67 Shovel Engine rings under load

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Mongrel505558
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Re: 67 Shovel Engine rings under load

#16

Post by Mongrel505558 »

hdmarkus wrote: Mon Jul 19, 2021 2:51 pm Now I’m using 95 octane. I will change to 98 octane, this is the highest I can get…. Maybe I try that before I retard the ignition timing.
I'd nail down the timing first. With that correct you shouldn't have to run 98 octane. The highest I can get around my region is 93 and with everything else set up correctly it's fine. I have on a few occasions ran Cam 2 racing fuel (110 octane) that used to be available at a couple of places sort of near me. Doesn't make more power, but the bike could probably climb Mt. Everest without pinging. Cost's a fortune per gallon, though.
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Re: 67 Shovel Engine rings under load

#17

Post by RooDog »

Higher octane fuels do not make more power, but do allow a more powerful engine to be more finely tuned to produce more power. The HO fuel is merely an enabler....
hdmarkus
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Re: 67 Shovel Engine rings under load

#18

Post by hdmarkus »

Update:

adjusting the ignition had no positive effect to the behavior of the engine. Now the bike is in good hands at my friends workshop.

Will keep you guys updated

Markus
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Re: 67 Shovel Engine rings under load

#19

Post by hdmarkus »

She’s back from the workshop and runs like on the first day :D She’s got new pistons, valves, valve collars and guides.

Regards Markus
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Re: 67 Shovel Engine rings under load

#20

Post by nifty »

So why was it "ringing under load"?
Detonation?
From carbon build up?
Sharp valve margins?
Nifty
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Re: 67 Shovel Engine rings under load

#21

Post by hdmarkus »

As I understood, the old pistons caused a too high compression, because they where bigger than the original ones (0,4mm higher). I don’t know if this alone causes the detonation. Markus
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