what you are used to riding.

I found the 16T way too short even in city riding. I was changing gears too often. Or maybe I just like to wind her up too quickly I put the 18T on before the NY rally last year and I'm going to stick with it from now on. Like Satxron I found it to be much better (for me) for all power bands.

Me and a friend both bought new 05 speedmasters in February. Last weekend we had our first chance to do some long high speed riding. After the ride, we both decided we needed taller front sprockets. I checked the sprocket we had and it was a 16T. I called the dealer we bought them from to see if he had a taller one and told him I had a 16T. He asked me my engine number and told me 05 speedmasters after a certain number were supposed to come from the factory with a 18 tooth front sprocket! Our numbers were after the change so the dealer is going to change our sprockets to 18 tooth for free under warrenty! Long story short, if you have a speedmaster check your engine number with your dealer, you may be able to get a free sprocket!

(By the way, I've been lurking around here since February but this is my first post!)

That is interesting. I didn'y know that. My dealer has been saying that the speedmasters still come stock with the 16T. but, hey.... free is always a good price.

Soren

I do most of my riding in the North Georgia Mountains (eat your hearts out!), and think the 16T is well suited for that terrain.

I have it...It helps a little @ higher speeds & I couldnt really tell any loss of power.

The 05/06 speedmasters with the 865 and cams optimized for low end torque develop thier max torque at a lower RPM than any of the other twins including 04 and previous speedys. Whether that goes any length to makes them more forgiving with more teeth i don't know. But what i CAN say is that i found that with the 17 the bike seems to accellerate faster. Yes, i know what you're thinking. But look at it this way....if the torque is enough so that it will wind to redline w/o taking any longer with a 17 than the stock 16, then you would be accellerating quicker because at redline you're at a higher speed. So technically the bike will accellerate quicker IF the bike is capable of pulling to redline as fast with a 17 as with a 16. My feeling is that it does, at least thru the first maybe 3 gears. after that it seems about the same. I realize i'll get flamed for this, but contrary to what many of you will be thinking when you read this i'm not stupid or naive and i do notice the bike pulls just as hard. Look at it this way.....if triumph is putting an 18 on them now wouldn't you think theres a reason? I suggest they realized AFTER they released the 05's that the new engine's increased torque didn't need a 16 to deliver max accelleration. After all, there IS an ideal sprocket size for every bike, and it would be naive to assume all manufacturers get it right every time. I could be wrong about this because my bike is modded and has considerably more grunt than it did stock, but in any case these are my findings.

I'll be calling the dealer to see if that free sprocket is available for me because i'd now like to try an 18. I have a feeling the 18 might just be one tooth further than it can handle w/o starting to struggle a bit, but it may be a worthy trade-off. And if i can try it free, WTF.

Free is free! It's a 20 min operation anyway. The only time I seem to struggle with the 18 is starting on a hill 2 up. Other than that, it's fine. And I can hit 70+ in second gear...

I went up 18 on mine.Noticed some power loss but but made up for it by airbox mods and rejetting.Love the smoother ride on cruise speeds and bumped up my MPH.

Just called my dealer and talked to thier warranty guy and he knew nothing about this deal with the free warranteed 18 tooth sprocket. But he's going to call triumph and see what he can find out. I'd like to try an 18 even tho i'm quite happy with the 17 as long as i could try it free !

I think an 18 would make first gear a little to long in the tooth as far as starting from a dead stop. It'd be fine otherwise though I expect.

I like the bike to have a little ju ju in first gear from a standing start. I do note a slight very slight loss with the 17 as opposed to the stock 16.

All a matter of preference.

I went with the 17 at the same time I put straight thru pipes, replaced the air box w/the freak and rejetted. For me it's the perfect set up, the hwy is better and it's still "torky" around town and in the backroads...

I went to the 18th on my TA right of the get go. Why? Always looking for that 6th gear as I do a lot of highway driving. Also when I take off real hard I like changing to 5th at 130-140 km. It's fun doing that.

BikerT