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Crank bearings

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So I made a post earlier about a noise in my bike. I bought this yz125 dirt cheap, guy said was making a noise from a transmission bearing but took it to my guy and he said he's never seen a transmission bearing go out and just try to slap it together to see what would happen. So I looked more deep and noticed there was the slightest bit of movement on my crank bearing in the case not from the actual crank. Is that normal to have a bit of play or should I get a new one ?

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No, if jugs off, any up down on rod is bad. Side,side normal. Crank bearings are different. Easiest would be to pull the left ignition cover off and any movement is bad on the flywheel, any!

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No, if jugs off, any up down on rod is bad. Side,side normal. Crank bearings are different. Easiest would be to pull the left ignition cover off and any movement is bad on the flywheel, any!

Cranks in 100% good shape the bearings in the case though, right side seems fine left side has a slight bit of play the bearing is out now and the whole motor is torn down but is there supposed to be slight play in that bearing at all ?

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Zero tolerance! Any play replace both. I also recommend doing rod bearing! It's a long way to go to get to a possible rod bearing in a day,month maybe year

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Unfortunately bearings don't last forever. Hence the noise . Time for a rebiuld :thumbsup:

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Zero tolerance! Any play replace both. I also recommend doing rod bearing! It's a long way to go to get to a possible rod bearing in a day,month maybe year

New crank and piston already brotha!

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5 minutes ago, Kflight said:


New crank and piston already brotha!

So you put new crank and piston but not crank bearings and seals?  That's just silly 

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So you put new crank and piston but not crank bearings and seals?  That's just silly 

No I didn't previous owner did then claimed had a noise then tore it all down now I got the pieces lol

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Ordered? Or installed with problems!

Installed by previous owner have recipts for all the study done to the bike before I got it I received it all in pieces

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If it looks new, replace crank bearings,seals etc. When it's apart look for any cracks, chaffing and so on. Mic the cylinder and piston to be installed to be sure clearances are in check! If your worried Lol I feel confident as of lately, so send to motox367 or yzdoc! Or send a bazillion pics and specs and I'll help you!:goofy:

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1 hour ago, Smoking 2's said:

If it looks new, replace crank bearings,seals etc. When it's apart look for any cracks, chaffing and so on. Mic the cylinder and piston to be installed to be sure clearances are in check! If your worried Lol I feel confident as of lately, so send to motox367 or yzdoc! Or send a bazillion pics and specs and I'll help you!:goofy:

 

1 hour ago, Kflight said:


Installed by previous owner have recipts for all the study done to the bike before I got it I received it all in pieces

You should listen to smoking 2's. He had his crap all over a table, asked a bazillion questions (KEY POINT) and listened to good info. You on the other hand keep saying you got this, and still the bike is in pieces. 

I don't care what a previous owner claims (especially if I buy the bike in a box) what he did to it. I have bought at least three bike-in-a-box bikes and replaced everything out of spec and questionable. This is what you should do. The big picture is you want a bike to ride and last a long time. If a case is split, I don't give a rats how old the main bearings are, they are coming out. I'll put the crank on the jig and measure run out and rod play and replace if questionable (even if the guy said it was new). It's my insurance to a solid engine, that will throw down many hours of under the helmet grins. 

So, do not second guess a thing, get a new gasket kit from RMATV, add the crank seals, MEASURE everything, and get to riding... 

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