Bonneville America Forums Forums Technical Forums Performance Mods Jetting question

YES! I searched the forums, and tech vault, and either did not see what I was looking, or have read too much to comprehend it anymore. I am not a gear head, I perform preventive maintenance and I understand basics of car engines, but know very little about motorcycle engines. I have obtained a set of specialty spares shorts, and am trying to figure out jetting. Pat's calculator says I should use 130 mains if everything else stays stock. My question is do I need to mess w/ the pilot jets?

I am talking about a stock '07 TBA

Any insight would be appreciated.

If you have searched and read everything, good for you.

Always mod one thing at a time so you will know if you affected your bike adversely.

I would suggest leaving the pilots alone for now...

I 2nd Phil's advise.

If you decide to go with an airbox mod, then lets talk again.

Thank you both. I appreciate it very much.

I have a 07 speedmaster with the air box modified with hole under the air filter and air filter cut, cut the baffle down half way in the air box,uni filter and modified chevy 605 pipes with another six holes in the pipes..full throttle hesitates but when I back off surges forward..have not rejetted as of yet..Idles ok..What direction do I go???

I'd drop the jets a bit. What size are the mains now?

Sounds like you have increased your airflow quite a bit, but with no increase in fuel. I'd try starting with 130 main jets and see if things improve at WOT. A lot of people also run the Thunderbird sport needles which fattens up the midrange nicely. 130's may end up being too small, but would be a good place to start. I ran through a number of jetting combinations before settling on a solution that worked well with my setup. Also, others on the board may have more experience with your exhaust setup.

I would start by going to the tech vault and downloading Dinqua jetting calculator. I found it to not be perfect but it is a very good place to start.

all stock 120 main 42 pilot..

I have heard of some different mains not all 120 right from the factory. It has been posted on here.

hdlowrider, welcome to the forum. Click here for Dinqua's site, then click on jetting calculator. Had a similar setup as you except with a richer needle, stock pipes with 3 of the 4 baffles removed. 125 jets, 3 turns out on screws, stock pilot jets worked for me.

I put the Specialty Spares long cannons on my 05 speedmaster and SS provided the jet package. I f you didn't get the pipes from SS (got them used or otherwise) then you should contact them and ask for a recommendation. They have already done all the work on figuring it out.

Gary