Needle height jetting?

reelinfeele

reelinfeele

Been Around the Block
Hey guys, so i scored some stock headers with no mufflers to keep me from having to cut mine off. I added those with a set of shorties. I have pods. CV keihins are the carbs. After an initial 3 mile jaunt to rouse the neighbors with my new found noise makers, I pulled the plugs to check. I am officially on the white side of tan. Lean. Both primary and secondary mains are larger to compensate for the pods. Pilot jet is unobtanium.

So, if i raise the needles with a shim, to richen it, I will be affecting the prt throttle running. Its running like a champ, just lean. Defintely fighting a high idle. I suspect i have a leaky carb holder. Pilot fuel screws have no affect on it. Suggestions?
 
First you need to determine if you have an air leak and repair it. After then you can start jetting. This describes the correct way to jet. http://www.factorypro.com/tech/carbtune,CV,high_rpm_engines.html
 
You can't jet an engine with an air leak.

The white side of tan is correct color for a plug. We don't have leaded fuel anymore. Tan plugs mean you are too rich. A good plug color with modern fuels is just off-white.

The needle IS your midrange. Raising the needle has greatest effect on mid-throttle.

You said it's running like a champ. What does that tell you?
 
Doesnt a lean condition cause popping when chopping the throttle? Bike is not popping or backfiring.
I have a jet that is covered by a plastic plug in the bowl. Why? This is my first set of cv's that i have had to deal with. I sure miss my flat slode mikunis now.
 
reelinfeele said:
Doesnt a lean condition cause popping when chopping the throttle? Bike is not popping or backfiring.
Click to expand...

Backfiring and decel popping are not the same thing.

Decel popping is caused by a lean condition at idle. Does not reflect on overall jetting or the main jet.

reelinfeele said:
I have a jet that is covered by a plastic plug in the bowl. Why?
Click to expand...

Because. That plug is required.
 
So, i have another set of carbs that i bought to replace a bad carb body. That set had larger pilot jets!! I never looked. That is what is under the plug. Anyway, changed to the larger jet. Seems to have helped my idling issue. Also seems to pull harder now. I also changed to 105 main jet. Stock was 90. Found my air leak with a shot of wd40, seal at carb holder. Of course last time had this issue n my z1000, it turned into the broken bolt nightmare of all time.
If i use sealer on the inside of the holder, will it be a bad idea.?
 
Pilot jet is under plug, it's fed from primary main jet so total fuel flow can be set.
You need to fix all air leaks before even trying to do anything else, remove the manifold and change the 'o' ring
 
The last manifold i removed from my z1000 ended up being a cut off the munting ear from the head. Having a new area welded up and redrilling and tapping hole. I will try all else before going through that possibilty.
 
ok, not a proper plug chop but these look a little lean, or do they.
 

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Ngk br7es, stock plugs. Timing spot on thanks to crazypj. Runs friggin great.
Stock jets are 90 secondary, 70 primary, 35 pilot
As jetted now, 105 secondary, 80 primary, 40? Pilot. Not sure number on pilot, but holes look to be 30% larger.
Pods with emgo shorties on stock headers. I use only 93 octane 90/10 ethanol that is available here in FL.
Starts right up, choke off after 2 minutes. Idles good at 1600.
 
Those plugs are getting hot, ground strap is too white
I would go back down on pilot jet and up secondary main
 
reelinfeele said:
ok, not a proper plug chop but these look a little lean, or do they.
Click to expand...

Yeah, they look a bit lean. Thing is, you can't really judge too much from plug color without doing a "proper plug chop."
 
The plugs look great if it was a flat out plug chop. Side electrode is white but not clean so that's OK. Looks black down inside the shell and can't really see the mixture ring but it looks like its maybe a touch rich.

B U T that assumes it was high load clean chop on clean plugs. At anything less than that, we would expect the plug to not be as hot and therefore covered in brown or black soot deposits.

Idle speed sounds a little high, so I'd try and get that right and get the idle and just off idle fine tuned. That may need smaller pilot jets as PJ suggested. I would have gone up another size on the primary main jet to richen the whole range up.

Tell us how you did the plug chop might help.
 
Air leak fixed. Pj provided some 110 mains. Rode it yesterday for 60 miles. Spot on. Maybe a little fat in the middle. Maybe a little lean in the middle. Power pulls through 5000 then power tapers until 7500 then pulls again. Stock the bike was flat at 5000 to 6000.
Seat of the pants power is very good. Actually will accelerate after 75. She's still done at 84. No doing the ton on this thing. Of course the typical old kaw wobbles at high speed dont help.

Thank you PJ!!!
 
carbs off again soon for some mid range mods ;)
Was going to call and see how things went.
what are plugs like now?

Probably still a little bit rich to 7K
 
So, i finally had some time to fiddle with the carbs. Went to ace for some needle shims. Get home, remove right side slide and , BAM, needles are too long. When i got the other set of carbs that used to source my pilot jets from, i had swapped over the diaphrams because mine were split. I never looked at the needles. Anyway, switched to original length needles, mid range is back with a vengeance. Not to mention it has that crisp rev from idle when you blip the throttle. NICE.
The difference in needle length was at least 1/8", at least. Have not doenroper plug chop, was having too much fun with my new found midrange. Will do tomorrow.
 
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