Topic: Leaking carbs / fixing the float. 550k1

[turin39789]

While I was tracking a problem with my ignition wires awhile ago, I got sidetracked and ended up playing with my carbs.  Did a minor clean-up and some new rubber and put it back together.  For a few rides I had gas coming out of my overflow tubes, and was forlorn, but the problem fixed itself.  Unfortunately I also managed to lose my reserve tube at some point during the process.  My petcock was a bit leaky anyway, so I got a used one off ebay, it doesn't leak, used some teflon tape to be sure, and now I have reserve again and I'm not going to be running out of gas again.


I installed the new petcock, and the overflow tubes are leaking again.  It was just #3, but I pulled it out yesterday and they were all doing it.  Some rubber mallet hammering and it looks like I'm down to just #3 again.

Do I need to pull the rack and check the floats?  I didn't do much with them last time I had the carbs off, I floated them in water for awhile and sprayed with wd 40 and remounted.  I couldn't find a shop that sold the fancy measuring calipers you always see in pictures to measure float height.  I started to try with just a ruler, but couldn't quite figure out the procedure.  Do I need to mock the carbs up on a stand so they sit level? where exact to measure etc.
 It has been pretty cold out here, but I don't think the overflow tubes would have cracked. 

I have a new set of insulator boots on hand, and I'd like to think that I'm going to go outside, pull the carbs and bring them in for an hour and be ready to go and slide them back on, but I remember how much the reinstall sucked.

So, should I pull them or hope it autocorrects?  If I pull, what needs to be checked and how?


Brrr it's cold outside, but I'm doing work around the house today and it would be nice to have it fixed for when it warms up or I feel like freezing myself.

Thanks

\

[Kevin400F]

If you don't have inline fuel filters, it is quite likely that when the petcock was being replaced, some bits of crud got dislodged and are now sticking in the float seats.  Sometimes you can leave the drain screws open and let a fair amount of fuel flow through the carbs to flush out the junk.  I tried that maneuver with my CL160, but it turned out to have flecks of solid junk that wouldn't go through the float seats.  Ultimately, I had to pull the float seats out and pick the junk out. 

[turin39789]

If you don't have inline fuel filters, it is quite likely that when the petcock was being replaced, some bits of crud got dislodged and are now sticking in the float seats.  Sometimes you can leave the drain screws open and let a fair amount of fuel flow through the carbs to flush out the junk.  I tried that maneuver with my CL160, but it turned out to have flecks of solid junk that wouldn't go through the float seats.  Ultimately, I had to pull the float seats out and pick the junk out. 

Yea, no inline filters.  I've thought about it but my tank always looked clean, and I can't for the life of me find 5.5mm fuel line.  I've seen a few sections up on ebay, but I think it gets pricey.

Do I need to pull the carbs to pull the float seats?  I'm trying to imagine doing it upside down while it's still on the bike.

[05c50]

Yeah, You could probably pull the float bowls off in the bike,but it's not worth the effort. Pull the rack,so you can have a good look at whats going on. I second the vote for the fuel filters. I don't care how clean a tank is,crud can get in and screw up the needle and seats. You should be able to buy fuel line from any local metric bike shop. They sell it by the foot. When you set the floats, you don't want the full weight of the floats on the needle (theres a little spring in the needle) Stand the rack on end and just let the floats put a little pressure on the needle. It's not that hard to set the floats with a ruler. Just take your time. By the way.....it's cold out here too- 14 degrees !
   Stay warm

.....Paul

[SteveD CB500F]

I can't for the life of me find 5.5mm fuel line.  I've seen a few sections up on ebay, but I think it gets pricey.

I've used 6mm fuel pipe quite successfully. You can buy it everywhere. Get the 10mm O/D stuff.

[turin39789]

Yeah, You could probably pull the float bowls off in the bike,but it's not worth the effort. Pull the rack,so you can have a good look at whats going on. I second the vote for the fuel filters. I don't care how clean a tank is,crud can get in and screw up the needle and seats. You should be able to buy fuel line from any local metric bike shop. They sell it by the foot. When you set the floats, you don't want the full weight of the floats on the needle (theres a little spring in the needle) Stand the rack on end and just let the floats put a little pressure on the needle. It's not that hard to set the floats with a ruler. Just take your time. By the way.....it's cold out here too- 14 degrees !
   Stay warm

.....Paul

Guess it's time to put on some shoes and get the carbs in. 


It's a balmy 18 here right now.  I've checked the local honda and suzuki dealer, but they only have 5 and 6mm.  I might call some of the others. What's the general filter most use?  I have some plastic in line filters for my VW, might see if theyw ill work.

[pollpegj]

5mm will work fine. I actually used 5mm from an aircooled vw supply website because it has a nice braided outside covering.

[turin39789]

5mm will work fine. I actually used 5mm from an aircooled vw supply website because it has a nice braided outside covering.

I might try that, I have about 6 feet of that stuff laying around already.

[turin39789]

Alright, it's officially too damn cold to be working on the bike. 

I have it parked outside the front door so I can run back in and check up on the game.  I got as far as removing the tank and loosening the screws on all the boot clamps.  Then I got too cold to think and forgot how to get the carbs off.  I pushed and pulled on them some, can't remember if I'm supposed to take the front boots off with the carbs or not.  Then two of my fingers fell off, and I came back in to superglue them back on.

I'll look through the forum for the standard procedure to get them off, but if anyone has gotten good at it and wants to explain their procedure, I wouldn't mind hearing it.



 

[Gordon]

I'll look through the forum for the standard procedure to get them off, but if anyone has gotten good at it and wants to explain their procedure, I wouldn't mind hearing it.

Getting them off isn't usually much of a problem, that is unless the rubber boots are frozen solid.  I'd suggest a hair dryer or heat gun to soften them up some first. 

[TwoTired]

The K1 came with a perfectly good, very very fine mesh in tank fuel filter mounted right on top of the fuel petcock.  There is nothing that can get past that, that can't get through any working jet orifice in the carburetor simply by running the engine.  Adding an in line filter is a near worthless addition and may actually be a detriment if the the fuel line routing leaves air pockets to slow or disturb the gravity fed fuel path.  Plus, you just added another maintenance item to check periodically as they clog up as they trap particles.
If you don't wish to examine the in tank filter itself, you can tell if it is doing its job via two methods.  One is the remove the float bowl from a carb.  Pick whatever carb is doing the overflow thing, to see if sediment/crud is present to block float valves.  The second method is place a clean shallow pan under the carb bowl drain screw, open it and examine the drainage for anything other than clean fuel.

If you find crud in any of the bowls then you must determine its source.  Are your carb vent lines clean, clear, and properly routed?  If so, then it is time to scrutinize the in-tank filter for integrity to see just how bits of crud get to your carbs.

All this can be done easily with the carbs still attached to the bike, and is far easier than taking the carb bank off, and back on, cold and old rubber couplers.

But, if you like taking things apart, I'm sure not going to stop you.

Cheers,

P.S.  Yes, it is possible to check/adjust float height with the carbs in place.  I've done it a few times. Good and proper tools are most helpful. Care and understanding of what the needs are, is rather essential, I would think.

I've explained the cb550 carb removal and installation procedure several times on this forum.  If you can't find it, I'll do a search.

[Deltarider]

The K1 came with a perfectly good, very very fine mesh in tank fuel filter mounted right on top of the fuel petcock.  There is nothing that can get past that, that can't get through any working jet orifice in the carburetor simply by running the engine.  Adding an in line filter is a near worthless addition and may actually be a detriment if the the fuel line routing leaves air pockets to slow or disturb the gravity fed fuel path.  Plus, you just added another maintenance item to check periodically as they clog up as they trap particles.

Couldn't agree more. I once had extra in-line filters and they caused nothing but trouble. If I may add a suggestion, if you change your old fuel lines for new, have them as close as possible to the original, both in diameter as in length. You'll find their dimensions specified in the Parts List that covers your model. Although harder to find maybe, Ø 5,5 mm is available.

[Deltarider]

One more tip. I've made it a habit to drain floatchambers every two months. Not completely, just a little bit. It's best done after the bike has been standstil on the centre stand for a day or more. You'll get rid of particles that by that time have sunk to the bottom of the floatchambers, close to the exits. 

[turin39789]

Blargh.


I fought the carbs off, drained the bowls, there was some crud in each. 

Tried my first float adjustment, it seemed like they were all adjusted to 25mm or more, spec is 22 so I believe I corrected them. 

Got them back together, twisted old insulator boots off, put new ones one, tried reassembly, cursed, fought and twisted new insulators off, went to store, bought some vasoline and then put carb on in air cleaner first, then added the insulator boots, got it all together, put battery back in, hooked up everything, last of the daylight is fading.  Got the tank on, and she fired up, and one of the carbs is still leaking out of the overflow tube like a sieve.

Rode up and down the street anyway, wished I'd put my jacket on first.  Pulled into the drive shivering, and there is a neat little line showing my path and a small puddle under the bike.  Turned off bike, made post.  Cried about 3 hours of wasted effort(I'm slow).

Do I just try this again, track the carb that is leaking and adjust the float to a larger or smaller gap?  pick up a new float valve?

Thanks

[BobbyR]

If it is leaking from the overflow tubes, it could be a crack in the overflow tube inside the floatbowl. This has been reported a few times.

[turin39789]

If it is leaking from the overflow tubes, it could be a crack in the overflow tube inside the floatbowl. This has been reported a few times.

I kept an eye out for that, but the tubes have looked fine.  I know the cracks are suppsoed to be small, so it's possible I overlooked it, but I did check both times I've had the carbs off.

Right now I'm thinking I either need to take the carbs off again and increase the float height which should make it close earlier, but that seems like a work around instead of an actual fix, or to get a new float valve, but I've heard that they pretty much don't go bad.  Right about now is when twotired usually comes in and sets me straight and tells me to stop babbling.

[TwoTired]

You mean getting to ride the bike didn't warm the cockles of your heart?  You should at least give yourself a pat on the back for getting that derelict moving under its own power!

It's all just details now.

Did you replace all the orings in the carbs?  Did you find the source of he crud you found in the bowls?  How do you know more crud didn't get in the carbs again to block the float valve ... again?

A progressive diagnostic approach.  Stop when you find the issue.

One.  Do you know which carb is leaking?

Two. To isolate a cracked stand pipe, swap the bowls with a carb that isn't leaking.  If the leak follows the bowl....

You can remove the bowls while the carbs are still on the bike.  The inner bowls are easier if you take the outer one off first.  Correct length screwdrivers are a must.  If you don't have the correct length, go buy a new one that does.

Three.  Verify the correct float height setting at 22mm.  Don't reduce setting on whim.

Four.  Ensure that you have not installed a float upside down.

Five.  Examine the float needles and seat under magnification.

Six.  Did you replace the oring for the float needle seat.   Did you do it correctly?

Seven.  Float needles and seats CAN go bad.  But, it isn't common.  You've got three other carbs that don't leak, right?  Move the suspect one to another carb.  Does the problem follow the part?

Some Zen:
I've never heard of any emotion making a bike (or machine) run better or worse.
Isn't your bike a learning experience, or intended to be a relaxing hobby?  It's just another puzzle to figure out.  Mental exercise and manual dexterity tuning. Do you really think you are done having those "AHA" moments in life?  Aren't those enjoyable? Do you think you or your bike will ever be...perfect?  Aren't you closer to your goal than you were yesterday?

relax

Breathe in,  Breathe out.

If a leaking carburetor is the worst thing that happens in your life, you are truly blessed.  No need to cry over spilt ... gas.

Cheers,

[turin39789]

snipped to keep the thread short

Ah!  Love the Zen. When's the book coming out?

The o-rings got replaced in november, and at that time, my in tank fuel filter was lost, the carbs got leaky but then freed themselves up.  Just got a newtome petcock and filter, and after installing I got the leak back, so I'm hoping the crud came when I wasn't running the filter and should be stopped now.  I pulled the bike out a week ago in cold weather to try the "hit carbs with rubber mallet to free up float" trick, and more than one carb was leaking.  Some pounding got it back down to one, #3 I believe and I'll check to see if thats the one still acting up.

I'll run through the swapping test, just need to locate the right screwdriver.  I'll take pictures, and if I don't figure out the problem I might actually go to the trouble of posting them.  I should have a few hours of daylight this week to work on it.

[turin39789]

just wanted to update this thread before I start the new one for the new problem.

It wasn't the tubes.  I ran up to sears and got a stubby phillips screwdriver, took #3 and #4 bowls off, both looked pretty clean, a few black dots floating around but they were small.  I swapped the bowls, no change. 

I think I figured it mostly out before I swapped, but it's bee n a week and I can't remember my exact thought process.  Anyway, I was peering in and the float on the #4 seemed to be closing up right, but #3 was my leaky guy, so I managed to find an angle where I could observe the float hitting the needle, and it wasnt!  The float was set right, but the needle was being pushed up, and was getting stuck/bound and not falling and was allowing gas by it.

 I started to order new ones, but just took the floats and needles out, swapped them amongst the carbs, and they were working fine.  Swapped them back to where they started and they are doing just fine.  Reinstalled and I'm looking good, go for a short ride around the block. 

Sounds a bit funny and now I have a new problem for a new thread. #1 doesn't seem to be firing and gas is leaking from the exhaust welds.  Tune in next time for another episode of my bike always breaks on nice days.

[turin39789]

One last issue for this thread - The thread was made because my #3 carb was pouring gas whenever the gas was on.  I got this fixed playing by wiggling around the stick needle valve and it appears to be fine now.

Now my #4 is overflowing, but no constantly like #3 was.  Every 30 seconds while idling on the center stand it will squirt our a 1/3 cup of gas in a spurt and then stop, 30 seconds later repeat.  I'm planning on getting it back apart and rechecking the float and everything else I can see while the carbs are on the bike, but wanted to see if someone could pinpoint it on that description.

[TwoTired]

took #3 and #4 bowls off, both looked pretty clean, a few black dots floating around but they were small

Do you think one of those black dots could be blocking the float valve from closing?

Fuel isn't supposed to have black dots in it, BTW.

[StevenA]

Hi folks. This is my first post on the forum but I've been messing around with old Honda's for a long time. I noticed someone said "no use crying over spilled gas." A couple of years ago I was working on a 74 550. Just got it running but not very well and went for a short ride, about a quarter mile from my house. I did not have the breather box on it or overflow tubes since it was the first test ride. I had done this many times with other bikes in the past. When I stopped to turn around the bike was sputtering and gagging. I looked down at my engine and gas was pouring out of at least one carb. Within a few seconds, one backfire and flames were licking my legs. I was wearing shorts at the time! I knew I had a half tank of gas and I wasn't going to wait for the explosion so I dropped the bike on her side and stood back 100 feet or so and watched her burn to the ground. It's amazing how much stuff burns on a bike. I live pretty much in the woods here in Canada, no other houses around so I didn't get into trouble with the law but watching that bike burn was the polar opposite of that great feeling when you finally get one of these old bikes going.   

So be warned. Do not mess around with leaky carbs! Track down that problem and fix it before you move on to other issues. I know I was very lucky but unless you want to see your bike burn, be very carefull with gasoline. Most of us don't ride with a fire extinguisher. I really liked that bike too. Still have it but it's pretty much "TOAST".

Steve.

[Bob550four]

Pull your carbs, clean em well.  DO NOT put em back until you've got inline filters.   

I spent nearly a month trying to come up with a rebuild kit, and THEN realized my bike was running like crap because I didnt have a fuel filter on carbs for 1+2, so some junk got pulled in, and was making the floats stick open.   

You CAN pull the bowls while carbs are on the bike, its not completely simple. but you can do it.  I used a screwdriver bit, a little ratchet and the 1/4" socket to pull the bowls, since that allowed the space needed. 

  I'm going to be replacing my screws with allen heads soon to make it easier in the future.