95 Nighthawk CB750 no power

[Eric Stewart]

Just purchased a 95 Nighthawk CB750 with 17k miles. Prior owner purchased 5 years ago and drove it for 1 year and then it sat in his garage for 4 years. When I purchased it wouldn't start. Extremely clean and very nice. Paid a commensurate non-running price. Put new battery in and was able to start at idle but that was it.
Took to my local motorcycle repair for carb cleaning. They have cleaned them and now starts fine but does not ever generate full power. After picking up would not go over 60. The choke doesn't really matter where it is for power. When it is warm and you take choke off it idle revs to 4k.
Mechanic says it may need a carb rebuild kit to resolve.

I have had same model of Nighthawk in the past and really like them. I know they have plenty of power when working right.

Any ideas on what this issue is?

 

[brettp]

What did the shop do to clean the carbs without a rebuild kit? Did they reuse the old float bowl gaskets?
How does the bike behave trying to get above 60? Does it act starved for fuel? Does it cut out like losing power?

 

[Eric Stewart]

What did the shop do to clean the carbs without a rebuild kit? Did they reuse the old float bowl gaskets?
How does the bike behave trying to get above 60? Does it act starved for fuel? Does it cut out like losing power?

I assume they reused all the gaskets and needles. Just has no power. Goes slow to get to 60. Full throttle gets you to 60 and no more. Fairly smooth with no power. If I leave it in lower gear can go the same 60 or maybe a bit more

 

[brettp]

I'll bet the carbs' piston valves need a good polishing. Sounds like they aren't sliding up easily.

 

[Biebs]

Sounds like the shop that did the carb cleaning just added SEAFOAM or other carb cleaning solution to gas tank.
How much $$$ did they charge you??

Clogged jets

 

[brettp]

Jets are easy to clean and I bet the shop did that (but who knows). The piston valves (that hold the needles) are what carries you through the mid range, and I doubt they touched them. That's why I suspect those need work.

 

[Eric Stewart]

Sounds like the shop that did the carb cleaning just added SEAFOAM or other carb cleaning solution to gas tank.
How much $$$ did they charge you??

Clogged jets

Some other items but $700

 

[BIKERDAD]

Wow .that's a chunk .. im going to have to take a look at cleaning mine as I don't have that sort cash ...

 

[Eric Stewart]

After three months in the shop and a compromised on repair bill, all problems came down to a vacuum/emissions hose that was not correctly routed!
But I have a lot of new parts, that weren’t needed, that will surely keep the bike running for many years