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Discussion Starter #1
What experience have you had with the main jet size, I have a K&N air filter, snorkle removed, Thruxton needles and baffles removed. The bike runs quite well, I did screw out the mixture screw out about a quarter of a turn which helped a hesitation down low.
As far as I know the mains are stock 110. I sort of feel the motor runs hot but I dont know if that would be normal.
Fuel economy is good.
The plug reading is very white on one side of the centre and brown on the other side of the centre tip.
The plug is a NGK R DPR9EA 9 and looks in good condition. the Haynes manual says the standard plug is a DPR8EA 9.
The bike has done 29500km
I have a set of 120 mains should I put them in.
 

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main jets

Yes, fit the 120's. My Bonnie is almost to the same spec as yours and I fitted 120's and it runs very well, although I do intend to have it checked on a dyno in the spring.
 

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You dont mention which bike you have, but Im assuming its the same 790 Bonnie you had when first you raised this subject.....

http://www.triumphrat.net/twins-technical-talk/80432-what-pilots-and-mains.html

Im not 100% sure how the 790 compares to the 865 when it comes to jetting but, with the mods you have, the 120's may be a little on the rich side.

A good source of info is other peoples signatures which include their settings and mods.
Here's one taken at random...........

2005 Bonneville 790cc, AI removed, Staintunes RC, Unifilter, no snorkel, 120/40/Thrux needle/1 shim/3 turns,

Scrolling thro others may help in your enquiries.

There's also a lot of info in the "Great sources of info" sticky at the top of the page.

V.
 

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Every bike is different ( where you live,etc) . You have to rejet for sure, any time you do anything with intake. Get the general info and start there, you will have to play around with it, but thats the fun. Good luck
 

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I have 120s with a similar configuration (see below), and they seem to work well, but I'm going to try slightly smaller (118) next season, just to see if I can tell a difference.

My guess is that the correct size is in the 115-120 range for this configuration, based on what I've read on this forum.
 

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Discussion Starter #6
Got the floats bowls off without removing th carbys and fitted the 120 mains, took the bike for a 400km run, much better. forgot to check the pilot size. started the bike and set the mixture screws at 2.5 turns out.
I have Thruxton needles but no shims, how much different would a shim make?
 
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