SOHC.co.uk Forums > CB500/550

What is the spring for?

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petersy:

--- Quote from: Bryanj on March 19, 2015, 04:13:38 PM ---Its so the pressure stays when the floats are bounced by the supersmooth roads

--- End quote ---

Just taken the carbs off my CB550 K1 again (which I could have done without).
After taking the float bowls off and turning the carbs upside down, I lifted each float in turn and let it drop back onto the needle valve.
One float sprung back (off the spring in the valve) and the other 3 just dropped flat.
So I'm assuming that the tab on the float spindle is pushing the (weak) spring into the valve 'before' pushing the valve up into it's seat - hence the valve not completely closing and my carbs overflowing.
I'll take acloser look later.

petersy:
Further to my previous post:

I'm assuming that I might need new float valves but they are not cheap.

Having looked on eBay I found these:

http://www.ebay.co.uk/itm/AFTERMARKET-CARBURETTOR-FLOAT-NEEDLE-VALVE-HONDA-CB550-CB-550-74-78-NEW-/281612951431?pt=UK_Motorcycle_Parts_13&hash=item4191709f87

They definitely do not look like the ones in my carbs.

Has anyone tried these before or is the eBay listing incorrect?

mike the bike:
They sound better than your existing ones, go for it.
When setting the float heights, adjusting the tab on the floats, remember not to compress that float spring atreat all.  I stand mine up on end to keep the weight of the floats neutral.

petersy:
Once the bank of carbs were off, I put them on he work bench with inlet ports facing upwards, which leaves the tab lightly touching the sprung needle.

After checking them in this position, all the heights were 22mm.

When blowing down the fuel line and then pushing the floats upward, the airline is blocked on all carbs, so I assume that it is the weakened springs that is letting the fuel through and causing the carbs to overflow.

petersy:
Ordered new set of four float valves for £35 compared to £64 at David Silver.
Waiting for them to arrive and get them fitted, to see if it solves the overflow problem.

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