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rm 250 top end como question

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I have a 2004 rm 250 and have a few questions i hope you guys could help me with.

-can i use a stock oem cast yz 250 piston in my bike?,and if so what would the affects on compression/running manners if any.

-if i can run the piston,what wrist pin\bearing combination will i have to use?

I have searched this fourm\site and only found one referance to this combo.The wisecoe yammaha gp piston interchangability is well documented.

I,m only asking about this because my local shop is a yammaha/honda dealer and they are very supportive of local mx and have always treated me well.

note:not trying to start a debate on cast vs forged,run whatever you like!

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If i cant get absolute confirmation on the cast yammaha oem piston i,ll prob end up with the complete stock suzuki set up from another dealer in my area.Most of the shops in my area,eastern Canada,only want to sell oem,wisecoe or pro-x-ask about vertex,woosener,athena etc and they look at you like you need something from the moon.

This is my first rm since 96 and i am anxious to try it out-spring is almost here!

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Back when I had a 03 RM250 there was a single ring YZ250 wiesco piston that everyone including myself had switched to its a speical piston not the normal wiesco yz250 piston. but since suzuki coppied the yamaha cylinder a few yz parts bolt right up like the piston and reed blocks vforce and boysen both use the same part number

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Unless you want the lighter weight of the stock RM or YZ piston, then I recommend getting the Wiesco. Most riders cannot even tell the difference between the two, and the Wiesco will last longer than any OEM cast piston.

Matter of fact, that's all I run in my RM's and I just installed one in both my '08 RM250 and my '96 RMX250.

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Thanks for all the input.As far as wisecoe goes,i have no bias one way or the other.I have used them in some of my recent bikes along with oem pistons as well with no issues or concerns.

The only reasone i,m investigating options other than wisecoe is because my early spring riding temps will range from -1 to 5 or 6 dergrees celsius,so i thought a cast piston might be the better choice.

I must admit that i,m going to try the single ring wiseco this year for sure just to see if i can feel the difference.

Thanks again for all the input.

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Why would the temperature have any bearing on what piston you buy? It should be a longevity and reliability issue. In the wintertime here in AZ its not uncommon to get to the track in the morning and be around or below 0 celsius. Hell sometimes there's even ice! We get along just fine here with Wiseco. The single ring Wiseco is so much better than the stock piston there shouldn't even be a discussion. There is a 1 hp increase just with a piston change. You know how hard it is to get an actual 1hp increase on a dirt bike? Its not easy.

Good luck

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Thanks for the input 2strokenut,top end stuff will be ordered monday next week so i,ll decide this weekend on what set up i,ll go with.

Maybe someone could answer me this one-If i use the single ring yz set up from wiseco,do i use the complete kit or do i need the clips,pin and bearing for a rm250\04.

Just finished fork seals\bushings tonight so motor is next on my to doo\get done list.

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Piston might fit but the wristpin bearing is different size compared to the rm. I looked into it and decided not to chance it, Just got a good old reliable pro lite piston.

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Thanks for the input 2strokenut,top end stuff will be ordered monday next week so i,ll decide this weekend on what set up i,ll go with.

Maybe someone could answer me this one-If i use the single ring yz set up from wiseco,do i use the complete kit or do i need the clips,pin and bearing for a rm250\04.

Just finished fork seals\bushings tonight so motor is next on my to doo\get done list.

Here's everything you need right here:

http://cgi.ebay.com/ebaymotors/Wiseco-YZ250-Racers-Choice-piston-kit-NIB_W0QQcmdZViewItemQQhashZitem2558a1b9feQQitemZ160400783870QQptZMotorcyclesQ5fPartsQ5fAccessories

Have fun!

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Thanks again for all the input guys,figured i,d give you an update on what top end stuff i went with.

I ended up buying the complete oem set up from my local suzuki dealer.It looked to be the stock set up that was in the bike when i took it apart.My cylinder actually measures slightly small,only .0005, but small none the less.the bike ran ok when i purchased it,even though the ring end gap was .022 ish!.

Using the stock set should give me a base line to work off in the months ahead.

I had the chance to check out a stock yammaha set up for a 08yz250 and noticed a a few things that some others could chime in on.

1-window on the intake side was smaller than the piston i took out of my bike,only by about .025 or so,but it kept me from getting it.Would this make a differance?

2-yammaha piston had a shiny\polished"finished"look,while the stock suzuki piston I received has a dull or matt finish to it.

3-the needles in the yammaha top end bearing were slightly shorter than the suzuki,s.The overall width,od and id were the same.

If the bike works out and i like it,the next top end will be the single ring wiseco.Looks like a neat set up so around mid summer i,ll give it a go.

Still two weeks from any riding here,still snow on the ground!

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Whats wrong with Wiseco? They are great pistons and my piston of choice..... Wiseco.com TT store

have you ever heard of this brand? i found it on ebay seems like a good deal just never heard of them.

Namura Piston

http://cgi.ebay.com/ebaymotors/SUZUKI-RM250-RM-250-01-02-PISTON-KIT-TOP-END-GASKETS_W0QQcmdZViewItemQQhashZitem5886a45535QQitemZ380216038709QQptZMotorcyclesQ5fPartsQ5fAccessories

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Thats a racing piston with a very short life. People have had good luck with them, but they are cast just like oem.

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