Amal carbs and modern 'petrol'

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jessplop
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Amal carbs and modern 'petrol'

Unread post by jessplop » Tue Aug 11, 2015 6:37 pm

I am struggling to get my T140 to run well on modern petrol, having retarded (or the other one) my ignition several degrees, it will now pull to a mind numbing 80mph on this soapy water they call petrol. Either my carbs are goosed, or I may have to get more serious, like fitting Johnny foreigner carbs, new Anal carbs or re-jetting the existing ones.
Any pointers as to which method might bring ye olde twumpet back to running as it was supposed to?

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Zunspec
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Re: Amal carbs and modern 'petrol'

Unread post by Zunspec » Tue Aug 11, 2015 8:23 pm

Hello JP,

I am informed that Shell V-Power is 99 octane (RON), about as good as you can get at a regular pump, It might make a difference.

However even on cooking unleaded I might suggest that you have something more fundamental out of kilter. Tappets/ign. timing/carbs/rings/compression/valve & seats/plugs/points/exhausts/air filter, crikey where do you stop lol. On the other hand 80 mph is good for a T140 (runs and hides).

Good luck :D

Cheers Geoff

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jessplop
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Re: Amal carbs and modern 'petrol'

Unread post by jessplop » Tue Aug 11, 2015 8:55 pm

The motor hasn't been disturbed, so valve timing is out of the question, recent-ish top end overhaul saw new guides and lapped in valveses. Could be air filters, I'll give them a swap and see if that makes any difference. I'd love to have it as close to how it was in the old days, then take it to MC Piston Rally in Picos de Europa some day :)

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Hooli
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Re: Amal carbs and modern 'petrol'

Unread post by Hooli » Wed Aug 12, 2015 1:05 pm

How long since the top end refresh? reset the clearancesess recently?

Mine used to pull well over 80 even with stupidly short gearings.
Classics ain't built in Metric

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jessplop
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Re: Amal carbs and modern 'petrol'

Unread post by jessplop » Wed Aug 12, 2015 3:33 pm

I'll get it on the bench when I returns home, could be lack of use.... :D

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Zunspec
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Re: Amal carbs and modern 'petrol'

Unread post by Zunspec » Wed Aug 12, 2015 3:43 pm

jessplop wrote:I'll get it on the bench when I returns home, could be lack of use.... :D
That's what it needs JP, a damn good thrashing :D

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jessplop
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Re: Amal carbs and modern 'petrol'

Unread post by jessplop » Wed Aug 12, 2015 4:26 pm

I would, if only it would reach thrash velocity... :D

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Re: Amal carbs and modern 'petrol'

Unread post by Zunspec » Wed Aug 12, 2015 10:43 pm

My T140V has a set of 34mm MkII Amals fitted, that, along with all the other mods means it goes like a good 'un. If we ever bump into each other you can take it for a "Thrash" .

Cheers Geoff

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Re: Amal carbs and modern 'petrol'

Unread post by supersix » Thu Aug 13, 2015 12:04 am

My 72 A65L must be on similar carbs. OK it pinks a bit a times and is a bit lumpy low down, but there is no lack of top end and it still pulls beyond 80. Have you tried a plug chop, or simply jetting it up a bit? Yes today's petrol is crap but I think you have other issues!

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Hooli
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Re: Amal carbs and modern 'petrol'

Unread post by Hooli » Thu Aug 13, 2015 1:21 pm

supersix wrote: but I think you have other issues!
Are we still talking bikes? :lol:
Classics ain't built in Metric

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