New yz450f owner, When to rebuild?

Hey guys recently picked up a 14' yz450f with very low hours (about 8),

 

Being new to yamaha (coming of 14 kx250f) and new to a 450… The bike is UNREAL! 

 

It handles very well and the extra torque is great in loamy,sandy condition. 

 

I must say I'm very impressed. 

 

A couple of things i would like to address….

 

Are 450's normally a bit harder to start then 250's?   Ive noticed it has taken me 4 or 5 kicks to start when cold (using choke).  When its hot, it starts first kick.  When the bike has been sitting for about an 1 hour (in between practice sessions), I could only kick it over using the choke again… (live in australia, so the weather isn't cold).

 

How long do you guys like to wait before replacing the top end?   Im thinking around the 50hr mark?  Im pretty strict with maintenance doing a air filter every ride and oil/filter every 4hrs..

 

How many hours have you guys got on your 14 yz450f? any problems? 

 

Thanks Jack.  

For one thing, the cold start knob isn't a choke.  The one on the carbs of the older bikes isn't either, of course, not in the true sense, but in the EFI bikes, the CSK doesn't make the mixture richer; it raises the idle speed, much the same as cracking the throttle open slightly would do. 

 

When to rebuild depends on a lot of things relating to how and how much the bike gets used, but I just did the first top on mine not too long ago with over 300 hours.

it all depends on maintenence take care of it and it will last.i would tear it down between 100 to 150 hours and seen whats worn probly would only need a new piston and rings.

Mine is usually about two kicks when cold. First kick to prime the efi system and second to start it.

mine also starts after sitting weeks on second kick maybe you just have to get used to it.

So pistons do last longer on 450s than 250f? I was thinking of tearing my 08 down at 60 hours. I clean the air filter every ride and am easy on the bike. But I am ticky about maintainence. 300 hours out of a piston? That's awesome

Yeah, hearing over 300 hrs on the guru's piston makes me feel good about my 90 hr 2009 piston. I know you can break it down to measure and inspect but If I go that far I will probably just bite the bullet and swap it with a new one.

Kick it fast once, get it up to TDC on comp stroke, nice smooth kick and it should pop right off.

Hey guys recently picked up a 14' yz450f with very low hours (about 8),

Being new to yamaha (coming of 14 kx250f) and new to a 450… The bike is UNREAL!

It handles very well and the extra torque is great in loamy,sandy condition.

I must say I'm very impressed.

A couple of things i would like to address….

Are 450's normally a bit harder to start then 250's? Ive noticed it has taken me 4 or 5 kicks to start when cold (using choke). When its hot, it starts first kick. When the bike has been sitting for about an 1 hour (in between practice sessions), I could only kick it over using the choke again… (live in australia, so the weather isn't cold).

How long do you guys like to wait before replacing the top end? Im thinking around the 50hr mark? Im pretty strict with maintenance doing a air filter every ride and oil/filter every 4hrs..

How many hours have you guys got on your 14 yz450f? any problems?

Thanks Jack.

I have a 14 also and it's currently at 72 hours. Hard miles. But I change the oil and air filter after every ride (85)miles. Edited by Jonesy11

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