Diaphragm has grown by 20%!

[ukzknos]

Bike recently out of winter wraps and as previously reported had not been running too well at low RPM.

Dropped the float bowls and blew out the jets with compressed air......a little improvement but still a low speed splutter.

Decided to take the tops off to inspect/clean the needles and noticed one of the diaphragms looked to be a bit rippled where it fixes to the slide. Having disassembled the parts it was very evident that it was never going to go back together because the diaphragm had grown c.20% since I fitted it new last April!

Is this because it is a cheap 'pattern' diaphragm or, did we conclude in a thread last year that using a 'lead additive' had this effect?

(I've been using a Redex lead additive)

Regards
Steve

[Barry]

Steve

I'm fairly sure Lou had this problem with diaphragms when using a petrol additive. He's sure to chip in when he reads this.

I've never used any sort of fuel additive and have no problems except for having to retard the ignition 1 or 2 Deg to keep the pinging at bay.

[ukzknos]

Barry

If you're not using an additive do you use standard unleaded (95 RON) or super unleaded (98 RON)?

Steve

[nhmaf]

IT could be the type of the rubber/thickness of the rubber is different from that of the original BING diaphragms contributes to this.   I do know that certain fueld additives here in the states can cause rubber seals to swell if in high enough concentrations.  One product which can do this sometimes is "Sea Foam", which is a popular carb/fuel system cleaner and gasoline stabilizer.   I still use it though, but do not put it in 100% concentration into the carbs

[Barry]

If you're not using an additive do you use standard unleaded (95 RON) or super unleaded (98 RON)?

I've used both but now only use standard 95 RON since I learnt that the higher octane fuel is more likely in fact almost certain to contain the maximum allowable 5% of ethanol. Also I can't detect any performance loss by retarding the ignition the small amount necessary to prevent pinging.

I may be misguided in this in that by now maybe all UK fuel contains 5% ethanol. It's near impossible to find out from the big oil companies. I've tried.   We are lucky it's not been increased to 10%. Apparently this was on the cards and about to be implemented across Europe when somebody realised at the last minute that it would damage some older vehicles.  

[nhmaf]

10% ethan0l is - or will shortly be - mandatory in most states over here.   I think that our state (New Hampshire) is already mostly switched over.
I suspect/plan to replace more fuel lines more frequently on older machines now.

[Lucky_Lou]

Two important points here...first dont bother with the additives ive been down this road standard unleaded is fine, second only use original bing diaphragms Motobins do them but i think Motorworks only do generic ones.I had alot of problems when i first rebuilt mine and most of it was due to the Diaphragms expanding.
I posted some pictures of the impact additive had on the material and the significant difference between the original vs generic diaphragms.
I will have a look back and give you a pointer to where the previous posts are.
Lou

[Bob_Roller]

We've had 10% ethanol fuel here in the Phoenix area for about 8 years or so, and I haven't seen any adverse effects of the alcohol in any of my vehicles yet .

[montmil]

...i think Motorworks only do generic ones...

Motobins offers both. The Bing OEMs are more expensive but can obviously prevent the problems mentioned on this thread and others previously posted.

Monte