Clutch problem possibly??

[Dumbquestionguy]

Hi I have a 1981 cb750k it's been doing good lately runs really strong but when cruising at about 45-50 I'm doing like 5 to 6 thousand rpms it also won't idle down at lights stays at 3,000 any help would be appreciated

 

[mrtwowheel]

Not enough slack in the throttle cables or a vacuum leak at the cylinder port or carb boots. Do a search on vacuum leaks, they can do serious engine damage.

 

[Loose Chain]

It sounds like two different problems. The high RPM at 45-50 sounds like you may have a slipping clutch. Is the clutch adjusted properly? If the clutch has been slipping for a while it might be too late for just an adjustment. How many miles on the bike. The high idle, mrtwowheel has it covered.

 

[Dumbquestionguy]

It sounds like two different problems. The high RPM at 45-50 sounds like you may have a slipping clutch. Is the clutch adjusted properly? If the clutch has been slipping for a while it might be too late for just an adjustment. How many miles on the bike. The high idle, mrtwowheel has it covered.

The bike has 2500 It also has awful Murray carbs but that's all I have so this is what I'm working with

 

[Dumbquestionguy]

Not enough slack in the throttle cables or a vacuum leak at the cylinder port or carb boots. Do a search on vacuum leaks, they can do serious engine damage.

Can I use carb clean to look for vacuum leaks

 

[brettp]

Yes you can

 

[stevewaclo]

When this happened to my ‘93 CB 750, the issue was failed spacers between the carbs and the head. All were causing vacuum leaks. Happened on spring startup.

 

[Dumbquestionguy]

When this happened to my ‘93 CB 750, the issue was failed spacers between the carbs and the head. All were causing vacuum leaks. Happened on spring startup.

Like the carb boots where bad I just put new ones in might need to tighten them down more

 

[Dumbquestionguy]

It sounds like two different problems. The high RPM at 45-50 sounds like you may have a slipping clutch. Is the clutch adjusted properly? If the clutch has been slipping for a while it might be too late for just an adjustment. How many miles on the bike. The high idle, mrtwowheel has it covered.

I don't think the clutch was on adjustment and I'm trying to figure out how to adjust it

 

[Dumbquestionguy]

Not enough slack in the throttle cables or a vacuum leak at the cylinder port or carb boots. Do a search on vacuum leaks, they can do serious engine damage.

I've been looking into it and since I have crap Murray carbs the a/f is probably off clutch needed adjustment and I haven't checked it but I beet i got a big air leak some where bike is running extremely lean

 

[Loose Chain]

I have crap Murray carbs

Are they crap, or maybe you don't understand them?

 

[Dumbquestionguy]

I've been looking into it and since I have crap Murray carbs the a/f is probably off clutch needed adjustment and I haven't checked it but I beet i got a big air leak some where bike is running extremely

Are they crap, or maybe you don't understand them?

Both I'm not smart enough to tune them and they dit come tuned even though he yelled at me not to touch them which I didn't so I'm worried now they could be my issue with the bike running to lean

 

[brettp]

Both I'm not smart enough to tune them and they dit come tuned even though he yelled at me not to touch them which I didn't so I'm worried now they could be my issue with the bike running to lean

Murray does offer help, I believe. But check for air leaks around the manifolds by spraying carb cleaner while it runs.
And when was the last valve job?

 

[Dumbquestionguy]

Murray does offer help, I believe. But check for air leaks around the manifolds by spraying carb cleaner while it runs.
And when was the last valve job?

I'm guessing around600 miles ago it has new gaskets I might pull it off to check valve clearance here what Mt plugs look like there running rich

 

[brettp]

Yes, they are. I'd be looking at coils and timing now.

 

[Dumbquestionguy]

Yes, they are. I'd be looking at coils and timing now.

Just had the bikes charging system replaced other than the coils
I should mention the bike has 2600 miles on it

 

[Dumbquestionguy]

Yes you can

No leaks around the boats or anything

 

[Dumbquestionguy]

Update. Bike is fixed I suck at tuning carbs a synching

 

[brettp]

You'll get better at it.