Bonneville America Forums Forums Technical Forums Performance Mods time for jets and needles

ok heres the deal. 2005 ba. almost time for first service so i am going to remove the snorkles, add tbs needleds. i have thundernike pipes on it. just curious which size jets to put in. i was thinking 130 or 135's. really wanna do this one time and leave it alone after. any suggestions?

Frank

I think 135. I had 160s in mine and the dyno showed way to rich and would fall off at the higher rpms. I have 135s with Bubs and the Thruxton needles.

Just keep backing out the air/fuel screws until she stops popping on decel.

ok so i will go with the 135's. keep the pilots the same and hjopefully this is right. thanx

Frank

Frank,

135's should be ok. I have the TBike pipes and TBS needles and I went with 130 mains. Check your plug color when you're done, that will tell the tale.

Hey Grump, quick question on plug color, will the color of my current plugs change as I adjust my mix? I have new plugs ready to go, but wondering if I should get the mix right first, ya know?

Hi Benny,

Tax time and I'm still at the office so I'll jump at this. Get her dialed in then use the plug color to fine tune. My understanding is that you must run the bike hard on a level road, hit the kill switch while you are up on the rpms in a high gear, pull the clutch in and then coast to a stop and pull the plugs and examine for color. You want to see the plugs at the main jet use not at the idle circuit (pilot jets) thus the high speed shut down. Just running the bike parking it then pulling the plugs would only show you the idle circuit color.

Hope this helps...

This is kind of depends on the bike and your altitude.
I was running TOR pipes with all snorkels removed, the AI
removed, and a Unifilter and everything was good with 130
mains 42 pilots and stock needles. I switched to Epcos
and was way lean. Switched out the stock needles for
the Tbs neddles and was too rich. I opened up the
bottom of the air box and filter and now I am just right
running 130s and 42s with Tbs needles, my plugs look perfect.
I see here that a lot of guys are running much bigger jets
than I do. The moral to this story is that lean on an air
cooled engine is very bad and a little rich is OK and too
rich will cause problems too and that tuning is rarely a one
shot deal. There is generally no set it and forget.
Todd

thanx todd. i am in the new england area so there will always be massive changes in alltitude and weather when i ride. i will try 135 and see what happens. thanx

Frank

Thanks for the help guys. I'm on long island so basically I'm 6 feet above sea level. I do ride to new england a few times a year, but I doubt I'll bother changing anytihng drastic for that ride!! I've got the perfect road to do the high speed shut down method right near my house, so I'll give er a whirl!

I got a question, i've been searching for the link for the spark plug reference pictures (that show examples of lean and rich plugs).

Another question, do the NGK Iridium spark plugs show richness the same as the stock plugs?

Reason for these questions: I put 155 main jets, 45 pilots, thruxton needles, mix screw is out 3 1/4 turns. I got large cannon specialty spare exhaust and the freak installed. The plugs look lean, no matter what i do they still look lean to me. No nice chocolate color yet.

Hi Chuck,

Some of the members are using 160 mains.

When you are looking at the spark plug color,
"To get a true plug color reading you must run the engine,on a level road, at the throttle setting that you want to test, for about a mile, then kill the ignition, pull the clutch in and coast to a stop. Then pull the plug and look at it. This could be a real thrill on most of the newer street bikes."
excerpt from Dan's Motorcycle Page: Spark Plugs

Dan's Spark Plug reference chart

The NGK Iridium spark plugs should be true to color. These plugs should not burn hotter, instead they are at least theoretically more efficient. (I could stand to be corrected on this point though.)