Two-faced symptoms

[MisterCinders]

OK - ordered some parts to revisit this fuel flooding issue. These include, new oil filters (to change the gas/oil now and have some back ups), new needle seat o-rings, and some new valve needles from Z1.

After searching more forum posts, I think the plan of action will be to

a. "blow test" the float needle assemblies to see if they close;

b. drop the floats into some petrol to confirm they float and do so evenly;

c. massage the floats back to even level and plumb to make sure they aren't crooked or catching on something within the bowls;

d. replace the seat o-rings and needles with new parts for best sealing and even spring loads;

e. set the floats at the higher end of specs (about 25mm as best I can tell);

e. put the rack on a stand to test the valve seals and float levels with my drain/tube level tool;

f. even if there is no gassy smell in the oil, change the oil and filter to flush out any gas/oil mixture; and

g. be awesome.

 

[BigD_83]

Do you think the Mikuni Guide might be a typo? That is so wildly different than the other manuals

However, I checked in on a KZ forums, and one link to a photos with your carbs definitely shows 17mm being measured...

I also read about one case where the floats were hanging up on a bit of excess gasket sticking into the float bowl

 

[MisterCinders]

Do you think the Mikuni Guide might be a typo? That is so wildly different than the other manuals

However, I checked in on a KZ forums, and one link to a photos with your carbs definitely shows 17mm being measured...

I also read about one case where the floats were hanging up on a bit of excess gasket sticking into the float bowl

I included some new bowl gaskets in that order. Not sure if they are hanging up the floats, but having to go in and out of the bowls so many times, I just know I am going to tear one of the gaskets at some point.

Now that back ups are on the way, of course, my current gaskets will last forever.

 

[paco13]

Did you ever solve the rust in tank problem you mentioned in th OP?

Also, I check my needle and seats with a vacuum pump (mighty vac). Carbs inverted with just the weight of the floats on needles hook vac line to fuel inlet, see if holds vacuum. If not you can usually hear where the leak originates. Use drops of fluid in different locations 'til you find the source when it seals, slows the vac leak.

 

[MisterCinders]

The rust has not been an issue for awhile. Still need to do full clean on that tank, but the fuel flows clear with no rust or sediment.

 

[keman]

Forgive me if I missed it in the thread, but have you replaced the manifold orings between the intake tubes (after carbs) and the head? Those buggers can cause a world of bizarre symptoms when they leak.

Setting the screws for highest idle... The only way I could hear it was by starting 1 turn out, turning 1/4, wait a few seconds and listen. .. turn another 1/4 and wait a few seconds. .. repeat. .. on my bike, it took almost two seconds for it to change. Once I got a noticeable change, I back it off 1/8th and listen. .. no change, you're done with that one. If it changes, go back out 1/8th and call it done.

 

[MisterCinders]

Replacing the intake o-rings and those ****ty chalk screws with some SS Allen heads was one of the first things I did when I got the bike.

Blow tests on the float needles came back good. BigD may be onto something though. The bowl gaskets seem to jut into the bowl a bit, and they contact the floats. I will carefully trim those back and see if that frees up the float movement. If that fails (or, more likely, if I botch the trimming and mangle a gasket), hopefully the replacement gaskets are a better fit in the bowl.

I also pulled the floats themselves to straighten them out. They weren't too bad in shape. But when I reset the heights this time, I will reverse my process. Instead of setting the height and then evening the floats, I'll get them as close to parallel first at whatever height and then set the height with the tab.

Maybe that slow and steady approach to highest idle will break my impasse on that test. Once the oil is changed and the carbs aren't barfing gas, I'll try the turn and wait method to see if that gets results on those air screws.

 

[MisterCinders]

Update for posterity - still waiting on the oil filter, so I have not started the bike.

I messed with the float settings for ages though. Best I can tell, the bowl gaskets were too close to the floats in places and causing them to stick. I took an xacto knike to them and carefully shaved them back about 1mm to give more clearance.

Although I have not tested them on a running engine yet, static fluid checks show fuel sitting at the right level. They also stopped puking gas out of the overflows when I feed them petrol.

Fun tip: a handy thing to use for these "wet" tests is a metal tray that you use for paint rollers. I put the tray on the bench and then used a couple of wood blocks to stand the carb rack up. The bowls can drain (or flood) into the tray. The gas is not worth recycling except maybe to clean some parts, but its contained so you aren't splashing accelerant all over the garage.

 

[BigD_83]

Glad to hear that you are now pointed in the (Let's hope) right direction. Little things like that are quite frustrating when you know that everything else points to all being okay.

 

[MisterCinders]

Great, now I've come full circle.

Changed the oil and filter. Changed the gaskets and needles to eliminate the flooding problem. Set the floats at about 23.5 mm and did a static float test to confirm (i.e., using the drain plug tool, but not on a running bike).

Everything looks good, though one of the bowls still drips a bit at the drain screw. I am chalking that up to the bowl itself, since the float level shows up below the gasket line.

When I put the bike back together, I am back to fluctuating and hanging idles. Lean symptoms. Plugs are still pretty sooty. Another oddity, the bike struggles to start at first without some choke and tries to die when you close the choke. But . . . wait for it . . ., that hesitance vanishes if you blip the throttle. Thereafter, it idles without choke no problem except for hanging and wandering. The sputtering struggle to start is only at the very beginning and always disappears after it warms up for a minute if I do a little throttle blip. It's like the revs clear up the blockage or something.

Yes, my valves are good. I just checked them a week or two ago. All were still in very healthy spec clearances from last year's adjustment.

For the next go around, I have cleaned and will refresh my pods, in case that fuel flooding through them screwed things up.

I haven't found any air-leaks that might cause this, but to make sure I also double checked my intake boots and o-rings. My o-rings are new as of last year, and they looked fine. The boots are soft enough and have no cracks, etc. The o-rings were fine. I let the rings soak in some petrol for a half-hour or so to freshen them up, and then cleaned the boots and intake surfaces to put her back together.

As for jetting, my latest set up is:

Fuel screw - 1 1/8 turn out
Air screw - 1.5 turns out
Pilots - 17.5
Needle - 4th slot
Mains - 122.5
Float levels about 23.5 mm

Before this tear down, I had a slight richness problem with 15 pilots, fuel screws 7/8 - 1 turn out and air screws 2-3 turns out. Now I cannot get the idle to behave?!? I am loath to bring the floats down more, since the flooding problems. The flooding might just have been a sticky float issue, but I don't want to push the envelope there. Plus the level test looks good on the floats.

Will try again tonight with freshened and lightly oiled pods (they needed to air dry overnight).

 

[Nightcrawler]

Mister Cinders

I just read this whole thread, I hope my 550 doesn't go through anything like yours is going through now I would lose my mind. But to note I had a hairline crack barley noticeable in the overflow tube on the inside of one of my bowls. It caused a fuel drip outside the bowl about where you are describing yours. At first I thought it was flooding until after a few hours i noticed the fuel level was normal when I took off the bowl yet it was still dripping. I just plugged it and am looking for a replacement bowl. Is it more of a sweat from the drain plug or actually pouring out?

 

[MisterCinders]

Just a slow drip that forms at drain plug. I've been watching the sides to see if gas is seeping out and forming at the bottom. The sides seem dry, so I think it's just that bowl. The plug and oring are fresh, so I am ruling them out as culprits.

 

[MisterCinders]

Getting warmer.

Put it back together and the bike starts and idles nicely. No more hanging, the RPMs move up and down with the throttle very crisply.

Synched the carbs and took a stab at the highest idle setting. Then noticed the No. 3 carb dripping fuel from the pod. Shut down immediately, and checked the oil smell. Thankfully, there was no gas odor in my new oil.

Pulled the rack and dove into the float situation on that carb. Inspected the, float, needle and seat and bowl again for obstructions. There is some crude or oxidation on one part of the bowl that has never come out (despite soaking, scrubbing, etc.). Just in case that is somehow snagging the float, I took another bowl from my set of spare carb parts, soaked it, scrubbed it and sprayed to get rid of the dust and grime it picked up while sitting around. I also swapped out the float with a spare.

The needle and seat pass the blow test, and I have a fresh washer in place. The new float is just a hair thinner than the other one, and moves nice and smoothly on the pin. The new bowl is nice and clean with nothing that could possibly snag the float (though I am not sure the rough surface in the other one really did anything).

Upped the float level from 23.5 to 24.5. Checked the fuel level with my drain tube, it settled in nicely at about 1-2mm down.

Put it back together again. Bike started and idled well again, but I still see some fuel spurts from the No. 3 drain tube. Nothing in the pods this time.

Tonight, I'll dive back into that No. 3 carb. Up the float level some more to about 25mm (top of spec), and triple-check the needle/seat and float level. Something's got to give.

Note that all of this happens with the tank off and to the side of the bike at roughly the operating height (maybe an inch or two higher), connected with a long fuel line, and the vacuum line plugged. So my petcock has no opportunity to fail AFAIK (fuel cannot be flooding through the vacuum line, since it's plugged).

I considered the choke assemblies, but have cleaned them vigorously and they all seem to move smoothly on the springs. Plus, IIRC a stuck choke would leak fuel into the venturi chamber, not the bowl. So a stuck choke might have caused fuel to seep into the pod, but not overflow the bowl itself. Is that accurate?

The float is the solid rubber version, so it cannot leak or take on gas through a pinhole, etc. Other than tinker with the height and hunt possible snags in the bowl, I got nothing. The old gaskets might have been catching the floats, but the new ones are a better fit. Each time I put it back together, I scrutinize the gasket edges to make sure the float clears. It has solid clearance on all sides.

If I am just chasing my tail on this, I am open to other ideas on reasons for this overflow problem. If the needle and seat continue to check out, and the float is moving without snags, what the hell else could be causing that carb to flood?

 

[MisterCinders]

I may have rooted out the last problem here.

Pulled the carbs again to figure out what caused No. 3 to overflow down the tube. Removed the bowl and set the rack up in a large plastic oil drain pan I've been using to test leaks and float levels for the carbs.

Ran fuel in the line and lifted the float to see if it leaked. Turns out the needle in that assembly was sticking closed AND the new o-ring I put on the seat was failing. So fuel would dribble into the bowl and never stop.

Changed that O-ring, reset the float to about 23.5 mm, checked the fuel level, and retested without the bowl. Now fuel flows through the needle valve (not around it) and stops when you lift the float.

Huzzah.

Didn't have time to put the bike back together and test the carbs on a running engine, but (fingers crossed) things are looking better.

Still cannot believe that when rebuilding/cleaning these carbs 3 different times in the past, all I ever needed to do with floats was measure and maybe slightly adjust them. Getting the float situation right on this go around has been an ordeal.

 

[BigD_83]

Why was the needle sticking?

Why was the needle sticking?

"Turns out the needle in that assembly was sticking closed AND the new o-ring I put on the seat was failing."

Was there any indication as to WHY the needle was sticking? Was the o-ring so cockeyed that it was narrowing the seat space?

Good luck with startup. Sounds like you are almost there.

 

[MisterCinders]

"Turns out the needle in that assembly was sticking closed AND the new o-ring I put on the seat was failing."

Was there any indication as to WHY the needle was sticking? Was the o-ring so cockeyed that it was narrowing the seat space?

Good luck with startup. Sounds like you are almost there.

Not really. I have spare seats and needles, so I just swapped that set out for a set that moved more freely.

 

[Crankthat]

Saw a link to this post in a recent post i was reading. I was having a similar problem Carb leaking with my sisters honda after i had cleaned carbs. They were on 84? cm 450 with keikhin carbs. The carbs had a small (pipe) comming up from drain plug to normal fuel level so when they would overflow it would come out bowle drain plug-screw even when screw in closed position. The floats had no adjustment on them so i was looking at $72.00 a float after rechecking the float needles and seats a few times so i tried a few diffrent things first. Had a extra set of carbs for my 550 nighthawke all cleaned and wrapped in plastic the floats were diffrent but the seats and float needles were the same switched out still leaking went in for supper and not able to peel carbs off bike for another week so they sat with gas in them and not hooked up to tank. When i got back to the bike a week later it no longer leaked. My guess is that the rubber on the float needles had dried and mabye gotten harder then normal while not feeling so or atleast enough to stop needles from sealing correctly? Or might have had a bubble that had settled out during bike sitting have caused this? I dont know as i will ever know for sure but my float needles will forever after sit in gasoline while doing carb work... I know this is a old post but i thought it may help someone doing a search some day.