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RogerP

Does the 450 require a new piston as part of maintenance?

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Ride a Honda now, but getting tired of the expensive piston and valve replacement schedule. Wondering if the Yamaha has the same requirement every 6 races etc.

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Yamaha recomends replacement at 50 hrs. You could probably go much longer.

if this is true.. i need a new piston... im about 110 hours i believe..

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The schedules in the manual for hardware replacement are wildly pessimistic, it seems to me. My '03 went over 400 hours without needing anything at all, not even a valve adjustment. My older '06 had about 125 on it when I had it apart on suspicion of a head gasket leak. I dropped rings in it, but the piston was fine.

If you race it weekly, then it would just be smart to put a piston in every year. The valves could either be replaced at the same time, or you could wait until they start to move. If you ride recreationally, every other year could well be plenty soon enough.

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The schedules in the manual for hardware replacement are wildly pessimistic, it seems to me. My '03 went over 400 hours without needing anything at all, not even a valve adjustment. My older '06 had about 125 on it when I had it apart on suspicion of a head gasket leak. I dropped rings in it, but the piston was fine.

If you race it weekly, then it would just be smart to put a piston in every year. The valves could either be replaced at the same time, or you could wait until they start to move. If you ride recreationally, every other year could well be plenty soon enough.

+1 for yammie, I have a 07 with one season just needed some rings, I ride with a crf250 and rmz 450 and both need more attention then yammie

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Assuming you purchase and extended warranty. It states that you must maintain it according to the manufacturers recommendations. For my CRF450 that meant I had to replace the piston every 15 hours! That is why I am asking what is stated in the manual? It sounds like the Yamaha 450 pistons are more reliable than the Honda?

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Assuming you purchase and extended warranty. It states that you must maintain it according to the manufacturers recommendations. For my CRF450 that meant I had to replace the piston every 15 hours! That is why I am asking what is stated in the manual? It sounds like the Yamaha 450 pistons are more reliable than the Honda?

I wonder if the Author of the Honda service manuel gets commission from all the piston sales.

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Thanks - big benefit for Yamaha for sure! My son's 06 CRF450 crank went south, the warrant company said since I did not replace the piston on teh required maintenance they woud not cover the claim... Took several calls to get them to cover the crank, but everything that had to do with the piston, cylinder, gaskets etc came out of my pocket.

Crazy for sure.

Anyone have an 08 or 09 YZ450 that can confim what the 07 manual says?

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Quit worrying about it. From my experience an extended warranty on a Yamaha is not necessary and from the sounds of what you have to do on other bikes to get the warranty service it may not be worth it on those either. Get a Yamaha and put 300 hours on it and be happy.

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Thanks - big benefit for Yamaha for sure! My son's 06 CRF450 crank went south, the warrant company said since I did not replace the piston on teh required maintenance they woud not cover the claim... Took several calls to get them to cover the crank, but everything that had to do with the piston, cylinder, gaskets etc came out of my pocket.

Crazy for sure.

Anyone have an 08 or 09 YZ450 that can confim what the 07 manual says?

I have the '07 manuel in front of me. In the section titled "regular inspection and adjustments maintainance intervals", it says to Inspect every 5th race/1000km. Inspect for: cracks,carbon deposits and also to replace "As required"

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Nice - looks like it is time to dump the Honda! !!!

Okay so next question what is the difference betwwen 08 and 09 YZ450?

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Nice - looks like it is time to dump the Honda! !!!

Okay so next question what is the difference betwwen 08 and 09 YZ450?

Don't quote me, but I don't think the engine was changed at all. The only major thing I can remember reading about was a cmpletely different swing arm where the linkage mounts underneath instead of through, altough the rising rate remains the same. I think they focused on shedding unsprung weight.

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Nice - looks like it is time to dump the Honda! !!!

Okay so next question what is the difference betwwen 08 and 09 YZ450?

Don't quote me, but I don't think the engine was changed at all. The only major thing I can remember reading about was a cmpletely different swing arm where the linkage mounts underneath instead of through, altough the rising rate remains the same. I think they focused on shedding unsprung weight.

You are correct mwf. The other major change was to the top triple clamp, there is much more adjustability for the bars. I think there are two different mounting holes for the bar clamps, and of course the bar clamps can be reversed. There were a few other small things done to the bike, but those are the major two items that changed.

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thanks - I live in SoCal and the best price so far is 5995.00 OTD for the white ones. Any better deals in so Cal?

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I have a 2004 YZ 450F which has never had the piston or rings replaced or had the valves adjusted. It probably has 250 hrs +/- on it. It is my track bike and I am mostly a trail rider so it doesn't get used as much as the trail bikes. Just recently (This season) it has been getting harder to start (5-6 kicks) and doesn't seem to pull as hard or respond as quickly as it used to. I'm thinking about redoing the top end. Any input as to what most folks are doing appreciated (ie; piston, rings only, valves, etc.)

Thanks,

Brad

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On my 06 I have 77.3 hours on it(just looked on the hr. meter) and when It turned 50 hours I took it to my friend which owns the yamaha shop where I live and also is a yamaha mechanic and had him to do a top end.

He said everything was in good shape he just replaced the piston and rings checked the cam chain but said it was fine(no wear) valves and everything else looked good. At that time I had about 18 races on it along with practices.

I ran three races last year with it until I tore My ACL and had to have surgery after I healed up and started back riding I have put roughly 15 or so hours on it practiceing getting ready for mx season next month.

Iam going to wait until I get 100 hours on it till I take it back to him for another top end. I would like to do it my self but I cant get myself to do it.

I pretty sure I can do it I just seem a little scared with 4 strokes.

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I have a 2004 YZ 450F which has never had the piston or rings replaced or had the valves adjusted. It probably has 250 hrs +/- on it. It is my track bike and I am mostly a trail rider so it doesn't get used as much as the trail bikes. Just recently (This season) it has been getting harder to start (5-6 kicks) and doesn't seem to pull as hard or respond as quickly as it used to. I'm thinking about redoing the top end. Any input as to what most folks are doing appreciated (ie; piston, rings only, valves, etc.)

Thanks,

Brad

It depends on how much money you are willing to spend on piece of mind. At minimum I would replace the timing chain. It's cheap, and not to difficult to replace.

If the valves haven't started to move yet you could let them go until they do. However, with that many hours on the bike I would inspect them ever 5-10 hours.

Other than that, just a regular top end. Piston, rings, wrist pin, cir clips, new head and bases gaskets.

I'm about to do a complete top end on my 05, head and all in the next few weeks. Mine was raced by a local privateer for about a season. The valves were tight when I bought it and they're starting to move again since I adjusted them so I figured I'd get it all done

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