ldub128

Member
May 31, 2009
24
0
Hey everyone im gonna be replacing the connecting rod bearings in my 03 ktm 125sx. I know first thing is get a service manual but besides that does anybody have any words of wisdom or any pointers i should watch out for? And how big of a pain in the butt will it be. I was gonna bring it to the shop but they want $80 an hour and said it would take like 7hrs total for labor. Thanks in advance
 

julien_d

Member
Oct 28, 2008
1,788
0
Pretty large pain in the butt. You know you are splitting the cases, right? Then you're gonna have to have the crank rebuilt. Unless you are greatly experienced with rebuilding cranks you'll need to send it off along with the rod kit.

It's not terrible, and it's a good idea to do the work yourself provided that you get the service manual and the proper tools you will need.
 

dirt bike dave

Sponsoring Member
May 3, 2000
5,349
3
You should price a new crankshaft assembly compared to rebuilding your old crank.

For some makes (Honda for example) the price new is not bad. I think when I replaced the crankshaft assembly on my '99 CR250 Honda, it was about $160, which includes brand new crank, rod and big end bearing. And no worries that the part was not true, or that the shop screwed up re-assembling the crank.

I'm sure the KTM parts will be much more, though.
 

FruDaddy

Member
Aug 21, 2005
2,854
0
I also recommend the rod kit (Hot Rods). You can rebuild your stock crank and save it for nest time. Make sure you have all of the tools. While taking things apart make sure that you are meticulous about keeping track of where every little piece goes, especially the little shim washers that seem to be everywhere. Some of those things are hard to see with the coating of oil on them. Use a lot of assembly lube. Install new bearings so you don't have to go back in next week. Freeze the bearings before you start, and heat the cases with a heat gun. Oh, and take your time, I did my first bottom end about 6 months ago, these are just the issues that I remember. It took about 6 hours for me to replace the crank using my local shops tools. Oh, and have a shop check the crank alignment before you put it in, whichever route you take.
 

ldub128

Member
May 31, 2009
24
0
Yea a friend also told me to just get the crank and rod assembly but hot rods doesnt make one. I can get just the rod through them but no assembly i checked their website. What do you mean by freezing the bearings? And are you talking about heating the cases to make them easier to split? Thanks for all all the help!
 

julien_d

Member
Oct 28, 2008
1,788
0
Nope. The bearings are a press fit into the case. In order to get them in easily, you can put the bearings in the freezer and heat the cases. Install the seals and crank bearings while the cases are hot and the bearings are cold, this will decrease the amount of interference fit and let it slide in much easier. Let everything come to room temp, and then you can heat your case halves with bearings installed and freeze the crank. This will make it easier to press the crank through the bearings. Make sense?

Some of the items you will need

flywheel puller
case splitter (I used a steering wheel puller)
freezer
heat gun, or oven

IMO it's perfectly acceptable to put the case halves in the oven at about 150 - 175 degrees. They will see that temp in use regularly anyway, and the oven will provide more even heat than you can achieve with a heat gun or torch.
 
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