to bottom end or not to bottom end?

ojasia

Member
Mar 13, 2013
52
0
I have top end off, fly wheel cover off and clutch cover off. What all can I do to inspect the lower end. Just recently bought a 2000 CR 125 and blew the top end, being frustrated I just wanted to start fresh to know what i got. I bought Bottom end rebuild kit, full engine gasket kit, OEM crank bearings and seals, OEM jug, OEM head, Stock top end rebuild kit. PV seal E-Clip, Ex. Flange, Ex. seal, Clutch kit, head studs, few others for it as well. but now that I have exactly pinpointed form what I can see is it was a top end Malfunction. And that I should save my new bottom end kit for when my bottom end goes. Any opinions, keep this in mind after the piston smashed spark plug and exploded it and I shut it down the kickstart was seized. but I cant feel any vertical play in the Rod... Just a little horizontal wiggle play. If anyone needs info on what happened ... Reply
 

Rich Rohrich

Moderator / BioHazard
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Jul 27, 1999
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You have the parts, you have it apart, and you have no idea how much time is on the current bottom end. Sounds like a textbook reason to rebuild it.
 

_JOE_

~SPONSOR~
May 10, 2007
4,697
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For sure! That brand new top end will be a paper weight if the crank bearings come apart. Once you have the top end and clutch off it's really not much more work to do the crank. It's always more expensive to repair a blown up engine than it is to replace functioning parts as maintenance.
 

Rich Rohrich

Moderator / BioHazard
LIFETIME SPONSOR
Jul 27, 1999
22,811
16,878
Chicago
Yes, absolutely. The idea that people wait till parts are flopping around in the engine to change them is ridiculous. After a certain number of hours parts in an engine are junk, even if the bearings aren't wobbly.

Don't rebuild the crank though, just buy a new one if possible. They tend to be cheaper in the long run and usually more reliable unless you have access to a really good machinist with the proper crank alignment tools. Those guys are few and far between these days.

You'll buy yourself a few seasons of "piece of mind" by starting with a engine that has been properly rebuilt top to bottom.
 
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