Which size jets - Need help tuning carb

[tubarney]

I'm removing the airbox and going with pods. I'm using Keihin jets. Which size main jet should I use? I have a full exhaust and stock carbs. I just need to get it run so I can ride it to the dyno.

[Racer x]

40 pilot
110 main but that is a start point. Take some shims and larger and smaller jets

[cuz]

^^^This very good starting point.

Im #@ sea level w/pod & slip on (leo vince)

110 main jet
40 pilot
2 shims under both needles

[tubarney]

Thanks. Thats exactly what I got so I should be good to go. Was getting confused cos i couldn't find Factory Pro size conversion.

Picking up my head tomo. will post some photo's

[cuz]

http://www.ninjette.org/forums/showthread.php?t=10208

[tubarney]

Thats what I was looking at. One thing, are Factory Pro jets the same size as Dynojet or Keihin.

[choneofakind]

Keihin.

[tubarney]

^^Thanks for clearing that up. I thought they might be considering no one said anything about it.

With the factory Pro kit. How far does the needle jet move up when you put it on clip position 3?

Or how thick are your 3mm washers? Mine are only 0.68mm/0.027inch thick. I think i'm going to need more than 2.

[choneofakind]

If you have a factory pro kit, these instructions will help you out.
http://www.factorypro.com/tech_tunin...m_engines.html

The washers I used were roughly half a mm.

For starting, put the needle on the middle position. Worry about getting that right after you've gotten the main jet size figured out.

[tubarney]

thanks for the link and your help. Really appreciate it. I don't have the factory pro kit but everyone else seems to.

Just trying to get it as close as possible so save my tuner the effort cos his time aint cheap. It would help if my head was ready, not till next week.

[cuz]

http://www.jetsrus.com/a_jet_kit_str...50R_Ninja.html

[choneofakind]

If you want to help your tuner out, do the basics with the jetting; test different size mains until you get one that feels right. Then adjust needles until it feels right.

If the butt dyno says it feels smooth, it will be a good starting point for the dyno guy.


What did you have done to your head?

[tubarney]

I think I will have a go tuning it for a week before I take it in there.

My head is getting ported on a 5 axis CNC machine by guys with a flow bench. The guys doing it service the entire race industry of my state so I'm not surprised it aint ready.

Whats burning me the most is that I can't get Keihin or even Yoshi carbs until early April because both are on back order.

[choneofakind]

Ah. Flowbench. Nice!

I don't have any reference point for jetting a bike with head work, so the only advice I can give you is on method of testing jetting.

[tubarney]

Jetting settings are the same for a ported head. A free flowing head does not change the ratio of air or fuel entering the combustion chamber. Just more gets in.

The only thing you need is a set of good carbs. This is when you will get a decent gain from carbs. The mixture of air/fuel will be slower through the larger ports (even if you don't want them bigger, they have to be smoothed out so they will always be bigger), so you need something to speed that mixture up before it gets into your head.

[agentbad]

Where is a good place to get the #4 shims/washers? Lowes?

[subxero]

Originally Posted by agentbad

Where is a good place to get the #4 shims/washers? Lowes?

you can find some at lowes. I got mine at lowes. I also found some at a Hobby shop later that were a little smaller that i liked better.