Topic: Dad's 1978 Honda CB550k

[joegeis]

no good. I put it all back together and carb three started leaking again right away. I guess I'm doing a full carb breakdown and cleaning now?? Should I replace the float and needle? The ones in there are Keihin and look fine to me...

[denward17]

^I think I would be looking at the gas tank as well, to check for loose sediment.

[joegeis]

Okay, I whole-assed it today, taking the carbs out and giving them a good run through:

1. Fully disassembled and cleaned each carb, blowing out all passages with carb cleaner and compressed air
2. Polished all brass (I did not do this last time, not sure if this makes a difference at all, but since I was in there...)
3. Polished the float needle seat (I didn't do anything to this area the first time I went through the carbs. It made a BIG difference)
4. Replaced all floats and float needles
5. Set float height to 14.5mm

I tested on the bench for leaks and everything looked good (using gas I had poured into a clear container to ensure there were no debris)

Next I went to inspect my fuel. I drained pint or so from the tank (using both main and reserve) and noticed a fair amount of debris in it. Then I checked my gas can, which also had debris in it! It got late so I stopped for the night. Later this weekend I'll empty and rinse both the tank and the can. I truly think the gas tank is in pretty good shape. There was no visible rust at all from the opening. My plan is to remove the petcock and run water through the tank until there is no more debris. Then I'll spray it out with compressed air refill with fresh gas. Is that good enough? Is there a better way to get all the water out? Or should I not rinse with water?

[denward17]

When I cleaned my tank, it soaked with Evaporust for a couple of days, then with petcock off, I used a water nozzle to put a little pressure with the water and rinsed very good.

I used compressed air to get most of moisture out, then put petcock back on, then added about a quart of rubbing alcohol and rotated tank many times.

Then emptied and compressed air again, then fuel.

[newday777]

Next I went to inspect my fuel. I drained pint or so from the tank (using both main and reserve) and noticed a fair amount of debris in it. Then I checked my gas can, which also had debris in it! It got late so I stopped for the night. Later this weekend I'll empty and rinse both the tank and the can. I truly think the gas tank is in pretty good shape. There was no visible rust at all from the opening. My plan is to remove the petcock and run water through the tank until there is no more debris. Then I'll spray it out with compressed air refill with fresh gas. Is that good enough? Is there a better way to get all the water out? Or should I not rinse with water?

Did you take pictures of the debris?? Is it rust, black chunks, old gummed gas? Or what is the debris??

[newday777]

As cal says, water isn't a good rinse. It's very hard to get it all out ss it seeps into the lower seams of the tank and starts rust in the seams.
My recommendation, get 5 gallon bucket of Evaporust and fill the tank full, close the cap and let it soak 2-3 days, empty through the petcock opening( remove the petcock) then shake out through the lid. Then rinse with a gallon fresh diesel fuel,  shake well to collect and rinse out the residual Evaporust, drain into a clean 5 gallon bucket through the petcock hole(remove petcock), pour in another fresh gallon of diesel fuel(not what you dumped out as it has to settle a couple days to separate), shake again  and dump into the 5 gallon bucket, repeat another rinse at least once, 4th time is better(I just buy 5 gallon of diesel). Diesel fuel has oil in it to help curb flash rusting. Then wipe out the tank with a flexible grab stick with a clean rag to see it anything is is the tank. Then pour in 3-4 oz of 2 stroke oil and swish all over the tank to coat it well(prevents rust). Then drain out the excess (a little bit in the gas doesn't hurt and lubes the carbs, you can add an oz every other fill up as preventative maintenance.

[joegeis]

Here is the debris. The gas is pink because I added a little Marvel Mystery Oil to the first tank. This was drained from the petcock without the filter in line. Now that I think about it, when I removed the petcock, I don't believe it had a strainer on the end. I haven't been able to find a rebuild kit specific for my model (maybe a previous gen kit would work?). I have the single outlet that faces 180 degrees away from the valve, back towards the engine.

What are you doing with all the scrap diesel fuel??

[joegeis]

Okay, I'll drain and add evaporust for a couple of days. Thanks!

[newday777]

Once the Evaporust settles to the bottom of the bucket in the diesel fuel, I carefully bucket out the good fuel back into a fuel can to use another time.

Evapo-Rust The Original Super Safe Rust Remover, Water-based, Non-Toxic, Biodegradable, 5 Gallons https://a.co/d/cx5ldqs

[joegeis]

I fully drained the tank and put in the 1 gallon of evaporust that I had on hand. I sloshed it around really well. I'll let the tank sit normally for a few hours and then flip it upside down overnight.

Only a couple more tiny pieces of sediment came out, so I'm hopeful it's not a bad situation.

I'll drain the evaporust tomorrow and see how it looks. I'll probably just rinse with gasoline since I have it on hand.

[newday777]

I fully drained the tank and put in the 1 gallon of evaporust that I had on hand. I sloshed it around really well. I'll let the tank sit normally for a few hours and then flip it upside down overnight.

Only a couple more tiny pieces of sediment came out, so I'm hopeful it's not a bad situation.

I'll drain the evaporust tomorrow and see how it looks. I'll probably just rinse with gasoline since I have it on hand.

It has to be full to do the full soak.......

[grcamna2]

I fully drained the tank and put in the 1 gallon of evaporust that I had on hand. I sloshed it around really well. I'll let the tank sit normally for a few hours and then flip it upside down overnight.

Only a couple more tiny pieces of sediment came out, so I'm hopeful it's not a bad situation.

I'll drain the evaporust tomorrow and see how it looks. I'll probably just rinse with gasoline since I have it on hand.

It has to be full to do the full soak.......

+1

[joegeis]

The tank was put in storage full, I believe with ethanol free gas. That makes sense about the top being most likely location for rust to form. I'll flip the tank and soak the top.

[newday777]

The tank was put in storage full, I believe with ethanol free gas. That makes sense about the top being most likely location for rust to form. I'll flip the tank and soak the top.

It'll run out the vent.

[joegeis]

The tank was put in storage full, I believe with ethanol free gas. That makes sense about the top being most likely location for rust to form. I'll flip the tank and soak the top.

It'll run out the vent.

HA, yeah, I just learned that the hard way! Lost a few ounces before I realized it   

I'll lean it on its different sides and keep sloshing it around.

[joegeis]

I was looking for a sock filter / strainer for my petcock, and I think maybe the one I have is off a CB750. The one I have looks like this. Because it is riveted, I believe it is not rebuildable. It is working fine, but I can see that the o ring is pretty squishy and there was no strainer on the straw, and I'm not sure which parts will fit this one.
Is something like this going to fit?

[grcamna2]

I was looking for a sock filter / strainer for my petcock, and I think maybe the one I have is off a CB750. The one I have looks like this. Because it is riveted, I believe it is not rebuildable. It is working fine, but I can see that the o ring is pretty squishy and there was no strainer on the straw, and I'm not sure which parts will fit this one.
Is something like this going to fit?

I like the OEM Honda fuel petcock best. I usually 'go on a hunt' for an NOS or good used part to replace what's missing;part numbers are good to locate the ones you need. The filter screen is #16952-388-005 and it includes the rubber seal.

[joegeis]

Okay! I drained and rinsed the tank today. There was some rust "powder" and a few small pieces that came out. I used gasoline to rinse the tank a few times. I did this until I got no more sediment whatsoever. I then filled the tank with fresh fuel and the carbs are no longer leaking! I ran the bike for 10 minutes at idle and no issue! Yay!

It was having a hard time holding a steady idle though, even once warm. I would set the idle at 1,800 and then rev it. It would want to stick at 3,000, it would slowly come down with a little coaxing by lowering the idle speed screw and then it would drop a little too low and I would have to raise it back to 1,800.

I decided to take a temperature reading at each exhaust header. 1&3 were at ~215 deg, #4-175 deg, but #2 was only at 115 deg. The exhaust felt cool to my hand even. Does this mean #2 is not firing? Or something else? What would be my next steps to troubleshoot?

[joegeis]

Plug was dry and didn't smell particularly strongly of gas? Below is a picture. Maybe I'm just throwing money at the problem, but I did just buy new coils, plugs, caps and sparkplugs. I went with the Sakura coils from PartsNmore #17-6823 based on a recommendation from Hondaman. I bought caps from the same site (NGK FD05FP and XD05FP). I still have Hondaman's ignition to install as well, which I'll do when I receive these new coils.

I ran it pretty good through the neighborhood today, getting the engine up to 6k RPMs. It continued to struggle with holding a steady idle. I had it warm at 1,800 before leaving and a few minutes later at a stop sign, it was idling at 3,000 again. All cylinders were at 220 degrees except #2, which was at 135 after the 10 minute ride.

I checked for spark and was getting spark, but it was orange, not blue. Given I have done literally everything feasible to the carbs within the last week, I'm not sure what else I can do.

[BenelliSEI]

That plug looks dry and I agree with above. Check see there is fuel getting into the float bowl. Did you “bench sync” the carbs? Put vacuum gauges on them yet?

[joegeis]

Yes, gas drains when I open the drain screw with the petcock on. I did "bench sync" when putting the carbs back together again, but it did not needed adjustment. I vacuum synced them right before taking them off the last time, but have not done it since the recent cleaning/polishing, when I also replaced the floats and float needles.

Going back and looking at my posts from when I was trying to sync the carbs last time, and I did an exhaust temperature check, #2 was fine, it was actually #3 that was low temp, which is fine now!

[RAFster122s]

You would not be the first, nor the last, to pull a float bowl to find a jet either loose or in the float bowl. Start with your cylinder exhibiting the issue...likely no need to mess with any others.

[BenelliSEI]

You would not be the first, nor the last, to pull a float bowl to find a jet either loose or in the float bowl. Start with your cylinder exhibiting the issue...likely no need to mess with any others.

Or an upside down float….. don’t ask me how I know.

[joegeis]

okay, I'll get my short screwdriver and try to get the bowl off without removing the carbs again 

I'll report back this afternoon!

[grcamna2]

okay, I'll get my short screwdriver and try to get the bowl off without removing the carbs again 

I'll report back this afternoon!

I like small allen-head screws(better than phillips-head)for float bowl screws;it helps to remove them when the carb. rack is installed.  Make sure not to over-torque them,which will strip the small threads.