ET: Engine (Twin) Rubber and shrinking

oexing

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VOC Member
Once again, alcohol (ethanol) is NOT the problem, it is all sorts of thinners that make up the modern fuel. I invite you to sink an o-ring or NBR shaft seal in your V-Power or any 98 Super. Wait three days and take sizes after soaking: The seal will grow so much so it does no longer touch the shaft with its lip. No different to E 10 .

Vic
test with HRD rubber:
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Peter Holmes

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Probably off topic here, but for me boiling water works every time, never had one split yet, I wouldn’t bank on the rubber recovering after being soaked in modern fuel, I forgot to turn my outboard motor fuel tap off when I laid it down in my van, the leaking fuel swelled and distorted the rubber flooring, it did shrink back quite a lot over a long period of time, but certainly not fully.
 

oexing

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VOC Member
Yes, it shrinks again later to initial size -but it stinks from fuel for some time. I think this is more effective for fitting on footrests than trying hot water, a lot more flexible in this soaked condition.

Vic
 

oexing

Well Known and Active Forum User
VOC Member
Peter, you´ll be right, no doubt. I would not bet on my rubbers min. 30 years old getting soft enough with hot water. But soaking in fuel worked, actually it was just to show what modern fuel does to hoses and seals when no Viton.

Vic
 

Peter Holmes

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VOC Member
The first part of my working life was spent in the printing industry, thankfully only about 10 years of it, we used to use a noxious substance named MEK (Methyl Ethyl Ketone) later found to be highly carcinogenic. It was used to swell small dents in the rubber transfer blanket to bring them back to the correct surface height, but it was only normally a temporary fix to finish a print run, eventually the transfer blanket would need to be replaced.

With regard to fitting footrest rubbers, you only ever have to do this once in the life of the footrest rubber, when they are worn out you can simply either twist and pull them off, or if that proves too difficult, slit them off with a sharp blade, I don’t think I have had a footrest rubber last 30 years in use, I was politely told by one of my “Old Boy” MOT testers, RIP. that he could fail my bike if the footrest rubbers were significantly worn out as your foot could slip off them!
Mine currently need replacing as the HRD lettering has completely worn away (both sides) they were fitted new for the International in Italy, so have not done too bad, better get the kettle on without any more ado!
 
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