Triumphrat

doggoneit · 07-25-2007

Hi,

I live in New Zealand and have recently purchased a 2004 Bonneville. I have removed the air injection and put on some free flow pipes. I am concerned it is running lean as it backfires a lot on overrun and the pipes have blued a lot more. I have looked at the information by Jenks Bolts which is great. I am not sure whether to change the jets or try the thruxton needle. I wish to add a K&N filter and removew the snorkel as well. I know I should go into the shop and get them to dyno it but that will cost $800nz. Is it that difficult to change jets/needles etc at home by yourself? Any advice would be really appreciated.

Cheers and thanks in advance

Geoff · 07-25-2007

use the jenks settings, whatever they may be for your set-up. I did, and it dynoed spot on , shocking the dyno operator, myself, and several innocent passers by.
G

doggoneit · 07-25-2007

Cheers Geoff.

Would it be easier to use the thruxton needle rather than change jets. Also is it a very difficult thing to do?

Many thanks.

merlin · 07-25-2007

the needles are a relatively easy change. I'm not saying its the right thing for you to do, you have to determine your own set up. You need to take the tank off, but that's easy.
Changing jets is relatively easy.. but I like anything else, only when you know what you are doing. Done wrong, you can damage the carbs which is $$$$$$$ no matter what currency you use. Sorry, I don't have the link, but find a photo, diagram, etc of the carbs and undestand just what you are doing before you go in there. Do NOTHING without the right tools, specifically a useable size screwdriver that EXACTLY fits the jets you are about to put in... You will want to replace the cheesy carb screw (that hold the bowl and the cap) with hex head screws (see Newbonneville.com)
Any change like what you are doing deserves a carb balance afteward.. always smoothes things out. Others, will contribute, continue your research, act in haste, repent in lesure...