CB750 Nighthawk doesn't sound right.

[Bogs]

1. Carb sync, DONE
2. installed 4 new spark plugs, after few weeks of runing ended up with 2 busted plugs.
3. 1 exhaust pipe had a hole.

What seems to be the problem?

 

[brettp]

What are your symptoms? I didn't really hear anything wrong.

 

[Bogs]

What are your symptoms? I didn't really hear anything wrong.

Doesn’t sound like an inline four engine

 

[brettp]

Start the bike see if any of the headers are staying cold. They get hot pretty quick so start feeling them immediately. If you have a temp gun, that is good, too. If all four pipes get hot, those cylinders have combustion and your sound is the result of your exhaust. Drilled out, rotten, debaffled, etc.

 

[Biebs]

You have a cylinder not firing. Check exhaust temp for each cylinder. Plugs fouled??
When you ride it does it kick in 3000 rpm?? And above??

 

[Bogs]

You have a cylinder not firing. Check exhaust temp for each cylinder. Plugs fouled??
When you ride it does it kick in 3000 rpm?? And above??

I have it checked, 2 plugs are busted.
Yes, it kicked 3000rpm above

 

[Bogs]

Start the bike see if any of the headers are staying cold. They get hot pretty quick so start feeling them immediately. If you have a temp gun, that is good, too. If all four pipes get hot, those cylinders have combustion and your sound is the result of your exhaust. Drilled out, rotten, debaffled, etc.

I haven’t checked if all pipes are getting hot. But there’s a hole in number 3 pipe. I’ll update once i have it fixed (the pipe hole)

 

[brettp]

If you have 2 plugs busted, that's probably it. But after the new plugs are in, check those headers to see if all 4 are getting warm.

 

[Bogs]

Repairs:
No 2 exhaust pipe hole - patched/welded
Fresh 4 new plugs - before the 2 plugs are busted
Re-synced carburetors

 

[brettp]

Sounds WAY better. All cylinders getting gas? All headers getting warm?

 

[Bogs]

Sounds WAY better. All cylinders getting gas? All headers getting warm?

Yes!!! All cylinders are getting gas and all headers too.

 

[brettp]

Enjoy the miles!