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Hey guys, I'm getting my bike ready for the LS trip this year and want to put a new topend in my bike. I'd like to go ahead and bump the compression a little bit. Which piston is the most reliable and can still run pump, (91)? I'm also going to dyno my bike again while I'm down there, except this time I'm going to dyno it with the new topend and stock cams, then switch out the intake to the 08 intake cam and dyno it again. I want to see what the real deal is with the 08 intake cam for myself. I will post up the results as usual. Thanks for the top end help!

Also, should I go ahead and order up a new oem jug while I'm at it, or can I just scuff the cylinder with a brillo pad or something? I don't want any down time! When I take this sumbitch apart, I wanna put it back together the same day.
 

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cp makes a reliable piston as well as weisco if you ok with running something off the shelf... as far as the cylinder goes, you wont be able to analyze the condition until its taken apart... once apart, look for any scoring or wear marks, specifically on the thrust side of the cylinder... if the wear marks can be felt with your fingernail then its time to re-coat the jug, or in your case buy a new one.....
 

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you might as well order a new cylinder... if your existing cylinder is wore, you already have a replacement..... install the new one and send your old one out for a re-coat and put it back on the shelf for next years top end rebuild....

please post up what numbers you come up with on the intake cam situation! good luck!
 

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Sounds good man, thanks for the help! I've had excellent luck with wiescos in my banshees in years past, how do they perform in the 4 strokes? As far as needing a top end, I'm just going to put one in for the hell of it. I have no idea how bad its worn, as I've never had it off. I've put two summers on it, so I suppose I'm doing it just to not have it go to hell on me while I'm on my trip. What do you mean off the shelf? I'm all about putting quality stuff on my bike! Do I need to contact a builder for a better piston that is custom made or what?
 

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Sounds good man, thanks for the help! I've had excellent luck with wiescos in my banshees in years past, how do they perform in the 4 strokes? As far as needing a top end, I'm just going to put one in for the hell of it. I have no idea how bad its worn, as I've never had it off. I've put two summers on it, so I suppose I'm doing it just to not have it go to hell on me while I'm on my trip. What do you mean off the shelf? I'm all about putting quality stuff on my bike! Do I need to contact a builder for a better piston that is custom made or what?
From my research the CP#MX1026 Is about as good as it gets for "off the shelf" unless you have your top end built and the builder makes a custom piston to suit his build. I'm running a wiseco right now and it's pretty good, and, light but the CP is even lighter, it's only about 5 grams heavier than the stocker so you are gonna have absolute minimal balance issues. The CP also has the best combustion design. The CP is about $100 more, but.... I have learned that if there is anything you should not compromise on for cost concerns it's a piston! For multiple reasons and performance is at the top of the list. Even though the ProX and wiseco have served me pretty well, my next one will be a CP.

The total weight for the 5 pistons with rings, pin and clips are this -

Stock: 337g
CP MX1026: 342g
Wiseco: 355g
ProX: 359g
JE: 381g

Also, a re-coated cylinder is superior to a new stock cylinder. I hear that once you have, say, Mellinium re-coat it you will never have to do it again under normal circumstances. Also, when you re-coat, you send your piston in with it and they will get your clearance perfect to spec. That's what I'm gonna do with my new CP piston in a few weeks. Tight =less blow by=more power.

Btw - When you open your motor, if the cylinder looks good and specs out, you just need to have a shop give it a quick hone with a diamond hone for the nikasil coating before you install your new piston. If it's got scoring or developing a lip at the top you need to re-coat or get a new cylinder.

Mudtruck, you might want to read this thread -

http://www.yfzcentral.com/forum/86-yfzr-x-powertrain/108358-question-engine-builders-domed-piston-vs-flat.html

But then read Mixxer's sticky'd thread on "high compression".

My 2 cents.

Oh, Btw - the CP-MX1026 is a 13.5.1 race gas piston. CP makes a 12.5.1 pump gas psiston (I think CP-M1000) but I don't think those have the "Project X" technology...? You can call CP and ask. Not sure how much difference there is between the 2.

You can d/l the CP Powersports catalog here - http://www.cp-carrillo.com/LinkClick.aspx?fileticket=%2b%2fzYFv%2fZnyI%3d&tabid=82
 

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Very good info here^^^^^^^^^.

The only bad note on the wiseco pistons in these quads is its lack of oiling features for the wrist pin.
 

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Whats the difference between the standard CP Pistons and the "Project X" Line? The price difference is about $50 between the 2. Is it worth the extra $50 to have the "new underside" with the 1mm shorter wrist pin?
 

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Very good point...^^^^ yes on the big bore/stroker cranks its very tight with the x bracing.
 

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Whats the difference between the standard CP Pistons and the "Project X" Line? The price difference is about $50 between the 2. Is it worth the extra $50 to have the "new underside" with the 1mm shorter wrist pin?
The x bracing gives the piston stability around the weak points by the wrist pin. A down side is there heavier.
 

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Careful with the cp project X piston ive seen the x style forging on there pistons hit 07+ Yfz oil squirters. I believe they have the problem fix on there new pistons thow.
Thanks, I will definitely check with CP about that.
 

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The x bracing gives the piston stability around the weak points by the wrist pin. A down side is there heavier.
Mr. Taco, Is the CP-M1000/M1002 a lighter piston than the project X MX1026? I didn't ask CP about that and they are closed today...

Also, what do you guys think about the MX1P26 Project X long rod & piston kit? CP explained the idea and bennefits of it to me but is there enough gain to warrant the extra cash? Too expensive for me but just curious.
 

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I have also found that the standard CP piston is 13.75:1 where as the Project X CP is 13.5:1. If the standard piston is in fact lighter I think I will be going with the standard piston and put the $50 somewhere else.
 

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My other question is the piston top design and what the differences are if any between the X and standard. That's major important. If no one here can answer I will be talking to CP tuesday. I know Mixxer would know, I believe CP used his design on these pistons...
 

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yes, the added bracing for sure is going to add to the total weight of the piston... As for the top design of the piston when it comes to the higher comp pistions for standard bore or very close to standard bore it will for sure have some type of dome to the piston...


This is just a example.... but for say a 13.1 95mm bore it may be flat if not may have a bery slight flat toped dome... for say a 14.1 95mm bore it will for sure have a slight flat style dome.. Now for 96mm to say 97mm the 13.1 will most likely be very close to flat with a super slight DISH top not dome.. now the 14.1 will be super close to flat with maybe a super slight flat dome... Now on say a 98mm bore the bore is going to play a huge role in the comp. So in this case the piston will not need to have such a dome shape... the 12 to 13.1 piston will for sure be dish style, and the 14 and up will be very close to flat... NOW on the venom style pistons form John he makes the most out of the squish as possible to increase comp... This is done by changing the wrist pin height placement in the piston it self by very slightly lowering the pin placement witch will tighten the squish therefore giving a higher comp... Your end goal should be a total squish around say .030 or so.. I like mine real tight for better burn and power output....and you want the piston to be as close to stock weight as possible for less vibration and total mass... You also want the top of the piston to be as flat as possible to prevent dome top from interfering with the intake and exhaust charge flow...
 

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Thanks, do you have another pic from a different angle that is a little more clear? It looks like the top is totally flat, yes?
 

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Thanks, do you have another pic from a different angle that is a little more clear? It looks like the top is totally flat, yes?
NO, that piston is not totally flat... It has a very slight dome to it.. very very slight... Look at the one in my sig pic... 98mm bore, 14.25 comp. It has a very slight DISH not dome...:lol
 
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