Free 1993 750 Night Hawk Help Needed

[No1uno]

This is my first post on this forum and right out of the gate my bike has issues, I was given a Nighthawk 1993 750 and it was sitting for two years under a tarp in my friends driveway. He gave it to me since I love motorcycles, he no longer ride being 87 and has health issues. So I was lucky enough to be gifted his trusty ole Night Hawk.
Now I got it home, bought a new battery and tried to turn the key and nothing, so this is what I have done so far.
1) Emptied the gas tank and put a little new gas in it
2) Bought a new battery and put in on the bike after I fully charged it up.
3) once the battery went in I did not see sparks come from the battery when hooking up the battery to the bike? I thought I would see something.
4) turned the ignition switch and nothing happened, it was like I did not even have a battery in the bike

So I just downloaded a manual online, does anyone have any ideas on what could be wrong so far? I just want to get it to light up first and they try to start it, to see how much work I have to do...

I am open to suggestions..Thanks in advance

Robert

 

[brettp]

I don't have that bike but if you put in a new battery and you get no headlights with the igniting on, or sounds like a main fuse off the battery is blown or your battery negative to the frame is bad.

 

[No1uno]

I don't have that bike but if you put in a new battery and you get no headlights with the igniting on, or sounds like a main fuse off the battery is blown or your battery negative to the frame is bad.

I will give that a try, and see what I find out. With a brand new battery I should see something happen. Thank you!

 

[No1uno]

The starter relay almost fell apart in my hands, so I guess I found the first problem!!

 

[brettp]

That starter relay is definitely one problem!

 

[No1uno]

I guess I should not complain about a free motorcycle, so I will order a new starter relay, then if needed a ignition switch... and go from there.
The carbs had no fuel in the bowels so it looks like a rebuild there. I will start posting pictures in case anyone is interested. So far team, thanks for the support!! Here starts my new journey with a Nighthawk!!

 

[slmjim n Z1BEBE]

Petcock is vacuum operated. It won't flow unless vacuum is applied to the opening diaphragm. Easy test is to connect a handheld vacuum pump to the vacuum port on the petcock. Doesn't take much, 5 inches. Hg. will easily do it. Open all the float bowl drain screws two turns or so to observe fuel flow.

EDIT: electrics on a Nighthawk aren't complex. Knowing basic DC electricity is a must. You'll benefit from using a multimeter & knowing how to use it. Throwing parts at a 'free' motorcycle to see what sticks is how the saying "The most expensive motorcycles are free." came to be.

Good Ridin'
slmjim & Z1BEBE

 

[No1uno]

Thanks for the word of advice yeah I’m an electrical engineer by trade and a DVM is like wearing a pair of glasses for me as far as the bike goes. I’ve ordered the manual shop manual for it and the relay I knew I was gonna need since it fell apart my hands in the ignition switch I did a DVM test nothing so I purchased not only start a relay the ignition but a carb kit because the bowls were dry. The floats are sticking and it needs a good rebuild on the carbs other than that that’s as far as I’ve gotten into it I am able to look at the shop manual. I’ll check everything out to make sure it’s functioning get her started and then I’ll do a deep dive into any other issues it may have , it’s a nice bike. It’s clean sat outside with a tarp on it for over two years amazing zero rust I think I’ll keep it.
Anyway, more to come with pictures as I move along, but I did find acorns inside the air cleaner and a snake skin and looks like an old rattler had use the backrest to pull its skin off because it was still in one piece, but that’s when the fun begins.
Thanks for looking more updates to come

 

[No1uno]

Well I bought a ultrasonic tank to clean parts and started to remove items off the bike. So at this point, looking for where you all get your parts for a Nighthawk? Any special websites I should know about?

 

[Biebs]

Honda dealer to start.

 

[No1uno]

1. Can I eliminate the vacuum lines on the Nighthawk 750?
2. It is a 1993. I want to get away from Vacuum lines as much as I can.
3. Sorry for not posting anything in a while, but work has got in the way
4. So now I am taking the carbs off, cleaning them up in a ultrasonic cleaner and rebuilding them. but I want to make the engine look very clean with out a lot of hoses.
5. So any help from anyone out there would be very helpful, even pictures would help. Let me know your thoughts. It does not appear there are many of them but I want to make sure I do it right with all of your help.
6. Any pictures you have of what you have done or you know of some one that has done it... I know the petcock has a vacuum and how do I by pass that situation? Thank you.
   
   Note:
   Just for fun I have included some pictures, pictures of the Nighthawk and it's brother a GL 1500 both bikes are 1993's

 

[kirky]

i put a normal petrol tap in the tank fixed a tube to the carb inlet rail and plugged up the vacuum carb , this got rid of all the vacuum set up.

 

[No1uno]

Do you have a picture of that? I would love to see it, and what did you do with the line coming from the top of the engine facing the carbs? from the rear...

 

[slmjim n Z1BEBE]

i put a normal petrol tap in the tank fixed a tube to the carb inlet rail and plugged up the vacuum carb , this got rid of all the vacuum set up.

Insufficient data.

What specific petcock & from where?

Good Ridin'
slmjim & Z1BEBE

 

[kirky]

i took away this vacuum gubbings and put a tap in the tank and tube direct to the carb inlet rail tube and blocked off the vacuum pipe on number 2 carb, bit dark in the garage but you can see the clip on the carb rail downtube ,don't know about your other pipe that comes from the engine mine just has the breather pipes

 

[No1uno]

i took away this vacuum gubbings and put a tap in the tank and tube direct to the carb inlet rail tube and blocked off the vacuum pipe on number 2 carb, bit dark in the garage but you can see the clip on the carb rail downtube ,don't know about your other pipe that comes from the engine mine just has the breather pipes

Thank you for the pictures, it makes it a lot clearer to understand with pics. Thank you sir

 

[slmjim n Z1BEBE]

i took away this vacuum gubbings and put a tap in the tank and tube direct to the carb inlet rail tube and blocked off the vacuum pipe on number 2 carb, bit dark in the garage but you can see the clip on the carb rail downtube ,don't know about your other pipe that comes from the engine mine just has the breather pipes

Doesn't look like a '93 CB750. If it is, what petcock is that & where did you find it?

Good Ridin'
slmjim & Z1BEBE

 

[kirky]

it isn't a nighthawk it's an FZ but all you do is screw a tap into the tank

 

[slmjim n Z1BEBE]

it isn't a nighthawk it's an FZ but all you do is screw a tap into the tank

Thread title is re: '93 CB750 Nighthawk.

The tank's bung & thread sizes are odd on '91 - '03 CB750 Nighthawk. A manual petcock alternative to the OEM-design vacuum petcock would be desirable compared to the crap chinesium items infesting fleaBay.

A post re: FZ isn't relevant & just confuses the issue.

Good Ridin'
slmjim & Z1BEBE

 

[kirky]

all the nighthawk tanks i have seen have a screw in tap like mine, so are these 1992 etc nighthawk tank pictures wrong and people advertising 1992 -3 tanks for sale selling the wrong tank?