Bonneville America Forums Forums Technical Forums Performance Mods What size front sprocket ?

I have an 02 America with the stock sprockets . What size is the original sprocket , and what should I get for better top end? I don't want to give up too much low end performance.

Standard is 17 if I remember rightly, I run with an 18 and seems better for cruzing. I would say the 18 is about best do not loose much on take off and keeps the revs down a little on motorway riding.. If you do a lot of motorway work go with the 19. That's my two cents worth, i'm sure you will get other comments as we all ride differently

Ok thanks I think I need to up my main jets a size or 2 also. I have the freak and epco's . The dealer jetted it on a dyno.The main jets are 145's I believe, and I have TBS needles with 1 shim. I have trouble hitting 100mph. At wide open throttle after 80 mph it feels like there is nothing left. It does creep up to about 95 mph maybe 98. Also my gas mileage is only around 30-35mph.

17 is stock. You should be doing better than that. I get about 40, have upgraded exhaust, ghetto FREAK, and mine pulls pretty well past 80. I can get to 100 . I think you are going about tuning it somewhat backwards. Proper tuning on the bike means that you should reach be able to reach red line in top gear. The bike should run out of beans about the same time it reaches max RPM. If you do not have a tach, it will be had to determine whats going on there. If you are reaching top speed at only 6k rpm, you could work on th gearing, but I suspect something else.

I think I will try 150 main jets. Any other ideas?

I have the 2002 TBA, with the original 17 tooth counter sprocket. With windshield and large saddlebags, I still accellerate quickly past 85mph and get to 100mph, but that is about it (I am running on ethanol but considering switching to regular mid-grade gas). Balancing carbs is important at higher RPMs, as is free-breathing of the engine and good spark from the coils. I used the 16 tooth front sprocket for a while, but went back to the 17 for the road. Also, I get 40-44 mpg with the 17 tooth sprocket.

Also, check Pat's (Dingua) website:
http://www.dinqua.com/Triumph/carbs0.html

If you've freaked you may be running lean at the top. Up your main jets to 150's to 155s. I've got the 17 w/ 155s, t-bikes. No problem hitting 100+ and get about 45-48 mpg.

An 18t sprocket will give you what you are looking for.

Soren