Which Piston for an 02 / 04?

[nesc103y]

I'm mating a 02 head to a 04 lower end.

 

I see Vertex High Compressions pistons run 02 - 08

 

Then I see replica pistons run 02 - 03 @11.5:1

And

04 - 08 seem to be the same.

 

 

I assume I can run the 02-03 piston with the 04 lower end. Is that correct?

[mrmoto35]

Is the 02 head going to include the 02 cam? If so I highly recommend a 13.5:1 piston. Wiseco has an good inexpensive 13.5:1

 

I have an 02 with the 13.5:1 piston and it runs really well with the 02 cam. The 02 cam was different then all other CRF cams and is the most aggresive of them all

[Diggla117]

Def 13.5. If your going for quality get a cp piston. And if you wanna really get quality get the project X cp piston..

[Diggla117]

02-08 is all the same piston to answer your question.

[nesc103y]

02-08 is all the same piston to answer your question.

 

Yeah that was the question.

I just thought it was strange that Vertex offered a 02 -03 replacement then 04 - 08. 

I'm rebuilding this for a recreational rider. If you saw my other posts about it you know he grenaded the cases.

He's getting the low performance / low compression 11.5:1 replacement piston.

I got a him complete 04 lower end, and I'm bolting his 02 head and cyl, onto the new block. 

It's the most cost effective way for him to be able to ride again.

 

Thanks to all that answered my questions here and my other posts.

My experience is only with the FI bikes. Thankfully theres still enough guys around that have experience with the carb'd bikes. 

[Jeremy Finley]

I ran a 13.5:1 CP piston in my 04, and it made quite the difference in mine.  it held up awesome I had around 100 hours on it of hard mx riding when I sold the bike.  and it only lost 5psi of compression from the time I put it in and the time I sold it. 

[brucegregory]

J&E pro series is a great piston and ebay sellers have them at the door for about 170 about 80 dollars cheaper than cp. no doubt cp are good pistons i do not think they are worth the extra money, i think vertex are cast pistons and like the oem the cast do not seem to last as long.

[Shawn_Mc]

No manufacturers make a cast piston for the CRF450R or even the X engine. The skirt is too short, hell, there's not even room for enough for the piston to survive more than about an hour before it turned sideways.

 

JE and CP are interchangeable in my opinion. Ive got a Wiseco in my personal bike because I got a super super crazy good deal on it. Entire top end kit for like 65 bucks or something from somebody on ebay that didnt have a clue as to what it was or how to list it. I shoulda bid lower...nobody else even bid on it. Probably coulda got it for 40 with the gaskets!

 

I ran a 13.5:1 CP piston in my 04, and it made quite the difference in mine.  it held up awesome I had around 100 hours on it of hard mx riding when I sold the bike.  and it only lost 5psi of compression from the time I put it in and the time I sold it. 

 

Id be willing to bet the leak down was from the valves and not the piston. My OEM 03 piston with 110 hours on it only had a 3% leak down. I did the damn test three times because I figured it had to be wrong...The narrow rings seal very very well. even on a worn out piston.

[brucegregory]

i had a oem piston shatter i to pieces, i don't think they are a true forged piston, i might be wrong though but i have never seen a forged piston shatter

[camman]

i had a oem piston shatter i to pieces, i don't think they are a true forged piston, i might be wrong though but i have never seen a forged piston shatter

It was a squeeze cast (liquid forged) piston. It is somewhat of a hybrid process that requires liquid aluminum to be squeezed into a piston die under pressure. The aluminum is near solidification yet still liquid enough to flow through a die. You can use a higher silicon aluminum yet get (forged type) grain flows. I have been involved with the development of several squeeze cast pistons and they are a royal pain in the ass!

[mrmoto35]

The CP has a wider skirt, which means something in a motor known for flipping pistons. You also get a complete gasket kit (Cometic, which is good), a DLC coated pin, and the Kramm Lox are a nice little update, for that extra $80.00

[Diggla117]

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Edited June 2, 2014 by Diggla117