Wiseco piston vs CP


28 replies to this topic
  • Goosedog

Posted June 02, 2009 - 04:49 PM

#1

I'm rebuilding the top end on my YZ450 that already has an MaxPower RPM 488 kit. When I called to order a new piston kit they said they were out of the Wiseco 488's so were sending a CP instead. Now that it's arrived I'm holding the new and old side by side and the new CP is clearly 3mm thinner from face to edge of skirt. Is this a concern with longevity in mind? Does CP have as good a reputation as Wiseco? And should I send it back and insist on replacing with exactly the same brand as they originally used when they bored the motor?

  • grayracer513

Posted June 02, 2009 - 07:02 PM

#2

Does CP have as good a reputation as Wiseco?

Porsche and Ferrari use them, as do many others. They are my first choice, too, for what that's worth.

http://www.cppistons...99/Default.aspx

  • ThumperKid250F

Posted June 02, 2009 - 07:20 PM

#3

ive had good luck with wiseco befor my wrist pin snaped on my 2006 450 and took out my motor, so since then im useing CP piston and im very happy with it, i got 28 hours on it and it still going good.

one thing you will notice about CP is that its a better made piston just by looking at it, the wrist pin is a lot thicker than the wiseco and ther is more oil holes along the sides of the piston also..

i would use CP

  • Aka.Goose

Posted June 02, 2009 - 11:33 PM

#4

CP has had a good reputation in the auto/drag racing world for many years...

  • 642MX

Posted June 03, 2009 - 09:25 AM

#5

CP has a good reputation.... so does Wiseco. I've been using Wiseco so long that I don't even consider another brand when I order a top end kit.

  • Aka.Goose

Posted June 03, 2009 - 06:32 PM

#6

CP has a good reputation.... so does Wiseco. I've been using Wiseco so long that I don't even consider another brand when I order a top end kit.

yeah, I don't know about Wiseco being considered as having a good rep...Maybe as decent replacement parts...But definitely have a rep for using metals from all over the globe...
CP has a good rep for making superior parts with superior metals in the racing forum...pistons for drag cars that if faulty could mean lives...

  • mercier24

Posted June 03, 2009 - 06:37 PM

#7

Wiesco pistons are fine as long as you break them in the right way, they are forged and require a longer procedure than cast pistons, but last longer in the end.

  • 642MX

Posted June 03, 2009 - 06:54 PM

#8

yeah, I don't know about Wiseco being considered as having a good rep...


Just think, Wiseco probably sells 100 pistons to CP's 1 (in this industry). Naturally your going to read about more issues and problems....

  • grayracer513

Posted June 03, 2009 - 10:28 PM

#9

forged (pistons) require a longer procedure than cast pistons, but last longer in the end.

I challenge you to support either of those assertions.

Just think, Wiseco probably sells 100 pistons to CP's 1 (in this industry). Naturally your going to read about more issues and problems....

The sales figures may be correct in the US, but now I'd like you to compare on a percentage basis the number of YZ450 wrist pin failures using OEM Yamaha, CP, and Wiseco pins.

  • 642MX

Posted June 04, 2009 - 04:23 AM

#10

The sales figures may be correct in the US, but now I'd like you to compare on a percentage basis the number of YZ450 wrist pin failures using OEM Yamaha, CP, and Wiseco pins.


You provide the data, I'll make the spreadsheet....lol.

Seriously, I've read about a half dozen Wiseco wrist pin issues..... but, never seen one up close to investigate. Maybe its defective product, maybe its an installation problem?....

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  • mercier24

Posted June 04, 2009 - 04:42 AM

#11

I challenge you to support either of those assertions.
The sales figures may be correct in the US, but now I'd like you to compare on a percentage basis the number of YZ450 wrist pin failures using OEM Yamaha, CP, and Wiseco pins.



Whats to challenge? I know a kawasaki mechanic out of CT and he only uses wiesco pistons and he has used them for a long time for street and dirt applications. i have used them as well without problems, its all in the way you break it in.

  • grayracer513

Posted June 04, 2009 - 06:23 AM

#12

Half a dozen is 6 more than I've seen with stock Yamaha or CP pistons. That's my point.

  • 642MX

Posted June 04, 2009 - 06:41 AM

#13

Half a dozen is 6 more than I've seen with stock Yamaha or CP pistons. That's my point.


Point seen... but you see my point that if Wiseco sells 100 pistons to CP's 1 piston that naturally you will read about more problems?

Just like YZF's compared with CRF's.... Many more CRF's are sold than YZF's.... so naturally your going to read about more problems with the CRF. Of course, I think the YZF is a better bike, but I'm a little biased.

As far as OEM pistons are concerned.... they must be darn near bullet proof, because I've never read anything negative about them. But OEM doesn't offer high compression options & big bore options like the aftermarket does.

  • grayracer513

Posted June 04, 2009 - 06:56 AM

#14

Whats to challenge?

The challenge is to this statement:

forged (pistons) require a longer procedure than cast pistons, but last longer in the end.


Neither is true.

Forging a piston as opposed to casting it does not affect break-in procedures in any way. If a piston is fit and finished correctly, the piston itself will need almost no break-in at all; it's the rings that are critical. Any piston that requires a cautious or extended break-in would seem to me to be admitting to a fault in design or finish.

Unmodified aluminum expands faster and farther than steel and iron. Piston manufacturers learned long ago that they could add silicon to control the expansion so that they could fit pistons tighter in the bore and get rid of all the rattling and slapping that used to go on with a cold engine. Years ago, the forging techniques in use were incompatible with high silicon content, so forged pistons still had to be fit loose, and still had to be warmed up carefully, especially when new. This is where all the folklore about cold seizures, and forged piston noise got embedded in the culture, and it hasn't ever come back out.

It also hasn't been true for over 35 years. Modern metallurgy and forging technology moved past that long ago. The forged pistons I installed in small block Chevy's in the early seventies were fit at .002", and were as quiet as the stock ones. On top of that, now that the bore itself is aluminum, there's not even a material mismatch to deal with anymore.

Most forged racing pistons are physically stronger than OEM, but the only time that results in increased longevity is if the engine is subjected to conditions that exceed the strength of the OEM piston. That may be something that your friend runs into with Kawasakis, but it isn't an issue with a YZF except under the most extreme circumstances, and I can't remember when the last broken Yamaha OEM piston I saw in a YZF was (not counting those broken by improper snap ring installations). The stock, original piston in my '03 went over 350 hours without a problem, so when you say that a forged piston will last longer, I have to ask, "under what conditions?"

  • Aka.Goose

Posted June 04, 2009 - 10:45 AM

#15

Just think, Wiseco probably sells 100 pistons to CP's 1 (in this industry). Naturally your going to read about more issues and problems....


I almost always go for the product made by a small US company built from some of the top innovators and craftsmen of the industry, as opposed to a mass producing large company...And I don't get caught up in hype, I'm often critical of anything read...I go by what's being said by people whom I respect, and what I see (in garages, factories, racetracks, and trails)...
I live in Southern California and often do actually go out to the factories and offices of many of the top motocross companies based here...You'd be surprised how friendly, accommodating, and full of free flowing knowledge people can be if you show up instead of call...
CP pistons is in Irvine, go check out their facilities, I'm sure they'll show you around and answer any questions you may have...
Then stop by Wiseco's corporate Ohio offices, or their distribution facilities in Canada or the Netherlands, then you might figure out where the pistons are actually manufactured, then travel all over the world to see where the metal came from...

  • 642MX

Posted June 04, 2009 - 11:36 AM

#16

I almost always go for the product made by a small US company built from some of the top innovators and craftsmen of the industry, as opposed to a mass producing large company...And I don't get caught up in hype, I'm often critical of anything read...I go by what's being said by people whom I respect, and what I see (in garages, factories, racetracks, and trails)...
I live in Southern California and often do actually go out to the factories and offices of many of the top motocross companies based here...You'd be surprised how friendly, accommodating, and full of free flowing knowledge people can be if you show up instead of call...
CP pistons is in Irvine, go check out their facilities, I'm sure they'll show you around and answer any questions you may have...
Then stop by Wiseco's corporate Ohio offices, or their distribution facilities in Canada or the Netherlands, then you might figure out where the pistons are actually manufactured, then travel all over the world to see where the metal came from...



Easy there Goose. I've never said anything bad about CP's.... I'm sure they are wonderful pistons and wonderful people to deal with. I work somewhat in the industry and know several people from Wiseco which are top notch guys too.

FWIW, we have an Arctic Cat 650 (with a 700cc big bore kit) apart at our shop right now. The customer has had the big bore kit for 2 weeks.... and it smokes like a freight train. The tech just pulled it down and found the top compression ring gap at .035" and the lower ring at .045"........ BTW, its a CP.

  • grayracer513

Posted June 04, 2009 - 11:58 AM

#17

FWIW, we have an Arctic Cat 650 (with a 700cc big bore kit) apart at our shop right now. The customer has had the big bore kit for 2 weeks.... and it smokes like a freight train. The tech just pulled it down and found the top compression ring gap at .035" and the lower ring at .045"........ BTW, its a CP.

Without the specs on what the bore should be, what the bore actually measures, what the piston clearance should be and the actual measurement, all that is is an interesting anecdote. The problem could be in any one of 3 places. That the ring gap is that large indicates that the rings are for a cylinder .007~.010" smaller than that one is.

  • Aka.Goose

Posted June 04, 2009 - 12:13 PM

#18

Easy there Goose.

Hahaha, no worries...I was typing all that with a smile...
Sometimes my typed words are nothing like the exact same words spoken...
Just throwing my 2cents out there...
I am however very impressed with how these small California companies are able to withstand this economy and pressure from these larger corporations...And trust me, they can't do it without our support, which they know they can only get through having a superior product, and service...

  • mitchicle

Posted June 04, 2009 - 12:25 PM

#19

[QUOTE]and I can't remember when the last broken Yamaha OEM piston I saw in a YZF was (not counting those broken by improper snap ring installations). [QUOTE]

I'll show you a picture of one tonight when i get home from work.

  • 642MX

Posted June 04, 2009 - 12:40 PM

#20

Without the specs on what the bore should be, what the bore actually measures, what the piston clearance should be and the actual measurement, all that is is an interesting anecdote. The problem could be in any one of 3 places. That the ring gap is that large indicates that the rings are for a cylinder .007~.010" smaller than that one is.


Here is the info. The bore is 4.0157, piston is 4.0137, clearance .002 The top ring gap (per CP manual) is bore x .005, the second ring is bore x .006

So the ring end gaps should be .020 and .024.

Here's a pic of the gaps....

Posted Image
Posted Image
Posted Image
Posted Image

I'm not sure what happened to it?....





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