Clarification of Stage 3 Pilot Jet Instructions

[niclpnut]

Still having some problems getting the bottom end calibrated correctly.

I'm still lean after installing larger pilot jets (Up to 47.5 from 45). 4 full turns out on the mixture screw, and DJ 160 pilot air jets installed.

The instructions on the kit read:

"NOTE:​

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The pilot air jets (DH160) are optional. Using the pilot air jet will
lean out the bottom end. Use the jet if you are experiencing excessive
loss of mileage or bike starts without choke when cold. Using this jet​

will warrant a richer mixture screw setting."

The 1100 ES comes stock with Mikuni 180 pilot air jets. The dyno pilot jets would equate to 150 based on the conversion charts.

Wouldn't the smaller jet RICHEN the mixture...not lean it out?

I took the bike by a local shop today and they put it on a sniffer. It's definately lean (as my plug chops told me.)


Thanks,

Nic

 

[Steve]

You do not use the equivalency chart for the pilot air jets, only for the main jets. :-k

You are still lean?
On what circuit?
Pilot?
Needle?
Main?

Installing a smaller pilot air jet will richen the PILOT mixture (only), but won't affect the rest of the circuits enough to notice.

What MAIN jets did you install?

.

 

[posplayr]

Still having some problems getting the bottom end calibrated correctly.

I'm still lean after installing larger pilot jets (Up to 47.5 from 45). 4 full turns out on the mixture screw, and DJ 160 pilot air jets installed.

The instructions on the kit read:


"NOTE:

The pilot air jets (DH160) are optional. Using the pilot air jet will​

lean out the bottom end. Use the jet if you are experiencing excessive​

loss of mileage or bike starts without choke when cold. Using this jet​

will warrant a richer mixture screw setting."​

The 1100 ES comes stock with Mikuni 180 pilot air jets. The dyno pilot jets would equate to 150 based on the conversion charts.​

Wouldn't the smaller jet RICHEN the mixture...not lean it out?​

I took the bike by a local shop today and they put it on a sniffer. It's definately lean (as my plug chops told me.)​

Thanks,​

Nic​

You can read in the manual that the pilot jets meter fuel, and the pilot air jets meter air (read under SLOW SYSTEM)​

Increasing pilot jets==> richen
Increasing pilot air jets==>lean​

You need to get the main set correctly first so it pulls strong to redline​

http://www.factorypro.com/tech/carbtun.html​

When you said you were lean you did not explain where in the throttle range you were lean? ​

You do plug chops or measure AFR at specific throttle setting. AFR will vary with RPM as well, but you are typing to get it proximately correct pulling a load at that fixed throttle position.​

Pilot jets are going to be at about 1/8-1/4 throttle
1/4-1/2 throttle is going to be more needle which you did not mention.

http://www.thegsresources.com/_forum/showthread.php?t=164565&highlight=AFR​

Most people end up with a 47.5 pilot jet to richen the mixture a bit from the 45 stock 1100E in the BST34's​

At the moment I cant find where you got the 180 pilot air jets from (not in the manual), but I would say that is suspect. If a 160 leans the mixture that means stock is smaller.​

http://www.dynojet.com/pdf/3133.pdf​

The pilot circuit is the one of the last things to do. Get the main done, then the needle then do a AFR check at 1/2 to Full throttle. If that is set then you can play with the pilot which I suspect is not needed if you have the 47.5.​

I don't remember what you did with the intake side, but the pods, air box or air box without lid and even the amount of oil in the K&N's has a dramatic effect on the required main size. Hopefully you are not changing any of that but getting the main set for however you plan to run the beast.​

 

[niclpnut]

I've followed the factory pro instructions.


I'm lean on the pilot circuit. AFR showed lean off idle.

Float level 21.4 up one mm from 22.4
Pilot jet 47.5 up from 45


Using the 138 mains with pods/pipes. Needle raised on notch from recomended 3rd from top improved midrange

Pulls steadily and evenly through the mid range and WOT.

Constant gurgling at 1/8 throttle and occasional pop on high rev decel.


Plug chop at 1/8 throttle 2500-3000 rpm:

The dynojet kit comes with a 160 pilot air jet (optional)

Stock is a 180 mikuni.

I though that the dynojet (smaller) would richen the mixture, and not lean it as it restricts the air flow.

Instructions on the kit say otherwise.

Nic

 

[posplayr]

I've followed the factory pro instructions.


I'm lean on the pilot circuit. AFR showed lean off idle.

Float level 21.4 up one mm from 22.4
Pilot jet 47.5 up from 45


Using the 138 mains with pods/pipes. Needle raised on notch from recomended 3rd from top improved midrange

Pulls steadily and evenly through the mid range and WOT.

Constant gurgling at 1/8 throttle and occasional pop on high rev decel.


Plug chop at 1/8 throttle 2500-3000 rpm:

The dynojet kit comes with a 160 pilot air jet (optional)

Stock is a 180 mikuni.

I though that the dynojet (smaller) would richen the mixture, and not lean it as it restricts the air flow.

Instructions on the kit say otherwise.

Nic

So dyno jet says the 160 will lean the low end; you are lean. Why did you put it in?

How do you know stock the pilot air jet is 180? EDIT: OK I see in the back the factory manual says the ESD is 180 and the EZ is 170.

Tell you what I have two sets of DJ 160's sitting in an old jet kit box. What does that tell you? Don't use them. Put the 180's back in.

 

[1948man]

http://www.thegsresources.com/_forum/showthread.php?t=163297&page=2

start about post #33 in the above thread. There seems to be no concensus on the effect of smaller pilot air jets (I think called main air jets in the parts fiches). Dynojet sends you smaller jets to lean out the bottom end so maybe smaller jets means less fuel gets sucked in?? Maybe you could just go back to the 180's (thats what alpha sports shows for your bike) and see if that richens it the right amount. Maybe PM Ray.

 

[posplayr]

http://www.thegsresources.com/_forum/showthread.php?t=163297&page=2

start about post #33 in the above thread. There seems to be no concensus on the effect of smaller pilot air jets (I think called main air jets in the parts fiches). Dynojet sends you smaller jets to lean out the bottom end so maybe smaller jets means less fuel gets sucked in?? Maybe you could just go back to the 180's (thats what alpha sports shows for your bike) and see if that richens it the right amount. Maybe PM Ray.

OK I remember that thread.

If the
EZ 34mm are #170
ED/ESD 34mm are #180
GS1150 36mm are #125

I'm wondering how DJ can just make a statement that a 160 will lean out the mixture for all of these bikes?

 

[niclpnut]

OK I remember that thread.

If the
EZ 34mm are #170
ED/ESD 34mm are #180
GS1150 36mm are #125

I'm wondering how DJ can just make a statement that a 160 will lean out the mixture for all of these bikes?

That's what I was wondering.

hence my problem

I'll try the 180's again :-s

 

[posplayr]

<LI class="g w0">

<LI class="g w0">[PDF] Mikuni Carb tuning

- 4:13pm File Format: PDF/Adobe Acrobat - Quick View
The stock VOL Mikuni carb is this: Carburetor type: Mikuni BDSR34. Bore size : 34 MM. ID#:41F1. Idle RPM: 1100 +/- 100. Main Jet: #132.5. Main Air Jet: 1.8 ...
www.myotherdrive.com/dyn/dl/727.../Mikuni%20Carb%20tuning.pdf
<LI class="g w0">

If you do google search for the file above you will find this that might explain the polarity (it is for a MIKUNI HS40 carb)

---------------------------------------------------------------------- MIKUNI HS40 Carb Tune
IDLE CIRCUIT (PILOT SYSTEM) The idle circuit supplies fuel at idle speeds and has a major influence
on fuel flow up to 1/4 throttle. There are three tunable parts in the idle circuit: 1) PILOT JET ---
controls maximum fuel flow through the idle circuit. 2) PILOT AIR JET--- controls the maximum
amount of fuel that will flow through the pilot jet by allowing a higher (smaller air jet) or lower​

(large air jet) vacuum signal at the pilot jet.

So if I am reading this correctly

Decrease Pilot Air Jet==> Increase Vacume==> Increase Pilot Jet fuel FLOW (i.e. less air means richer)

Increase Pilot Air Jet==>Decrease Vacume==>Decrease Pilot Jet Fuel FLOW (i.e. more air means leaner)

 

[niclpnut]

That's how I read it.


I'll most likely find out for certian when I try the stock pilot air jet tonight.

 

[posplayr]

That's how I read it.


I'll most likely find out for certian when I try the stock pilot air jet tonight.

This is saying the same thing:

Larger Pilot Air Jet is leaner
install a larger (leaner) pilot air jet.
install a smaller (richer) pilot air jet.


http://www.volusiariders.com/70-jets-injectors-pipes/113996-how-tune-your-mikuni-carb.html


FINE TUNING THE PILOT SYSTEM
NOTE: Before you apply any of the information in
this section be sure that the basic pilot system is correct. Be
sure that your engine idles smoothly with the mixture screw
between one and three turns out from its seated position.
The pilot and pilot air jets have slightly different
effects on mixture strength within the effective tuning range
of the pilot system (0/0 to 1/4 throttle). When you change
the pilot jet, it has a slightly greater effect on mixture
strength at zero throttle than it does at 1/4 throttle. On the
other hand, when you change the pilot air jet, it has a
slightly greater effect above 1/8 throttle that is does below
that setting.
If your engine has slightly soft acceleration just as
the throttle is raised from the idle position, the size balance
between the pilot jet and and pilot air jet may be incorrect.
If the softness is more pronounced whe the engine is at
normal running temperature, install a larger (leaner) pilot
air jet. If there is minor coughing or ?popping? through the
carburetor when the engine is cool, install a smaller (richer)
pilot air jet.
After you have changed the pilot air jet, you will
need to re-adjust the mixture screw. If the new mixture
screw adjustment is outside the one to three turn range,
change the pilot jet. If the mixture screw must be more than
three turns out to get a correct idle, install the next larger
(richer) pilot jet. However, if less than one turn is required to
get a good idle fit the next smaller pilot jet.
It is unlikely that changing the pilot jet will require
changing the pilot air jet.

 

[posplayr]

http://www.ds650.net/mikunivsdynojet.htm​

Actual jet sizes are highlighted.
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DynoJet jets are marked according to the diameter of the hole in the jet .. ie: DJ150 = 1.5mm and DJ175 = 1.75mm.


This is not true for Mikuni or most other OEM equivalent jets. This size Mikuni jet, (N102.221 Super BN), is marked according to its' flow rate, ie: 150 = a rating of 150 cc of fuel per minute.

​

So the question is how is a Mikuni air jet measured? In fuel per minute????? I doubt it.​

 

[Guest]

The pilot air jet does two things. That is what pulls the fuel out of the bowl via the main jet and diverts it to the pilot jet since the main and emulsion tube is blocked by the jet needle.
It also supplies the air in the fuel/air ratio.
The smaller the pilot air jet the slower the fuel is metered and also decreases the air in the F/A ratio.
It is a fine line but trial and error is sometimes the way to unless you have neat toys like Jim.
When I ran stock with an airbox I had 47.5 pilot jets and a 170 air. Stock on my 16 valve motor were 160. I'd try to dial in the 180 and if it's a no go try a 170.
Also Dynojet pilot air jets sizes are the same as Mikuni.

 

[TheCafeKid]

This is no exacting science. There are trade offs to be made with the kit. As there are trade offs to be made with pods and a pipe. Different pipes will yield different trades. A pipe with large diameter headers and midpipe is going to lose a touch of bottom end grunt but will give you an amazing rush from 6k up. It's like a retro rocket lit off. A pipe with a smaller diameter header and midpipe will retain a lot of the stock low end torque and not have that amazing blast off up top so much. But that same pipe might make you happier around town riding whereas a larger pipe would be more suited to the track or back road corner strafing.

The same can be said for the kit. Your sniffer is likely going to find a lean spot somewhere. You can richen the bottom end up till it's "wet and soggy" with bigger pilots or less air or whatever but it will suffer elsewhere.

If you're experiencing back pop on closed throttle decel, you need to figure out where it is. I always thought that it would be the pilots but recently learned otherwise.
For instance, MY old 1100ES wouldn't pop on closed throttle til it came out of the higher rpm range and got down around 3.5-4K. I fiddled around with bigger than stock pilots and the adjustment screws and it either didn't help or I was so rich the bike felt soggy and flat and had a wet tone to it down low. What I found that worked was raising the needle another HALF step. Cut the popping out, and the bike pulled clean and smooth without sooting or slop through the entire power band. Just something else to try. Basically your pilot to needle transition stage might actually be where you're lean.. Give it a shot.