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Discussion Starter · #1 ·
At just over 23K miles my original chain is done. I've spent some time poking around the forum reading about the relative advantages of different sprocket sizes and have decided to try a 17T. A bit more torque sounds like fun on the mountain twisties…

I'm assuming, but wasn't able to confirm, if I should keep the stock 43T in the rear. Also, will the current number of links remain the same if I switch to a 17 or do I need to adjust that as well?
 

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The 17 tooth will make a very good improvement to your Scram.
Ive had one fitted on mine since soon after buying it.

The torquey 270 Scram engine lends itself well to the 17T and you'll certainly notice a difference when say pulling out of bends and from standing starts.
Ive never had an issue with the additional few revs at the top of the gears.
With a Scram there's generally no need to go up there anyway!

Keep the stock 43 on the rear and no need to alter anything with the chain.

Enjoy!! :)





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Discussion Starter · #6 ·
Thanks for the insight, folks. I guess my next question is where do I get the parts? Thought the local dealer would have everything in stock—no luck.

My intent is to use the OEM continuous chain. Thought it wouldn't hurt to do a bit of maintenance on the swingarm while I'm replacing the chain.
 

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The 17T is pretty standard kit. Can even be bought on EBay over here.
You could order a 790 Bonnie sprocket from a Triumph dealer. They were fitted with 17T as standard.

Why go for an endless chain? Your choice of course, but quite a bit of extra work involved there!
Is it really worth it?

I'm just in process of fitting a DID 525 X-ring chain, gold Renthal rear sprocket and 17T front.

Works great for me!! :)






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I have one on my Bonnie and love it, although I might wind up going back to the 18 for extra mileage on my road trip this summer. I can't remember whether I got mine from Bellacourse or NewBonneville, but I went with the one that also sold the appropriate socket on the same page. It's a gigantic thing and something not readily available elsewhere.

As for the chain, I was able to do the swap without removing the stock chain (mine's still in great shape at 12k miles). You could probably go one link less and give yourself a bit more room to adjust out (chains generally stretch, not shrink).
 

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I have one on my Bonnie and love it, although I might wind up going back to the 18 for extra mileage on my road trip this summer.
Burphel, you could possibly find that increasing the size to 18T, albeit lowering the revs for a given speed, actually has the opposite effect on your fuel consumption, which could see it actually increase.
I take it thats what you mean by "for extra mileage".

If your Bonnie is jetted well (assuming its carb'd) for your present gearing you'll likely find it enrichening at the lower revs you'd be running with the 18T.
This is due to engine loading being a contributing factor to the resultant a/f ratio.

Have a look at the following thread, from Gumps post on...............

http://www.triumphrat.net/twins-tec...s-to-lowering-your-gearing-6.html#post1925868

Gump has an A/F gauge fitted and his jetting was fairly optimal for the 18T.
Increasing to 19T led to richer running and increased consumption.
Of course this could be recovered by rejetting again, but how many of us do that when changing sprockets!
Its all down to the engine loading being increased for a given speed at the lower revs, and the effect this has on decreasing the a/f mixture.

On a separate note, Gump and I have been on many long road-trips together.
Up to recently he ran a 19T front and I a 17T. Both bikes running a/f gauges with spot-on jetting.
At every 100'ish mile fill-up, on every trip we've done, we were only a couple of cc's different on the fuel used.
Almost exactly the same every time. Same distance, same speeds, same consumption.
Its not the tooth size that makes the difference to consumption, its the a/f setting at that particular gearing/engine loading.

All IMHO of course!! :)

Would be interesting to hear others experience on this! Sure we will!! :D

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So, at the risk of sounding like a squid....will the 17t actually let my scrambler wheelie?

Im not expecting a stunt bike, but it should would be nice to be able to loft the front wheel when encountering some off pavement obstacles, and for the hooligan in me...
 

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older thread I know but I thought I would chip in my my cents... I followed a couple guys' advice and threw on a 17t front sprocket... awesome don't hesitate. Super worth it. Feels much better from a stand still and helps with the throttle lag in the corners. Now to plan and save for the rest of my mods:)
 

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Went with a 17 up front and a 45 on the rear. Used the stock chain. Bike is used mainly for back roads. Love the instant get up and go from basically any gear.
 

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I have been running the 17 tooth countershaft sprocket for some time on my T100. I don't know about the endless chain, but Triumph sells a chain and sprocket kit that comes with a 43 tooth rear, a 17 tooth front, and a chain that requires a chain tool. The Triumph chain tool and DID chain tool are the same tool and it is pretty expensive.

The good news is that the chain and sprocket kit costs less than just buying the chain: $192.50 for the kit. I have a brand new kit waiting for installation in another 700 miles or so.
 

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Will a 16 tooth sprocket from a speedmaster fit on a 2014 scrambler
 

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Reviving this old thread :) Can anyone tell me by how much the speedometer is affected by the 17T? I own a 2015 Scrambler, so speed is not measured at the front wheel anymore...
 

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