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My bike has run at 71C since I bought it. That's cooler than any vehicle I've had, but if that's what Yamaha wants, who am I to argue?
 

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I don't understand why this would damage the engine? As long as the lubricants get in to working range it fine. If you ride a lot in city traffic with limited air flow its more damaging to the engine to run to hot than running at 70ish °C at the highway.
An engine running too cold suffers from contaminants building up in the oil and forming sludge which can block oil ways. It will also suffer from fuel contamination of the engine oil which will reduce its lubricating properties.
Then engine go bang.
 
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Ok, but shouldn't an engine designed by Yamaha operate in a Window that keep it out of danger - Hi or Low?
It does. Yamaha are one of the foremost engine designers out there, and have been for decades. Look at the LFA V10, and the various others they have had design input with.
 

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Maybe Yamaha deliberately run it cooler to reduce the likelyhood of detonation. After all it's an fairly torquey engine with flat curve from low revs, it must have quite high cylinder pressures at low to mid range.
 

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Why? Some build up is normal, if there's a lot, there's a problem with over fuelling or oil burning.
 

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Engines are much cleaner now. When I stated my mechanics apprenticeship in 1968 getting a "decarb" at 20 or 30,000miles was normal.
 

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Beyond today's cleaner fueling systems, modern metallurgy and oil technology has helped a lot. Along with things like water jacket design/placement. When bores are able to stay round and keep crankcase oil out of the combustion chamber, carbon buildup is greatly reduced. Vehicles really are better than they've ever been.
Except for ease of access. We could probably have had the head off and stripped before you can get to the heaad bolts on a modern engine. Maybe even completed the whole job.
A VW engine took 15 - 20 minutes to remove. Same with a Fiat 500.
 
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Its a good thing reliability has improved on consumer engines. Wouldn't want the engine to be like old Ferrari engines to get some power out of it🤔
Sure is, 150 to 200 hp/litre from everyday car engines with 5 year warranties was a fantasy even 25 - 30 years ago.
 

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So this is why they put all the restrictions in the ecu, cant get more power and meet the emissions without destroying the engine?
No, it's about legal cheating. Map it to pass the noise and emissions protocols. It's arguable that more realistic mapping may be better for engine longevity.
 

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It feels like the engine is less stressed after removing restrictions, also runs smoother.
If an engine is making more power, it is more stressed. But if it remains within design parameters it won't go bang.
 

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That's not so much stressing the engine as the drivetrain.
 

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Tens of thousands? That's reassuring. I suspect it'd be in the hundreds if it's not abused and well maintained. It'd probably outlast the bike.
 
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Alloy work hardens. But it's not an issue that affects vehicles probably in the owners lifetime. Aircraft are another matter due to the flexing stresses placed on componenets.
 
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