Bonneville America Forums Forums Technical Forums Performance Mods should i change my pilot jets

I'm putting on the turnout air filters and changing the mains to 157. How important is it to change the pilot jet? Also, will i have adjust my idle mixture screw? I didn't really want to drill it out to adjust it but will i have to?

157 is pretty big, what else have you done? You should probably have a 45 pilot, or at least a 42. Definitely drill out to get to your screws, it's fun to adjust!

thats what the jet calculator is telling me to put in. jc whitney turnouts. thats it

I am running the "ram" style turn arounds with 157 mains, tbs needles ( I think one shim but dont hold me to that lol ) and stockpilots 2.5 turns out. Oh, and running Scepters... other than that, stock 790...

You need to document the rest of your airflow changes before any of us can guess. If it's only the one part, then that's probably too large a main and the pilot might still be okay...really we need more info or it'll be just WAGs.

i'm not sure what else i can tell you. I have the stock air box with stock filter. i changed my mains when i put on my 32" Turnouts. air injection removed as well.

With the stock air box that main will be way too big and you can leave the pilots at stock size but adjust them.

So far adjusting mains in small increments has amazed me as to the very noticeable increases in performance (120>125>130) while not having much affect at all on fuel economy.

Bumping the pilots from 40>42 did make a difference in fuel economy (about 10 miles/tank to reserve), but not so much in performance. More importantly, to me anyway, was the difference it made in the tone of the pipes. It lowered the tone, and kind of "beefed it up" in a good way - well worth the change.

You can get the "D" tool on ebay too for a lot less than through the websites. I also didn't have to drill my screws at all. I agree with Dog too that 157 would be way to big for stock airbox and filter. Also keep in mind the jet calculator tends to run a bit rich.

I think it's too big also, I have a 157.5 main jet in mine, but I have the airbox out, Scepter pipes, 904 with headwork, and bored stock carbs with high flow intakes, and the dyno read my air fuel mix at 13.2 on top end.

i think you missed my first sentence. i'm changing my stock air to the turnout style air filters from mikes xs cycle. (way cheaper than k&n's) thats why the calculator told me to go that high. although it didn't have the turnout style in the calculator, i just used the pods to get a jet size.

You still have to let us know how the air is getting out to get a substantive guess on the jets.

Another thing-what year is your bike we're talking about. The later models don't have the cover on the pilot adjustment screw that you need to drill, but you'll need a D tool.

And didn't you say you're running JC Whitney Turnouts for your exhaust and intake is stock box and filter?

ya, jc whitney 32" turnouts. stock air box to the turnout style w/pod filters. 04 speedmaster. I'm pretty sure last time i rejetted for the pipes that i didn't mess with the pilot screw because it was "plugged". Something about drilling on carbs i've never liked. Maybe it's just me. I'm going to this time because i ordered the D tool so i'm going to make myself use it.

Alright-now it's all coming together. So you're changing your air intake system from the stock air box to turn outs with essentially K&N's on it. And you have the JCW's on there now-so no change to exhaust. I see where you get the 157 from the calculator (assuming sea level).

In that case-you're original question was should I change the pilot jets and adjust the pilot screw? When I did mine it called for 160 mains-I put in 155's. Almost everybody that I talked to said you want to go with 45's for the pilot jet. And the general rule of thumb is when adjusting the pilot screw if you have to go more than three turns out you need a bigger pilot jet (in case you leave the 42 in there). I left my pilot screw at 2 turns out-haven't dynoed yet so no hard results-but she runs well.

Maybe one of you '04 guys can chime in-my understanding was if the pilot screw is plugged it's a standard screw driver not a D tool type. Triumph put that "fancy" screw on so we couldn't screw with the screw

Not always, mine were plugged and had the D tool type screw. I used a dremel and small cut off wheel and cut a slot in the D head. Pulled the screw out with small hemostats before cutting the slot.

There you have it-glad you ordered the D tool then

Did you see this thread on here too about RAM filters. A strategic PM to some of those guys might help you too with the jetting issue. And when I played with the calculator I assumed the JCW would be the right choice-or would that fall under "misc open pipes" for his set up?

http://www.bonnevilleamerica.com/forums/...ge=0#Post394454