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Hi, please could anyone advise me what make off replacement sprocket is best to purchase for the job off lowering the revs on my 790 bonnie. I believe i need an 18 or 19? and the standard will be a 17 on the bike. Or has anybody got a decent used one for sale (I live in the UK) THANKS :???:
 

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FYI, mine came with the 18 stock and I switched to the 19 and hated it! Some like it, but a lot have switched back and found that they like the 17/18t better than the 19t.

I went from 18t to 19t, back to 18t, and now I'm using a 17t and like it best.

that said, I think you should try the 18t. I don't know where you can get it in the UK, maybe Norman Hyde? or mototwin (RIP?)...
 

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Got my 19t at Bellacorse.com. They are made by Esjot, and Bellacorse says it is the OEM manufacturer of sprockets for Aprilia, KTM, and BMW.

I love my 19t sprocket. Hitting 60 in first gear is sweet.
 
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On 2006-12-01 10:29, asphyx9 wrote:
Got my 19t at Bellacorse.com. They are made by Esjot, and Bellacorse says it is the OEM manufacturer of sprockets for Aprilia, KTM, and BMW.

I love my 19t sprocket. Hitting 60 in first gear is sweet.
Hi, That sounds sweet, so i need me a 19 me thinks!!!!!! :-D
 
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On 2006-12-01 10:14, sweatmachine wrote:
FYI, mine came with the 18 stock and I switched to the 19 and hated it! Some like it, but a lot have switched back and found that they like the 17/18t better than the 19t.

I went from 18t to 19t, back to 18t, and now I'm using a 17t and like it best.

that said, I think you should try the 18t. I don't know where you can get it in the UK, maybe Norman Hyde? or mototwin (RIP?)...
Thanks for your reply, did the 19 drop the revs by much? and did you not like it cause it lost out on zip at the bottom end? :???:
 

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they're too cheap to consider a used one, which'll have a wear pattern on it from use
G
 

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the difference in revs at 70mph was about 450-500 rpms lower with the 19t vs the 18t, and about the same difference with the 17t.

I think now I'm at around 4800-5000 rpms at 70mph with the 17t, and was around 4500 with the 18t, and closer to 4000 with the 19t.

The biggest difference is not the revs at highway speed, it's the gear spacing that changes dramatically.

here's my impression:

17t:

1.waaaa 2. waaaa 3. waaaa 4.waaaa 5:waaaaa

18t:

1. waaaaaa 2. waaaaaa 3. waaaaaaa. 4. waaaaaa. 5. waaa

19t:

1. waaaaaaaaaaaaaaa 2. waaaaaaaaaaaaa 3. waaaaaaaaaaa 4. waaaaaaaaaaaa 5. waaaaaaaaa

I felt a huge loss of acceleration, and it seems like it takes forever to get through the gears.

Also, with the 19t at 70mph at 4000 rpms there's not a ton of passing power without downshifting.

with the 17t at 70mph at 4800-5000 rpms I just whack the throttle and I'm gone!

the 19t you have to slip the clutch more to get moving, it feels like starting in 2nd gear.

I hated it, your experience may differ, and they're cheap enough and easy enough to change, so if you're interested give it a shot!
 

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I got a Renthal 18T from Mototwin & it has been an improvement.

It is a solid piece and after 4000 miles is still looking new, so I don't think it will wear in a hurry.

I thought about the 19T, but was told that the 790 engine didn't really have enough power to get the bike to pull well with a 19T.
 

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Just an FYI,

Note the bikes in which someone who has done a front sprocket change and if they liked it or not...

I may be wrong, but I believe the Thruxtons come with a differant front sprocket than the bonnies... ?

I have "enlarged" my front sprocket on my Thruxton and it is much better than stock.
 

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Hello Folks,

I inquired earlier this month about upgrading my 2003 T100 to a larger front sprocket. Thanks to everyone for their input.

I called a local Triumph dealer here in Connecticut to ask if they would have an 18T in stock. Yes they did, and they offerred to install while I wait. I asked to set up an appointment, and they said they could do it that afternoon, so I took a few hours off from work and brought the bike in.

1 hour and 10 minutes later, I was on my way back to work. Total parts and labor invoice was $76.87. Life is soooo good.

My observations are as follows:

17T @60mph=3500 rpm, 70mph=4200rpm, 80mph=5000rpm

18T @60mph=3400 rpm, 70mph=3900rpm, 80mph=4600rpm

It feels just about right. Again, thanks to everyone.

Best regards,

Barry
 

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I have a 2001 Bonne, stock is 17T, I went straight to a 19T and really like it. Yes I can feel a change in the speed of the acceloration but like the cruisen much better. I pretty sure when I did all my working out I found for every one tooth up change on the front sprocket the RPM drops 250 for the same MPH road speed.
My 790 has been debaffled, A! removed, thruxton needles, K&N filter, snorkel removed, mixture screw adjusted a little richer.
May be the 18T would be just right but I have no intentions of changing the 19T.
 
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