Bonneville America Forums Forums Technical Forums Performance Mods The plan : 06' speedmaster

Checked dinquas re-jet calc.1000-2000 sea level,TB pipes-stock,UNI single filter,TBS needles{2-5mm shims}(per needle?),42 pilot jets,De-snorkeled,125 mains. plan: Take AI out,Add:130 mains,18T sprocket 3.33:1 as opposed to my 16T 2.62:1.I'm hoping that will increase my low end, besides I don't run a ton every other day.All this through Bike Bandit and New Speedmaster.com for about $93.00 w/o shipping. Realize though this is only a start on the mods more to come I'm sure. Think it will fly for now? SMK

If you go to 130s, you might want to take at least one shim out.

Phil ,since the shims come into their glory at 2/3 throttle do the shims hold them partially open?Also the mains by increase mm opening, allow more fuel hence the acquisition of more air , such as the freak or nark beyond 2/3 throttle.What do you think about the 18T will it help low end. Could I increase my mains with my current projected set-up? SMK

The shims hold the needles further out of the main jet which allows a richer condition when they are actively 'in use'. The best chart I've seen to illustrate how the carbs work is this one:



(From that page):
The air screw is most effective between idle through 1/8 throttle. The pilot (slow) jet is most effective between 1/8 through 1/4 throttle. The slide valve is most effective between 1/8 through 1/2 throttle. The jet needle is most effective between 1/4 through 3/4 throttle. The main jet is most effective between 3/4 through wide-open throttle.

Start with the 130s and see what happens. I'd still remove a shim though.
btw, are you not sure whether you have two shims per needle? I see your question (per needle?)


I believe that going from a 16 to an 18 is going to negatively affect your bottom end torque. It's an easily reversable mod, so try it and see what I mean.

Yes. one or two per needle. I thought the 18t would help the low end since it takes less revs than the stock sprocket or maybe I have it backwards could it be for high end ?

The 18 will give you a better top end with lower revs...

Better omit the sprocket then and concentrate on more air /fuel such as freak or nark maybe bigger mains would that then help increase my low end?

The Freak and bigger mains will definitely help!

Will the bigger jets help at 4000rpm?

You know, I was hoping this wasn't going to come up again.

"IT'S THROTTLE POSITION - NOT RPM! NOT SPEED!!"

Jeez Pat, don't you read your own posts?

O.K. Pat and Phil have a beer or ten. Where have I heard that before? ......Then from 1/3 to 2/3 throttle what position (the position I'm in),or currently in. Really don't want to re-bore;In other words,I'd like to goose it for a minute and leave my stomach behind. Don't get me wrong it has plenty of torque. Just looking for a right direction from the very start so I don't have to pay good money in front of bad.(I'm learning too! It's throttle position not RPM's) Well? You know now, what I'm looking for and not looking for,i.e. sprocket. ......now I forgot the question? see what you think ! If you guys think of anything I'll be over here at the corner of walk and don't walk. ( At 4000 RPM wouldn't I be relying on the needles? Somewhat?)