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Zaj 243

Copper Alloy valve seats

11 posts in this topic

My 06 YZ450F has had engine work done from the previous owner. The head has copper tin alloy valve seats installed. With stock cams, valves, springs, retainers, etc., was is the benefit of installing these on such a reliable head to begin with? Any info is appreciated!

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There isn't much of an advantage putting them in a Yamaha since Yamaha's already have a good valve train set up that is reliable. These seats were more helpfull in the first generation of RMZ250/KX250F (along with stiffer valve springs) where they had so many valve issues to begin with that pretty much everything in the valve train needed to be changed to make them run for more than 10 minutes.

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Yeah thats pretty much what I was thinking, my '01 426 and '02 250f are still on original valves and seats, couldn't ask for a better setup. I was hoping to hear something different, this "mod" motor that was a 1800 bill for the previous owner ends up being a high compression piston and valve seats that were pointless. I'm not even certain that the ports were even touched other than matching in the new seats.

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Yeah thats pretty much what I was thinking, my '01 426 and '02 250f are still on original valves and seats, couldn't ask for a better setup. I was hoping to hear something different, this "mod" motor that was a 1800 bill for the previous owner ends up being a high compression piston and valve seats that were pointless. I'm not even certain that the ports were even touched other than matching in the new seats.

Those seats are expensive, and probably took up a good chunk of that bill. They are good seats, but they are not worth the money in a Yamaha IMO. Good thing you didn't pay for them :banana:

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Maybe they were put in becouse there was a problem. I have an 08 yamaha 450 that I am having the copper bromide seats put in, but I am going with a little stiffer spring too. I have 100 hours on my bike and I need to keep it another year...Thats why I'm doin it

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I know there were no problems with the stock seats. I've been familiar with the bike since it was brand new. The engine was supposed to be a replica race motor for a Canadian motocross team, but turns out everything is off the shelf parts besides the seats. Not a big deal, the YZF engine is great as it is and should put out enough power for me anyways. Thanks for the input guys.

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Those seats are expensive, and probably took up a good chunk of that bill. They are good seats, but they are not worth the money in a Yamaha IMO. Good thing you didn't pay for them :banana:

KJ, would it be smart to just get a new complete head from Yamaha when the time comes? After all it seems like the word around here is that people easily get 100 hrs. on their stock valve train. Is it possible to buy a complete head for less than what you would pay to rebuild one with all new valve train, seats and machine work on your worn out head?

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KJ, would it be smart to just get a new complete head from Yamaha when the time comes? After all it seems like the word around here is that people easily get 100 hrs. on their stock valve train. Is it possible to buy a complete head for less than what you would pay to rebuild one with all new valve train, seats and machine work on your worn out head?

I wouldn't say so. If you buy a head, you still need to buy the valves anyways. If the engine hasn't blown up then there is nothing wrong with the head, it's the parts in the head that need replacing. You can replace all 5 OEM valves with all of the other parts you need (springs, guides, seals, keepers, etc) and get your seats cut for around $370 give or take a little. A new head is around $650, and that doesn't come with valves.

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I've owned several yamaha 4 strokes over the years and not one has needed new valves or seats, or needed adjustment more than twice. I bet my '03 450 had over 200 hours on it when I sold it, and 6 owners later, still running today with its current owner.

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I wouldn't say so. If you buy a head, you still need to buy the valves anyways. If the engine hasn't blown up then there is nothing wrong with the head, it's the parts in the head that need replacing. You can replace all 5 OEM valves with all of the other parts you need (springs, guides, seals, keepers, etc) and get your seats cut for around $370 give or take a little. A new head is around $650, and that doesn't come with valves.

I thought you could buy the head complete with parts installed.

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