Carb issues, I think - Kawasaki Concours 1000

[kuksul08]

I'm working on a Kawasaki Concours 1000 aka Connie. It sat for a year before I picked it up.

I took out the carbs, cleaned the jets thoroughly. Bought new float needles and gaskets. New spark plugs.

It starts up great and idles fine. Just off idle is smooth. However when you're in the mid-range and whack the throttle open, it bogs and hesitates before accelerating, then it revs to the moon. Like there is a big delay there.


I am quite confident in my carb cleaning job. The diaphragms all looked good and behaved similarly. Any thoughts of what to check?

 

[motomania2007]

Needles too low or too high

 

[kuksul08]

Needle isnt adjustable on it, there's only one position.

 

[Stormdragon]

CV carbs do tend to do that. Roll open, don't whack.

 

[bobl]

Needle isnt adjustable on it, there's only one position.

Needles can be adjusted with shims.

 

[EastBayDave]

Sounds like an air leak to me:

diaphragm (carb & carb gaskets)
rubber hoses AND plugs
vacuum leaks
petcock rubber gasket leak (known problem w/ZRX's)
(cheap replace o-rings/gaskets) http://www.kwickstand.net/Hyper-Formance.com/Carb_&_Small_Parts.html

Just a guess; but when those CV's have problems, most just do the whole job (detailed at above site) & they typically come around. $20 well spent...

 

[Ironbutt]

I think it's clogged pilot jets..

 

[GPzPop]

agree

 

[El Feo]

A hesitation and blast off is a rich condition.

It starts up great and idles fine. Just off idle is smooth. However when you're in the mid-range and whack the throttle open, it bogs and hesitates before accelerating, then it revs to the moon. Like there is a big delay there.

Mid-range of what? Throttle or rpm?

Needle isnt adjustable on it, there's only one position.

Jet needle, not float.

Sounds like an air leak to me:

diaphragm (carb & carb gaskets)
rubber hoses AND plugs
vacuum leaks
petcock rubber gasket leak (known problem w/ZRX's)
(cheap replace o-rings/gaskets) http://www.kwickstand.net/Hyper-Formance.com/Carb_&_Small_Parts.html

Just a guess; but when those CV's have problems, most just do the whole job (detailed at above site) & they typically come around. $20 well spent...

I'd start here. Check the boots to make sure their seated and clamped.

I think it's clogged pilot jets..

It's almost always this. However, sounds like it's running rich.

 

[Ironbutt]

It's probably partially clogged pilots. The bike won't start or run well with unsynced carbs or fresh plugs either. It's a combination of those things. Also, did you check your float height? it is exact?

These carbs will let you think you did a good job till you get them all the way back in and the bike does' turn right. LOL Take them out again, and again and again.. They nearly broke me when I was learning. I was confident back then too.

C

A hesitation and blast off is a rich condition.



Mid-range of what? Throttle or rpm?



Jet needle, not float.



I'd start here. Check the boots to make sure their seated and clamped.



It's almost always this. However, sounds like it's running rich.

 

[kuksul08]

Thanks for all the input Yeah, I am a f*ckin pro at removing these carbs now, unfortunately.

I did not check or adjust the float height. I have never done this. When cleaning the pilot circuit, I was very careful to block off the pilot jet screw port and observe that all 4 pilot orifices were working equally on each carb by spraying cleaner through the air port on the intake side. Then I removed the pilot screw and made sure those were working well.


I took it out for a ride today, and after about 5 miles and a few high RPM blasts, it was working pretty great. I could blip the throttle at any RPM and it would never bog like it was doing before. It's just not the most responsive and there seems to be some kind of 'delay' between opening the throttle and actually accelerating as the engine builds up speed. On the plus side, it's very smooth.


The ride was ended because the clutch locked up and started slipping. Turns out the MC was clogged.

I am going to put on more miles and see how it goes. If I run into issues I will look into the float height.

 

[injun]

More than likely dislodged a small particle of float bowl gasket or a gnat's wing, and it is floating around in there!
It's hard to set up without a thorough cleaning on smog carbs.

 

[JimE]

Sticky slides. Bike sat, carbs got gummy, dust and crap stuck like gum on slides. Carbs cleaned and jets blown but slides needed a dunk and channels cleaned. Delay was slide sticking. After awhile, with a little fuel blown around in there as a solvent, some of the gummy on the slides came off and it's working okay. I hate CV carbs.

 

[El Feo]

These carbs will let you think you did a good job till you get them all the way back in and the bike does' turn right. LOL Take them out again, and again and again.. They nearly broke me when I was learning. I was confident back then too.

C

The great equalizer; carbs are freakin' humbling!

More than likely dislodged a small particle of float bowl gasket or a gnat's wing, and it is floating around in there!
It's hard to set up without a thorough cleaning on smog carbs.

I was thinking this in the pilot air/fuel circuit.

Sticky slides. Bike sat, carbs got gummy, dust and crap stuck like gum on slides. Carbs cleaned and jets blown but slides needed a dunk and channels cleaned. Delay was slide sticking. After awhile, with a little fuel blown around in there as a solvent, some of the gummy on the slides came off and it's working okay. I hate CV carbs.

Oooh, good call!

 

[ST Guy]

Gotta clean EVERYTHING. Not just jets and a few passages. And yes, you need to set the float levels properly.

Also check the rubber boots that hold the carbs on the head. The rubber will harden with age and heat and when that happens, small air leaks can occur. If the rubber is hard, replace all four.

 

[motomania2007]

Glad to hear you made some progress.

Before you go troubleshooting jets, make sure there are no blockages in the air filter, air box inlet and in the exhaust.

I have seen nice and wasps nests and rags in those locations that screwed up the airflow ...

To try to demistify carbs: Basic jetting troubleshooting tips are:

Less than about 1/4 throttle is controlled by the pilot circuit and the air-fuel screws
between 1/4 and about 1/3 throttle is overlap of main jet and pilot circuits
above about 1/3 throttle it is all main jet circuit as the pilot jet flow so little of the fuel at this point it is mostly irrelevant. In some carb designs the pilot circuit stops flowing entirely due to the air flow dynamics in the carb.

The following tests are done under load, while riding someplace in middle or upper gears. I usually use 3rd or 4th gear on a 6 speed.

If you are cruising at mid throttle and then you whack the throttle WFO and the engine bogs, hesitates and then leaps forward, that is usually lean main jets or slide needles are too low or the slides are not moving up fast enough or combinations thereof

If you are cruising at mid throttle and then you whack the throttle WFO and the engine bogs, hesitates and you crack the throttle back slightly in the closed direction and the engine immediately leaps forward, that is usually rich main jets or slide needles are too high or the slides are moving up too quickly (very rare) or combinations thereof.

If you are riding at WFO and you slightly crack the throttle in the closed direction and the bike lurches forward, then usually the main jets are very lean.

Hope these tips help.

 

[ST Guy]

What kind of air filter? And if it's K&N, did you reoil it? If so, you might have over done it.

 

[kuksul08]

Glad to hear you made some progress.

Before you go troubleshooting jets, make sure there are no blockages in the air filter, air box inlet and in the exhaust.

I have seen nice and wasps nests and rags in those locations that screwed up the airflow ...

To try to demistify carbs: Basic jetting troubleshooting tips are:

Less than about 1/4 throttle is controlled by the pilot circuit and the air-fuel screws
between 1/4 and about 1/3 throttle is overlap of main jet and pilot circuits
above about 1/3 throttle it is all main jet circuit as the pilot jet flow so little of the fuel at this point it is mostly irrelevant. In some carb designs the pilot circuit stops flowing entirely due to the air flow dynamics in the carb.

The following tests are done under load, while riding someplace in middle or upper gears. I usually use 3rd or 4th gear on a 6 speed.

If you are cruising at mid throttle and then you whack the throttle WFO and the engine bogs, hesitates and then leaps forward, that is usually lean main jets or slide needles are too low or the slides are not moving up fast enough or combinations thereof

If you are cruising at mid throttle and then you whack the throttle WFO and the engine bogs, hesitates and you crack the throttle back slightly in the closed direction and the engine immediately leaps forward, that is usually rich main jets or slide needles are too high or the slides are moving up too quickly (very rare) or combinations thereof.

If you are riding at WFO and you slightly crack the throttle in the closed direction and the bike lurches forward, then usually the main jets are very lean.

Hope these tips help.

What kind of air filter? And if it's K&N, did you reoil it? If so, you might have over done it.

Stock air filter. Sort of a gauze/cotton thing. I didn't oil it.

I've been working on the clutch and brake systems so I haven't been able to ride it again, but I'll keep all these things in mind next time to see what could be the cause. Thanks everyone!