abhimanyu31

Proper warming up of the engine also a factor in engine wear? Most engine wear and tear happens within the first few minutes of starting the engine.

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Xenologik

Yup as the oil is more viscous when and takes time to circulate around the engine, esp the head of the cylinder. I minimum let it idle for a minute and in colder conditions another minute at least before starting off, keeping the speed and acceleration mild enough for 3-4 kms at least before speeding up. Just start-n-go will certainly hamper engine life a lot.

High rpms for a long duration will certainly reduce engine life. Have experienced that on my cbz-x. However I think keeping the bike at 70-80% of its max rpm would be a safe region rather than gunning it to 90-99% of its capacity.

If one notices, car engines last way longer than bike engines, since an average car's rpm wouldn't cross 4.5k even while on the highway, and for diesel cars the rpm is even lower. The old premier padmini which was at home about a decade ago did well over 1,50,000 kms without even a change in the piston rings, and that car wasnt really the best of the cars during that time. Rpm + vibrations is certainly the main cause of premature engine wear out.

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rags

Ideally you should ride within the powerband of the engine because that's where its the most efficient and avoid redlining it often. I guess the range of rpms you mention are within the powerband for the R15 so it must be ok to ride in that range but remember its not advisable to ride the bike at the same engine speed for a long time. In city riding you automatically ride with varying speeds but on highways it would make sense to vary speeds in between.

The oil for engine lubrication requires to reach a certain temperature to attain the required viscocity and that's why you need to warm up the engine.

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vikram kumar

Just wanted to know
whats the harm in running the engine in the same speed??
I dont understand in what way will it affect it..
can somebody please help.
Thanks

Xenologik

Im not sure whether this applies after the run in period.. but during run in period its advised not to keep the engine rpm constant for a while.

Basically from what I understand of engines, the rings around a piston are more crucial than the piston itself. Now at a specfic rpm, an engine produces x amount of power(in whichever gear) , and with that the temperature due to combustion inside the engine will be near constant.

However since the engine is still in the "setting in" period, keeping the engine rpm constant for a while will result in the rings will have expanded due to the heat. Therefore the engine "gets" used to that rpm because of unchanging values of power developed. Now if the engine rpm varies after that then the rings will tend to shave off the bore due contraction (if engine starts to cool down) OR will not be able to seal in the compression developed by the engine. (due to sudden increase in temperature).

Which will lead to loss in power(due to compression loss) and eventually will require reboring or a new bore set in itself. Im not sure whether this is the exact reason someone who's more technically sound with engines would know better.

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TheDeadRider

Sorry I took time replying!

Thanks!

Will do, but i'm confused where to. Perhaps in the "Who are you?" section?

I'd heard the same too. I was worring about how soon this may happen, and if happens a lot in case of rev-happy machines like the R15.

Thanks a lot for the information, I agree with you! I've always felt that heavy gunning while not matching the load with the rpm causes "idled" rpm, which does not deliver to the wheels, but only heats up the engine.

And that's why I bought the R15

That's interesting. That last part about the oil is scary. Extensive damage could be done to an er...under-oiled engine by hard riding!

I change my oil personally every 1500km with the semi-synthetic oil I get at the yamaha spare parts shop

TheDeadRider

I did not know that. But I warm up my engine for 5 minutes everyday in the morning anyway. I've also heard that fuel-injected bikes should not be idled for too long, is this true?

Yes, I had noticed that. Cars last for much longer than bikes do. I had attributed the fact to a much heavier engine block, capable of handling much more stress that a motorcycle engine. But I see now that I'd missed out this fact too which will also matter a lot.

abhimanyu31

Ok, here it is simply.... the faster you rev an engine the more you will stress every part of it... I will quote the Superbike magazine... "Most road bikes have rev limiters which stop you damaging them, but even so, riding near the red line a lot of the time will wear an engine far faster than short shifting and keeping the the revs low"!!!

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TheDeadRider

Absolutely. If you're ready to rev, you're also ready to pay

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Xenologik

No, that's not quite true. Fi engines just dont need to be revved during idling like carbed bikes are. for example, the P220 dts-fi's system will automatically manage the fuel during idling, cause they have all sorts of sensors which can also sense whether the engine is stalling or not and feed the fuel accordingly. On the other hand there's no such thing in a carb-fed engine therefore the common procedure is to activate the choke so the engine wont stall during cold starts. However the time required for an fi bike to warm up is less, its better to ride around in an fi bike than let it idle.

Anyhow idling for too long is bad, since the engine runs without a load while on idle. If the engine isn't stalling when giving throttle then i'd rather drive off and ride slowly. But most of the carbed bikes need sufficient warming or the engine tends to stall.

Rev limiters limit the bike to the maximum rev the engine can handle without destroying itself. Since all 4 stroke engines have intake and exhaust valves which open /close all the time, after a certain rpm the valves will 'float' , which means that the valves will not close fully. This is because valves are pushed open by the camshaft, but during close the valve is pushed back by the spring. At high rpms the difference becomes evident and the spring is not able to push the valve back as fast it'd normally just because it doesnt get the time.

Due to which the piston itself might hit the valve(which is still open) and destroy the engine. Rev limiters limit the engine's rpm to the point where the engine can safely operate.

That does not mean that the engine will not wear out. Completely depending on the materials / casting of the engine parts, the wear will be accordingly. The engine won't die out too soon, but suppose it'd last 10k kms instead 40k.

Here's a website where a lot of detail can be learned about engines in general. Carbible-Engines

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