Bloody ethanol fuel

[Rob Farmer]

Whipped the carb tops off my airhead yesterday to alter the needles. Both diaphragms have swelled up making them very difficult to get back in. The fuels a nightmare

Anybody else having problems with it?

 

[Elvisto]

Yes Rob, I had the same problem a couple of weeks ago, fortunately i had a couple in stock,

I realised what had happened because I'd read about it some time ago on a US site, Randal Washington (RANDAKKS)

I think someone said they would have to start making parts from Viton or was it Nitrile, i'll try and find the write up

 

[Rob Farmer]

I believe the genuine BMW diaphragms are ethanol resistant but a lit of the aftermarket ones aren't. Guess I'll be ordering new ones from BMW.

 

[Beemerboff]

I dont think it is the ethanol that is the problem , but other stuff that they add, including Toluene, which is lacquer thinners.

If you have a couple of old diaphragms try putting one in meths, or Irish Whisky if you are out of meths, and the other in lacquer thinners, and compare them after a week.

The Amal Carb Co still have Zenith diaphragms at a good price, and I never saw one of them swollen.

 

[Rob Farmer]

great stuff. Thanks. I'll get a pair of zeniths ordered.

Fraction of the price of BMW ones as well

I've used Stromberg Diaphragms in the past but they tend to suffer as well, they're slightly thicker and heavier as well.

 

[ghiribizzo]

If you can let them 'air' for a day or so the problem may not stay as bad. That 'used' to work...

 

[Redboots]

The fuels a nightmare

Do you not get a choice?
Pumps here say if its E10. I use the other one

 

[stash]

great stuff. Thanks. I'll get a pair of zeniths ordered.

Fraction of the price of BMW ones as well

I've used Stromberg Diaphragms in the past but they tend to suffer as well, they're slightly thicker and heavier as well.

Hi Rob

I tried looking for Zenith diaphragms but no joy. Could you please give me the part number for them. I had the 40mm bings on my 100gs but am currently running 32mm bings. Any thoughts as to what has been achieved would be appreciated.

Stan.

 

[Beemerboff]

Try here - http://zenithcarb.co.uk/cd-diaphragms.html http://www.warco.com/pdf/WARCOBILTRITE_General Chemical Resistance Guide.pdf

This also confirms that both Nitrile and Hydrin are resistant to alcohol , so E10 shouldn't cause problems with the Hydrin Zenith items.

 

[stash]

Try here - http://zenithcarb.co.uk/cd-diaphragms.html http://www.warco.com/pdf/WARCOBILTRITE_General Chemical Resistance Guide.pdf

This also confirms that both Nitrile and Hydrin are resistant to alcohol , so E10 shouldn't cause problems with the Hydrin Zenith items.

Thanks for your response Beemerboff.
Would I be correct in thinking that the 150 and 175 were for the 32mm and 40mm Bings respectively.

Stash

 

[PaulRS]

Just wondering, is it the fuel of old age which wrecks those rubbers?

On my '73 I replaced them once several years ago due to them degenerate to chewing gum iso rubber, might as well after 25-30 years.

The new ones are holding up just fine, whatever I put in the tank.
And those rubbers are not in direct contact with the fuel.

Paul.

 

[dr nosh]

Thanks for your response Beemerboff.
Would I be correct in thinking that the 150 and 175 were for the 32mm and 40mm Bings respectively.

Stash

Which stock number are we looking for?

Thanks.

 

[Beemerboff]

The 150s fit 32 mm Bings, but I am not certain if the 175 s fit the larger Bings.

 

[England-Kev]

Whipped the carb tops off my airhead yesterday to alter the needles. Both diaphragms have swelled up making them very difficult to get back in. The fuels a nightmare

Anybody else having problems with it?

Did this have an effect on the running Rob?

 

[Rob Farmer]

No kev, I've been re jetting my bike and have had the tops on and off several times. The swollen diaphragms made it a pain to do.