Lead free valve seats

timetraveller

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Remember, this was not the worst one. Yes there are people who would have re-cut the seat and then what happens is that the valve gets pocketed, the gas flow is rubbish, you lose tappet clearance and might end up having to have short push rods made and finally the valve spring retaining cap (ET37) will at some stage hit the inside of the ET24 inspection cap causing the valve no longer to seat properly. An exaggeration? Sadly no, I have seen all these things on Vins.
 

roy the mechanic

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valve seats/time traveller

If re-cut with 3angles and carefully re-sphered the gas flow will not turn to sh-t. Itake your point about shorter push rods etc. You obviously have a greater experience of this product. Best Regards ,Roy.
 

Prosper Keating

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All I can say is that I have never experienced valve seat problems with unleaded fuel with any of the old motorcycles I have ridden since leaded fuel was phased out, including iron-headed singles and twins. Many British machines were designed to run as well as possible on low grade fuel.

The only significant changes I have noticed with unleaded fuel of the kind sold at pumps across the EU for the past decade or more are slightly hotter running, a nasty sensation on the skin when one washes one's hands in petrol after a roadside repair and a marked absence of sparrows and other small birds from urban centres, suggesting that they know how much more harmful to the health this stuff is than the old stuff.

I did have problems with Niton-tipped carburettor float needles in Amals and Bings because the additives in 95-grade unleaded made them sticky. A change to 98-grade cured this. However, I gather that 98-grade is due to disappear. Another irritation is the tendency of unleaded to "go off" much faster than the old leaded fuel. I have also found it necessary to remove water from float bowls far more frequently than previously, although this may be due to filling stations economising by not cleaning out their storage tanks as often as they used to.

In summary, I would say that I believe that my motorbikes used to run more sweetly on leaded fuel but that they run satisfactorily on unleaded 98, including the ones with tuned motors, as long as one retards the ignition by a couple of degrees or so. But I have never had a problem with valve seats and am inclined to view the whole valve seat recession thing as a bit of a scam. If it ain't broke, don't fix it. Having a replacement valve seat come loose at speed - or even at a standstill - isn't much fun.

Paddy Keating
 
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timetraveller

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Why would Don Canard think that using lead free seats is "a bit of a scam"? I do not sell seats or replace them for money. The photograph shows what happens if you use a twin for long distance commuting at normal motorway speeds for ten to twenty thousand miles a year. My own mileage was much less at about 6,000 miles and I still had to slacken the tappets at intervals of a few thousand miles. Each person should do whatever they think is right for their usage of their bikes but do not say you have not been warned if you do a rebuild without replacing the valve seats with unleaded items and then have to strip the whole thing down again to replace the seats.
 

Prosper Keating

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Non-VOC Member
The comment wasn't directed at you. I was recalling the scare tactics deployed by many interested parties in the automotive industry in general. As for having to haul engines down after rebuilding them, it's not a problem I have encountered and, as anyone who knows me can tell you, I put some serious mileage on my machines.

Lighten up...

PK
 

john998

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VOC Member
Valve seats

Hello, the wrought aluminium bronze exhaust , and iron inlet seats in my limited experience work fine. Both of my bikes do not need any adjustment to slacken off to allow for seat recession. If the seats need replacement then fit modern lead free inserts, if not leave them till they do.
Having made that statement, always remember never make a definitive statement about Vincents, even after forty years you never stop learning about them!
 

Alan J

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VOC Member
Valve seats.

A complex problem!! I had a Truimph spitfire and was told leave it alone!!-unless you drive like a maniac!! I have a shedfull of Morini's as some of you know. I put some wonder "stuff" in one of them,but nothing in the others- so far no valve seat problems!! My view is if you need to take your heads off- change the exhaust seats-otherwise leave things alone!! [but what do I know?]:confused:
 

timetraveller

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VOC Member
I'm light man, I,m light, or do I mean Je suis ligere, mon ami? The question that arises from all this is why do some bikes suffer from this and others do not? Clearly some bikes have all bronze seats and some have hard inlets and bronze exhausts. Round here all the local Vin riders have had to replace their valve seats or do not use their bikes over significant distances. I would typically cruise at about 3,500 rpm with odd bursts above that for overtaking. Bill was about the same. I do not want anyone to incriminate themselves but I imagine that in France one is using about the same engine revs. So why the difference? I know that my diesel cars seem to go better on French and Spanish diesel than they do on supermarket diesel here. Could there be a difference between French and English unleaded? With the insular UK view it is generally assumed that French petrol is inferior to UK but really this dates back several decades. How about now? Do we have an expert in the club on the quality of various fuels and if so will they let the rest of us know what is happening? We are looking for facts now chaps, not opinions. :)
 

Comet Rider

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UK fuel quality

Hi Norman,

These facts apply to UK supplied petrol only!

Most petrol will come from a single source, such as the Buncfield depot near to Hemel Hempsted, which is run by BP. Tankers for all retailers (Supermarkets, Shell Esso etc) fill up with the same base petrol, which will comply with the appropriatre ISO standard, then the fun begins:mad:

The supermarket petrol, will then just leave site and go to the appropriate supermarket for us mugs to buy. Shell BP etc have their tankers goto another filling station (on the depot site) where adatives are put into the tanker.

So if you want reliable running I would always goto a known brand (Shell, BP, Esso etc) rather than a supermarket. A point of caution to note is that a local car dealer has put the disclaimer in his warranty documentation, that the warranty is null and void if you use supermarket fuel...:rolleyes:

Buyer beware

Neil
 
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