Idle mixture screws are at different heights? (Idling/Starting Problem)

[MegaEgg]

Recently, my bike has had trouble starting and warming up, especially during cold temperatures or rainy days, and it no longer runs without the choke on. I've taken my carbs out to clean them but there is absolutely no gunk anywhere, though I've soaked and cleaned all the jets and circuits anyway.

I took a look at my idle mixture adjustment screws and it looked like one was definitely higher than the other. They were also definitely previously adjusted by one of the POs. Removing the screws, I saw that one of the o-rings broken in two pieces. Even after ordering a new one and reinstalling the screws, it seems that they both seat at different heights. After turning them both back out at 2 1/2 turns, one is flush with the inside of the throttle body, and the other is much lower to where you can't see the tip of the screw.

Should I just reinstall everything and attempt to adjust the idle on both carbs with the choke on? I'm not really sure what to do. Thanks.

P.S does "2 1/2 turns" mean the same as 2 1/2 rotations? or is a turn more like a half-rotation?

[csmith12]

Welcome!

First off 2 1/2 turns means 2 full rotations of the screw and a 1/2 rotation. And... the idle cannot be adjusted unless the bike is fully warm.

While your problem initially feels like a clogged idle curcit. Let's explore some other common issues.

Battery in good condition and good clean connections?
All stock or custom jetting?
Slipon, full system or stock?
Last time the bike ran fine and ridden with frequency? ie Was the bike in storage?
Condition of the air filter and is air box clear?
Last time the valves were checked and mileage of the bike?

That will be a pretty good start.

[redsnapper]

I have the same problem. Noticed looking from the front of the carbs. The right mixture screw is higher when I seated both the screws.

Warmed up the bike, turning them to 2 1/2 rotations.

Which makes.
Left Mixture screw richer (More Fuel) than the right side.
To tweak things, I used a infrared gun to measure header temperatures, blip the idle, watch the idle to see if it dips below idle, and adjusted with offset screw driver.
Don't know if it's the best way or why the mixture screws are not the same.

Note* I have a dynojet kit jets and needles installed.

Hope it helps.

[MegaEgg]

Originally Posted by csmith12

Welcome!

First off 2 1/2 turns means 2 full rotations of the screw and a 1/2 rotation. And... the idle cannot be adjusted unless the bike is fully warm.

While your problem initially feels like a clogged idle curcit. Let's explore some other common issues.

Battery in good condition and good clean connections?
All stock or custom jetting?
Slipon, full system or stock?
Last time the bike ran fine and ridden with frequency? ie Was the bike in storage?
Condition of the air filter and is air box clear?
Last time the valves were checked and mileage of the bike?

That will be a pretty good start.

- Battery actually just died on me and I think I might have killed it when I was trying to start the bike over and over, so I have a new one now that I haven't tried. Connections are good.
- Stock jetting, stock exhaust
- I'd say ever since I got it, which was less than 4 months ago, it's been like that, it's just gotten progressively worse.
- The air filter and box can definitely use cleaning, I think the PO overfilled it with oil so there is ALWAYS oil near the crankcase vent hose.
- Since I just got it, I haven't checked the valves, bike is at 18k.

I should have checked a lot of these things, and I will, I just want to make sure that there's nothing more I can do for the carbs before I put them back on ha.

[csmith12]

Originally Posted by redsnapper

why the mixture screws are not the same

They are not the same because the stock needles on a newgen are not the same. As you know, one side is richer than the other. The 2.5 turns is just a base starting point that should get your bike running. Further tuning is encouraged as needed.

[MegaEgg]

Originally Posted by csmith12

They are not the same because the stock needles on a newgen are not the same. As you know, one side is richer than the other. The 2.5 turns is just a base starting point that should get your bike running. Further tuning is encouraged as needed.

Wait, so is this the case with the pre-gen too? Are the holes different? I'm finding that whatever combination of screws, washers, and o rings always leads to the left side screw having more exposure.

[redsnapper]

For the Ninja 2008 and above with Stock Jets and Needles

Service Manual shows.
Pilot Screw Setting:
#L: 2 1/2
#R: 1 3/4

Be aware the Needles are NOT the same size.

For your Pilot Screws, I don't know why Yours and Mine are not that same height.

For Pregen (Yours) I assuming the settings are the same as the newer model????

What do you mean you soaked and cleaned your jets?

Did you actually remove jet tube, main jets, and pilot jets, and clean the super tiny holes with a thin piece of wire?

Running only with Choke you mentioned. Your Pilot jets are clogged, I had the same issues, and other people I know. I removed them and cleaned with a thin piece of wire, dam holes are SMALL!

The holes are so tiny, you could have missed something.

Check out this cool video for cleaning for a Ninja 250 Pregen.

https://youtu.be/Ksh-hcmz3U4

Hope you get your issues worked out!

[MegaEgg]

Originally Posted by redsnapper

For the Ninja 2008 and above with Stock Jets and Needles

Service Manual shows.
Pilot Screw Setting:
#L: 2 1/2
#R: 1 3/4

Be aware the Needles are NOT the same size.

For your Pilot Screws, I don't know why Yours and Mine are not that same height.

For Pregen (Yours) I assuming the settings are the same as the newer model????

What do you mean you soaked and cleaned your jets?

Did you actually remove jet tube, main jets, and pilot jets, and clean the super tiny holes with a thin piece of wire?

Running only with Choke you mentioned. Your Pilot jets are clogged, I had the same issues, and other people I know. I removed them and cleaned with a thin piece of wire, dam holes are SMALL!

The holes are so tiny, you could have missed something.

Check out this cool video for cleaning for a Ninja 250 Pregen.

https://youtu.be/Ksh-hcmz3U4

Hope you get your issues worked out!

Well, my pre-gen needles/screws are the same size (see attachment).

And yeah, I definitely removed the jet tubes, the main jets themselves, and the pilot jets and cleaned the holes. But I'll definitely take a look at them again, thanks!

[ducatiman]

pilot oring in the bottom of the pilot orifice....they are quite hard to see down there where they get squished and stick. And the orings don't normally come out with the screw. I'd wager somebody left one behind, then upon assembly added another ...result the screw will bottom, but not correctly... and be "raised".

I've seen orings and washers either missing or too many and most common...assembled out of order. Springs missing sometimes too.

Look very closely down the pilot orifice....look for "leftovers".

[redsnapper]

Yes, my mixture screws are the same height too. I should have said the holes were not drilled the exact same length from factory? I cleaned other people's carbs in the past and failed to noticed

Maybe factory defect or it's suppose to be like that?

[MegaEgg]

Originally Posted by ducatiman

pilot oring in the bottom of the pilot orifice....they are quite hard to see down there where they get squished and stick. And the orings don't normally come out with the screw. I'd wager somebody left one behind, then upon assembly added another ...result the screw will bottom, but not correctly... and be "raised".

I've seen orings and washers either missing or too many and most common...assembled out of order. Springs missing sometimes too.

Look very closely down the pilot orifice....look for "leftovers".

Looks pretty clean to me!

I notice that theres somewhat of a taper to the o ring, is there a certain way the taper is supposed to go?

[RacinNinja]

Originally Posted by MegaEgg

Looks pretty clean to me!

I notice that theres somewhat of a taper to the o ring, is there a certain way the taper is supposed to go?

No. That means the o-ring is worn out and needs to be replaced so it seals well. It should be round.

[ducatiman]

[QUOTE=MegaEgg;1087420]Looks pretty clean to me!
/QUOTE]

proclaiming carbs "clean" based solely on visual can be deceiving, not always accurate.

your actual cleaning methods and procedures are critical to success, and can be confirmed prior to reassembly and startup.

Did you employ compressed air in your procedure?

[MegaEgg]

[QUOTE=ducatiman;1087422]

Originally Posted by MegaEgg

Looks pretty clean to me!
/QUOTE]

proclaiming carbs "clean" based solely on visual can be deceiving, not always accurate.

your actual cleaning methods and procedures are critical to success, and can be confirmed prior to reassembly and startup.

Did you employ compressed air in your procedure?

Well, I meant "clean" in response to the ducatiman's suggestion to check the channels where the idle mixture screws went into, for any remnants of o-rings.

In regards to my carbs being generally clean, I haven't used compressed air, but I've followed the directions on the wiki for carb cleaning with carb cleaner and a straw.

[MegaEgg]

Originally Posted by RacinNinja

No. That means the o-ring is worn out and needs to be replaced so it seals well. It should be round.

Ah I see, thanks! I'll get a replacement.

[ducatiman]

so back to your pilot screw heights...install the screws without spring, oring or washer. lightly seat. You should see the mixture tips in the venturi drilling....both should appear to be protruding equally. If NOT, something is amiss with the drilling (threads? ) or screw.

Alternately...you could measure and compare the depth of each seated pilot screw head within the orifices....any major difference would indicate further scrutiny would be called for.

from your original post:

"Recently, my bike has had trouble starting and warming up, especially during cold temperatures or rainy days, and it no longer runs without the choke on. I've taken my carbs out to clean them but there is absolutely no gunk anywhere, though I've soaked and cleaned all the jets and circuits anyway."

I'll submit your pilot passages require further "attention" followed by resetting and proper adjustment of the pilot screws.

[MegaEgg]

Originally Posted by ducatiman

so back to your pilot screw heights...install the screws without spring, oring or washer. lightly seat. You should see the mixture tips in the venturi drilling....both should appear to be protruding equally. If NOT, something is amiss with the drilling or screw.

Alternately...you could measure and compare the depth of each seated pilot screw head within the orifices....any major difference would indicate further scrutiny would be called for.

from your original post:

"Recently, my bike has had trouble starting and warming up, especially during cold temperatures or rainy days, and it no longer runs without the choke on. I've taken my carbs out to clean them but there is absolutely no gunk anywhere, though I've soaked and cleaned all the jets and circuits anyway."

I'll submit your pilot passages require further "attention" followed by resetting and proper adjustment of the pilot screws.

Yeah...sigh, I guess it's just the drilling then. I've seated them starting from no o-ring, washer, and spring. Then, I add the spring only, screw them both in, check, take them out, and then add the washer, screw in, check, add the o-ring, etc. And I've done this with each screw set in each channel and that one side is always higher, it is visually noticeable.

Now, at this point I guess I kind of have to try and set them equal to each other to adjust them together. Now I'm wondering, as a starting point, which one is actually closer to the suggested or stock value of 2 1/2 turns? At 2 1/2 turns, one is pretty flushed with the interior of the venturi, while the other is a little recessed. I'd like to try and eyeball one to match the other, so they can be as close to the stock setting as possible when I put the carbs back in.

[ducatiman]

using your pic of the mixture tip in the venturi, i'd set the one protruding further inward to 2.5 turns from seated, and visually match the other, regardless of counting turns.

However...the bike must be able to idle off choke to "set" the pilots when warm, which is your next step.

However, you previously posted you aren't able to idle off choke.

I'd revisit the pilot fuel/air paths while the carbs are off.

Removing the pilot jets AND pilot screws, spray both openings with cleaner and use real COMPRESSED AIR...aggressively blowing to and fro between those openings. Repeat spray and blow out.

The pressure from a spray can ain't gonna cut it.

[ducatiman]

i've got a set of ^'08 carbs in my cold garage....I'll take a looksee after this post, just for reference. I'll post back if I see anything pertinent.

[ducatiman]

megaegg-

run both screws in all the way....shoot/post a pic of each metering tip

i want to compare "0" turns out (lightly seated) as a point of comparison.

Here's the '08, lightly seated, both protrude identically. These are the confirmed original pilot screws.

[MegaEgg]

Originally Posted by ducatiman

megaegg-

run both screws in all the way....shoot/post a pic of each metering tip

i want to compare "0" turns out (lightly seated) as a point of comparison.

Here's the '08, lightly seated, both protrude identically. These are the confirmed original pilot screws.

So here are both sides lightly seated. I looked at both screws dead on. I highlighted the height in relation to the hole in the throttle plate. The difference in height may look like it's just the angle of the pictures, but in person it is definitely noticeable.

[redsnapper]

Just a thought, Where are you?

Your Location says USA. Are you trying to get it working in cold weather?

I'm in Toronto, and had to replace my Main jets to bigger sizes because of the winter blues

For having to run with choke, I had one rider who cleaned the carbs 3X and still had issues.

We went extreme, and split the carbs. Removed all screws and parts and cleaned/inspected everything.

We ended up;
Spraying in all the holes with carb cleaner with a tube.
Brushed carb bowls and metals with tooth brushes.
Cleaned all rubber with mild dishsoap.
Took apart air enricher, cleaned.

After the Extreme clean. His bike ran super smooth.

Did you watch the video I posted earlier?

[ducatiman]

megaegg-

your pics indicate both metering tips are protruding equally at "0", simply turn out both 2.5- 3 turns as a starting point, pending fine tuning. Provided the pilot circuits are clean...the bike should start, idle, and transition at 2.5.

The pilot circuits still need to be dealt with.

[MegaEgg]

Originally Posted by ducatiman

megaegg-

your pics indicate both metering tips are protruding equally at "0", simply turn out both 2.5- 3 turns as a starting point, pending fine tuning. Provided the pilot circuits are clean...the bike should start, idle, and transition at 2.5.

The pilot circuits still need to be dealt with.

Well you can see the lines I drew in the pictures to indicate their height in relation to the throttle plate holes. The one on the left is below the hole, and the one on the right is positioned in the middle. In person you can tell right away that they are not the same height. Also, I figured if they were the same height, turning them out at 2.5 turns would have them end up in the same place, but the set of pictures before where I have turned them out says otherwise.

I might just wing it as I suppose I don't really have any other options with the way the carbs are now. I'll still give the pilot circuits a good cleaning as you have suggested, before I put the carbs back in.

[MegaEgg]

Originally Posted by redsnapper

Just a thought, Where are you?

Your Location says USA. Are you trying to get it working in cold weather?

I'm in Toronto, and had to replace my Main jets to bigger sizes because of the winter blues

For having to run with choke, I had one rider who cleaned the carbs 3X and still had issues.

We went extreme, and split the carbs. Removed all screws and parts and cleaned/inspected everything.

We ended up;
Spraying in all the holes with carb cleaner with a tube.
Brushed carb bowls and metals with tooth brushes.
Cleaned all rubber with mild dishsoap.
Took apart air enricher, cleaned.

After the Extreme clean. His bike ran super smooth.

Did you watch the video I posted earlier?

I'm trying to start it in cold weather but probably not your definition of cold, I live in California, and where I am, the coldest on average is probably around 35F.

I saw the video and my cleaning experience has been very similar. Maybe I'll take apart the air enrichener, could that cause an issue?

[redsnapper]

Air Enricher Don't know.

I open a few, one of them was filled with gas and crap.

No harm checking. Be careful there is a small o-ring, and a spring. Don't lose it.

Stick the carb cleaner straw in the jet and spray. See if it actually actual sprays out like a fine mist. Do the same for the passages in the carb. Wear Safety glasses, if you spray wrong, it will hit you in the face.

I ended using 2 cans for a friend who had a carb giving him grief, it looked brand new, but idle did not work. He had to run the choke at 3000 RPM to bypass the idle circuit. The idle jet/pilot was clean, it was the silly passage had crap in it.

Maybe you missed some spots?

Check this out and focus on the idle circuits.

https://www.ninjette.org/forums/showthread.php?t=147048

[ducatiman]

spray from a can just doesn't have the nuts to really clear clogged idle passages........a genuine compressed air source is called for...though you may get lucky

this is where ultrasonic also does well

Per your pic...the difference between the pilot screw projections is not in reality the radical difference as your original post described. Regardless, aside from 2.5 turn starting point, their being turned out in precise, equal values is a non-issue. After "live" tuning, they will (or should) end up at their independent "sweet spots".

Good luck with it.

these air before/after '72 Honda CB350 carbs i did last year using soda blast, ultrasonic and air....NO WAY an attempt with a spray can would net results as these

[Ghostt]

When was the last time the valves were adjusted? Believe it or not if the valves are out of specifications it will lead to close start issues, and/or idling issues as well.

But first make sure the carburetors are 100%, and also cheap for vacuum leaks, and petcock is working properly.

And while your at install an inline fuel filter, if you haven't already.


If your not confident in your carburetor skills, I highly recommend sending them to @ducatiman for a refurbishing, cleaning with a can-o-cleaner isn't the same as a full service refurbishing.

I have know Ducatiman for several years now and I personally recommend his services. I would trust him with my carburetors, and that's saying a lot coming from me.

[ducatiman]

Originally Posted by MegaEgg

Looks pretty clean to me!

your post #11 in the thread...looking *very* closely at your pics of pilot orifices...the pic on right is clear of any orings or washers (the clean concave oring sealing surface within is obvious) ....

now look very carefully at the left hand pic ...the same surface is discolored and *may* be flat

could this be a washer still present?

As pics are not like "being there"....*very* careful examination (with carbs in hand) using a lightsource and probe would be called for

May just be my eyeballs seein' things...

[MegaEgg]

Thanks for the tips guys, I'll definitely try a lot of things you guys have mentioned and report back.

[Ghostt]

Beyond common problems...... comprehensive carb cleaning is not for everyone, there is much to go wrong in short order. We've seen many members endlessly chase their tails, break stuff, assemble and adjust stuff wrong.

With some of the fleet becoming old, the vast majority require much more than "cleaning". The potential for leakage must be addressed, any less attention is irresponsible, and yes, this may even require thowing money and parts at them (gasp). Consumables...carb innards are not forever items.

And certainly there is MORE... much more....to it than simply addressing the pilot jets while they are out and on the bench.

Please...you're screwing around with FUEL...if not absolutely sure of what you're doing...send them to someone who is.