Hour meter explanation in a literal sense


3 replies to this topic
  • silentZ

Posted May 21, 2012 - 01:52 PM

#1

So I am starting to wonder if the hours recorded on an hour meter are really skewed. Something like how dog years relate to human years. The meter records every second that the bike is running, but doesn't differentiate between warming up the bike, taking sight laps, putting around or hard on the gas in the meat of the powerband.

There are certain guidelines to go by as far as when to do certain maintenance. A lot of people say to change the timing chain at X number of hours. Throw a piston in there while you're at it.

Is there some rule of thumb to go by as far as when to do the big maintenance?

For instance, according to some opinions it was recommended to do a piston, chain, and valves at 100 hours.
Mine was done at 207 hours. I am now in the 260's on the second piston. My hour meter recently rattled off while at the track. I imagine the adhesive was too weathered.

I was just curious if anyone uses any type of method in regards to the actual numbers and variations in the type of riding that is being recorded in time.

Thanks

  • grayracer513

Posted May 21, 2012 - 06:12 PM

#2

The true measure of engine life is in horsepower hours. How many hours at what level of output and load, that's the real question, somewhat as you have outlined here. When we get a meter to record that, we'll have a better idea.

There aren't any solid guidelines, because there's no really solid way to relate your riding to my riding or anyone else's except by rough estimation. 260 isn't unheard of for a piston at all, and I've owned YZ450's that went a lot farther than that, although if you're a regular racer, I think I'd put one in it soon.

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  • KJ790

Posted May 22, 2012 - 07:24 AM

#3

I always thought that a better method of setting a maintenance schedule would be in measuring how much fule the engine burns. If you are harder on the throttle you will burn more gas in an hour than if you are just putting around. It wouldn't be perfect, but it would be closer than strictly going by hours.

However, since an hour meter is all we have, that is what most people go by. For me, I have found a schedule that works for my riding and I just use the hour meter to perform certain maintenance at the same intervals since all of my riding is the same type (hard MX racing). For someone that is a casual trail rider they could probably get away with doubling the times I use for my schedule and be perfectly fine.

Things like a cam chain, an A-class MX racer is going to wear out a cam chain much faster than a tight single track rider just because the average RPM for the MX racer is much higher. When one engine makes twice as many revolutions per hour, it is going to wear out parts twice as fast.

  • grayracer513

Posted May 22, 2012 - 09:04 AM

#4

I always thought that a better method of setting a maintenance schedule would be in measuring how much fuel the engine burns. If you are harder on the throttle you will burn more gas in an hour than if you are just putting around. It wouldn't be perfect, but it would be closer than strictly going by hours.


Not a bad approach. Comes closer to a measure of horsepower hours than anything that comes to mind.

Things like a cam chain, an A-class MX racer is going to wear out a cam chain much faster than a tight single track rider just because the average RPM for the MX racer is much higher. When one engine makes twice as many revolutions per hour, it is going to wear out parts twice as fast.


True for the most part, but there are basically two kinds of moving, wearing parts in an engine, those that carry the output load, and those that don't. The cam chain you called out, and all the rest of the valve gear are in the second category, unable to tell the difference between an 8 grand cruise in second and 8 grand wide open in 5th. More time at a higher speed does just what you said it does to those parts.

The crank and the whole reciprocating assembly ) piston, rod bearings, etc. are affected by the amount of power produced in addition to the operating speeds, so that's another variable, and the fuel consumption would more accurately indicate that. But still, in the case of your example of a regular racer, that's going to increase, too.





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