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Discussion Starter #1
Hello Everyone!

I am having problems tuning my bike. When i run it with the choke on, it idles between 3000 & 4000 rpm's depending on engine temp! Without choke it idles steadily around 950 rpm's. What is going on?

Here is my config:

2008 Carbi Thruxton
AI removed
Predator mufflers
K&N filter in stock un-modified airbox
120 Mains
40 Pilots
Idle Mixture screw set 2.5 turns out
150ft Above Sea Level

I have tried 135 then 125 mains with 42 pilots but ran too rich.

Cheers,

Goran.
 

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Um...I think everything is OK there. That sounds like normal startup behaviour to me. Just don't give it so much choke while you're warming it up, gradually push the choke in until you're idling off choke, then ride it.
 

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I don't understand what you are asking? The bike is doing what is supposed to do...
 

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Seems normal to me too. The warm (non-choke) idle is right where it should be.
 

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Discussion Starter #5
The reason i am questioning why it idles so high while the choke is on is because i have owned it for 3 months now and it has never idled that high on choke. The maximum it idled on choke before was about 1500rpm. Also, maybe it's wrong to do so, but i am comparing it to the carbi cars i have owned....

Does anyone know what the rpm's should be with the choke on?

Thank you.
 

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Mine will rev to 3000 and higher for sure if I let it. Why yours would unly just start doing it I don't know - did it suddenly warm up where you are or something? :confused:
 

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Discussion Starter #7
It's been between 30-35 Degrees Celsius since pretty much christmas....

It only started doing it yesterday when i swapped the 42 pilots and 125 mains for 40 pilots and 120 mains.....
 

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That explains it - it wasn't runnning right before. It was probably way rich so it was bogging down or something. Basically you've fixed it, because it sounds like it's running more normally now. 42 pilots are too rich if you have the stock airbox.
 

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That explains it - it wasn't runnning right before. It was probably way rich so it was bogging down or something. Basically you've fixed it, because it sounds like it's running more normally now. 42 pilots are too rich if you have the stock airbox.
BAM!!! CAF, NOW your bike is running the way it is supposed to! You should notice a huge difference in how it runs, you basically just got a new bike!
 

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This info was obtained by some careful experimentation by Ventura.

Stock exhaust with snorkel................110 / 40 / no shims / 1.5 turns
Open exhaust + no snorkel................115 / 40 / no shims / 2.0 turns
Above + Restrictor gone....................120 / 40 / 1 shim / 1.0 turns
Above + enlarged filter inlet...............130 / 40 / no shims / 1.75 turns
Above + no airbox + no filters............145 / 40 / 1 shim / 2.0 turns
((assume) above with pod filters........140 / 40 / 1 shim / 2.0 turns)

The bold line is the most like your set up, and suggests you may still be a bit rich in the mid to higher ranges. Of course, bikes a vary a little bit, but having read many jetting posts by folks, this seems pretty typical for your set up, so I'd say you're in a pretty good position right now. You already correctly diagnosed the problem yourself when you reduced the jet sizes - so nice one, well done! If you pull the snorkel out (the rubber mouthpiece on the airbox that let's air in there) your bike will probably run even better yet.
 
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