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Discussion Starter · #1 ·
Hi Guys,
I've been busy this winter trying to get my own sevicing done. So far I've managed to change the oil and filter, spark plugs, fuel filter, changed to a K&N air filter. I've stripped and cleaned the front and rear brakes (what a difference having all the pistons moving - great improvement), unsiezed my chain adjuster, and am nearly ready to look at the suspension.
I've read a lot of posts referring to the use of the 18t front sprocket and would like to ask a couple of questions before I jump in the deep end.
Firstly what diference does it make to the power take up. I ride a lot in all weathers and would be concerned that fine throttle control in wet or icy/greasy/diesel covered roads may be more difficult.
Secondly are there any issues with the chain length. I will be doing the change at home using my centre stand and home tool kit, and wouldn't fancy having to chop out a link or two.
Thirdly does it affect chain life due to the extra force exerted by the smaller circumference pulley.
I'm really keen to do this, but just need some reassurance.

Regards and thanks,
Martin.

PS Can the Forum member I had the pleasure of meeting at the PSNI Trek at La Mon hotel get in touch. Due to too much Guinness I forgot your name.
 

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Everything will be fine. It doesn't turn it into a dragbike, just makes it better for sporty riding. The stock length chain works fine with mine. There's still plenty of adjustment left. I can't imagine it affects chain life significantly (if at all).
 

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Its a great "wake-up" mod for the bike. Like the previous poster said, it doesn't turn it into a drag bike but makes your bottom end more responsive.

It took me a while to notice any huge difference but it's there and wakes the bike up nicely.
 

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Hi Loosehead IMHO it is a great and simple cheap mod.

Unless maybe you do a lot of high speed Autobahn type riding the 18 tooth sprocket is the way to go.

I got 50,000kms out of my chain with the 18 th sprocket on and that was mostly 2 up mountain riding.

It makes take off from standstill and low speed manoeuvring easier and gives better drive out of corners in any gear.

It should make almost no fuel consumption difference either.

many here believe it should be std equipment but suspect noise control laws have caused the higher toothed 19 cog to be used instead.

There have been very few members who have regretted this mod and changed back.

DaveM:cool:
 

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I am 1 who has changed back, as I do more long distance rides for touring & rallies etc
So the added speed/mpg/tank range the stock 19T gives suits me. the 18T makes me want to be a hooligan .........wheelying all the time ;)
 

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There are no variations in calibration for any year RS or pre-'05 ST.

There is no down side that I am aware of. There is a massive improvement coming from full stop. The trade off is a few hundred RPM at cruising speed, barely worth mentioning.

Throttle response is better at very low speeds, though not so much better that you'll stay upright on ice. :p Seriously, the first time I went down on my RS was a rainy night coming off a stop sign on seriously beat-up pavement that had just had a coat of white paint in the crosswalk. I think I would have maintained control with the 18 where I lost it with the 19.

I suppose, in theory, it would be a good idea to run a chain that's one link shorter. In practice, there's no need.

Cheers, HTH,
-Kit
 

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Discussion Starter · #9 ·
Thanks Guys,
Your prompt replies were much appreciated.Just the sort of soothing, positive replies I was after. Thanks for that link, Jim. I dont understand it all, but I can see that its not as drastic as I thought.
Sometimes I find I need a bit of reassurance that what I'm about to do is not as scary as I make it out to be.
It was only from reading all the stuff on this board that gave me the confidence to try out the routine servicing. Once I got started I had loads of fun, freezing cold hands, skinned knuckles, oil all over my garage floor. I also have clean oil, brakes that have never been this good and plans for doing loads more.
Regards,
Martin
 

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Basically if you run the math there is a 500 rpm change. With these engines it's not worth thinking about.

Stock gearing is rather on the tall side and as DaveM said it's for noise drive by cert.

With the 18, around town is much easier and better for 2up.

No worries at all cruising and touring at 70 US mph = 4,000 rpm which is in the lower part of the torque curve anyway. These are not Massey Ferguson tractor motors and keeping them toward the middle of the torque curve is much better on them longevity wise and every thing else than lugging them around.

Mileage? I average 51 US mpg caning her butt off, what do you want egg in your beer? Actually, mine is much happier in an aggressive mode and gets better MPG than loafing on the interstate where it gets 47mpg.

Top speed? Trying both the 19 and 18 guess what? same top end at cut off in top gear with either sprocket. The 18 gets it there quicker though, much quicker. Better leverage (I slipped that one in again OnD:D)

I think I was the first to do this and my bike has been this way since about day one and would never consider going back to a 19.

There are no negatives to report on this modification.

A cheaper way to do it is to find an 18 off a TBird. TBird riders around here like the 19's and will swap. You local dealer might have a few stashed away but the AM ones aren't bad in price either.

Just do it you won't regret it.
 

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To do it cheap, just dont buy a Triumph sprocket. Many many many sprocket manufacturers sell ones to fit your ST. I used a JT Steel sprocket and it cost under 20 bucks cdn if I remember correctly.
 

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I have just put on a JT myself. It was over $20 US. About $2 over, IIRC. ;)

Cheers,
-Kit
 

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I have just put on a JT myself. It was over $20 US. About $2 over, IIRC. ;)

Cheers,
-Kit

The Cdn dollar was strong when I bought it. :) Unlike the Cdn peso of today. I think it was 18 when I bought it but they are about 24 now. I am going up a tooth on my Bonnie.
 

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I'm currently running an 18/45 combo on my RS and like it. Puts me at 5000rpm at 75mph- in the sweet spot- gets to 90 pdq when needed. Really helps in low and mid range twisties--because you can keep the revs and therefor intake suction up where you want it for better drive thru and out of turns. I think I'm seeing a little less driveline lash as well. no significant gas mileage change. Instead of going back to a 19 for any long trips, I think I'll be happy with just using a 44 or 43 on the rear- saves a good bit of work that way.

I used a JT at first for around 20 bucks but when I changed out my chain and rear sprockets I sprung for the oem 18t just because it is reputed to be a little smoother and quieter than the non rubber bushing JT. I can now sneak up on unsuspecting small animals.
 

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Why not go up a tooth or two on the rear? I did that on my Speed Triple with great results.
Two reasons, you'd probably need a longer chain and the difference would be minimal. You make gross rpm adjustments with the front sprocket and very fine tune with the rear.

Plus, changing out the front is easypeasy and the rear much more involved.

RSRAT has a good combo in the 18/45 but if one were thinking about that I'd wait for a chain change as you'd probably need a longer one and really, the 18/43 is very fine.

Don
 

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Discussion Starter · #17 ·
Cheers Guys,
Thanks for all the comments. Next set of days off I'll get out the tools and give it a try.
Regards,
Martin
 

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I went 18/43 and the -1/+1 combo keeps the wheel within 0.5mm of stock wheelbase.
It's also making me lazy, top gear overtakes are an absolute doddle as long as I start well back and just keep it rolling. Well into 3 figure speeds after passing two artics from about a 50mph run up
 

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I found it made it easier to keep the engine spinning while keeping to UK speed limits - with 19T, @30mph I always felt like I was in too high or too low gear. The 18T makes toddling round @30mph easier

Similarly for 70~75mph on dual carriageways.
Not the most glamorous selling point but handy now there seems to be speed cameras everywhere...
 
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