Street bikes - Hi. Restoring a 2001 Honda 750 Nighthawk.

Hi. Restoring a 2001 Honda 750 Nighthawk. Wrote up what I've done to get my thoughts straight. ..

Hi. Restoring a 2001 Honda 750 Nighthawk. Wrote up what I've done to get my thoughts straight. Much work done - if needed.

Without the gas tank, bike purrs like new now - using funnel into aftermarket gas line with gas filter. With the gas tank on, no luck. Opened the gas cap, no luck. Disengaged the vacuum hose, to see if gas was rerouting into the engine and flooding it again no luck. I took off the tank again. Set up my funneling system, and it fired right up, she is purring. Questions are:
1. The Vacuum hose. Should the suction be into the engine or into the Petcock? When not connected, I get an occasional ppfffttt of white smoke (Sea Foam used).
2. Is it the Petcock? I have disassembled and cleaned. Any suggestions around this?
3. How much suction occurs into the carbs? Can't see how that is the problem but...
4. Would it be worth trying a rolling start popping the clutch into 2nd gear? (Never failed as a kid but not young anymore).
Many thanks.
- Emptied and cleaned gas tank (nuts/bolts soap water repeated until clear of rust, comp air dry)
- Replaced airbox, plugs, battery
- Pulled carbs 4 times now. They are spotless. (Boiled them the last time after stripping everything. Noticed gas residue lines were different on the floats indicating at least two were bad. Replaced all four. Also, noticed float valves were sticky. Oiled and cleaned them until they were smooth. Everything else spotless and clear.)
- Disassembled and cleaned the Petcock. No obvious issues here.
- Removed in tank gas screen. Opting for glass, in-line gas filter.
- Replaced Honda gas line with aftermarket 14 line to accommodate the gas filter.
- General cleaning, changed oil/filter, tire pressure etc.

Are there 2 outlets on the petcock?
Has the petcock been removed from the fuel tank?
If not using the original fuel line for auxiliary fuel. Have you blown compressed air through it?
Glenn.

Hi. Yes. There are two outlets/vents. See attached. I did remove it from the tank - I broke it down cleaned it. Did not blow air through the new line -- works fine with funnel. Attaching doc I wrote with pics at bottom - better explaination of what was done.
Thanks Glenn.
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Some background including details from original note.
I have a 2001 750 Nighthawk that sat for 3 years. In getting it road-ready, here is what I have done so far.
- Emptied and cleaned gas tank (nuts/bolts soap water repeated until clear of rust, comp air dry)
- Replaced airbox, plugs, battery
- Pulled carbs 4 times now. They are spotless. (Boiled them the last time - after stripping everything. Noticed gas residue lines were different on the floats indicating at least two were bad. Replaced all four. Also, noticed float valves were sticky. Oiled and cleaned them until they were smooth. Everything else spotless and clear.)
- Disassembled and cleaned the Petcock. No obvious issues here.
- Removed in tank gas screen. Opting for glass, in-line gas filter.
- Replaced Honda gas line with aftermarket 14" line to accommodate the gas filter.
- General cleaning, changed oil/filter, tire pressure etc.
After all this, I was feeling pretty defeated and tired of pulling the carbs, installing the carbs, cutting knuckles, swearing not to do it again, and worst of all, siphoning the tank and reattaching it each time I wanted to try my next experiment - only to have the bike stall within a minute or so of starting it up - with choke.
So, last week after reading everything I possibly could and getting pissed off that I couldn't figure it out, I went to the NAPA and purchased two cans of Sea Foam and a good funneling system. Got home, removed the tank, taped the new funnel into the gas line, taped the whole unit onto the frame and slowly started dumping in the sea foam mixed with new 93 octane gas. Within two evenings of doing this, the bike was running consistently with the choke engaged. (Almost smoked my neighbors out of their houses though.) So, I kept at it every night and now, with no choke at all, the bike fires up like the day I bought it - brand new. Sweet. And once it is warm, it fires up well through the rpm range. There is still an occasional, low, pop in the exhaust but the sound is exactly right otherwise. (you know what I mean, I hope. I've owned several muscle cars and I can tell you when a mustang is going by without seeing it - same thing with the exhaust note from the bike, it sounds right).
Yesterday, checked the oil and it was now very dirty. Assumed that was the result of the Sea Foam so I ran to the dealer for an oil filter. While there, I spoke the repairs manager and asked about the inline gas filter and he said shouldn't be a problem - they do it all the time. But he mentioned to make sure not the crimp the vacuum line when putting the tank back on.
Went home and reattached the petcock and gas tank. Same as before - ran for a minute and then died.
Note: So I got to thinking that while doing the Sea Foam process I did noticed that if I held my thumb over the vacuum hose, it idled a little bit better. And when I didn't cover it, it would occasionally spit out a burst of white smoke same as exhaust except not so much - just an pppfffffftttt (hope that made sense).
This morning, with the gas tank still on, I tried again. No luck. So I opened the gas cap, still no luck. I then disengaged the vacuum hose, to see if gas was rerouting into the engine and flooding it - again no luck.
So, I took off the tank again. Set up my funneling system, and it fired right up! That sweet sound. Used the choke to start it for maybe 10 seconds, then no choke and an engine that is saying, get me on the road.
Still pissed, I decided to write this up and see if you can confirm that my problem is now somewhere between the gas cap and the fuel line and possibly suggest some magic bullet to finish this off.
I know this is long but trying to give you the right information.
Questions are:
1. The Vacuum hose. Should the suction be into the engine or into the Petcock?
2. Is it the Petcock? I have disassembled and cleaned. Any suggestions around this?
3. How much suction occurs into the carbs? How can I determine if that is the cause - obvious to me that there is not enough gas getting into the system - at least timely.
4. Should I just roll it down the hill and forget it at this point? (a joke)
5. Would it be worth trying a rolling start - popping the clutch into 2nd gear? (Don't think so but thought I should ask - that never failed me as a kid but I am not young anymore)
FUNNEL and FUEL LINE

The vacuum line to the petcock will come from the carb/intake boot on engine side. The vacuum pulls at the diaphragm inside of the petcock.
You can do this with the fuel tank on or off of the bike. Petcock attached to the tank with enough fuel to cover the petcock filters inside of the tank.
:Attach the fuel line to the fuel outlet at the petcock. Be sure to catch the fuel as it should flow if the petcock is good with this test. Use a separate hose or pull the one off of the carb/intake and attach it to the vacuum inlet on the petcock. Use a vacuum tool or simply place your lips on the hose and suck. Fuel should flow.
Does it?
Glenn

Okay. Didn't taste too good but done. Had to twist petcock and retighten to get close enough without kinking the line. Used extra fuel line (5" or so), attached vacuum line and balanced over a 5gal paint bucket. Sucked for about 3-5 seconds. Had about 1.5-2.0 ounces of gas afterwards in bottom of bucket.

The hose tasted bad? You should not have had to taste any fuel..
This tells you that the petcock os working.
The vacuum line that attaches to the petcock while the tank is installed.. Where is it attached on the engine, intake, carbs?
Picture maybe?

I think I tasted fuel because I had to turn the petcock. The hose definitely has an exhaust-type smell but one I would expect - I think.

Excellent picture.
Do you feel that the fuel flow that you saw come out of the petcock is enough? The flow should be steady.
When you put your finger over the vacuum hose attached to the intake, does the suction there seem to compare to the suction used on your petcock test?
You could put the tank back on the bike. Attach the vacuum hose to the petcock. Run the fuel outlet into the container and see if the fuel flows.

That is a good question. It was hard to see exactly. How about this. Based on everything I've told you so far, it sounds like you're leaning towards a problem at the petcock? I'm thinking that might be the problem except for Q1 below. So, last couple of q's if you don't mind.
1. When running with just the funnel, I get occasional "blowback" from the vacuum tube - white smoke which I think is the Sea Foam as it looks same as the exhaust. Sounds like ppsssstttt with wisp of smoke. Does that tell you anything? If so, what might be the correction.
2. Earlier you mentioned blowing through the new line. Can do. Just curious, what does that do?
3. I'll break the petcock down again make sure everything is seated well. Then try running the tube into a bucket to see what happens. If that seems good, what next?
Really appreciate your help Glenn.
Thanks.

1. The blow back is a miss or backfire.
2. Blowing through the line to be sure it is clear. You had mentioned after market in the first post and I was unsure if this was the same hose attached to the fuel tank when in operation.
3. It seems good already.. Was the fuel flow steady. Reinstall the tank. Attach the vacuum hose to the petcock. Run the fuel outlet into the container and see if the fuel flows while cranking. The engine does not have to run. It will pull enough vacuum.
Glenn