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megaman

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Jul 17, 2006
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I just spent a fortune having a new sleeve pressed in to my 2000 CR250 cylinder by a local professional boring shop. I gave them my new Wiseco piston to fit and whatnot as well....

I am a fairly good machanic in my opinion (although I don't work on many 2 stroke bikes).

I put everything together as per specs reading everything from the service manual to the wiseco installation instructions. I put the bike back together and it had no power at all... I finally found out (after a lot of googling) that I put the piston with the arrow pointing towards the intake side and not the exhaust side.

After pulling the cylindar back off the bike tonight I see the top ring has caught on the exhaust port and broke the top of the piston etc etc... All from being put in backwards.

I read over my manual AGAIN and the wiseco instuctions AGAIN and the Wiseco instructions say NOTHING about what direction the arrow should go. What I did see is the marking on the original honda piston went towards the intake so I assumed the same.

If I call Wiseco and explain that their instuctions say nothing about this and now I have a busted piston, a severly scored NEW sleeve will they even consider replacing the piston?

I am not about 450.00 in to this top end job and am ready to slit my wrists.

C
 

Ol'89r

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megaman said:
If I call Wiseco and explain that their instuctions say nothing about this and now I have a busted piston, a severly scored NEW sleeve will they even consider replacing the piston?

C

I seriously doubt it. :(

It is fairly common knowledge that the arrow points to the exhaust on all two stroke pistons. Most all of them have the arrow, OEM, Wiseco, etc. A factory service manual or most good service manuals point this out. This is not Wiseco's fault.

Now, for the bad news.

If you have pieces of piston down in the bottom end, it would be a good idea to split the cases and remove all of the pieces before you reassemble the top end and run the engine. If you don't do this and there are pieces in the crank, it will cause the crank to go bad and pieces can get back up into the top end and damage the new top end.

Chalk it up to experience. An expensive lesson learned.
 

megaman

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Jul 17, 2006
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Common knowledge for who? Line up 10 random people off the street and I bet none of them know that fact.

None the less it is back in for a re-bore and the next size up piston.

blah
 

steve.emma

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Oct 21, 2002
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Common knowledge for who? Line up 10 random people off the street and I bet none of them know that fact.

fairly common knowledge for a fairly good mechanic....

sorry mate but i think you will just have to learn from this and move on.
 

John Cena

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Nov 11, 2004
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megaman said:
Common knowledge for who? Line up 10 random people off the street and I bet none of them know that fact.

None the less it is back in for a re-bore and the next size up piston.

blah

It may not be common knowledge for people who don't own and fix there own 2 stroke, but for us that do it is. It should be stated in a manual with the specs for clearances.
 

2strokerfun

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May 19, 2006
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Didn't you notice the arrow?? If you did, I'm thinking it should have raised a question you'd have wanted answered. Now, a whole lot of people who actually know this have accidentally done the same thing, though. The guy who rebuilt my bike before I bought it did it with the same results you had. I paid for it, though. But got a new Wiseco on FBay for $42.00.
On lots of other engines, the arrow often points towards the front of the engine. BTW, next time you rebuild any engine, look at the inside edge of the compression rings. If there is any chamfer at all, the smaller side goes up. That way, the compression during the compression stroke helps keep the ring against the cylinder walls. Don't think that is a real issue with most motorcyle engines, though.
 

Rich Rohrich

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megaman said:
I am a fairly good machanic in my opinion (although I don't work on many 2 stroke bikes).


A "fairly good mechanic" as you consider yourself would get his hands on a service manual before he attempted a job like this. Even if said "fairly good mechanic" didn't have a manual , if there was a clearly marked directional arrow on a part that he didn't understand, most "fairly good mechanics" would stop and find out what it meant before randomly bolting an engine together and risk damaging it.

Wiseco has a Tech Line in place just for this type of situation. ;)
 

Green Horn

aka Chip Carbone
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Jun 20, 1999
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It irks me when people always want to point a finger at someone else. Suck it up and deal with it man.

Or maybe I'll start blaming Craftsman everytime I snap a bolt with my torque wrench. :think:
 

megaman

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Jul 17, 2006
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Rich Rohrich said:
A "fairly good mechanic" as you consider yourself would get his hands on a service manual before he attempted a job like this. Even if said "fairly good mechanic" didn't have a manual , if there was a clearly marked directional arrow on a part that he didn't understand, most "fairly good mechanics" would stop and find out what it meant before randomly bolting an engine together and risk damaging it.

Wiseco has a Tech Line in place just for this type of situation. ;)

Yeah I know I am an idiot... I already admited to that. I should have read more.

Don't get me wrong I am not bitching about this, in fact I am laughing about it now becasue it was such a stupid mistake.

The thing that gets me is the absolute failure if you put it in backwards. You would think the engeneers would design something that if it goes in backwards it will not start or something, anything other then damaging a fresh cylindar

:)
 

Green Horn

aka Chip Carbone
N. Texas SP
Jun 20, 1999
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A "fairly good mechanic" could also CORRECTLY spell the brand of bike he rode. Afterall it's gotta be stamped everywhere on the bike. :laugh:

megaman

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Bike(s): Hondu 2000 CR259
 

Rich Rohrich

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megaman said:
The thing that gets me is the absolute failure if you put it in backwards. You would think the engeneers would design something that if it goes in backwards it will not start or something, anything other then damaging a fresh cylindar.

The exhaust side is the major thrust surface in this engine, so the rings on are specifically designed to be non-rotating (aka pinned) to ensure the gap can never make it's way to the exhaust side of the cylinder. As long as you have wide port in the major thrust face of a cylinder wall there is no way to "engineer" around "your" backwards piston problem.

Or as someone much smarter than me once said. "there is no way to make a part foolproof, because fools are so ingenious."
 

Ol'89r

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megaman said:
Common knowledge for who? Line up 10 random people off the street and I bet none of them know that fact.

megaman.

This is why we recommend that people purchase service manuals for their bikes. It's little things like the arrow that random people don't know and service manuals point out.

If you line up 10 random people off the street, I'll bet none of them know who Rickey Carmichael is.

Don't worry, all of us make mistakes. Why heck, I heard that Rich even made a mistake once. :ohmy: :yikes: But, after further investigation it turned out to be a mistake. :laugh: :rotfl:

Ol'89r
 

Rich Rohrich

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Ol'89r said:
Don't worry, all of us make mistakes. Why heck, I heard that Rich even made a mistake once. :ohmy: :yikes: But, after further investigation it turned out to be a mistake. :laugh: :rotfl:

Ol'89r

I'm checking to see if I can put in a warranty claim on my brain. I think it's installed a little too far south. :whoa:
 

Rcannon

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Nov 17, 2001
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I put two circlips in the same side of a piston once. I wonder if I can submit a claim on that one?
 

Rich Rohrich

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No one is making fun of you for the initial mistake, those things happen to everyone at some point on the learning curve. Asking if you can get it warrantied when it's clear where the root problem lies, is what brings out the much deserved smartass comments. ;)
 
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j32

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Jun 8, 2006
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i know what your talking about-no i dont remember seeing any info on the wiseco instructions -but it does tell you to relieve the exhaust bridge and /or drill oil holes in the exhaust side of the piston for lube between the piston and exhaust bridge// to check the power valve-to cylinder clearance before assembly ect....
as for manuals mine says in=intake, no arrows ?
an arrow can be in or out lol
but every time i seen- it is out
humm?-- a car piston has a notch in the piston that indicates (to the front) if ny one wanted to know :cool:
 

pbforlife3

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Jan 1, 2005
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i recently had a top end rebuild go bad because of being sent the wrong size piston from the shop where i bought my bike...anyhow do the piston rings lock into a certan direction the piston? or do i just place them facing a certain way? if so does anyone know what way...its for an 01 yz 125
 
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