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Discussion Starter #1
Hi all, as stated in the title I have some questions regarding dirt bikes... I have no clue about them and I'm hoping someone would chip in and give me some clarification :)

As usual I love surfing the net and especially looking up what's for sale on my local classifieds and eBay etc.. Recently I stumbled upon ads selling kx450 crf yz whatever motorbikes and knowing myself to me very very nosy lol I click on it.

But what really gives me a head scratching moment are how they always say "13 hours", "3 hours " and so on.. What does it mean? Do dirt bikes last a few hours or something?

Sorry I cbf researching it on google plus I barely post threads and I wanna see how my literacy skills are. Thanks, Jason.
 

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that's how many hours that have been put on the engine since the last valve clearance check. dirt bikes will last, just maintain it a lot more than your street. Oil chance every race, oil change every 3 rides (practice at a track) get the valves checked every 30 hours worth of riding (not too hard to do) keep up with it or you may have a ticking time bomb
 

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As said above. Dirt bikes often don't have odometers and miles don't say the same thing as far as engine use as street bikes. Also to think about is that some of those bikes like CRF's are full on race bikes. They have very intense service intervals so wear is measured in hours not miles. It's not uncommon for some dirt bikes to need full rebuilds every season.
 

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Discussion Starter #5
Ohhhhh okay... Now I understand the concept. Thanks for clearing that up in a not so complicated way.

Oh and to the guy above, yeah I researched that it applies to 4 stroke bikes as well. Majority of dirt bikes now these days are 4stroke (I think).
 

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Even in 4 stroke engines?!
Specifically 4 stroke engines..... 2 strokes don't use valves, or need oil changed other than crankcase (trans). 2 strokes generally just need a top end now and then, or sometimes even just re-ringed. Very cheap and easy to do. 4 strokes are much more involved and a lot more expensive when they blow up. That's why I went with a 2 stroke, lol (and I absolutely love mine)
 

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How old, and fat are you?

Intended riding area?

answers to above will help you answer question about MX vs. Enduro vs.Trials bikes.

also mechanical maint. skills?

(as per above on valve clearance checks)
 

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Discussion Starter #8 (Edited)
I'm 20 and I weigh 74kg, I have no intentions of riding MX bikes or enduro and/or whatever. I'm just interested in knowing a little more about them, and that is all.

Oh and I have mechanical skills, on a scale of 1-10 I'm a 1.5 lol
 

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i was about to say, lets not be giving him the whole bible on a dirt bike, he just asked about hours :p and we gave him what he wanted. CLOSED THREAD!
 

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Specifically 4 stroke engines..... 2 strokes don't use valves, or need oil changed other than crankcase (trans). 2 strokes generally just need a top end now and then, or sometimes even just re-ringed. Very cheap and easy to do. 4 strokes are much more involved and a lot more expensive when they blow up. That's why I went with a 2 stroke, lol (and I absolutely love mine)
I've always assumed that 4 strokers needed much less maintainance compared to 2 strokes.

This only happens on Dirt bikes?
 

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Think of a 4 stroke dirt bike as you would a full superbike race engine build and you'll understand the maintenance schedule of it. That's what motocross bikes are: full tuned race motors. As well think about how they are run normally: full throttle, banging off the rev limiter, subjected to dirt and mud; ride one like you do your street bike and the maintenance schedule would be far less aggressive.

As a whole a "normally" tuned 4T (say XR250R) would require less maintenance than a "normally" tuned 2T (like say a KDX220) dirt bike. But when you're talking a motocrosser the ring and piston replacement intervals are about the same (usually around 20 hours for rings and 40 for the piston) but the 4 stroke adds valves, cams, cam chains, etc. which make them more maintenance intensive.

And more expensive to maintain if done right.
 

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Not all 4-strokes are as high maintenance and needed rebuilds as often as it sounds here but if you have a full blown Motocross bike it will. Bikes like the KTMs have ridiculous service hours and require frequent oil changes.
 

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I've had a 2005 WR450, only thing I have done is make sure the air filter is clean and change the oil as far as the engine goes, eats tires, but it's been a rock solid bike for some time now.
 
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