Modern fuels and ignition timing

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KevinDennis
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Modern fuels and ignition timing

Postby KevinDennis » Sun Dec 20, 2020 1:24 pm

Hi all, hoping to start my Mk11 Sq4 tomorrow after total rebuild and have been running everything through my head in case I have missed/forgotten something.
Just wondering if everyone is still setting timing to TDC taking into account modern fuels?

Kev

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simon.holyfield
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Re: Modern fuels and ignition timing

Postby simon.holyfield » Sun Dec 20, 2020 1:40 pm

I am, seems fine to me. Others are timing to performance rather than piston position...
cheers

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roger.fellows
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Re: Modern fuels and ignition timing

Postby roger.fellows » Sun Dec 20, 2020 9:50 pm

Hi Kevin, I'm sure you'll be aware of this, but use freshly bought petrol rather than what you got for the lawn mower back in 2019.

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Richard Kal
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Re: Modern fuels and ignition timing

Postby Richard Kal » Mon Dec 21, 2020 12:45 am

Amongst my collection are quite a few A10's.
I have dyno tuned eight of them, with the same result every time:
For the cast iron head bikes, factory timing called for 32 degrees BTDC. Best results on the dyno were at 30 degrees BTDC.
For the alloy head bikes (RR and SR's), factory specification is 35 degrees BTDC. Best results were with 32 - 33 BTDC.

Conclusion; 2 degrees retarded on factory settings gave best performance; this could be a consequence of modern fuels?

Richard
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