Napalm'Z tuning notes.

so i just pulled out the color tune and tuned my ide as i have been running rich for the last week. i noticed a lack of power in several ranges and figured it was time to get the bike running right. hopped on and after stopping for gas, i took off towards the freeway only to have no balls at 1/4-1/2 throttle and popping/sputtering.

i had this last time i tuned my bike and wanted to go down a needle size and see what happens since im running super lean on the lower midrange while the upper and peak run well (i think). but i forgot all this since im bad at notes. so im making a post as public record and hopefully i can figure this out and if anybody has advice, i would appreciate it.

current jetting
pilot 22.5
main 123
needle stock one notch down

intended change after cleaning passageways
pilot 22.5
main 123
needle stock/Y63-S bottom notch

i have the keyster nencho carb kit from z1 enterprises.
www.z1enterprises.com/keyster-premium-ne...z900a-1976-1977.html

things i just did to the bike or that i know are wrong.
just de-rusted and put red-kote in the tank- good?
points are close to if not perfect- good
1 and 4 coil might be going out- bad?
timing- good
im probably on set 5 of plugs while tuning- good.

ps. pardon the terrible punctuation, im in a hurry.

EDIT: i went one needle richer. third slot

EDIT2:i went to stock settings with the needle jet. it seems everything i try has the bike running terrible, but i have some hope on this one.

i use my color tune to get my bike running stoichiometrically on the rich side and any needle jet i install has the bike stalling from a dead stop to 1/4 throttle. the bike is currently riding better than it ever has, but she wont idle unless tuned stoichiometrically. if i richen the pilot mixture it runs great at midrange. this means the needle is lean?

i could drop it to the lowest slot on the needle?

EDIT3: when the colortune is stoichiometric, the bike takes off from a standstill nice and smooth. when i richen it to fix the 1/4 throttle issue, it stutters. i have #20 pilots and #120 mains ordered from amazon. i have to pull the carb one more time at least tonight. wish me luck.

EDIT4: one needle richer was too rich? tested middle notch and top notch. bike stalls at 1/4 throttle both ways.

stock was too lean. rode it for about 15 minutes at 1/4 throttle and coasted home for a plug check.

one notch down is also wrong. most likely also lean as it runs fine if i tune it richer. trying bottom notch on stock needle.

EDIT 5: bottom notch on stock needle looks lean. rode for about a mile through several stop lights. stalled multiple times. checked my pilot jetting with colortune before riding. 1 1/8 turns out creates an even blue combustion. at 1/4 throttle, the plug umm, tang?, turns white. the rest of the plug looks perfect. i would say this is the closest to stoichiometric i have gotten.

EDIT6: sometimes i need to get out of my head. multiple times i mentioned the bottom notch , but didn't try it till this morning. maybe it will be fine for now if i fatten it up 1/4 turn.

EDIT7: so i come from a 2stroke environment and always saw brown or charcoal grey with a little color on the insulator. now after research, my bike looks tuned about right. through 1/4 throttle.
the problem is that it backfires like crazy when engine braking, so i keep thinking it is lean. whenever i try to richen it, it makes the bike run like shit.

so, im going back to start one more time.

20 pilots-since they are on the way and the most suggested..
stock needle position-it always backfires coming out of 1/4 to 1/2 throttle. a helluva backfire too. like harley v-twin shotgun backfire bad.
120 mains

If you have a questionable coil, replace it. No amount of carb-fiddling can compensate for random ignition.
Have you confirmed the fuel level in each carb using the clear tube method? Fuel level affects fuel mixture.
Are valve lashes set to factory specs? Wildly out of spec valve lash can create what seems like carb problems.
Some experts argue that the best way to approach jetting is to start with the main jet, high rpm,
Then the jet needle at medium rpm, then finally the slow speed / idle circuit. The procedure has been posted several times, and may also live in the file base somewhere.

Do what TexasKZ suggested.

TexasKZ wrote: If you have a questionable coil, replace it. No amount of carb-fiddling can compensate for random ignition.
Have you confirmed the fuel level in each carb using the clear tube method? Fuel level affects fuel mixture.
Are valve lashes set to factory specs? Wildly out of spec valve lash can create what seems like carb problems.
Some experts argue that the best way to approach jetting is to start with the main jet, high rpm,
Then the jet needle at medium rpm, then finally the slow speed / idle circuit. The procedure has been posted several times, and may also live in the file base somewhere.

i just sent this message to jim@redlinecycle.com i figure the copy paste will be the fastest response to your question.

so, im fighting erratic idle and power loss at 1/4-1/2 throttle and weak takeoff. it runs decent at higher rpms, except it occasionally gets a cough.

i wanted to tell you what i have and have done to see if i can get some advice. if you don't want to read my crappy, poorly punctuated essay, please skip the the end and read the red text. thank you.


1976 kz900 a-4


i had a problem with 1/4 coil so i picked up the accel coils from you and it solved the issue.

voltage at the coils currently reads 10.5 volts. current battery voltage is 12.2. voltage drop might require the "wiredgeorge" mod? wgcarbs.com/index.php/using-joomla/exten...-categories/89-coils

replaced the regulator with one off another similar year z bike. i think it was off a 78/9 kz1000, but im not sure. it solved the problem i was having with blowing fuses and not charging the battery.(it happened a while ago and i don't remember everything)

points were adjusted multiple times and i had to keep readjusting them as the timing mark kept moving, i just tested, and the points are arcing when i hit the starter. possibly bad condenser too? i pulled my advancer and the springs are definitely loose. i can easily open them about 1mm by barely touching the cam. with the cam off, they come to rest where they would if the cam was still in place.

i know it may not solve my issues, but simply reduce the maintenance. im considering a dyna s with new hardware over replacing the condensers/points.

k&n pods. i want a stock or upgraded k&n or uni air filter so i can install the airbox, which is supposed to solve many engine tuning issues. i have the complete airbox, but no filter.

delkevic 4 into 1 with the middle baffle removed.

22.5 pilot, stock needle bottom slot, 123 main air screw is about 1 1/4 turns out. adjusted with a "colortune".

rust in tank. used a chain to break up the rust and electrolysis to finish the cleaning. then i coated it with red-kote.

carb passageways were flushed with carb cleaner.

synchronised carbs. the idle is too erratic at lower rpms and my carbtune pro tends to jump erratically at 1krpms, causing a hard read. i usually have to get the bike up to 1200-1500 to adjust them. this is where the bike idles smoothly.

the float bowls are level as recommended by the kz900 factory manual.

new intake manifolds sealed with a thin film of "right stuff" rtv. i made sure that when torqued, there was no excess material in the head/manifolds.

valves were adjusted and while i had the cover off, i adjusted the timing chain.

i checked my compression cold and dry, 130-110-115-125. i will warm the bike up and retest dry and wet on monday. ill reply with that info when you get back to me.

low compression and no clearance when i got the bike makes me think there might be carbon build up forcing valves to not close all the way. i might be putting too much thought into this as i have several issues going on at once that may all be causing similar problems. this could cause the inconsistent compression values as well as the chough. the bike also backfires on deceleration, but this may be normal.

parts needed: stock airbox performance filter. timing advancer or springs and, condensers, points or dyna s.

any advice or parts that you have to help me would be great. sorry about the long read.

thank you,
Josh


im at the jetting recommended for my setup by z1enterprisies, except the needle which is way rich.(i think) i pulled the carbs and manifolds last week and tried center and one notch down on the bike and it just stuttered terribly at 1/4 throttle. i haven't set it back to the bottom slot or played with any tuning as i am fighting too many issues right now.

Here is what stands out to me in your epistle....

Ignition
Coils should be getting full battery voltage, at least within 1v. All the wire connections between the battery and the coils need to be carefully cleaned and wires checked for fraying or breaks. Otherwise, the WG mod. Sounds like the advancer springs are weak and need to be replaced. Maybe time to replace with a less tired unit, or Dyna.

Fuel
Will not idle below 1200, sputtering, uneven transition from low to moderate throttle opening, fuel level ok, no air leaks. All of this points to clogged pilot circuits.

yes.

i checked the circuit this morning. i opened and cleaned the clamshell and the ignition, then put a light film of dielectric grease. i also opened and cleaned the bullet connectors with scotch brite and q-tips(for the females).

currently, i'm getting .4 difference on 1-4 and .6 difference on 2-3 compared to battery voltage.

if there is damage to the wiring, it either comes from bad solder or it's in the harness.

with ignition on, im getting 1.5v to open points.

the stuttering happened after i adjusted the needle jets. something could have gotten in when i had the carbs off. ill return them to the lowest position as it has ran fine there till now. when i do ill tear them down and clean them. i might get a harbor freight sonic cleaner and some sodium hydroxide based degreaser(lightly mixed as to not dissolve the carbs) and give them a thorough cleaning.

then i need to find some hills and extra plugs to do a chop test in 5th at wot.

all of this is mute till i get some new advancer springs.

EDIT: it will idle as low as 800, but it make lots of noise and you can hear that some cylinders are having trouble keeping up. basically, it runs like shit below 1200. this along with the timing advancer having loose springs, tells me the timing advancer is probably my main issue.

TexasKZ wrote: Some experts argue that the best way to approach jetting is to start with the main jet, high rpm,
Then the jet needle at medium rpm, then finally the slow speed / idle circuit. The procedure has been posted several times, and may also live in the file base somewhere.

wouldn't rpm have little to do with it as the fuel is provided at throttle position? if i had a steep enough hill i could do 50 @ wot without accelerating, would that not give me the same plug reading at 5k as 8k?

EDIT2: loudhvx had some great advice for tightening springs. i'm going to use this for now to set my idle. further adjustment may be needed in the future. ill find out with a timing light. kzrider.com/forum/2-engine/598967-noob-1...ance-question#681525

so, adjust timing, jetting is as suggested by z1enterprises.

have the premium carb kit #200-1102 and i replaced all the originals with the new parts. i went down 1 notch on the stock replacement needle and up one size on each of the jets.

You may want to increase the main jet at least one more size

cleaned the jets and passages.

i fired the bike up to test the adjustment i made to the timing accelerator springs.... aaand blew the 1-4 condenser.

i swapped the wiring and plugs for the coils and 1-4 still dont fire. coils are good. my old coils are probably still good. 1-4 never ran right. i had a feeling it was the condensers. time for a dyna s or a new set of points from redlinecycle.

they have a great deal on points.

Used point plate / complete $25.00 Limited Availability
(w/all good hardware / above average points)

or condensers from z1 enterprises

Condenser - Ignition - Z1 - KZ900 - KZ1000 - GS750
$11.92
Part # SU617-610
Equivalent to OEM: 21013-035 33261-45020-. Condenser; Kawasaki/Suzuki - Z1 (73-75)- KZ900 (76-77)- KZ1000-A/B/C/D KZ1000 (77-79) - 21013-035 / GS550E/L (78-79)- GS750B/C/N/EC/EN (77-79) - 33261-45020

bump

Throttle position does not determine fuel flow, it only determines the maximum fuel flow possible.

Air flow through the carburetors determines fuel flow. The more air flowing, the more fuel flows, up to the maximum that can flow through jets that operate at any given throttle opening.

If you are holding a steady 5000 rpm at a small throttle opening, most of the fuel will be drawn through the pilot circuit, an maybe a little from the needle. If you suddenly whack the throttle open, velocity in the carb will drop until the rpm begin to rise. The fuel metering will not transition fully to the needle until there is sufficient velocity again. The same thing happens when at high rpm and wot, when the fuel metering transitions from the needle to the main jet.
The throttle determines how much air can enter, while the various jets and the needle determine the amount of fuel available.