Topic: cb550f not running right

[a.raia]

 I have a1977 cb550f that was sitting for 25 years, tank and carbs were a mess, cleaned tank and carbs with new parts checked valves, new ele. ing., new plug wire caps,timing chain adjustment,ect. problem is at 4200rpm to 5200rpm she's not running right.bike has 16000 miles and real clean you can see bike wasn't run hard. Tony

[speedy gonzalais]

can we have a little more detail on what the problem is ?

[a.raia]

I had carbs off four times you can eat of them, floats are set 22mm timing is dead on, I had moved the clip on needle valve to the middle grove (2nd from top is factory) bike ran like it should , pulled rpms to 10000 but as I ran her  plugs fouled out in no time. with clip back in 2nd grove bike runs ok to 4200rpm , theres no back fire or popping but its not pulling right and I'll get a ratting noise ,( carbs were syc.) by 5200rpm she's pulling better but not like when clip was in middle grove, also from 5200 rpm she pulls till about 8500rpm which is not right for this motor

[TwoTired]

You say the you put new parts in the carbs.  Were these Honda Manufacture?   If not, did you check the dimensions/numbers on the new parts to make sure they were the same as those you replaced?

Also, carb tuning depends air filter restriction and exhaust restriction.  Are these the stock components on yours.  And, if the air filter is the stock type, is it more than a year old?

Another bit of info would be exhaust head pipe temps, as in are they equivalent?

Did you do a vacuum sync of the carbs, or bench sync?

Have you addressed the entire list of tuneup items on the 3000 mile maintenance schedule?

Cheers,

[Tower]

I'm going to assume you've synced the carbs and set the optimal idle speed.  (If not, then do that before running the tests below).  I'm also assuming that the main jet has already been selected for best top end power (above 7000 rpm) - this is the main jet that produces the highest top speed, or simply select the factory jet.  Also, the air filters are clean and exhaust pipes are in the final configuration for your intended use.

Needle clip height should be set for best power between 5000 - 7000 rpm. 
Test1: from 5000 rpm (3rd gear); then throttle up quickly and observe engine performance.
- If engine pulls better when cold, but soft when all warmed up, then its too rich in the midrange, so lower the needle one notch.

Test2:  in second gear give engine full throttle from 4000 rpm. 
- If engine doesn't accept this or feels sluggish (and it gets worse as engine heats up) then its too rich, so lower the needle

Test3: Give full throttle from 2000 rpm
- If engine bogs then accelerates (and this gets worse as engine heats up), then lower fuel height by 1 mm and/or reduce the fuel flow in the idle/pilot circuit.