• Can't post after logging to the forum for the first time... Try Again - If you can't post in the forum, sign out of both the membership site and the forum and log in again. Make sure your COG membership is active and your browser allow cookies. If you still can't post, contact the COG IT guy at IT@Concours.org.
  • IF YOU GET 404 ERROR: This may be due to using a link in a post from prior to the web migration. Content was brought over from the old forum as is, but the links may be in error. If the link contains "cog-online.org" it is an old link and will not work.

Carb float height: Setting correctly

M

MD634281

Guest
Guest
Further to my other posts about rebuilding my UK 1994 A9, I'm know trying to set the carb floats. The Kawasaki manual says to hold the carbs at an angle where the float bowl 'peg' just touches the valve. I've made a tool to set them at 17mm, as the manual says, butI cannot find a constant point. I have tried to see when the valve arm just touches the sprung tip of the valve, and check the height, but it varies by 1-3mm.
Harley state a set angle to check theirs, think its 20 Degrees. so you make a simple ramp, place carb on it and measure the float height.
Does anyone know what angle we should use? OR...do I get them close, and check the fuel level using an external hose and gauge?
The bike was running really well, butone carb keeps dripping fuel, I've checked the bowl, no leaks from anywhere, other than the overflow tube, which is obviously working!
 
I've always set the float height's using the external hose method. Now I also built a carb repair stand out of PVC pipes to work on and set carbs. Very handy because you can duplicate the angle of the carbs as they would be installed on the bike.
Not knowing how much research you may have done, but with the dripping carb(s), polishing of the needle floats seats can help eliminate that area as a potential issue, along with new parts of course.
HTH
 
Thanks victor: I've removed the carbs (again) and cleaned the faulty carb, number one, everything looks perfect. The float valve looks like new, the plastic coating on the tip is spotless, no sign of wear or damage on the seat, and it didn't leak before!
I swapped round the float bowls, the leak is still on number one. I'm going to try swapping round the float bowls and see what happens....
 
Mike/Vic; I learned a neat trick to see what's happening with the fluid level.
Like you, I also did the external hose method. {but was not happy with that method}
So, I sought another method of seeing the fuel level.
My Tinkerin' Tip; I cut off the bottom of a liquid detergent bottle. {Gas does not damage the plastic of a Liquid Detergent bottle}
Next; I removed 1 bowl, put the carb rack in my vise {or on a test stand}, held the bottle bottom up and beyond the base of the carb, and turned on the gas flow.
The gas would rise to the point that the float valve shut off the fuel flow,
<<< I could see the float valve move.
<<< I was able to see exactly where the level stopped.
<<< I could also see if the gas flow did not cut off.

Ride safe, Ted

PS: If the problem is, the O-ring gasket on a float bowl is leaking.
Make a putty of face soap and water.
Fill the O-ring groove with the putty.
Press the O-ring into the putty and wipe away excess putty.
Install the carb bowl.
Gas will not melt soap, so the putty will act as a seal if the O-ring has a problem.
 
Last edited:
Hi Ted, thanks for the advice. The bowls are sealing perfectly, in fact I forgot to fully tighten the 4 retaining screws yet they didn't leak.
I'm going to reset the float bowls so they sit a little lower, say 15mm, when the carbs are 20 degrees from level, maybe that will help.
I'm still wondering why the #1 carb is overflowing though as it was fine..until all the jets blocked up after just a few weeks not being ran. I think I'll swap the float valve from #2 carb and see which carb overflows, then check the fuel level, using some clear silicone hose and a 5ml syringe body šŸ˜
 
Ted, I like your use of the detergent bottle for the float bowl. It will let you see what the float is doing. It will also eliminate a leaking drain screw as the source of a small leak.

Mike did you use a clear tube to check the float level to see if it is above the overflow tube height? Did you leak check the bowls before installation? Is the overflow tube at the correct height? I will guess you have but just asking.

I had an overflow tube leak where it pressed into the bowl. It took several hours to show in the drain hole, but a light blown on the drain line would bubble at the base of the overflow tube.
 
Hi, I did test the bowls before fitting, all held fuel for 24 hours tested.
I'm sure I've set the floats poorly, I blocked the overflow tube and re-tried, this time the fuel didn't leak but did flood the carb jet/intake slot at the rear of the carb body. Today I've used my clear tube and syringe body to test the fuel level, it's about 4 mm above the bowl joint face...too high!
When checking the float height, does a smaller height equal more fuel?
 
Increasing the float height lowers the fuel level. The height settings is the starting point. It gets fine tuned with the clear tube to the split line. That takes in to account the actual point of each needle/ float closing off the fuel flow. A test stand allows you to do this without having to install the carbs in the bike.
 
Carbs completely rebuilt, spotless inside, like new. Fuel level set perfectly, then all rechecked.
Fitted the carbs today, and....its still runing like a bag of shite. :mad:
Had enough now, its still coughing and spluttering at idle, won't rev cleanly until 6000 rpm when it takes off, then the revs take ages to drop back down to about 1000 rpm, then it dies again. For sale.
 
Do you have a rich fuel smell? Black or white smoke?
Many times a carb problem turns out to be a electrical problem.
ie; I had a similar problem and it was the spark plug wires/caps.

Ride safe, Ted
 
Hi again Ted: fancy you saying that...
I had a cold number one exhaust header, just didn't get even warm, so I switched spark plugs 1 and 4... No difference, and plug #1 was just wet, not flooded, made no difference. Just been back to it after a few hours, it fired up, but now #4 is dead (y):D.
So, looking pretty certain that its a faulty spark plug! Just missed the local parts shop as its 4pm Sunday, but tomorrow is looking better ;)
 
Just to add, I've renewed the plugs (NGK DR9ES) and fitted high performance plug leads/wires, so I'd ruled them out...classic schoolboy error. I'mgetting a set of NGK D8ES or EA, as that is the correct plug for the earlier 'full power' versions. In the UK the A9 (1994, my bike) and onwards had smaller exhaust headers and carb top restrictors, for some strange reason. As both have been upgraded I need the 8 heat range, not 9's.
 
Do you have a rich fuel smell? Black or white smoke?
Many times a carb problem turns out to be a electrical problem.
ie; I had a similar problem and it was the spark plug wires/caps.

Ride safe, Ted
Could be the black box..had several go over the years on different bikes.gives the same symptoms as
bad carbs
 
Thanks for the advice danny: another thing I'll keep a watch over!
 
New spark plugs, now running much better!
One problem thats still there is the revs don't drop quickly. I rev the bike, to say 4000, then close the throttle, the revs drop slowly back to idle, when it settles and runs perfectly. I gave it a really good rev, certainly blew out the cobwebs at 9000 šŸ¤£
This time the revs stayed at 4-5000 for several seconds, then again dropped slowly back to a steady idle. Any more ideas please?
 
You might be "idling" off the main jets due to clogged idle passages and a high idle setting (throttle plates too open).

Those little holes just downstream of the throttle plates collect garbage and the idle air passageway from the intake side needs to be verified clear all the way to them. You have to use implements that are smaller than the holes and work carefully to be sure not to enlarge any orifices.

I found that setting the floats @ 17mm really was only a starting point. Getting the actual fuel level correct is what you are after and that requires multiple rounds of measuring, draining, removing float bowls, adjusting, reassembly, filling, measuring......
 
I've rebuilt the carbs several times, I did them and then left the bike for about 2 months, then got back to working on it, and the carbs were already gummed up, the ethanol in fuel is awful. I totally stripped the carbs, I used guitar strings to clear out every single fuel and airway, then set the floats and finally checked/adjusted the fuel heights: all 4 carbs have the fuel level exactly on the carb body joint. The manual says 1mm above but I didn't want to pull them apart and try to get another mm!
As I'm using a remote fuel tank, I've blocked the vac pipe on carb #2, I assume this is correct, and now using 'super unleaded' fuel as its got less ethanol in, but a slightly higher Octane rating..shouldn't make any difference. :confused:
 
I have read all your posts. I agree, it does not sound as it should. At this stage I would get
my carb sticks out and see if there is a difference between the carbs vacuum. If there is
correct that and see how it runs. Let us know.
 
I'll have a go at balancing the carbs, it idles quite nicely so should be able to get them balanced. The exhausts are blowing which doesn't help, I've got a new pair of Delkevic stainless cans waiting to be fitted. šŸ˜
 
its still coughing and spluttering at idle

For CV carbs, it is important that all potential vacuum leaks are sealed up or the engine will spit, sputter and run terribly. Even a loose band clamp on a carb boot (from air cleaner) can cause this.

Make sure all vacuum ports on each carb are capped or connected correctly and that carb boots from air cleaner to carbs are tightened down with no leaks etc. Don't try to gauge how things are running without the air box attached and filter installed.

You can find external vacuum leaks on the intake side of the carbs by spraying a fine mist of water at specific areas on the carbs while the bike is running. If the RPM's dip at a certain spot - you're on to something. Some spray WD40 in which case if RPM's rise when you spray at a certain spot then you're on to something. Don't spray carb cleaner ! Its hard on the rubber parts.

I've always understood that hanging RPM's indicate a turned up idle compensating for clogged or partially clogged pilot jet(s).

The exhausts are blowing which doesn't help

Are you referring to holes in the exhaust or the water drain holes behind the rider pegs? Those emit a small amount of exhaust on each side which is normal.
 
Hi, I've tried spraying easi-start all round the carbs, doesn't alter the engine speed at all. The inlet boots are new, as its impossible to use the old, hardened ones. The exhaust is a Motad Neta, and its blowing slightly between the front pipe/collectors, and the actual silencers, as I didn't reseal the joints, just clamped them back on: waiting to fit my brand new Delkevic cans once the bike is running properly.
I'm going to remove the carbs onceagain, double check everything, and close the pilot screws down to 1.5 turns, as I feel it's running a bit rich when idling, almost like the choke is on (chokes working perfectly, I've checked them) (y)
 
Hi Mike. It sounds to me like 1 cylinder still isn't running right.
I've fought the carbs on the C-10 lots of times. {Frustrating}
(I've done a lot of carbs, but for some reason these make me insane}

Hopefully the carb balance and check for air leaks have solved your problem.

If not; Some thoughts;
On the pilots, you may have them cleaned out, but I wonder, are the passageway's clear?
Try using a can of WD-40 {with red straw} and spray thru each passageway.
Flow should come out at a location on the carbs {somewhere}.
See that the flow is the same on all 4 carbs.
IMPORTANT: Use safety glasses. Sometimes the flow is directly towards you!

On these carbs the needle Jett carrier must be installed from the bottom.
(Some have installed them from the top).

If you turn the carbs upside down/without bowls/floats, there is a vent hole near the body of each carb.
That hole works with the choke/enrichener. Often overlooked.

The plungers of the enrichener valves should each have a rubber base. Check that.

Compression. Have you checked that?
May have a valve that is not sealing.
While there, check for a bent rod.

Plug wires. Be sure they are on the correct plugs.

Free power mod. have you done that? Pretty simple and free.
ie; Add a ground to the CDI Box. Some have a poor ground which effects how the bike runs.

Premium Fuel in the Eu has less Ethanol? Not so in the USA.
And a C-10 seems to like regular more than premium for some reason.

Hope that helps. Ride safe, Ted
 
Hi Ted, I've covered all the areas you say: I do have a feeling that #1 carb fuel level may be slightly low, it was dead level with the carb body/bowl joint. I've just rebuilt the engine top end, replaced the head and reground all the valves, new camchain etc etc. Carb tops, full bore exhaust headers and Free Power mods done by previous owner.
I replaced the plug leads, just replaced the plugs again as one failed whilst stood unused!
After the rebuild, it was running perfectly, I was then taken ill again and the bike stood another few months, this is when the crap fuel turned to glue and clogged up the carbs, and thats when the latest issues started :confused:
Could the pilots being half a turn too far out cause such poor running?
 
As to the fuel ethanol content, its quite hard to get exact levels from the makers! We've tried to find out and got nowhere: the Super Unleaded and other high octanes MAY still have 5% ethanol but I also use ethanol remover/fuel stabiliser.
Has anyone had success washing fuel, to split and remove the ethanol?
 
I've seen how to get the ethanol out of the gas on You Tube, but it wouldn't help if your on the road.
Additionally, you loose about 10% of your fuel and I know you already pay more than we do for fuel over there. arghhh!

You said; as I feel it's running a bit rich when idling, almost like the choke is on (chokes working perfectly, I've checked them)
"This sounds like a high float level".
But the pilot jett passageway plugs easily and is highly suspect.

Have you checked the diaphragms in the carbs? I've had 1 with a tiny hole/tear that prevented the slide from rising correctly.

Not sure where you are (?) but we have 1 very knowledgeable member in the UK. {Boomer / George Garratt}
You might be able talk with him on the phone to pick his brain.
{NOTE: Please don't tell Boomer I said anything nice about him (evil grin)}

Here, we add a few ounces of 2 Stroke oil (TCW3} to our gas occasionally to prevent Ethanol problems. Seems to work good.

Unless you have the air mixture screw badly off, I wouldn't suspect that as the problem.
Just thought of something. On each mixture screw there is a tiny O-ring below the tiny washer.
Do all 4 carbs have that O-ring?

Ride safe, Ted
 
. . . . and close the pilot screws down to 1.5 turns, as I feel it's running a bit rich when idling, almost like the choke is on (chokes working perfectly, I've checked them) (y)

I think you are referring to:
16014-1054SCREW-PILOT AIR
(circled in red below) which are adjustable from outside the carbs. They each have a spring, washer and o-ring which need to be in the right order, and in good condition.

Different from:
92064-1101JET-PILOT,#35
(circled with blue below) which are NOT adjustable, accessible only with the carb bowls off. Pilot jets have very tiny openings that need to be clear.

Both these parts need to be in good nick on all 4 carbs to idle well.

1605822402475.png
 
Stash has the O-ring that I was describing circled in red..

On these carbs the needle Jett carrier must be installed from the bottom.
The needle Jett carrier (probably wrong name) that I mentioned is #16017.

Ride safe, Ted
 
Top