Bonneville America Forums Forums Technical Forums Performance Mods CT Tech Day Results

Last Saturday at Uncle Charlie's, John and Erwin helped me install 130 main jets and Uni filter on my basically stock 07 America (actually they did all the work - its a PITA pulling the float bowls with carb still on bike - but they made it look easy). So anyway,I had pulled the snorkle but decided the bike was stll running lean at partial throttle openings, so I put it back in. Actually I had previously cut the lower part of it off, so I ended up putting both half's back in. Bike ran well with this setup on the way home with good throtle response and felt stronger on top end. So later that week I am reading some of the carb literature on Pat's site, trying to re-educate myself about carburators after owing a fuel injected BMW for 10 years. Found myself reading about needles and the use of TBS needls or stock needles with shims to improve midrange throttle response. On Wednesday I went to Gengras to order the tbs needles, which were not in stock, but did pick up AI eliminaton kit and oil and filter. So after installing the AI, kit, with the tank off, I figured I would take off the top of the carbs and look at the needles in anticipation of getting the TBS needles. Ended up putting in a shim washer on each carb. Took for test ride, felt good down low, but breaking up on top. Found thinner smaller washer and installed. Even better, but still breaking up at high rpms. Thinking that I would just have to wait till the TBS needles came in, but remembered that the top half of the snorkle was still in. Pulled over to the side of the road and pulled it. Got back on the bike and back on the throttle. Holy Sh*t, bike ran stronger than ever. Actually started to run out of straightaway space in third gear with bike still pulling at close to 80 mph! Wow, that is more like it. Bike feels like it gained a couple hundred extra cc's and still very tractable at low rpm's. Now I have to see if the TBS needles are an improvement over the current setup. Thanks to John and Erwin for helping with the main jets and thanks to Charlie for hosting Tech Day and getting me started with mods.

Wow!! gilligan let us know how the TBS needles work out for you.

Glad to hear your bike is running more like you expected.Im running the TBS needles/no shims/42/3.5 turns out with Tbike pipes and it runs great! Once you put in the TBS needles, youll need to get rid of a shim or 2. Another great simple mod I did was drill my carb slides. Amazing difference in throttle responce.

Last night I put in the TBS needles (no shim) and drilled out the carb slide to 7/64 per the Triumphant article. Rode bike in to work this morning. Much improved especially from 1/4 throttle on. With the stock needle and one shim, I was getting good results at 1/2 throttle and above, but not much better than stock below that. Now its good from 1/4 on up. One possible change that I may make is to turn in the mixture screws a little (I have kind of forgot exactly how far out they are at this point but would guess 3 1/2 to 3 3/4 turns) since initial throttle roll on feels a little muddy. Also, I am wondering if 128 jets might actually perform better than the 130's I am running. This morning, with the bike somewhat warmed up but maybe not completely, I got a little breaking up as I got close to redline in third gear. At this point, I have drilled a hole in the bottom of the airbox and am running a Uni filter, but I wonder if the short TORs just do not flow quite as well as some of the other pipese people have on their bikes.

good question I thought that later models came with the larger passages.

Not sure about the hole in the slide, drilling to 7/64 seemed to enlarge it only very slightly so maybe you guys are right and the hole already was bigger. As for the jetting, I think I just have to keep experimenting. Not sure if the low end is a little too rich or a little to lean. Could always try the 45 pilot and 128 main and see how she runs. Overall, though the bike is running pretty well. I am probably getting nit picky, but I sense there is room for improvement on top.

Do one at a time.... 45 pilot, ride it, then 128. I doubt you would have to lean out the main tho.

What Benny said, If you do both at the same time you don't know what was good or bad. If you do the pilot and it is good then you have an indication of going in the right direction. Same goes for any change you make.

Thanks guys, Just got back from Boulder, Colorado with my wife and kids. To bad I didn't have a bike out there as there were some awesome motorcycling roads and lots of bikes. Maybe I'll order the 45 pilot jets and 128 mains and do one change at a time. Really appreciate all the advice, the TBS needles really made the mid-range come alive on the bike and overall its running much stronger than stock.

Hey Pat,
Do you think the TBS needles made a big difference over stock with 1 shim?

With the TBD needles the improved mid-range comes on sooner like at 1/4 throttle whereas with the shimmed stock needle, it wasn't as noticable until about 1/2 throttle. So yes I am keeping the TBS needles in.

Actually, what I want to do if we do another tech day is have one of you guys test ride my bike (full throttle third gear pull up the Merrit Pkwy??) and give me some feedback on how its running and whether I should change anything.

Patrick, just a note:

when I installed the TBS needles (45 pilots and 130-or-so mains) and took it to the dyno, i was WAY rich between 1/4 and 2/3 open. I'm not that much higher than sea level, and running very similar to your setup (SS long cannon pipes, hole-in-the-bottom airbox, unifilter, etc).

that said, i did notice better throttle response through mid range w/ the TBS, but chose to move back down to stock needles w/ a shim which brought me back to a more acceptable air/fuel ratio on the dyno.

in short, i think being as close to optimal air/fuel will be better for the motor over its lifespan and get me better gas milage. i can live w/ a slightly deminished throttle response in that range.

You may have a point, since I am wondering whether my current setup is a little too rich on top. Without dyno testing hard to say, but maybe it pulled just a little stronger with the shimmed stock needles on top end. The offset is that I like the way the TBS needles fattened up the mid-range. Did your dyno run validate your choice of 130 main jets?

yeah the 130's seem to be correct - i don't have any issues at WOT.

i'm fairly confident that my bottleneck right now is air. i think the only way i'll get more is via a freak or similar setup if i go w/ new carbs.

The only reason I went to TBS needles was because of a dip in power in every gear from about 3k - 4k rpm. The TBS needles cured the problem.