How many hours before I need to replace main bearing on a 125?

Muscle-Milk-KTM
Currently my 18 YZ125 has about 32 hours from new on it. Was wondering how many hours before I should replace the main & crank bearings? Am I on the limit or can I go longer? I'm not particularly quick so it's not getting ridden really hard.
|
kb228
Profile picture for user kb228
Posts
6161
Joined
1/31/2018
Location
Mansfield, OH US
kb228 10/4/2018 9:03am
10/4/2018 9:03am
Just check your bearings when you do top ends. You can get 100+ hours out of a 125 bottom end. Its the top end on those that need constant attention.
Muscle-Milk-KTM 10/4/2018 9:15am
10/4/2018 9:15am
kb228 wrote:
Just check your bearings when you do top ends. You can get 100+ hours out of a 125 bottom end. Its the top end on those...
Just check your bearings when you do top ends. You can get 100+ hours out of a 125 bottom end. Its the top end on those that need constant attention.
So I'm well within then, I did think it would be a lot of hours before it needed changing but wanted to know when people did theirs.
Alec138
Profile picture for user Alec138
Posts
540
Joined
1/29/2018
Location
Bethania, NC US
Alec138 10/4/2018 12:55pm
10/4/2018 12:55pm
Depends on how hard you ride it as well. The guy who is on/off the throttle constantly or cruising through trails can probably get a few hours out of a bottom end. The guy who rides track and revs it out 4 times a week will need constsnt rebuilds...
CarlinoJoeVideo
Profile picture for user CarlinoJoeVideo
Posts
7358
Joined
11/30/2013
Location
Portland/Los Angeles, CA US
Fantasy
2361st
CarlinoJoeVideo 10/4/2018 10:46pm
10/4/2018 10:46pm
I did my KTM 125 bottom end at 90ish because I broke a tranny gear. Everyone told me that bottom ends should at least go 100 depending on the rider and maintance performed.

The Shop

See All »
chump6784
Profile picture for user chump6784
Posts
1692
Joined
5/9/2011
Location
AU
chump6784 10/5/2018 10:26pm
10/5/2018 10:26pm
Back when we were racing 125's we would do a bottom end every 4th piston. That put it around 80-100 hours
1
sandman768
Profile picture for user sandman768
Posts
6096
Joined
3/21/2014
Location
Saratoga Springs, NY US
sandman768 10/7/2018 7:08am
10/7/2018 7:08am
All good advice from everyone..... You can grab the fly wheel & push/pull move back & forth, any movement, in/out, up / down is play in bearings.
Billet526
Profile picture for user Billet526
Posts
57
Joined
4/4/2015
Location
Colorado Springs, CO US
Billet526 10/7/2018 8:18am
10/7/2018 8:18am
I cant speak for any other brand except for Yamaha. We have several 125s, 134, 144... We have no problem getting 100+ hours on the factory crank / bearings. We have not found a aftermarket crank bearing that lasts longer then 20 hours. Im sure there are great ones out there but we haven't found em.

Top end 20 hours
Lower end 100ish hours
Ethanol free fuel
Amsoil 40:1
1

Post a reply to: How many hours before I need to replace main bearing on a 125?