Topic: 83 CB550, new to motorcycles and having no gas from tank

[JeVightHawk]

Hello yall, Childhood friend gave me his old nighthawk 550 about 5 years ago and its never ran since before, I attempted getting it running in 2018-19 but didn't do carbs and gave up and he hadn't ridden it since 2014 when he parked it and then never rode it again. So in 2021 I took it to a Moto friends house and he called me an hour after I left that it was running but very poor and said carbs need work. Life happened and I never went back to his house til a couple months ago when I brought it home. So it hasn't ran in over a decade.

I have automotive experience from automotive school back in 2009 and then working for an RX7 racing shop(Mariah Motorsports). Rode motorcycles but never fixed one or messed with Carbs. So I'm new new. But I've rebuilt a few engines and countless part rebuilds, competent enough.

Heres where I am at, forgive me and please educate me on how to post or what information you need passed this...

Compression tested and got about 130ish across but #2 was a little low(120), put some oil and they went up a little, so rings I found, but it was still running fine even then, wanted to at least get it running before tearing it open. Should I apply some rislone? Interested in pros and cons.

New spark plugs and wires, new battery, cleaned and flushed tank, new fuel filter, new fuel petcock back in 2019 when I attempted, new oil and filter, new air filter, new fuel hose, and I removed, cleaned and rebuilt carbs.

Started up and ran, high idle I adjusted down to about 1,100-1,300rpm. I took it around the block and it ran fine. Came back, put on my old gear and took it around a few blocks. Lots of backfire then it started hesitating off and on until it had nothing from throttle. Like it was starving or lean. Each time it did start, if I touched the throttle it would just die out. I noticed zero gas coming into the fuel filter. I took tank off again and found big chunks of rust I must have missed, so I cleared it again, bought new petcock as old one had no filter, still nothing. No debris in slightest from filter nor fuel in filter at all.

I have set both old and new petcock from On and reserve.

I checked airbox and found boots were leaking so I sealed them up tight. Still nothing from the fuel tank into fuel hose. On here I found sucking on air hose should help flow, nothing.

I took carbs off again and checked everything inside, nothing I could find from rebuild. I put stock jets back on, PO had bigger jets on but stock airbox and exhaust. I set the mixture screws exactly same as they were by counting the turns in then backed each out same.

Questions:
Would out of sync carbs cause a no start AFTER it was already running for a bit?

On an attempt to get it to turn over BEFORE I pulled carbs and rebuilt, something happened and smoke came up from ignitor, smelled electrical and was worrisome, but then after rebuild it started up. Would that throw off timing or just not work at all?

I bought the 3 step tank cleaner by KBS I was gonna do this week but figured it should still start with flush I did, maybe just do it and see if that helps?

I have spark on all plugs, 1 and 3 were ashy while 2 and 4 were black and rich, I believe?

Should I look into adjusting the valves?

I only have one key so will copy to have another one tomorrow to open tank and try and start it.

Is there anything small I might be missing? I've replaced big parts in cars only to find a fuse or hose was malfunctioning. Any small ideas to try?

Any help is very appreciated. Its confusing cause it had fine power and was running well enough until it wasn't at all.

Once again I apologize if my post upsets anyone who's been here longer or I've left some information out. Not expecting an easy solution. I will rebuild top end if need be. Was hoping for over winter though considering I live in PNW and sun is running out.

Thank you the time it has taken you to respond.

[scottly]

Welcome! This forum is mostly for the SOHC bikes, but we do have an "other bikes" section, where this will be moved.
It seems you have enough compression, so I wouldn't worry about anything mechanical like valves or rings. I would concentrate on carbs and fuel supply.

[Sw1ssdude]

Do you have a picture of the petcock? is it vacuum operated? Older hondas have a straw-like fuel strainer in the tank, which usually is stuck in the petcock bung of the tank, cemented in there with sedimented rust particles. try to get that out, or: put your gas tank over a tub, and fill it with some gas, and see if the petcock or the stuck strainer is the problem. if it flows without petcock, your strainer is okay, if not, the plug is inside the tank. also: make sure you have flow both with gas cap and without.

inline filters are an endless source of problems. if your fuel line swings up even slightly before it goes down to the carbs, you have a siphon that traps air, and blocks flow. flicking the hose with your finger usually get things moving. with inline filters, this problem is almost infinite times worse. whats also not helping is the fact that during the tune-up-phase, most people have very little fuel in the tank, so the fuel pressure from gravity is just not high enough to ensure proper flow (during regular operation, people start to experience the same issue when fuel level drops).

if you have vacuum petcocks, find out if they have a 'prime' position. on this position, a little cam puts pressure on the vacuum diaphragm, making sure there is flow even without the engine running.

[Don R]

 You will get mixed reviews on additives and inline filters. I've experienced the inline filter non-flow and even posted a video of it once. Others have run them forever with no issues. I've had some luck with Marvel Mystery oil freeing up stuck valves, lifters etc, I've also used some Rislone from time to time with only anecdotal evidence that it did anything, it may have freed up the starter gear on my GL1000.

[Don R]

 The carbs can be cleaned without a total disassembly, drop the bowls pull the jets and emulsion tubes and spray carb cleaner through the jets, air bleed inlets and passages while observing where the cleaner comes out.   

[grcamna2]

I like the 83' CB550SC Nighthawk and looking forward to you getting this bike nice, Welcome.

[JeVightHawk]

WOW!!!! I feel so incredibly stupid! my fuel hose was too high and long so I cut off 2-3in and bike started right up. Thank you Sw1ssdude, your comment saved my headache. Ill be sure to post in correct section next time.