Jet kit recommendation....

[ScottW]

....or leave stock?

I have a 98 Tourer and I've always had some issues with idle and 1500 to 2000 rpm where it blurbs/bubbles/pops/farts and I can feel it popping back into the air box or something through the frame/hiway pegs.  I've finally decided to take some further action (other than the usual vac line replacement and sync) and am in the process of desmogging it and possibly doing a jet kit.  I know a local mechanic that could ultra sonic the jets for me, but would it be better to just do a kit?  Factory Pro or DynoJet?  HDL said that the Factory Pro one isn't available any more and that the DynoJet 1166 was the other option.  I know that the Factory Pro kits had the #38 slows, but didn't see what the mains were for the 1.0 kit.  I couldn't find out what jets are included in the DynoJet ones.

Anyway, I guess I'm looking for some recommendations.  The only change I've made in this area is a set of truck stacks so other than that, it's stock.

It's pretty tough to find any gas other than 10% Ethanol around here and that makes it run even worse!

Scott

[Foozle]

Scott, I'm facing roughly the same issue - and I think doing a complete desmog first and then reassessing the bike's performance is the most prudent course of action.  Especially since your bike is bone stock, making jetting modifications should (IMHO) be viewed as a later option (unless you just like tuning and experimenting).  Moreover, I've found that making multiple changes simultaneously is a surefire way to draw some erroneous cause-and-effect conclusions.  Just my 0.02.  Terry

[ScottW]

Yeah, I'm not so sure that I want to spend the money for a jet kit at the moment.  I have the carb unit out and will clean them up good.  I see that I have the standard 35/100 jets.  Just thought that maybe the 38's would help the idle/mid.  Can't tell if the DynoJet kit has jets and what size.

I fashioned myself a D-tool from an air tool chuck and saw that all my pilots were at just barely 1.75 turns.  That may explain part of it there.  I bought the bike with 7300 miles on it and the guy did say he had somewhat the same problem and I think it has just gotten worse since I have put another 30,000 on it.

I have a CNC router for wood that I can cut some aluminum plates for the desmog so were good to go there. Maybe all she needs is a good cleaning and readjustment.

Should I get the o-rings for the pilot screws and is there anything else that I may need to order for a good carb cleaning/readjust?

Scott

[Foozle]

Scott:  In addition to new pilot screw o-rings, I might also replace the petcock vent line (which I believe is the only vaccum line left after the desmog) and the intake runner o-rings.  Since you have the carbs off the bike, you could even go the whole nine yards and replace the carb bowl gaskets.  In addition to fashioning your own, you can get desmog parts from either of the following:

http://redeye.ecrater.com/

http://www.xf6-custom.com/partpages/desmog.html

Others who've re-jetted their bikes can weigh in on this topic.

Terry

[John U.]

Scott, you don't need a kit if all you want to do is change to 38's. I did that a few years ago because I couldn't get the OEMs clean. I needed to set the pilot screws to 1 3/4 turns out from lightly seated, and resync.
Anyway Sudco has them, but I believe Chapparal is cheaper. I used to have links but a computer crash took care of that.

[ScottW]

Thanks Terry,

Already have all those in my cart at RedEye.   

I'd like to find some kind of decorative plug for the desmog (upper holes).  Plan on tapping and using a 1/8-27 plug.

John,

Did the 38's help any with idle/mid?  Any change in mileage?  I'd hate to have to take them out again if I wasn't able to get them cleaned out (if they are crudded up).

Scott

[98valk]

....or leave stock?

I have a 98 Tourer and I've always had some issues with idle and 1500 to 2000 rpm where it blurbs/bubbles/pops/farts and I can feel it popping back into the air box or something through the frame/hiway pegs.  I've finally decided to take some further action (other than the usual vac line replacement and sync) and am in the process of desmogging it and possibly doing a jet kit.  I know a local mechanic that could ultra sonic the jets for me, but would it be better to just do a kit?  Factory Pro or DynoJet?  HDL said that the Factory Pro one isn't available any more and that the DynoJet 1166 was the other option.  I know that the Factory Pro kits had the #38 slows, but didn't see what the mains were for the 1.0 kit.  I couldn't find out what jets are included in the DynoJet ones.

Anyway, I guess I'm looking for some recommendations.  The only change I've made in this area is a set of truck stacks so other than that, it's stock.

It's pretty tough to find any gas other than 10% Ethanol around here and that makes it run even worse!

Scott

first try opening up the mixture screws 1/2 turn at a time. u can go up to about 4 turns out from lightly seated.  Factorypro.com has a write up on this in the tech section. once u have the mixture screw dialed in u can try an extra washer on the needles. usually the front two carbs what to be leaner than the other carbs on the needles.
for a stock bike this is most likely all u will need to do.  airbox mods and/or aftermarket exhaust would need a jet kit.

[z1eyedjack]

airbox mods and/or aftermarket exhaust would need a jet kit.

I'm at this exact place right now.  With a '97 Standard, I have the carb bank off and I'm thinking about replacing the bowl gaskets and doing a jet kit, or at least swapping out the slows for 38's.  I have Cobra 6-6 and have confirmed that the jets are in fact stock 35/100.  Would you recommend going with the factory pro jet kit since I have the Cobra pipes?  I just completed the desmog too.

Thanks!

[98valk]

- and I think doing a complete desmog first and then reassessing the bike's performance is the most prudent course of action.   Terry

does not affect operation of the engine in anyway, unless there are vacuum leaks in the connection hoses.

[98valk]

airbox mods and/or aftermarket exhaust would need a jet kit.

I'm at this exact place right now.  With a '97 Standard, I have the carb bank off and I'm thinking about replacing the bowl gaskets and doing a jet kit, or at least swapping out the slows for 38's.  I have Cobra 6-6 and have confirmed that the jets are in fact stock 35/100.  Would you recommend going with the factory pro jet kit since I have the Cobra pipes?  I just completed the desmog too.

Thanks!

search is your friend

http://www.valkyrieforum.com/bbs/index.php/topic,8248.0.html

scroll down to my post about the tunning FP did for cobras to get back the lost HP.

[98valk]

....or leave stock?

I have a 98 Tourer and I've always had some issues with idle and 1500 to 2000 rpm where it blurbs/bubbles/pops/farts and I can feel it popping back into the air box or something through the frame/hiway pegs.  I've finally decided to take some further action (other than the usual vac line replacement and sync) and am in the process of desmogging it and possibly doing a jet kit.  I know a local mechanic that could ultra sonic the jets for me, but would it be better to just do a kit?  Factory Pro or DynoJet?  HDL said that the Factory Pro one isn't available any more and that the DynoJet 1166 was the other option.  I know that the Factory Pro kits had the #38 slows, but didn't see what the mains were for the 1.0 kit.  I couldn't find out what jets are included in the DynoJet ones.

Anyway, I guess I'm looking for some recommendations.  The only change I've made in this area is a set of truck stacks so other than that, it's stock.

It's pretty tough to find any gas other than 10% Ethanol around here and that makes it run even worse!

Scott

call Marc the owner of factory pro to see if the kit is still available. the needles are the expense, they have the jets, or other companies as posted

[John U.]

John,

Did the 38's help any with idle/mid?  Any change in mileage?  I'd hate to have to take them out again if I wasn't able to get them cleaned out (if they are crudded up).

Some will say that the 38s help with the mid-range flat spot. Remember though that you will be adjusting the pilot screw tighter to avoid an over-rich condition. I believe that once you do that you are adjusted back to where you started, but with a jet that's a bit harder to clog.
I'd be interested in hearing other opinions about this.
John

[98valk]

John,

Did the 38's help any with idle/mid?  Any change in mileage?  I'd hate to have to take them out again if I wasn't able to get them cleaned out (if they are crudded up).

Some will say that the 38s help with the mid-range flat spot. Remember though that you will be adjusting the pilot screw tighter to avoid an over-rich condition. I believe that once you do that you are adjusted back to where you started, but with a jet that's a bit harder to clog.
I'd be interested in hearing other opinions about this.
John

From FactoryPro.com

Pilot Jets

The affect of pj size change on idle and cruise operation


Question:

Greg Johnson wrote:
 
> I have installed one of your 1.0 jet kits on my R6 and I am coming to the final parts of tuning it.

> It runs well and passes most of the tests as provided on your tuning guide. It does, however, appear to be lean low down, as there is a "hole" when cracking the throttle wide open at below 2500rpm and at high rpm/part throttle, it shows some surging. I have though set the fuel screws, so that it idles correctly and returns to the correct rpm, when the idle is set below 1000rpm and the throttle is blipped.

> To fix the lean patch, is it better to go the next step up in pilot jets, rather than adjust the fuel screw?
> Will upsizing the pilot jet, require re-adjustment of the fuel screw and thus negating some of or all of the gains made by the larger pilot jet?

> Thanks,
> Greg J


Answer:

Greg - Good diagnosis on the pilot jet size -

As far as the pilot... Look at it this way...

There are 4 outlet holes for the pilot mixture. ~3-4 at the butterfly and one "downstream" of that (for 75% of the idle mixture).

1 hole is controlled by the mixture screw and with the other 3 or 4, max flow is limited by the size of the pilot jet.

At idle, 1 hole (metered by the fuel screw) and 1 un metered hole are open.

At cruise, when the "butterfly" is just "cracked", all 3-4 unmetered holes + the 1 metered one are uncovered -

So.....

At cruise, you get those 3 unmetered holes + the metered hole... So, at least 75% of the fuel delivered at cruise is limited by the size of the pilot jet.

At idle, you get 100% of the trimmed 1  hole + a butterfly valve-trimmed amount of the other 3-4 metered holes.

Rule of thumb....
If you go 1 size larger or smaller on the size of the pilot jet, you will change the fuel screw ~1.5x richer or leaner to retain the original idle mixture -

Example:
You have a #40 pilot jet installed (with the proper main, needle height and fuel  level already done)  and to get best idle, you are 4.0 turns out (from lightly bottomed out).
(Using another "rule of thumb", if you have the correct pilot jet, the fuel screw will end up at between 1.5x and 3.0x when set for best idle.)
Cruise seems lean....

So, I'd expect that I could richen the cruise with 1 size larger (42) pilot jet (size of pj is 75% of cruise mixture) and the "trim" the fuel screw "in" for best mixture for best idle (size of pilot is 25% of idle mixture).

To go back to ~ the same idle mixture, after going from 40 pj/4.0x to the 42........ try 2.5x

40 pj / 4.0x = our reference idle mixture
42 pj / 2.5x = ~ same idle mixture
38 pj /5.5x = ~ same idle mixture (this is a "stretch - after 4.5x, not much changes)

Marc