Carbs - Lack of power

[Sexysuzi]

Hi,

I have a GS550, all standard, 1979 with VM carbs.

A few weeks ago my bike lost power - slow to increase revs, idles fine.

I have since stripped and sonic cleaned all parts, including new o-orings all round. As per the guides on here.

I still have the same problem. As soon as the bike reaches 4rpm, it struggles to gain more revs. Could this be lack of fuel or air?

Couple of questions.

1. Should I try adjusting the air intake of the fuel screw?
2. Should I increase the height of the needle?
3. How do i tell if the bike is to rich or lean? I have looked at the plus and these look ver clean - lean.


If anyone who can reach gatwick, west sussex, help me, I am prepared to pay the going rates!

many thanks

[Nessism]

How's the maintenance status? Adjusted the valves lately? Checked the points? Bike running on all four cylinders? I could go on but think you get the point.

[Sexysuzi]

valves and points are fine.
- running on all four.

[Nessism]

If the bike was running perfectly before, then it's not a jetting problem. I wouldn't mess with jetting or adjustment. Maybe the petcock?

[Badooka]

Wires going bad or coil-

[Sexysuzi]

How do I test the coils ?

[barnbiketom]

petcock or loose vacuum line leaking vacuum or perhaps in tank filter?

Run it in prime and see if it gets better!

process of elimination logic based.