Bonneville America Forums Forums Technical Forums General Tech Start tunning my SM... where to start?

Good morning everyone!

Well, after introducing you my new bike, I'm planning to start facing some mods.

Apart from aesthetic considerations as trimming the rear fender or installing the solo seat, I'm considering tunning carbs, and there's where I need some help.

What do I want?

First of all I'm planning to chang pipes. I'm watching and comparing different high flow pipes, and I haven't decided which one to go yet. The long TORS are the ones I like more, but I'm open to consider another options.

Of course, after mounting the pipes, changing the air filter system is a must. Here I come with 2 different options: K&N filter with airbox drilling, or the most radical removal of the entire airbox and fitting individual pods. At least initially, I'm going for option #1, which is reversible and not so radical.

All these mods are easy to do, but I need to adapt carb settings. As I'm a newbie, I was watching the A/F ratio gauges to help me out, telling me if I am making the correct modifications without running lean or rich.

But, until I decide if I mount one of those gauges or not, I'd like to know what's the best way to go you'd you recommend me.

My idea is buy the pipes and mount them, do the modification of the air filter system, buy main jets from 130 to 150 and pilot jets from 38 to 45 and start jetting, but my impression is that if I don't get the meter gauge I'll be guessing and probably messing things up.

What you think? What sall I do?

Any advice will be very welcome!

Thank you !!!

With long TORs fitted, a K&N air box filter and 900ft above sea level I found 125 mains and 42 pilots to be a great match. That was on a 2004 790 engine. That bike was ridden from sea level to 6000 ft and ran really well.

http://www.bonnevilleamerica.com/dinqua/friar/

try this calculator it has proven to be pretty darn accurate for most people's purposes.

you will have to shim your needles due to being snorkel-less.

Thank you all!

What do you mean moe, with "snorkel-less"?

I love my long slash cut TORS, and they only get better with age, too.

As for airbox modification - I don't know how much you ride, or how you feel about riding in the rain, but stock, as is, I know the bike to be fairly reliable and wet-road ready. Eliminating the airbox to install pods, you might be sacrificing some reliability if you should ever get caught out in heavy rain.

My two cents....

I agree Keith, been there done that. I reinstalled the air box and long TORs after several years running pods and open type exhaust. The TOR's as you mentioned get better with age and keep the original lines of the bike in place.

Interesting thing, I've installed D & D's on the Tbird, love the sound but the TOR's on the America are noticeably louder on acceleration.

Thank you guys! Seems that long slash cut TORs + K&N filter + drilling the airbox is the way to go. I'm only afraid of jetting...

I ride in the rain all the time with pods with no problems. Been caught in some nasty stuff that I have to pull over because the road is pooling so bad and she runs fine. Good luck with your set up.

Ok, guys!

It looks like TORs're on their way home!

Haven't decided yet if I'm removing the whole airbox or just drilling it and fitting the K&N or UNI filter...

I'll keep you in touch!

BTW, where can I buy the jets?

Thanks in advance!

I found the best prices for jets (and many other parts) to be on either http://www.bellacorse.com/ and/or http://www.newbonneville.com/

There is a Jet Calculator on this here Forum somewhere where you can check off all of your mod changes and then tells you what main jets to go with. I cant find it now, though. I'll keep digging and update it here if i do.

Nevermind - just read all the way through this thread and realized the jet calculator link is already noted here.

Good luck with the mods and happy wrenching!

I actually have a question regarding all of this, myself, too. So i have an 07 Bonnie (standard) and plan on doing the same mods - but also doing the air injection removal. I already found/ordered used TOR's for my bike that match the stock pipes' shape; they're just a few inches shorter in length with a larger diameter/opening at the rear.
But, regarding the jet calculator, I was planning on using a K&N as well and drilling it and the air box. The Calculator only shows the Uni Single option, though. Can I presume there shouldnt be much difference between that and the K&N when it comes to calculation?
Me and a buddy of mine just performed this same work yesterday on his 07 America (he used a uni single) and we jetted main to 130 - seemed to go very well and played very nice with this jetting. Presumably, this should suffice the same for me since we're talking same engine/carbs. I'm just not totally sure with me using the K&N instead and my air box might be a bit different (not sure about that, though).

K&N s and Uni s are fairly close. The jetting calc is a start point, to bring them in requires dyno runs and or air/fuel onboard sensors. You can also read your plugs or just judge your performance by the seat of your pants. Remember, it's throttle position, not MPH or RPM. Pilot jets for idle to 25%, Needles for 25 to 75% and mains for 75 to wide open. They do slightly over lap, but that's the jist of it. I suggest you get allen fasteners and change out your carb s Phillip head screws if you haven't already. care&feeding
Tune_proced. That should be enough to chew on for now.

Nice and much appreciated, Ryk. And "by the seat of your pants"...ha. I see what you did there. Really good info here with those links, too. Even just quickly skimming over it opened my eyes up a bit more to the world of internal combustion. Definitely planning on going to get a dyno test and spot check done at an authorized dealer once im done with my above mods (as will my buddy whom we just completed the work to his bike on yesterday) just for sanity check and make sure things are running as they should. Thanks again for all this info! I am digging this forum a lot and glad to have joined here recently.