should I split cases???

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Crash Master

Member

Apr 1, 2008

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• Apr 1, 2008

• #1

I recently purchased a 94 yz250 and my buddy mixed the gas way to lean ( should have done it myself ) . the piston broke off the skirt on the exhaust side jamming the crank stopping the bike instantly. I removed the topend turned the bike upside down jiggled the crank and the offending pieces of piston skirt fell out. I have cleaned up all metal filligs and pieces and the crank turns perfectly smooth with no noise or slop. Will I be able to put in a new topend and go or should I split the cases?

Also there are a lot of little bits of aluminum from piston in my pipe , can I flush them out with water and then dry my pipe thanks for any advice.

 

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colbyc28

Member

Dec 1, 2006

67

0

• Apr 1, 2008

• #2

Might wanna invest in one of those magnetic oil drain plugs.... I know it wont really help for the aluminum, but it can collect some of the bearing debris that may be floating around.

 

C

Crash Master

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Apr 1, 2008

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• Apr 1, 2008

• Thread starter
• #3

I didnt break through into the transmission. It's a dry sump motor being a 2 stroke so there is no oil to drain. I did drain the tranny to check for aluminum bits and there were none.
Most of the bits are in my pipe

 

C

Crash Master

Member

Apr 1, 2008

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• Apr 1, 2008

• Thread starter
• #4

I just found a thread on another site. a guy had the same thing happen and he split the cases only to find a very small amount of fillings. The aluminum was so much softer it was reduced to almost nothing. he wasn't so sure it was nessasary to split cases. I just want to get the summer out of this bike and rebuild in the winter. :think:

 

Rich Rohrich

Moderator / BioHazard

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Jul 27, 1999

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• Apr 1, 2008

• #5

Don't be stupid. Split the cases and fix it right. It will cost a lot more if the crank comes apart and you break the cases.

 

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ysr89

Member

Dec 4, 2007

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• Apr 1, 2008

• #6

I agree with Rich, all you need to do is blow the bottom end and a relatively small problem turns into a big, expensive problem very quickly.

 

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crazytrails

Mi. Trail Riders

Member

Dec 25, 2005

213

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• Apr 1, 2008

• #7

Its a good idea to split the cases and replace the main bearings.. But if its something you really don't have the money for then the best you can do is pull the engine out of the frame. Pour fuel or mineral spirits into the crankcase and wash it around then tip it upside down and let it run out while rolling the crank over.. Then make sure you pre-lube the main bearings with 2 stroke oil..... And no the metal wouldn't get into your transmission.. perks of have a 2 stroke compared to a four stroke.. And the worst i see happening if you run the bike without splitting the cases is the main bearings seizing. good luck

 

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BigRedAF

Member

Jan 9, 2005

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• Apr 1, 2008

• #8

Rich Rohrich said:

Don't be stupid. Split the cases and fix it right. It will cost a lot more if the crank comes apart and you break the cases.

Click to expand...

Roger that!

 

whenfoxforks-ruled

Old MX Racer

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Oct 19, 2006

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Merrillville,Indiana

• Apr 1, 2008

• #9

Rinsing the case out is futile. Better luck can be spent on lotto tickets. Split the cases and you may see why. 1 piece of that piston can ruin the crank, cylinder and head, if not poke the rod out if the engine.

 

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Crash Master

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Apr 1, 2008

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• Apr 2, 2008

• Thread starter
• #10

Guess I'm splitting the cases.thanks for the info! it's just so free no more piston parts are coming out. I'm just stir crazy and want to ride asap! Why did I let my buddy mix the gas?? :bang: anyway I got work to do!!!!

 

Reesknight

~SPONSOR~

Oct 31, 2002

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• Apr 2, 2008

• #11

You may find the cases are already cracked when you split them as they are double walled if I remember correctly. You definately need to get ALL the filings out or it will kill you're bearings at least.

 

C

Crash Master

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Apr 1, 2008

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• Apr 2, 2008

• Thread starter
• #12

I lost my cool. I'm gonna flush it out, new top end and pray!!
if it blows it blows. just labour alone in this town is 100.00 bucks an hr. I ain't doing it myself as the bike will probably never run again.

I suggest you start a poll on how long she lasts!
mins,hrs,days.

I read a response by ric sieman to a guy with the same problem and he said a really good flush would do fine for now.
I only want 30 40 hrs this summer. I'll pay out the big bucks in the winter and have the engine totally done bottom up I promise :worship:

 

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ysr89

Member

Dec 4, 2007

108

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• Apr 2, 2008

• #13

For the money you spend getting it done at a shop, you could probably find a full 94 motor.

 

C

Crash Master

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Apr 1, 2008

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• Apr 3, 2008

• Thread starter
• #14

ysr89 said:

For the money you spend getting it done at a shop, you could probably find a full 94 motor.

Click to expand...

Yeah thats what I'll probably do.

 

Ol'89r

LIFETIME SPONSOR

Jan 27, 2000

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• Apr 3, 2008

• #15

Rich Rohrich said:

Don't be stupid. Split the cases and fix it right. It will cost a lot more if the crank comes apart and you break the cases.

Click to expand...

You can lead a horse to water,,,,,,,,,,, :coocoo:

 

Rich Rohrich

Moderator / BioHazard

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• Apr 3, 2008

• #16

Ol'89r said:

You can lead a horse to water,,,,,,,,,,, :coocoo:

Click to expand...

.... but sometimes he'd rather just tip the trough over. :bang:

 

D

dirt bike dave

Sponsoring Member

May 3, 2000

5,348

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• Apr 3, 2008

• #17

Choice A:
New top end: $125
Gas to flush crank case $1
Crossed Fingers to ward off big end failure: No Charge

Choice B:
New top end: $125
New Crank Bearings: $60
New Gasket set: $70
Split Cases, Examine Crank, Install Bearings, Rebuild: $200 labor, +$200 if a new crank is needed

The problem is if you choose A ($125) and the crossed fingers don't work, your bike will now need at least everyting on list B ($655), with the risk of adding a new cylinder ($300+), new crankcaske halves ($200 each), powervalve parts ($150?), new head ($75?), etc... Oh, plus whatever medical bills you incur if you seize up at a really really bad time.

 

IndyMX

Crash Test Dummy

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Jul 18, 2006

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Amo, IN

• Apr 3, 2008

• #18

What do you expect from a guy called "Crash Master"?

Take note of the second line in my sig... Fit here perfect.

 

whenfoxforks-ruled

Old MX Racer

~SPONSOR~

Oct 19, 2006

8,129

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Merrillville,Indiana

• Apr 3, 2008

• #19

Now wait a minute, Rick Sieman said it would be good to go? The piston went for a reason, it could well still be there. There is a very small place that debris can get through the main bearings and seal. You can not wash or blow this area clean, positively. I am sure there is a lot of people who have already done this for whatever reason, myself included. Most of the time it ends much worse.