CARB JETS

[paul G]

Hi all,
            Took the 400/4 in for its MOT at the weekend as I can change the tax to historic from the 1st April.
It sailed through the MOT but I have an issue with the jetting now.
I fitted a Silvers aftermarket silencer and it now runs crap, won't pull and won't rev through the range (you have been warned if you are looking at one).
Checked the plugs and as I thought it is running weak. Looking to get some oversize jets if anyone can recommend somewhere or has anyone tried these .
http://www.motorradbay.de/jet-c-97-2.html
Just in case anyone is wondering, I have packed the mint original exhaust system away under the bed 

[philward]

Have a look at this company - don't know about 400 carbs but they seem to have a huge range of jets - http://www.allensperformance.co.uk/carb-kit/keihin-jet-identification-chart/

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[paul G]

Have a look at this company - don't know about 400 carbs but they seem to have a huge range of jets - http://www.allensperformance.co.uk/carb-kit/keihin-jet-identification-chart/

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Cheers Phil.

[Bryanj]

Same type of jets as 500/550 as I remember(push in held with a clip) Siriusonic in Canada do all of them and even a box of several sizes

[Trigger]

Seems like the exhaust has no back pressure, I would try a bit of wadding.

[mike the bike]

Make sure you've got fresh juice in it.  Modern juice goes off after a couple of months and the engine won't pull the skin off a rice pudding.

[paul G]

Make sure you've got fresh juice in it.  Modern juice goes off after a couple of months and the engine won't pull the skin off a rice pudding.

Fresh that morning Mike.
It's just down to the crap silencer, I bought it last summer or I would be back on the phone to them.

[andut]

You could always try raising the needle a notch or 2, and you can get fine metric drills if you have spare jets available to increase in 0.05 increments.

[paul G]

Stripped the carbs down and went up a size on the jets.
80 main and 45 on the slow jets.
Double checked the float levels and new rubbers all round.
Took it out for a quick spin and it bogs down on initial acceleration but then pulls like a train.
Didn't go far enough to check the plug colour or do a chop.
What do you think rich or weak.

[andut]

Paul, if it's initial accel, try adjusting idle mixture screws maybe 1/2 turn at a time and see if it makes a difference - should give you an indication of rich / lean and a damn sight easier that pulling the carbs on and off which gets pretty tedious if you're chasing carb settings !

Andy