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Pilot Jet/idle Mixture Screw Settings


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I think I went a bit overboard on my settings as the bike smells slightly rich at idle. What is suppose to be the factory setting on the carbs? I've got mine at 2.25 turns out from bottom with a slip on. I think I'm .5-.75 a turn too far out and of course it's all back together.

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post-8974-0-07575600-1394304222.jpg

It says "slagen" which in my book is a half turn.....

But I suspect they mean turns here

!#$%^ Dutch manual

But VFRBert will know and I trust he will jump in :-)

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Doing one carb at a time, slowly unscrew mixture screw and take note if rising idle. After some more going out, the idle will start to fall. Now screw back in to the sweet spot. Do all 4. Now re-adjust idle speed. There is no magic number of turns. Each carb on each bike wants it in different settings. Never mind if one is 2.5 turns out and one is 3.75. It doesn't matter.

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Doing one carb at a time, slowly unscrew mixture screw and take note if rising idle. After some more going out, the idle will start to fall. Now screw back in to the sweet spot. Do all 4. Now re-adjust idle speed. There is no magic number of turns. Each carb on each bike wants it in different settings. Never mind if one is 2.5 turns out and one is 3.75. It doesn't matter.

Also interesting..

Been reading up about carbs and adjustment of recent as i will have to do this soon...but info is often vague at best...

So the mixture screw is easily accessible when on the VFR?

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Timmy, good advice, but the issue with the 4th gens is it is difficult at best to access the 'screws' and I have 'notched' them, but they still don't really want to turn. I'll give it a go but I'm not looking forward to burning the shite out of my hands, lol

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" I'll give it a go but I'm not looking forward to burning the shite out of my hands, lol"

I use an old GI nomex flight glove to get in the V to do both the mixture screws and the sync. Still not comfortable but much better than 'bare knuckles'.

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also: dont over tighten them or the needle portion will snap off and remain in the orifice for the rest of your life. This should need to be done more than once every coupla years so it is worth the effort. If you want to get fancy, folks sell a thumbscrew version

mvbrUpjYDVD7idqkd7DNU5A.jpg

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Yeah, me too, those looks great! The stupid 'D' head mixture screws are a PAIN to work with. Are these long enough to extend past the shroud around the mixture screws on the 4th gen carbs? I'd love to try 'em out.

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  • 9 months later...

Doing one carb at a time, slowly unscrew mixture screw and take note if rising idle. After some more going out, the idle will start to fall. Now screw back in to the sweet spot. Do all 4. Now re-adjust idle speed. There is no magic number of turns. Each carb on each bike wants it in different settings. Never mind if one is 2.5 turns out and one is 3.75. It doesn't matter.

Hi - I finally got my home made manometer hooked up and spent a good hour getting them all as close as possible. I was still burning a bit rich (must have confused q-jet with these lol) and turned mixture screws out a bit too rich. went back to about 2 turns out per carb.. however id still like to get them syncd better - I tried this method but even closing screw fully hardly made any difference - i just tried one carb tho just cant seem to get it to idle up or down -

any ideas/tips?

is it better to run two rear cyls a 1/8th turn richer since they dont cool as well?

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Being water cooled, I'm not sure it's all that important, but 1/8 richer won't hurt things. It sounds like your pilot jet might be off, and that is why your mixture screw its having its intended effect. Mixture screw is for fine tuning.

Regarding the balancing - when did you check your valves last? Remember that your balance relies heavily on your valves being within range.

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set the valves last month when i replaced faulty gear fork.. I cleaned jets and carbs out as well cos i had backfiring and found 3 of 4 pilot jets blocked by gunk. Bike seems to run well, but want to get it dialled in real nice.

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How do you turn those 'D' screws? Is there a special tool? How would you remove them to put thumb screws in?

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How do you turn those 'D' screws? Is there a special tool? How would you remove them to put thumb screws in?

would you like to take a guess ?? :comp13:

take the carbs off ..borrow the D shaped tool...

cut a slot on the D head .use a screwdriver to reinstall :fing02:

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Where do you borrow 'D' shaped tool from? Is it something you can get from a tool source [snapon, Tooltopia]. What a PITA is this an EPA thing.

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Where do you borrow 'D' shaped tool from? Is it something you can get from a tool source [snapon, Tooltopia]. What a PITA is this an EPA thing.

maybe here on vfrd, or your local cycle shop. take your carb with you and ask a mechanic.. NOT the desk or a manager. tip him 2 or 3 for a beer :beer:

looks like this.. or or close to it..

tool_zps3d8811b4.jpg

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