Crank for my 94' KX 125

[Brandon H.]

So I had bought a 1994 KX 125 a month ago for cheap that needed bottom end work. The bottom rod bearing is bad on it because the rod is hard to turn on the crank by hand with the top end off. With the top end on it doesn't feel any different when pushing the kick by hand, but if u pull the plug and try to turn the kick it fast it makes a clunk clunk cluck sound.

What are my options?? Is it possible that the crank is still good and I can get it split and replace the bearing?? How much does that usualy cost?

I can not find a replacement crank anywhere.

 

[julien_d]

You can split the cases and have the crank rebuilt and replace the crank bearings. Should be the best solution. Off-hand I do not see a complete crank kit for 94 kx125 either.

 

[Brandon H.]

You can split the cases and have the crank rebuilt and replace the crank bearings. Should be the best solution. Off-hand I do not see a complete crank kit for 94 kx125 either.

Well I know that, but how much does it usualy cost to split the crank and replace the bearings and press the crank back together??

 

[kawraper]

I got quoted about $70 from my local shop. My 93 did the same thing im rebuilding it right now. You prolly can get away without replacing the crank if the rod bering is the problem. Mine spit out the bering but didnt damage the crank. When you get the rod kit it comes with a new crank pin. Id recommend having a shop put the crank together cause even with all the equipment in my shop im having a hard time truing the crank. Im gonna have a shop square it up for me.

 

[julien_d]

Yup. 50-75 is normal labor for a crank rebuild. This is assuming you can split the cases and remove the crank yourself. Getting the new main bearings in isn't too bad if you freeze the bearings and heat the cases. As mentioned, you need someone with proper tools and experience to replace the rod and rod bearing though...

 

[Brandon H.]

alright sweet. hopefully my crank is still in good condition, or else im screwed.

 

[julien_d]

Ah. The crank in my KDX looked like hammered hell, and the machine shop claims they're able to square it away for me no problem. I think you'll be ok ;) Rebuilding it replaces the rod, rod bearing, and piston pin. Unless the threads for the main gear or the shaft for the flywheel are very warped you should not have any problem.

J.

 

[kawraper]

Yeah even if the crank got hammered you could have a machine shop take a little material off if its not too bad. Unfortunatly the cranks for these older kxs are hard to come by. btw go to pesp.biz they got rod, pistons and gasket sets for not too expensive. I picked up everything i needed for like $205. They take their time on shipping but I wasnt in a rush so it worked out good.

 

[Brandon H.]

Yeah even if the crank got hammered you could have a machine shop take a little material off if its not too bad. Unfortunatly the cranks for these older kxs are hard to come by. btw go to pesp.biz they got rod, pistons and gasket sets for not too expensive. I picked up everything i needed for like $205. They take their time on shipping but I wasnt in a rush so it worked out good.

Alright sweet, I didn't know they can take material off the crank just like building a car motor. Do I have to use oversize or undersize bearings?

What is that website? I already have a engine gasket set, and I am going to need a rod with bearings, and a piston and ring because im going to redo the top end. I talked to eric and he said he will do it for me. Right now the only thing that is stopping me is the dang flywheel, I dont have the puller for it. Where can I get one for cheap, because the local dealer (Cahills) wants $30 just to pull the flywheel off.

 

[kawraper]

www.pesp.biz

The material you would have to take off the crank wouldnt be much unless its hardcore thrashed. You could prolly get away with less that .25 mil on either side. Just enough to smooth it over.

The rod will come with a new bering, crank pin and washers. So the part of the crank that the rod actually rides on is the pin that comes with the rod. Its just the sides of the crank that need to be smooth if it actually spit the bering out.

Goodluck with the flywheel. My shop is auto repair/ machine shop so we got a tool for every job.

 

[Brandon H.]

Alrighty sweet, so if I get a rod and it comes with a crank pin, then I should be ok. I had no idea they came with those pins, I always though the cranks were 2 piece, with the journal that the rod connects to solid to the crank on one side. It didn't spit the bearing out or anything, its still in there, but I think a needle or 2 is trash. Either way I will be taking it all apart to clean and inspect it, put new crank bearings, rod, piston/ring, cylinder redone, clean carb, check reeds and such.