Carb setting question

[wraith]

Yes I know, everyone asks carb setting questions 

Just wanted to run this by you lot.

B12 engine, ported DOT head, gsxr cams, gsxr750 38mm carbs, K&N filters and open exhaust.

So I've put 40 pilot jets in and new aluminium washers under needles (as standard plastic ones where well worn)

Bike runs very well above 4.5-5 rpm

Runs well in hindsight gear at 2000 rpm

But if I open the throttle or try and ride around the 2.5-4.500 rpm it stutters and bumbles in any gear. 

Definitely running rich.

Can't decide to alter pilot jets screws or drop needles by one first?

So what would you all say? Pilots or needles?

[DAZ]

Are the emulsion tubes round still or Have they ovaled  out to cause the rich running ? I don't know if it's as much of an issue with the 38s as the 36s, also do the needles show any wear from the wobbly plastic washers ?  

 

Edited April 13 by DAZ

[wraith]

7 minutes ago, DAZ said:

Are the emulsion tubes round still or Have they ovaled  out to cause the rich running ? I don't know if it's as much of an issue with the 38s as the 36s, also do the needles show any wear from the wobbly plastic washers ?  

 

The emulsion tubes are still round and the needles look in good condition (for the year ) 

I'm thinking dropping the needles one groove first. 

[wraith]

After having a think, and chatting to the bike  decided to alter the pilot jets screws first, as that's the only real thing that has changed, apart from the aluminium spacer/washers under the needles, but that got them sitting straight.

So turned the screws in half a turn and yes what a difference, still needs maybe a 1/8 to a 1/4 turn but it runs smoothly all the way through just had a bit of a bumble at 3.000 rpm, but like it was before where it was embarrassing riding at that revs 

So just letting the engine cool before I start putting my hands between the carbs and engine 

[Jaydee]

2 hours ago, wraith said:

it runs smoothly all the way through just had a bit of a bumble at 3.000 rpm

If you're getting positive results from leaning out the mixture screws, it might be no harm experimenting with dropping down a size on the slow jet to 137.5's (which is a bandit 12 standard slow jet so you probably already have some).

[wraith]

1 hour ago, Jaydee said:

If you're getting positive results from leaning out the mixture screws, it might be no harm experimenting with dropping down a size on the slow jet to 137.5's (which is a bandit 12 standard slow jet so you probably already have some).

They had the 37.5 in original, had the pilot screws set at 3.5 turn out but it didn't like any less  so when I had the carbs off to give them there yearly clean and replace the needle washers, I put the 40 in, had the pilot screws set at 2.5 and now at 2 seems to be working 

We all know what carbs are like