1975 Honda cb550F sputtering through all ranges

jtsierra77

jtsierra77

New Member
1975 Honda cb550F

We've done pretty much everything to the carbs i think we can cleaned, rejeted them, checked float heights, even adjusted the valves. Still getting sputtering through all the range, and after driving for about 30 minutes it stalls when I get to a low speed. When I get it started again it then struggles to get to 45mph, but if i let it sit overnight it runs decent again, but sputters and then when i ride about 30 minutes same power issue. Anyone have any suggestions where to go from here?
 
you aren't saying anything about ignition
you need a strong consistent spark to make boom boom
also, check that fuel is flowing properly, clogged fuel tap or vent in cap can cause wicked problems
 
thats the first thought I had as well, but there is no history being given on the bike or any pics
 
See if the coils are noticeably hotter when it starts to mess up. I would bet that's why it runs fine after a night of cooling off.
 
As said earlier, may be fuel starvation.
Try running with the fuel cap cracked open.
 
alzcbz said:
As said earlier, may be fuel starvation.
Try running with the fuel cap cracked open.
Click to expand...

This. Start with the simple things first, move to the more complicated things last.
 
As long as your running stock airbox and pipes ....with clean carbs....make sure each one has gas in it by cracking the bleed screws........coils/ timing points etc should be next .....unless you need a battery have a janky fuse low compression and no cam lobes....good old 1975.... Hopefully it was the gas cap thing rite....
 
Seemed to be getting fuel when we checked, but I will look further into these suggestions. Thanks.
 

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Another picture. I had trouble finding a stock air filter, so I changed to pod filters. I have heard several times that velocity stacks are easier to tune. Any thoughts on that?
 

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put the stock air box back in and get a filter, not that hard to find. then get it running right.
Pods could be your problem....? but its hard to tell because you may have multiple problems and just compounded with pods
 
Definitely go back to the stock airbox. Pods don't deliver consistent equal air to all 4 carbs as well as the airbox. Also, cheap pods tend to restrict airflow altogether.

The carbs also need to be sync'd with a manometer if you can.

Double check timing, valve clearances and sync the carbs.
 
550 coils were junk when new, 40 yrs hasn't done them any favors.
You can make K&N filters work and get MUCH better fuel economy (40+mpg vs 25mpg)
Of course, if you putter around at 30~40mph it is possible to get 50+mpg with stock carbs and airbox
 
On my 550 the condensers were bad and only showed issues after riding around a bit. When they got hot they started not working properly causing sporadic weak spark. Sounded exactly like whats going on with your bike.

May want to check the plug wires too.
 
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