Jump to content
Sign in to follow this  

YZ125 water pump

Recommended Posts

Hello all. I recently discovered that my '99 yz125 is leaking coolant into the transmission oil. Ive been doing research and this seems like a fairly common problem and a relatively easy fix.

Ive never done this before so im wondering what exactly i will need to fix this. Ive found this water pump kit from the local shop http://www.pilgrimpowersports.com/KS-YAMAHA-WATER-PUMP-REPAIR-KIT-detail.htm?productId=10852367&ez=water%20pump%20seal which costs about 35$. Im pretty broke and looking to do this for as cheap as possible.

Looking at the yamaha motors website i priced out what i think i need for about half that. http://parts.yamaha-motor.com/partimage.gifx?d=124861,2,0,sport ...but im worried i may be leaving something out. From the yamaha site id need parts 6, 7, and 10...and i think also one big gasket for the crankcase. Is there anything else that id need? If coolant has leaked into the tranny and sat for a while will it have messed up other parts? Ive read that its possible the bearing will need to be replaced but i will not know until i pull it all apart.

Share this post

Link to post
Share on other sites

I just finished doing the same thing to my 06 yz125. I think my seal went out cause I ran straight hose water and te bike sat for a month and allowed little calcium buggers to build up and eat the seal when I ran it.

You will need at the very least 6 and 7, one is the seal to keep the water from the tranny, the other is to keep the oil from the water. You might be able to reuse 10 but its pretty cheap so I would replace it. Same goes for the case cover that you will need to take off inorder to get to the WP. you really wont know what you need till you open it up and take it apart. Just check the bearing and make sure it is OK which it should be, and be sure not to bend the clip (3) all to hell. Also check the shaft of the WP where the seals ride, it should be smooth and have no groves or pitting. If you need to just clean it up with some emmry cloth, or scotch bright.

When installing make sure you have the seals going the right way, a tech manual should help with this which you can find for free on the net. Clean the area where the outside of the seal sits in the case the use a socket that is the same outside diamiter as the seal and use it to press the seal in the case.

Best case you just need 6, 7, 10, and case gasket. Worst case you need those plus WP, and bearing. I got my stuff from bikebandit and it arrived in about 3 buissness days.

PS. I wouldent worry about the water/coolent mixing with the tranny. Just flush it good and take a look at everything once you have the case cover off to make sure no rust or any obvious signs of damage.

  • Like 1

Share this post

Link to post
Share on other sites

Ah. thanks for the feedback :smirk: Will hopefully be able to pick up the new seals and gaskets next week and start ripping it apart. Its always nice to have a second opinion on something your not familiar with!

Share this post

Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Reply with:

Sign in to follow this  

  • Similar Content

    • By doolan
      Hi guys I have a 2018 yz250 looking at changing springs front and rear I'm 200 pound ride b class moto.
      Having problems choosing spring weights using the calculators as mx tech say I need .45 fork springs and 5.2 rear but racetech say .48kg forks and 5.8kg rear.
      What are other bigger guys
    • By YamahaYz1
      Hey TT, I know there's endless topics on YZ250/ two stroke tuning in general but I have not been able to find one that helps me get my 09 YZ250 set up for my riding style and where I ride so I'm here asking for help. I got this bike around 1.5 years ago and have not known how to set it up properly. I know no one can give me a perfect set up but I'd like a good starting setup to work from and tweak to perfection. Throughout this time I've had this bike, its always been covering the bottom of the entire silencer and dripping all over the swing arm and rims with oil. Also, the joint between silencer and expansion pipe has oil around it too but I've heard I have to close the gap a little to squeeze the silencer a little tighter and stop the leakage there. I don't have too much experience messing with carbs but I've messed around with previous two strokes and tuned them a little better. I change the oil on my bike after 15-20 hours on it and clean and oil the air filter after almost every ride. The sparkplugs never last me more than a few months but recently have been lasting me no more than a few weeks. With the excess oil from the pipe and spark plug fouling you can see why I need to set my bike up to stop this. 
      The bike:
      Completely stock with V-Force 3 Reeds and a FMF Shorty silencer. 
      Usually running around 32:1 premix with 91 pump fuel because I prefer to keep it well lubricated instead of running rich.
      I ride enduro in Ontario, Canada. So mostly single track and some fire roads but nothing close to MX and not a lot of time wide open. Therefore, probably mostly 1/4-1/2 or 1/4-3/4 throttle range.
      Where I ride:
      Usually 0-500' above sea level. With temperatures ranging from around 15-35 degrees Celsius (55-95 Fahrenheit).
      If anyone can give me a setup to go from, that would be very much appreciated. Even multiple set ups for different temperature ranges or any suggestions would be much appreciated. Thanks and sorry for the long read, I just didn't want to leave anything out. Ask any questions if you have any, too.
    • By Goon Rides
      Hey guys... so I have a problem... I took the bike at Cal City, broke it in, and while I was doing so, the bike was bogging in first gear (Yes, first gear). Also it doesn't idle at all. I have to keep blipping it otherwise it'll stall. So I adjusted the screw circled in image 1. Well I was listening to the sound of the of the bike, yet the rpm's weren't increasing, and it was still stalling. So then, I unscrewed the screw in image 2, well I found out that it was fully twisted to the right. So then, I twisted it to the left, still nothing; it was still stalling... where's the idle screw? I am sure that the screw in image 1 is for the air/fuel mixture screw, and the screw in image 2 is the idle screw, just broken? I don't know, any and every help would be appreciated.

    • By Nolan Mitchell
      I’ve got this 85 yz 250 with a odd rev problem, it starts and runs fine, good compression but when you Give it wide open throttle in newtral the bike will rev to around 5.5 k rpm like platow for a bit there, once you’ve waited  a few seconds there for it to clear itself out until it reaches its max rev whatever it might be 7k rpm even happeneds when the bike is defenetly warmed up after a wide open pull. But it doesn’t bog at idle to 3k. The trotte response when riding seens normal. However i don’t feel that the motor is getting its full potential. Honestly I’m just confused on what’s goin on and i need some help