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Louie, Technician
Category: Motorcycle
Satisfied Customers: 12675
Experience:  25+ yrs. experience
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My Honda 750 Nighthhawk works perfectly up to a speed of 65

Customer Question

My Honda 750 Nighthhawk works perfectly up to a speed of 65 miles. Then one cylinder stops working. If I continue the speed, the engine stops. After a while it is possible to start it again, but it does it reluctantly. But when I have succeeded to start it, it works like before the problem startet. So I wonder what can be wrong. The spark plugs may be? Or something else?
JA: How many miles are on the car? When was the last time the plugs were changed?
Customer: 22 000 miles at all. 2 000 after change of plugs.
JA: What year is your 750?
Customer: 1993
JA: Are you fixing your 750 yourself? What have you tried so far?
Customer: I mainly fix it myself also changed the plugs.
JA: Anything else you want the mechanic to know before I connect you?
Customer: Don't think so. I have had the Nighthawk since 2011. There have been no other problems with it.
Submitted: 2 months ago.
Category: Motorcycle
Expert:  Louie replied 2 months ago.

Hi and welcome to JustAnswer, I’m Louie. Sorry you had to wait awhile but I’ll do my best to help.
Initially, have you checked the burn colors of all the spark plug tips? ...cleaned them or better yet replaced recently?

Customer: replied 2 months ago.
No, I haven't. That may be a good start. I'll do that and contact you later.
Expert:  Louie replied 2 months ago.

Yes please and an update when able.

Customer: replied 2 months ago.
The spark plugs look fine. Now I think there might be something wrong with the carburetor.
Expert:  Louie replied 2 months ago.

Drain each of the carb bowl separately top a suitable container through the drain hoses by loosening the bottom drain screws.

This would allow checking and comparing fuel quantity and quality of each carb.

Of course the prescribed approach is carb pulldown for soaking, cleaning, float check/adjustment and possibly balancing.

Customer: replied 2 months ago.
The engine runs fine as long as I don't push it to hard, so I'll use it as it is in these few summer weeks. In winter I'll take out the carbs and clean them properly. I'll contact you later when I have done it.
Expert:  Louie replied 2 months ago.

I understand.

Good luck and thank you for the opportunity to share the information.