Never seen this before with a Carby issue

[michaelmatta]

Hi All,

New Ninja owner and new to the forum, after mainly just reading threads I now require some help/info from anyone and everyone. Thanks in advance.

Link to original page on YouTube.

Above is a link to show whats happening as it is so much easier than trying to explain it with text. It is whats happening as at the end of all of below.

I recently purchased this for a steal as it needed some work. It had been sitting for around a yr and I know all about the issues that can be associated with extended sitting times. I have had many bikes before and am quite mechanically minded but I have NEVER seen this before!

What I have done so far: I drained the fuel and topped up fresh. Bike started perfectly with choke and back to idle with choke off. I noticed it had a bit of a flat spot in it if you blipped the throttle so I took the carb's off and gave everything a clean and hit with air. There was a little bit of gunk in the bowls. Put carb's back in and started her back up, this time the flat spot was gone

There was some damage to the tank so I bought a new one. New one turned up a week later and I swapped everything from the old tank to the new tank.
Started her back up with choke.. no problems.. choke off and... virtually nothing! barely idle and I could screw the throttle all I wanted but the rpm stayed the same. It started blowing some black smoke whilst in this state and stunk so obviously over fueling. I disconnected the line to the fuel diaphragm and once the fuel level came down in the bowls I could rev it once again. I repeated this a few times and it kept happening. Had/has me confused as to how this could be happening?

So, I pulled the carb's off again and checked everything over. Checked the floats to which they were spot on at 17mm. Re cleaned and blew everything out. All the jets looked spotless. At this stage I reset the pilot back to factory settings. The existing setting were identical on the left and it was now 1/4 leaner on the right. Carb's back in and of course no change! arrgghh! This thing has me stumped! Seems like the floats are set to high?

Carb's back out and this time I stripped it down completely from top to bottom and cleaned/checked everything once again. All diaphragms etc are perfect. This time a put the pilots to 2 turns each and lowered the floats to 16mm. It started and everything was much better still not perfect and taking a little time to return to idle (a bit lean) but not doing nothing! fiddled with the pilot and got it closer to the mark. Shut her off and put everything back together to go for a ride (minus plastics). Jumped on and started her... then... arrrghhh back to what you see in the clip. It has to be the pilot circuit right? I took it for a ride and if I kept it above 4-5000 rpm it rides perfectly, just does not like anything under that. I am completely stumped on what else to try/do?

Any info would be great as I had to stop before I lost the plot completely!

[csmith12]

Hmmm.... fuel, air, spark right...

You cleaned the carbs, so that is not it.

Airbox & filter clear?
Any vac leaks? Try the mist test.
How bout the plugs?

Other things that I have seen cause similar crap. Weak battery, faulty spark plug, a coil that was about to fail, odd acting ecu; crap stator and cracked spark plug wire/boot.

I am getting the feeling you have a vac leak somewhere. Mist some carb cleaner around the vac hoses and listen. You will know when/if you find a leak.

[jkv45]

Any chance the choke is stuck on? Air screws have a washer and an o-ring?

As Chris noted - what's the battery voltage?

Plugs are correct? I'm assuming they are black, but take a look.

Are both cylinders firing? Check the exhaust with a temp gauge if you have one.

Check that the carb slides rise and fall smoothly by lifting them and letting them drop.

[DaBlue1]

What's up with the exhaust?
Is there an airbox or pods on this bike?
Any prior carb work done?(jetting changes)
What's your engine idle speed?

[quarterliter]

As Blue noted, it does sound louder than stock. Has there been appropriate changes of jetting to compensate? Almost seems like the needles need to be raised.

[michaelmatta]

Thanks Guys,

Air filter is stock and has been cleaned

New plugs fitted this morning but did not change a thing. They were heavily sooted though but I expected that as it seems to be fueling up at the low rpm.

Battery is brand new

It has a musarri slip on pipe which requires no jet change

The choke is working perfectly

Carb slides are working freely and has stock jetting

I dont have a temp gun as of yet but it definately sounds like it drops to one cylinder when its up to sh it

Today I have now worked out that it will run ok with the suction line to the petcock disconnected (until it runs out of fuel) so I thought that it might have a tear in the diaphragm and be sucking fuel straight into that line and therefore the left cylinder. Pulled it apart and all good. I can suck on it and no leaks so its not that. I have to block the line with my finger in order to maintain good idle or the extra air drops the idle naturally. If I leave it on PRI it runs too but then seems to over fuel then bog down again and do nothing.

I cant understand why when I turn the fuel off and the bowl level comes down the bike runs perfectly! The float levels are perfect and the needles are seating spot on, nothing is sticking or bent etc. In my 20yrs playing with bikes I am officially stumped!!!!!

Hoping someone might even jog my brain to find the answer as the last resort is the shop and well... that just costs money that can be spent on beer!!

Cheers

[jkv45]

Could the needles be hanging-up and/or sitting too high - letting too much fuel in at small slide openings?

I would say you need to remove the carbs and go through them again at this point.

[quarterliter]

Does it still have the snorkel in? Some exhaust manufacturers say you don't need to rejet so noobs aren't scared to buy their products. I would say it has changed the A:F ratio and if it doesn't have the snorkel it would exaggerate this even more.

Have you checked the vacuum hoses?

Also does it run better when cold or warm?

[DaBlue1]

Originally Posted by michaelmatta

...Air filter is stock and has been cleaned

....It has a musarri slip on pipe which requires no jet change

....Carb slides are working freely and has stock jetting

Originally Posted by michaelmatta

.... I took it for a ride and if I kept it above 4-5000 rpm it rides perfectly, just does not like anything under that.

Although the stock air filter has been cleaned, it's still old if it has not been replaced. Kawasaki recommends replacement @ 2 years. I noticed the stock filter will compress with age and use. Most aftermarket air filters flow and perform way better than OEM. Poor airflow can cause poor idle issues.

Despite the fact that your slip on exhaust said no rejetting is required, many perform better with a least shimming the needles and removing the snorkel. This can help with low idle problems and smooths out the rev range a bit, but is mainly beneficial to the midrange. Many of riders with 2008 models remedied their issues by shimming the stock needles and making sure the warm idle speed was set properly (1300 +/- 50 rpms)

The diaphragms begin to move about 1/4 throttle (approx 3k rpms). If you bike runs fine after that, I would say shimming may help your problem provided you don't have a compression issue on one cylinder.

[quarterliter]

On review of the video is does sound rich when it stumbles. Try turning the idle mixture screws in a full turn and see the result.

[mgentz]

Lean bogging. Motor is getting too much air and waiting for the needle/main to kick in. Clean the carbs again.

[michaelmatta]

Hi,

This is an ongoing issue from my last post but I now have good idle it just has now power once under load? (runs ok above 5k rpm)

Link to original page on YouTube.

I have tried:
pilot adjustments.. no change
New plugs.. no change
Cleaned the carbs waaayyy to many times and they are spotless... no change
Adjusted float levels.. no change
One 0.9mm shim on needles
Mussari can installed
All carb diaphragms are look fine, one looks at little 'stretched' but not torn or anything.
Snorkle removed
Air filter is new
compression is good
Carbs are synced
Battery brand new and charged 13.1v
Fuel is new
Fuel filters are clean
Bowls are full - checked with draining them several times


I am lost.. ignition maybe? or the carb slides might not be lifting up? I know the pilot circuit covers this rev range but it is all spotless. Bike smells a bit rich after it bogs down and the revs come back up and clean it out. Plug is mostly black soot but not fouled. Some light tan on where the arc occurs only but they are brand new and have yet to be ridden on.

Any info would be great before I have to start replacing bits to try and solve it. Carb slides first I am thinking.

[Yarhj]

Just to be sure, when you say you cleaned out the carbs -- did you take a small piece of copper wire or guitar string and clean out the small pilot circuit outlet and transition circuit outlets (see this page, halfway down)?

[Alex]

/merged them, so people can follow progress and understand what has been already tried.

[jkv45]

Not perfectly clear to me if it's a lean or rich issue. I would add choke when it starts to run poorly to see if it makes it better or worse. That would confirm which it is.

I'd also put the snorkel back it.

When you said adjusting the idle mixture screws didn't do anything, did that mean anything to change the issue - or anything at all?

As Yarhj said - did you run something through all of the holes in the jets and jet holders? Did you remove the idle mixture screws and spray carb cleaner though the passages? Adjustment screws should have a washer and o-ring in addition to the spring.

[michaelmatta]

Yes I have been as thorough as I could ever be on cleaning a carb and have proven that all holes and ports are clear - hence my frustration!

It ran the same with the snorkle in, I just removed it as a Mod found from all the reading I have done.

The mixture screw did what its supposed to when I wound it in by which it started dropping that cylinder from being too lean. O-rings etc are perfect.

Im thinking the diaphragms are not lifting, then its a matter of why?? I am away atm but will check compression and vacuum for each cylinder and go from there... at $110 a diaphragm I want to make sure they are the issue first!

[jkv45]

Before buying a diaphragm I would pull off the airbox and watch the slides (with the engine running) and see if they raise when you blip the throttle.

[Yarhj]

Before spending $110 on a diaphragm, I'd consider buying an entire carburetor assembly off of ebay. You should end up with at least one usable diaphragm, you'll have the option to swap out the entire carb assembly, and you'll have all the spare parts you'll need if the problem isn't the diaphragm after all.

I'm not sure if you can use the pregen carb assembly on a newgen bike -- if so, there are some cheaper carbs available on ebay.

[mgentz]

Michael,

I have a set of carbs that I can sell. I know they work and I can even sell them jetted, and/or with the factory pro kit if you'd like. PM me to talk.

Let me think more on your issue.