12 replies to this topic

[maccers]

I am recommissioning a 998cc running an HS4 carb. I have stripped it all and replaced a few components where fuel has dried and glued. The float needle and valve seat cleaned up nice and work smoothly now when dry. 
Just curious what is the tiny spring loaded pin on the bottom of the valve? Is there an internal valve there within the body of the valve? Or is something to do with the clip that’s connected to the plastic float?

[Tds76]

I’m guessing that it is the one used to lift the piston up to check it drops easily and mixture setting.

Cheers, Paul.

[nicklouse]

I am recommissioning a 998cc running an HS4 carb. I have stripped it all and replaced a few components where fuel has dried and glued. The float needle and valve seat cleaned up nice and work smoothly now when dry. 
Just curious what is the tiny spring loaded pin on the bottom of the valve? Is there an internal valve there within the body of the valve? Or is something to do with the clip that’s connected to the plastic float?

Picture? Sorry your words are not really leading to a part that exists. There is no spring on the float. There is a spring on the piston lifter but your words don’t match that.

[maccers]

I’m guessing that it is the one used to lift the piston up to check it drops easily and mixture setting.

Cheers, Paul.

 

So that one I found and is on the body of the carb. The one I mean is the tiny little needle that sits inside the fuel bowl, and is responsible for moving up and down as the plastic float rises and falls, and as it does so slides into a seat that either stops or allows fuel in. On that tiny little valve is an even smaller tiny pin that pushes in and out. I was just wandering the purpose of it. Does it operate a second smaller valve within the main, but still small valve..!?

[maccers]

This bit..! Arrowed.. 

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[nicklouse]

This bit..! Arrowed.. 

that is a new one on me. Sure all mine were solid.

[nicklouse]

 

This bit..! Arrowed.. 

that is a new one on me. Sure all mine were solid.

 

I see that there are now spring and unsprung versions available.

[coopertaz]

new ones with the neoprene tip do have these i thought it was to do with maintaining position into seat. i know the float arm does press on it but that was all i could think of. always worked ok though so never bothered about it, and never had problems with sticking which used to be a problem many years ago

[mad4classics]

I think it was added as an anti-vibration feature.

[maccers]

Cheers all for the input. The float is working fine now I have cleaned it and the brass seat, was a bit sticky following a 5 year lay up. Was just wandering about the small pin. 

[slidehammer]

It is there to regulate pressure on the seat / needle tip (it gives a bit of wiggle room before damage to the needle tip will occur)

[Miki Leyland]

Interesting... my only concern is if these would be also reliable in time

[Spider]

There were some I believe after market Needles that had this feature. It appears to me it was fitted in an attempt to get the Needle to seat harder in to the Seat. I found this style of Needle none too good or long lasting.