Bonneville America Forums Forums Technical Forums Performance Mods Can you improve performance and still be "stock"?

Other than a few cosmetic changes to my America, after a year of ownership (and, yes, only 3500 miles) I haven't made any performance mods. I don't like the idea of surgery (drilling airbox, gutting pipes) yet, and I kind of like being quiet. (I think the last time I saw Pat, he asked if I'd started it up yet. Funny guy.)

Even so, I'd like it to be as quick and responsive as it can be.

Are our bikes set up optimally from the factory w/ 120 mains, 42 pilots & stock needles? Is there room for improvement with different filters/jets/needles/etc that can provide incremental gains without opening the pipes or airbox? Can only a dyno know for sure?

Our bikes are definately NOT set up optimally from the factory I have gained both HP and torque. Our bikes are set up to pass emissions.

sure... pull the snorkle, change to a uni filter, and rejet slightly to make up for the less restricted air flow...but your stock pipes are going to be you gating factor...you can only free up the air flow in as much as the stock pipes allow...but there is definately room for improvement

It is possible to lessen the pipe restriction and still not be too loud. Try knocking out 1 baffle at a time if you want to try it. until you are loud enough you don't want to continue.

Ignition coils, spark plug wires, and spark plugs. The hardest one of those 3 is the coils and only because you have to remove the tank to get to them, it's still a 15 min. job. You'll feel the difference without doing any surgery. I got to agree with Rob though, free up your air flow, you won't regret it.

Thanks all. Looks like some baffles have to go.

If you are concerned about gutting your pipes, you may want to consider getting a second set. Sometimes you can find some on eBay that have been modified, I think there are a couple guys on ebay that do that.

You should also consider high performance coils, wires and Iridium spark plugs they really do make a difference.

Soren

Pulling the rubber bit out of the airbox will help some. A free flowing air filter will also. If you have an 865 engine and are feeling brave, offsetting the exhaust cam a tooth or possibly 2 to make the valves stay open later is likely to help while still being technically stock.
Back when stock car racing still involved "stock" cars, fine tuning used to yield up to 30% power gains.

I'm not brave enough to mess with the cams!

I've decided that I'm going to pull the snorkel, put in a K&N filter, put in TBS needles w/ 1 shim, invest in premium plugs/wire/coils and pull 1 baffle from my pipes. The changes are easy, mostly reversible and according to Dr. Dinqua's calculator, I don't need to mess with the jets (which is still beyond my comfort level).

It's a start (and will most likely just make we want more) .

Has anyone done that to an 865? with the stock cams?

I'll try it at the 12k tune up. maybe this year or not- depending on how much it continues to rain.

I don't think you going to want a shim under TBS needles with the air box still in place.

depends...I got 2 shims under TBS needles...stock airbox, uni filter no snork....well my sig has my set up...but shims and TBS are definately not out of the question...but I'm not sure I would start with it...

Well, the conventional wisdom says to start with Pat's jetting calculator and go from there. With stock pipes minus 1 baffle, K&N filter, snorkel removed, stock pilots and TBS needles, it recommends a 121.5 jet size. With a shim, it drops to 119.5. As I'm sticking with the stock main of 120, I thought the 119.5 being closest was best.

Anyway, thats my logic (with absolutely no other experience to back it up ). But I'm here to learn, so advice is always welcome.

I'm also interested in making performance mods that don't require rejetting, but I'm a little confused about what to enter into Pat's jetting calculator for my '07 Speedmaster. My main source of confusion is the needle. The Jenks' Bolts site says that Triumph started using a stock needle that's closer to the Thruxton needle on the '06 models. Do the later models also have different jets? If so, what size are they? And if not, what did they do differently to compensate for the Thruxton-like needles? And finally, how can I adjust for these differences when I use Pat's calculator?

Am I making all of this a whole lot more complicated than it really is?

Thanks,
--Brandon

Don't worry about any supposed changes from prior years, I have a 2007 America and found the jetting caluclator to work very well. If you don't want to rejet, but want to start with an easy mod, go to the Triumphant site and read the piece about installing TBS needles. It's not that hard to do (easier than rejetting) and might go well with the snorkle removal and uni filter installation. In any event, its all reversible if you are not satisfied with the results.