Official Nighthawk thread

[Meter Man]

Originally Posted by AZbiker

Also make sure the boots going from the carb to the airbox are soft rubber--exposure to the elements hardens the material and then you won't get a good seal. Also the manifold from the carb to the motor shouldn't be cracked--that can also let air in.

The reason it runs good on the choke is that you're running lean. Either this is the result of a plugged pilot jet (just buy a new jet when you get the carb apart, only costs $5-7), or air entering the system at another place besides the air filter.

My bet is the the pilot jet. You should be able to pull the carb, clean the carb, replace the pilot jet in a few hours if you are slow, an hour if you have done it before.

[Purcell69]

I need some help troubleshooting a no-start issue with my 1985 CB700SC. The other day when riding home from work, I stopped to fill the tank about 15 miles from home. The bike had been running flawlessly for the past 30 miles. When I went to restart the engine, I push the start button and nothing happened. The headlight dropped out of circuit, but no click from the starter relay. Everything else worked as it should. I tried to push start, but there were no signs of life.

I have the bike home now and have tried cleaning the start button with electrical parts cleaner. No change. I can jump between the starter solenoid and the + terminal on the starter motor, with the key on and the clutch pulled, only the have the motor crank over but no spark. The Run/Stop switch is in the "Run" position and does not get used.

Suggestions?

-Joe

[Ailkel]

Hi Joe,

Have you checked the fuses and the fuse block? I have seen some really weird things on motorcycles.

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[Purcell69]

Originally Posted by Ailkel

Hi Joe,

Have you checked the fuses and the fuse block? I have seen some really weird things on motorcycles.

Sent from my Motorola Electrify using Tapatalk 2

Yep, I checked those while I was waiting for the wife with the truck and trailer.

I was playing with the test light this morning and found that with the key on, clutch switch bypassed, and the start button pushed, I only get power to one of the two poles that should be powered when the start button is pushed. I looks like it is a bad start button/switch.

-Joe

[Purcell69]

The "start" button is bad. I picked up a momentary switch from the auto parts store and wired it in to the right switch harness. The bike starts and runs perfectly again. I just need a more permanent solution, since this switch is not weather proof. I bought a used right switch assembly on E-Bay that will get me back to OE, but it's still almost 30 years old. I am thinking about trying to install the starter push button from a newer Nighthawk in the 1985 assembly. At least then I would have a new switch.

-Joe

[Ailkel]

Good troubleshooting. Hopefully the used switch will work out without the need for any mods. After all all vehicles run on used parts.

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[AZbiker]

Originally Posted by Purcell69

The "start" button is bad. I picked up a momentary switch from the auto parts store and wired it in to the right switch harness. The bike starts and runs perfectly again. I just need a more permanent solution, since this switch is not weather proof. I bought a used right switch assembly on E-Bay that will get me back to OE, but it's still almost 30 years old. I am thinking about trying to install the starter push button from a newer Nighthawk in the 1985 assembly. At least then I would have a new switch.

-Joe

Would probably be better to go with new(er) switchgear if possible. My HawkGt had a killswitch from a Duc and a 1/4 turn throttle. 1/4 turn throttles are FUN.

[njpaddler]

Originally Posted by Purcell69

The Run/Stop switch is in the "Run" position and does not get used.

That, my guess, is the problem. If it never moves, never gets used, likely the contacts are corroded and not passing current through. Using it keeps it clean.

I'd take it apart and first check it with a meter before doing anything else, then clean it thoroughly.

[Purcell69]

Originally Posted by njpaddler

That, my guess, is the problem. If it never moves, never gets used, likely the contacts are corroded and not passing current through. Using it keeps it clean.

I'd take it apart and first check it with a meter before doing anything else, then clean it thoroughly.

The "Start" button was worn out. Cleaning it did nothing, but I was able to resolve the issue with a $5 momentary switch from the auto parts store, wired in place of the "Start" button. It is not weatherproof, but it's getting the job done for now.

I have purchased a used right side switch assembly, which hopefully has a good "Start" button. I am considering getting a new right side switch assy. from a later model Nighthawk, either to see if I can fit teh "Start" button from the new assembly into the old housing, or just use the new gear as-is.

-Joe

[jimmycorp]

Hey guys, new guy and recent lurker here. Taking my MSF next week and thinking of getting an 84 700s for my first bike. I'm 6'2 and 270, wondering if this bike would be a good fit?

Thanks!

[njpaddler]

jimmycorp,

Absolutely. I bought a 1985 650 as my first bike & I'm 6'3". I still have it. I also bought a 1984 650, and I still have it, too, if that answers your question ...

[RABBIT170]

So whos going to be the first to instal the 41mm Dual Disc Brakes Forks/Rim off the new CB1100 onto a Nighthawk 750?

[jimmycorp]

Originally Posted by njpaddler

jimmycorp,

Absolutely. I bought a 1985 650 as my first bike & I'm 6'3". I still have it. I also bought a 1984 650, and I still have it, too, if that answers your question ...

I'm assuming this is smaller physically than a 700s?

If so thanks for the input!

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[Purcell69]

Originally Posted by jimmycorp

Hey guys, new guy and recent lurker here. Taking my MSF next week and thinking of getting an 84 700s for my first bike. I'm 6'2 and 270, wondering if this bike would be a good fit?

Thanks!

The S is a great bike. I've been riding for 36 years now, mostly what is now considered "Dual Sport". I picked up a gently used S this May and I absolutely love it. Around town, at 6k RPM and below, it is very well mannered. When you open the throttlewide and she hits 7k, the bike begins to accelerate very rapidly, this happens again as you pass 9k. Save that for a time when you have more experience and lots of open road ahead.

Originally Posted by jimmycorp

I'm assuming this is smaller physically than a 700s?

The 1985 CB650 is dimensionally almost exactly the same as a 1984-1986 Nighthawk S.

-Joe

[jimmycorp]

Originally Posted by Purcell69

The S is a great bike. I've been riding for 36 years now, mostly what is now considered "Dual Sport". I picked up a gently used S this May and I absolutely love it. Around town, at 6k RPM and below, it is very well mannered. When you open the throttlewide and she hits 7k, the bike begins to accelerate very rapidly, this happens again as you pass 9k. Save that for a time when you have more experience and lots of open road ahead.



The 1985 CB650 is dimensionally almost exactly the same as a 1984-1986 Nighthawk S.

-Joe

Thanks for the input! Going to check out an S in a couple weeks, once I do my MSF course. Wish me luck!