Spluttery under 5000rpm after overhaul - Pilot Screw?

[mattvfr400]

Annnnnd I'm back again posting on here again! Recently overhauled the carbs + replaced a whole lot of bits. And in the overhaul I reset the pilot (air/fuel) mixture screw to 2.25 turns out from fully in. Although originally more like 3 full turns out from fully in. I understand the pilot screw is in charge of idle/initial pickup, needles midrange and jets full throttle and 2/3 of those things are bang on perfect. Carbs are perfectally balanced and everything is clean and new. So it has to be the pilot screw setting?

I don't have an accurate RPM gauge to do it the proper way but anybody had any experience with this? Should I start by going in or out with the screw? Also any chance of turning the screws with the carbs on the bike? I just got them sat and sealed so well!

[Neosophist]

you have to tune pilot screws with the engine running.

2 turns out will be fine anyway... it will only slightly richen or len your idle.

if you want to do it bang on you need a rev counter capable of working in 50 rpm increments, start from stock steting and turn out 1/4 turn at a time and notice rev change / increwse.. after you get to the point it doesnt rev any higher you need to turn back 1/4 of a turn.

2 or 2.25 for slightly richer than stock will be ok for most cases

[mattvfr400]

you have to tune pilot screws with the engine running.

2 turns out will be fine anyway... it will only slightly richen or len your idle.

if you want to do it bang on you need a rev counter capable of working in 50 rpm increments, start from stock steting and turn out 1/4 turn at a time and notice rev change / increwse.. after you get to the point it doesnt rev any higher you need to turn back 1/4 of a turn.

2 or 2.25 for slightly richer than stock will be ok for most cases

I stuck the pilots at 2.25 and it was boggy under 5 grand, if I stick them to 2 turns out will that change much? Running out of ideas as to what it could be!

[Neosophist]

what are you float heights set to?

try ti at 2 turns and see, cant hurt

[mattvfr400]

what are you float heights set to?

try ti at 2 turns and see, cant hurt

Floats are set to factory which is 6.8mm I believe? I set them to 2 turns out and the bike has gone a bit farty sounding haha

[mattvfr400]

So after setting them to 2.0 turns out in neutral its really farty, doesn't pick up well and all round a bit soggy feeling. Felt better before when it wasn't boggy in neutral but only as I went to pull away in 1st. Don't know whether to turn all the screws out another 0.25 of a turn or in 0.25 of a turn. It idles beautifully when cold and as it warms up the idle gets rougher and rougher.

???

[mattvfr400]

bump!

[Neosophist]

no need to double post anything.

you have changed a lot of stuff with your carbs. you haven't mentioned how it ran before you messed with it?

how did you check / set your float heights? are these nc30 carbs? nc35 carbs have different float heights.

pilot screws shoudlnt make much of a difference unless you have them really off..

how are you counting the turns? you sure your not doing half a turn stead of a full turn? put a dot on the handle of a screwdrvier to help you count each turn, when the dot comes back to the start its 1 turn.

[mattvfr400]

no need to double post anything.

you have changed a lot of stuff with your carbs. you haven't mentioned how it ran before you messed with it?

how did you check / set your float heights? are these nc30 carbs? nc35 carbs have different float heights.

pilot screws shoudlnt make much of a difference unless you have them really off..

how are you counting the turns? you sure your not doing half a turn stead of a full turn? put a dot on the handle of a screwdrvier to help you count each turn, when the dot comes back to the start its 1 turn.

I see you deleted my post, dont mean to be a pain but did that other bloke reply to my comment? I was in a conversation with him and he was very helpful. The bike is running spot on now cheers, it was the pilot screws btw. I set them to 2 full turns out (proper turns!) and ran like crap...preferred 2.75 turns out and ran perfectly. Cheers anyway!

[Neosophist]

the difference between 2 and 2.75 turns shoudlnt make a great deal of difference unless you have other problems.

perhaps one of your small air passage from the slow jet or even the slow jet is partially blocked up creating a lean condition and over-richening the pilot screws are compensating for this.

Or the float heights could be slightly off creating this kidn of condition, i've seen it before where over-compensating one thing sorts everything out.

The service manual recomends 2 turns out on the later carbs and 1-1/4 turns on the 89 model.

anymore than half a turn richer / leaner is compenating for too much / too little fuel elsewhere.

if its running satisfactorily now then i'd probably just leave it be