Which carburetor needle to choose, I need your advice.

[Batlet]

This is my first post, before writing it I searched the forum and maybe I didn't look properly, but I didn't find the solution.
I'll explain my problem. When I bought the Vmax, I took it apart piece by piece, cleaned it, painted the frame, engine and rims , changed all the engine gaskets, adjusted the valve seats and then adjusted the valves. The engine was perfect. The carburettors were cleaned and the gaskets were changed. The engine runs perfectly, sounds perfect, but it doesn't run well in the mid-rpm range.
I know the problem is with the carburettor needles, the bike runs dry in the mid-rpm range. I changed the position of the needles from P3 to P5 and it improved a little, but it still fails in the mid-rpm range. Right now I'm wearing the 5DZ19 needles, I also have the 5EZ50 and 5EZ43 needles but the last two are not adjustable in height, they only have one clip position. I have also tried them and the problem continues.
I have seen different needles on the forum, and by the shape they have, I think that the ones I should install are the Dinojet Stage 7. Do you think that will solve the problem?
Remember that my bike is European, it has a 2EN engine with the Vboost system installed. At low speeds it runs perfectly and at high speeds it runs like hell, it seems like it will tear your arms off. The high and low jets are the European standard.

Thank you in advance.

 

[Fire-medic]

On an internally-stock engine, I've had good luck with the Dynojet Stage 7 needles, and 147.5 mains. Miami is at sea-level (for now).

 

[Batlet]

Thank you very much for your advice.
I would like to ask you a few questions.
I live in Mallorca, a small island in the middle of the Mediterranean Sea, with quite pleasant temperatures, I think the climate is very similar to Miami. In what position do you have the Stage 7 needle?
Right now I have a 150 main jet, and the bike runs perfectly at high rpm, do you think I should order the 147.5 or should I first try with just the needle and then change the main jet?
Do you know the references for the Stage 7 needles? I suppose that with these references it will be easier to find them.

Thank you very much again

 

[MaxMidnight]

Attached are the instruction for fitting the DJ S7 which has the part numbers of the components.

Is there somewhere you could get it on a dyno so you had factual data to work on? (Aw c'mon, you would have been disappointed if I hadn't asked! )

 

[Batlet]

I found this:
https://www.dynojet.com/jet-kit-for-1985-2007-yamaha-v-max-4716-1/

But its incredible price for 4 needle and 8 main jet, its crazy

 

[apsolus]

I found this:
https://www.dynojet.com/jet-kit-for-1985-2007-yamaha-v-max-4716-1/

But its incredible price for 4 needle and 8 main jet, its crazy

im going to try shimming the needles out with small washers. make sure they fit in the caps the needle sits in propelry. that kit sure is pricey!

 

[Batlet]

There isn't a good Samaritan around here with 4 needles to sell, right?

 

[Tom Determan]

im going to try shimming the needles out with small washers. make sure they fit in the caps the needle sits in propelry. that kit sure is pricey!

I can't recall where we bought them but there are kits available with different thickness shims that go under the clip so you can get exactly where you want to be by varying the shim. (Assuming your needle has the correct taper for your engine and tune set up.) We did it on our sleds with data collection systems that collected throttle position, RPM, EGT, all the inputs one needs to nail the A/F ratio where you want. Try all the parts houses for "Mikuni shim kits". Then think about where your throttle will be most of the time. Without a dyno and measuring A/F or EGT, I don't know how you can get really dialed in across the full range of operating conditions.

 

[Traumahawk]

You need to find out if the midrange is lean....or rich. Until you know that, everything else is a guess. It might be an educated guess.....but still a guess.

So, think of the airbox, carbs, and exhaust as something that works together. Are you running the stock airbox? With or without the "Y"? What are you running for exhaust? Stock set up, or slip ons? Aftermarket exhaust?

Even a little bit of a change, will go a long way.

Years ago when I was getting the 07 dialed in, this is what I used.

https://www.innovatemotorsports.com/lm-2-basic-kit.html

 

[Batlet]

Hi Traumahawk,
It's not a supposition, it's a certainty. The bike runs worse in winter, or in the mornings if it's cold. When the air temperature is higher, it fails a little less. This is a sign that it runs dry in the mid-range. The air box is now the original one, before it had high-flow filters and the problem was accentuated.
The exhausts are Supertrapp, and I don't remember if anything changes with the originals, because I haven't used them for a long time.
What I'm not sure about is what needles I need. I know I need them with a thinner cone, but I'm not sure if the stage 7 will be too thin for me. I'm not sure if I should try something in between before trying the stage 7.
That's why I'd like to know if someone with the European engine and the Vboost system installed can tell me what carburettor settings it has, and if the bike runs well in the mid-range of rpm.

I know it's a complicated question, because most of you are from America and have the American or Canadian model, I think there are few users with the European engine in the chat. Am I wrong?

Greetings

 

[Traumahawk]

Hi Traumahawk,
It's not a supposition, it's a certainty. The bike runs worse in winter, or in the mornings if it's cold. When the air temperature is higher, it fails a little less. This is a sign that it runs dry in the mid-range. The air box is now the original one, before it had high-flow filters and the problem was accentuated.
The exhausts are Supertrapp, and I don't remember if anything changes with the originals, because I haven't used them for a long time.
What I'm not sure about is what needles I need. I know I need them with a thinner cone, but I'm not sure if the stage 7 will be too thin for me. I'm not sure if I should try something in between before trying the stage 7.
That's why I'd like to know if someone with the European engine and the Vboost system installed can tell me what carburettor settings it has, and if the bike runs well in the mid-range of rpm.

I know it's a complicated question, because most of you are from America and have the American or Canadian model, I think there are few users with the European engine in the chat. Am I wrong?

Greetings

CV carbs run richer as they get warmer.

The reason why I asked about the exhaust, is an aftermarket exhaust, you actually flow more air OUT, so you PULL more air in (making the carbs richer.....so with an aftermarket exhaust you go LEANER. Slip-ons, not so much....they are basically stock.

Some people will pull the Y off, and shave the inner lip of the K&N filter off, and will allow too much air into the carbs. The Y is on there to regulate the amount of incoming air.

You could do the stage 1 needles (they are smaller than stock, would allow more fuel, and are cheaper to get, most people dont like them) I was still about to get fairly decent HP with them.

I wonder if swapping to stage 1/stage 7 springs would help? The allow the needle to pull out of the emulsion tube quicker, which should allow the needles to kick in sooner.

Please see the attachments. One for jetting of European and US bikes. One for different needle shapes, and 1 for the different carb circuits.

You could go with a slightly fatter PAJ#2, which would make you slightly richer off idle to redline. (less air makes the A/F ratio richer)