Re jetting

[scott02464]

Right I'm more or less fully 'read up' with regards to re-jetting the carbs now but a couple of final questions before I start the process (so to speak)

I will be putting on a K&N filter, I have aftermarket pipes on but my question is....

When i put the filter on (and I know every set up will be different) but what size jets should I start with to try first?

Is there a particular kit to use?

And finally, should I leave the needle as it is and just experiment with the main and pilot jets?

Regards Scott

[alternative_vtr]

I have read that increasing just the pilot jets to a number 48 is a big help.

[seb421]

I've got the pipercross in mine with yoshimura R&D exhaust, my pilots are 48's, mains are dynojet 190's, needle are on the 4th clip, and mixture screws are now at 2and a half turns, very nearly feels spot on, going to try back it off quarter of a turn tomorrow see how that goes, at present it is very rideable just a little off bellow 4k, above 4k and it pull like a rocket ship to the red line

Sent from the Bat Cave via Cup and String

[scott02464]

I've got the pipercross in mine with yoshimura R&D exhaust, my pilots are 48's, mains are dynojet 190's, needle are on the 4th clip, and mixture screws are now at 2and a half turns, very nearly feels spot on, going to try back it off quarter of a turn tomorrow see how that goes, at present it is very rideable just a little off bellow 4k, above 4k and it pull like a rocket ship to the red line

Sent from the Bat Cave via Cup and String

Thanks mate, ill start with that then go from there to see what difference it makes to mine.

What do you mean when you say the needle is on the 4th clip Seb?

Can't wait to see what difference the filter and jets make!

[VTRDark]

If you go down the Dyno jet kit route then start with their recommended starting point. 180 mains, needle 4 clip from top. Unless you have full race exhaust including race headers then use the 190's

Alternative-vtr is quite right but with the K&N it's a bit hit and miss, so I would up the mains and needle as well. If you had standard filter and just the aftermarket pipes then just changing the pilot would be good and shim original needles.

You may find your bike already has 48 pilots inside You won't know until you open them up. And the Dyno kit does not supply pilots. With 48's I would try setting the mixture at 2.5 turns out and go from there.

Me personally would either buy Keihin jets or get the factory pro Ti kit. Titanium needles is the real advantage with the FP kit. And by using Keihin or FP (which uses the same size jets) IMO makes it slightly easier to setup/tune in.

at present it is very rideable just a little off bellow 4k, above 4k and it pull like a rocket ship to the red line

That's nice to hear mate. Sounds like you are winning.

(:-})

[VTRDark]

What do you mean when you say the needle is on the 4th clip Seb?

Aftermarket needles have slotted grooves that allow the e-clip (like a little circlip type thing) to be moved up or down a position. The lower the needle is it leans it out and the Higher it is richen's it. The needle is tapered and goes inside a hole in the side of the main chamber, so as the slide opens and closes under the vacuum from the diaphragm that taper opens or closes the gap in the hole. So to richen move the clip towards the pointed end and to lean it out move the clip towards the blunt end.

(:-})

[scott02464]

Agh just when I thought I was getting my head round it lol

I was referring to the Dynojet kit as a generic term.... Now I know it's a certain brand (stupid me) :-(

So if I stick with 48 pilots

Buy Keihin 180 main jets (off eBay)

Which needles do you recommend it buy?

Sorry for being slow, think it'll be easier understood once Iv stripped the carbs down :-)

[VTRDark]

Don't forget the keihin jet sizing is different from Dynojet don't compare them both. This is why the Factory pro jet is easier to set up because they use the same scales as Keihin.

If your going to buy Keihin jets make sure they are the right ones for the carbs, IIRC 6mm thread keihin jets. I will try and find a link later for you.

I would try Keihn 178 or 180 in the front and either a 180 or 182 in the rear. If you have standard carb set up at the moment then you will have 178 in the rear already so could use that for the front. And the standard front is 175. The rear cylinder uses a slightly larger main to help keep it cool.

Three's no guarantees though. You may even have to go slightly larger on the mains.

(:-})

[scott02464]

Brilliant thanks for all the info, it's given me plenty to go at and feels a lot more understandable now!

I'll start by taking out the carbs cleaning them out and writing down what sizes I have inside (all standard but just for my own info) and get to know these little fellows!

As long as I count how many turns out (from fully in) the mixture screw is, am I fine to take this out to clean inside?

[VTRDark]

That's a good start mate. Get to know them. Count the turns in on the mixture, but don't overtighten or you damage them. Then if you take them out completely for cleaning you can then tighten them back up and count the same amount of turns back out. Watch out for the little spring, washer and rubber O ring on the end of the mixture screws.

(:-})

[seb421]

Re jet sizes this might help you out, warby posted this ages ago so credit due to him.

Width------Keihin # -- DynoJets # -- Mikuni #

0,0540---- 140--------- 130--------- 121,9
0,0550---- 142,5------- 132--------- 123,8
0,0560---- 145--------- 134--------- 125,6
0,0570---- 147,5------- 136--------- 127,5
0,0580---- 150--------- 138--------- 129,4
0,0590---- 152,5------- 140--------- 131,3
0,0600---- 155--------- 142--------- 133,1
0,0610---- 157,5------- 144--------- 135,0
0,0620---- 160--------- 146--------- 136,9
0,0630---- 162,5------- 148--------- 138,8
0,0640---- 165--------- 150--------- 140,6
0,0650---- 167,5------- 152--------- 142,5
0,0660---- 170--------- 154--------- 144,4
0,0670---- 172,5------- 156--------- 146,3
0,0680---- 175--------- 158--------- 148,1
0,0690---- 177,5------- 160--------- 150,0
0,0700---- 180--------- 162--------- 151,9
0,0710---- 182,5------- 164--------- 153,8
0,0720---- 185--------- 166--------- 155,6
0,0730---- 187,5------- 168--------- 157,5
0,0740---- 190--------- 170--------- 159,4
0,0750---- 192,5------- 172--------- 161,3
0,0760---- 195--------- 174--------- 163,1
0,0770---- 197,5------- 176--------- 165,0
0,0780---- 200--------- 178--------- 166,9
0,0790---- 202,5------- 180--------- 168,8
0,0800---- 205--------- 182--------- 170,6
0,0810---- 207,5------- 184--------- 172,5
0,0820---- 210--------- 186--------- 174,4
0,0830---- 212,5------- 188--------- 176,3
0,0840---- 215--------- 190--------- 178,1
0,0850---- 217,5------- 192--------- 180,0
0,0860---- 220--------- 194--------- 181,9

[VTRDark]

There is a few debatable arguments over how accurate that is. There's a few websites that have that, then others with slightly different conversions. It can confuse thing's so be careful.

Here's the site where that is from http://www.4strokes.com/tech/carbjetxover.asp

(:-})

[seb421]

There is a few debatable arguments over how accurate that is. There's a few websites that have that, then others with slightly different conversions. It can confuse thing's so be careful.

(:-})

It's a bit silly how they have different size's tho init for jet's

[scott02464]

Great! I'm off now for four days after tonight so I'm hoping to have a play :-) :-)

[seb421]

Great! I'm off now for four days after tonight so I'm hoping to have a play :-) :-)

Your Filter is picked up tomorrow mate will keep you informed with tracking etc, enjoy playing and tinkering, i will take pics tomorrow of how i manage to do quick sharp mixture screw adjustments if i decide to adjust it quarter of a turn