Stay up amal float versus original

Has anyone had actual experience of the original plastic type floats used in mk 1 concentrics either melting or affected by ethanol?
I only ask I believe that was the reason for amal bringing out the stay up type floats
I have never seen any damage but I only use 5% ethanol when I was running amals on my Norton

baz said:

I only ask I believe that was the reason for amal bringing out the stay up type floats

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That, and possibly because the hollow floats had/have the tendency to split usually along the joint line allowing fuel to seep into the float.

L.A.B. said:

That, and possibly because the hollow floats had/have the tendency to split usually along the joint line allowing fuel to seep into the float.

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Have you ever seen one split or melt because of ethanol?

baz said:

Have you ever seen one split or melt because of ethanol?

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No, only without Ethanol (pre-Ethanol petrol as far as I know) and before StayUp floats were introduced.

I've run them short periods with upto 10% ethanol with no determental effects. Were fitted when I got bike so likely about 50 yrs old. Now have premiers fitted but still have the original carbs with same floats working fine when taken off two yrs ago.

another positive attribute of the stay-up floats is the ability of the bowl fuel level to be adjusted by simply bending the metal tab.
I don't believe the hollow plastic floats lent themselves much to bending which instead required shifting the needle seat around in the bowl drilling.
Stay-up floats are a win win without detriment in my opinion.
All the best.

I am still running the original floats in my Amals have had no problems and can't see any reason to change, I was running PWK carbs for a while but have gone back to my Amals, the Norton seems to run better with the old Amals, have never had any problems with float height using them.

Ashley

My mate was saying that he'd seen a long term test maybe on "triples online" where it was found ethanol had no effect on the original floats? hence my question

baz said:

My mate was saying that he'd seen a long term test maybe on "triples online" where it was found ethanol had no effect on the original floats? hence my question

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I guess if someone has an old float kicking around, try soaking in ethanol laced fuel for weeks or months to put this baby to rest.

Non Oxy fuel has only been available here for about 10 years. The E10 fuel has no effect on the old plastic floats.

Years back I had an original float hairline crack letting fuel into it . Vibration likely .
Nowadays stay up floats , superior .

baz said:

Have you ever seen one split or melt because of ethanol?

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I've seen leaking plastic floats with and without ethanol. I had a Trident driving me crazy before I realized that the center carb float was not floating due to being full
of fuel. At that time, the gas was probably either E0 or E5 - don't remember.

I have not seen one melt.

I collected over 200 Amal carbs planning to refurbish and sell them. I disassembled them and checked the components. Quite a few plastic floats when thrown in a bucket of water eventually sunk. When I started refurbishing the carbs, I realized that it was not cost effective and all the new parts cost way to much.

This is worth reading: https://amalcarb.co.uk/ethanol-fuels

Ethanol has been around for a very long time and Amal has provided tuning info on the percentage of alcohol as long as I can remember. In the late 60s I often added denatured alcohol and/or "white gas" to my tank as it was less expensive that regular gasoline. Never had a float problem - of course, the floats weren't old.

Still got the original white plastic floats and use E10, no issues.

I had "brown" plastic floats, when I have got the bike in 1986, when the bike was warm the idle was not stable, because one float was slowly filled up with Petrol. Once I discovered some petrol in the float when I looked at it with lamp. Now with the white plastic floats no problem so far.

Marcel