How to raise the needle?

[zed1015]

I've been chasing down a stutter at 1/8th throttle for a while now and it seems to be right at the transition between the pilot and the needle transition.

What size is the stock main jet ?
Is it 115 ?

[danny01975]

What size is the stock main jet ?
Is it 115 ?

The stock size should be 115. This bike has 120 for the mains.

[zed1015]

The stock size should be 115. This bike has 120 for the mains.

Your issue is likely a lean spot on the transition from the pilot jet to the jet needle.

Normally this off idle hesitation is a result of removing the airbox and running open stacks / pods or modifying the airbox to significantly increase airflow .
The cure for this on your machine would be to fit air correctors for the hesitation and 145 mains for the increase air flow at midrange and top end .

All other jets and settings remain STOCK..

Removing the snorkel may have introduced enough extra airflow to initiate the hesitation but not enough to warrant the 145 main.

Personally i would fit air correctors and go with a 120/125 main if a top end plug chop doesn't show a lean mix.

Fitting bigger pilots and lifting needles blanket bombs the entire fueling slope which only serves to mask the hesitation whilst killing power and increasing fuel consumption.

[danny01975]

Your issue is likely a lean spot on the transition from the pilot jet to the jet needle.

This is what I have suspected all along. Which is why I was attempting to raise the needle.

Personally i would fit air correctors and go with a 120/125 main if a top end plug chop doesn't show a lean mix.

What is this "air corrector" you speak of? Are you suggesting bigger air jets and then a larger main to compensate? It's already got 120 mains.

Also, I have a replacement snorkel on order. Had to buy an entire airbox assy and have it shipped here from GB just to get the snorkel. We'll see if that changes anything at all.

[Nessism]

This is what I have suspected all along. Which is why I was attempting to raise the needle.



What is this "air corrector" you speak of? Are you suggesting bigger air jets and then a larger main to compensate? It's already got 120 mains.

Also, I have a replacement snorkel on order. Had to buy an entire airbox assy and have it shipped here from GB just to get the snorkel. We'll see if that changes anything at all.

zed has a link to the air correction jets in his signature. Turn on view signatures in your profile if you can't see the link

[zed1015]

What is this "air corrector" you speak of? Are you suggesting bigger air jets and then a larger main to compensate? It's already got 120 mains.

I make the air correctors specific for several Suzuki (and Kawasaki) models with both Mikuni VM or Mikuni CV carbs and can also provide recommended main jet sizes as a starting point.
They go in the main air jet passage to the needle jet tube which is located at the 4 'o'clock position in the mouth of all Mikuni CV carbs.
They require the passage to be tapped m5 x 0.8mm to 6mm deep and simply screw in and can be removed for reverting back to stock.
They richen the transitional mix via the needle jet tube and their effect feathers off as the revs rise so do not significantly alter the rest of the fueling curve.
This is the same method Mikuni uses on their smoothbore carbs for the same purpose.

Contact me at zed.1015@yahoo.co.uk if you require a set if the snorkel doesn't cure it.

They are £37 delivered worldwide sent 1st class tracked and signed.