I just recently got a '89 YZ 125, anyways I have had problems with it blowing headgaskets/o-rings. I know the reason it keeps blowing them is because the head and jug aren't perfectly flat(there both pretty much messed up). But I was wondering if anybody knew any tricks that I might be able to try, so that I won't have to spend months looking for a jug or trying to save up for a new jug. Any ideas would be greatly appreciated. Thanks!
'89 YZ 125 Problems
- Thread starter 89yz125
- Start date
wornknobby
Member
- Feb 5, 2004
- 625
- 0
what do you mean "messed up"? if the surfaces are not fluch you can usally give them to an auto parts store and have them do it, or you could send it out yourself to eliminate a middle man. i know here NAPA will do it for us for cheap.
you could try laying a piece of sand paper on a flat surface and, with equal pressure, sand the sealing surface of the head flat again...
I'd use a circular or figure 8 motion rotating it once in a while, make sure the surface is flat and you keep equal down pressure on the head, and keep an eye on it at all times, dont take off any more than you need too...
it isnt the "right" way to fix it, but I've used this method to clean up bad heads quite a few times, in fact when my brother got his quadracer last spring the head was so bad it would blow the head gasket everytime you started it, when I started re-surfacing the head I noticed that the only contact points between the head and sand paper was just a small ring around the bolt holes... it took me quite a while but I finally got it pretty flat again and it ran good all last summer with no problems...
I'd use a circular or figure 8 motion rotating it once in a while, make sure the surface is flat and you keep equal down pressure on the head, and keep an eye on it at all times, dont take off any more than you need too...
it isnt the "right" way to fix it, but I've used this method to clean up bad heads quite a few times, in fact when my brother got his quadracer last spring the head was so bad it would blow the head gasket everytime you started it, when I started re-surfacing the head I noticed that the only contact points between the head and sand paper was just a small ring around the bolt holes... it took me quite a while but I finally got it pretty flat again and it ran good all last summer with no problems...
- Thread starter
- #4
Sorry that I didn't explain everything. Basically, what happened was the previous owner had the jug sleeved at a NAPA machine shop... but when the dude at the machine shop put the sleeve in, he didn't get the sleeve "squared" in the bore and left some of the sleeve sticking up. So, the previous owner tried to fix it himself and took away to much material from the jug (basically, there's no groove for the o-ring in some spots). I hope this makes sense!
Nevada Sixx
Member
- Jan 14, 2000
- 1,033
- 0
HI, I also have a 1989 yz125 and its neat to see someone with a bike mine on here now and then....
Best thing you can do is sell the bike and buy a newer one around the 2500 price range, cause that is how much you will spend if you take on a big project to restore that bike like i did mine, and you still have an old bike..it cost as much to maintain an old bike as it does to pay off a new bike.
If you do need parts for it, go to www.bikebandit.com,, but you may have to enter your bike as a 1990 to find more parts for it.
but the 89 is a cool bike for trails as its low to the ground and has a nice wide seat.
i'll help you all i can on it if you have any other problems, watch out for stators going bad, and if you do ever need one, buy the stators already on the plate with wire harness..if your power valve is leaky, all the new gaskets in the world dont last long cause the problem is some rubber coated washers in the powervalve are deteriorating,,
you can a cool bike though, its pretty modernized...
one thing i did was go to 11/52 gearing in the woods, made slow hill climbs much much easier.......
good luck...
Best thing you can do is sell the bike and buy a newer one around the 2500 price range, cause that is how much you will spend if you take on a big project to restore that bike like i did mine, and you still have an old bike..it cost as much to maintain an old bike as it does to pay off a new bike.
If you do need parts for it, go to www.bikebandit.com,, but you may have to enter your bike as a 1990 to find more parts for it.
but the 89 is a cool bike for trails as its low to the ground and has a nice wide seat.
i'll help you all i can on it if you have any other problems, watch out for stators going bad, and if you do ever need one, buy the stators already on the plate with wire harness..if your power valve is leaky, all the new gaskets in the world dont last long cause the problem is some rubber coated washers in the powervalve are deteriorating,,
you can a cool bike though, its pretty modernized...
one thing i did was go to 11/52 gearing in the woods, made slow hill climbs much much easier.......
good luck...
Pete Payne
MX-Tech Suspension Agent
- Nov 3, 2000
- 933
- 38
You clould do this-- Take it to a reputable machine shop that is experianced with 2 strokes. You need to have the top and bottom of the cylinder machined while it is spun on the lathe mounted to an expandable mandrel . This puts the top and bottom of the cylinder square to the bore of the cylinder. Then have the head rechambered . Cometic gasket company can make you a gasket in a variety of thickness's. to help with the trapped volume and squish clearance.
Hope this helps,
Pete Payne
Hope this helps,
Pete Payne
- Thread starter
- #7
Thanks for the help. I would like to get a newer bike, but It's hard to get anything when your job doesn't pay well or depends to much on the weather (I work at a car wash). Besides, I only traded a rolling racing kart for it... I've only gotten to ride it for a total of 20 minutes, but I still had a freakin' blast. I'll probaly end up hanging on to it though. I just got an '83 KDX 200 today, which needs a new piston (shoudn't be to hard for me to fix). One of them will get fixed! Thanks again.