lilvinny

Member
Nov 11, 2008
13
0
Hey, im planning on rebuilding my top end on my 90 honda cr 125. Im just wondering what i need to buy to do a whole top end rebuild.

thanks.
 

jackflack44

Member
May 3, 2008
490
0
A new piston kit, Wiseco's good. Basic tools and knowledge. A Clymer Manual would help.
 

jackflack44

Member
May 3, 2008
490
0
Haven't heard much of that brand. Only heard great things about Wiseco though.
 

lilvinny

Member
Nov 11, 2008
13
0
ok i was just goin for the cheapest lol, because im 15 and money is hard to come buy. i should probably get top end gaskets as well right?
 

Rich Rohrich

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lilvinny

Member
Nov 11, 2008
13
0
ok thanks,
wich fluids am i going to need to buy??
sorry about all the questions but im new to riding.
i apreciate all of your patience
 

jackflack44

Member
May 3, 2008
490
0
Smear some 2 stroke oil on moving parts when your sliding them in so you don't chip the walls of anything.
 

rmc_olderthandirt

~SPONSOR~
Apr 18, 2006
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A full, change everything rebuild would also include the wrist pin bearing, which is probably another $15 or so. How long has it been since the last top end rebuild? You might be OK with just changing the ring.

The gaskets you absolutely need are the head gasket and the cylinder base gasket. Don't even think about reusing these gaskets. If it has been years since the last rebuild or you don't know the history I wouldn't take any chances, I would replace every gasket that you take apart. If you plan on re-using a gasket, take careful note as you take it apart, any other gasket that tears or otherwise looks questionable needs to be replaced. Often times you can buy a gasket set for less money than buying the essential gaskets alone.

A word of caution: Be sure to check the end gap on the ring before you install it on the piston. My experience is that the new rings are bit oversized, which allows you to get a very precise fit. You MUST put the ring in the cylinder (use the piston to push it down and get it straight) then use a feeler gauge to check the end gap. If the gap is too narrow, file the end of the ring a bit and try again. Failure to do this could cause a major seize as soon as the engine heats up.

The second tip is to make sure you have the end gap of the ring in the correct spot on the piston. If you inspect the groove carefully you will find a tiny pin in the ring groove. The end gap on the ring settles over this pin and locks it in place. If you don't have the ring in the right spot the pin will hold the ring out and it will bind in the cylinder.
 

lilvinny

Member
Nov 11, 2008
13
0
im not sure how long it has been since the last rebuild, because i bought the bike used and the old owner said it needed to be rebuilt. i plan on buying a whole gasket set. i also invested in a haynes service manual.
 
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