1989 KX 125

[andydunne]

Its high time I started a thread on my bike.
I bought the bike in sept.2011. The bike was for sale for 600euro but when i went to look at it, the seller cudnt start her for the life of him, so I took a punt on it, haggled him down to 300 considerin it wudnt start. Within ten mins of getting it home my mate and I got her started and it ripped, I was delighted. This is how she looked at first;



It had a few trick bits on her like an Fmf gold series pipe(as good as new) and renthal bars!

[andydunne]

After a couple of weeks problem free, I still couldnt believe the bargain I got, it was the bike that kept giving.
New tyres, tubes, rimlocks, handlebar grips were fitted as they old ones were knackered.
I also fitted bigger and better footpegs and springs as I disliked the older ones, kept slipping off them!
After some research on here and other forums, I decided to fit a newer 2000 KX250 rear fender to tidy the tail up a little. Here is how it looks;

[andydunne]

So one day I decided to take off the head for a look and knew something was wrong straight away when I seen this;



The exhaust valves were in rag order and no way were they working properly or working at all for that matter. I never felt the bike was slow despite this problem so I decided to order knew ones, which im lucky are still available, and see how the bike performs then
New valves, nice and shiny;

[andydunne]

Clymer manual, what a god send, id be lost without. Thanks to anyone who recommended it to me


New parts ordered;
Air filter, gasket kit, clutch lever and cable, throttle cable, swingarm bearings, seat re-upholstered.

The old swingarm bearings, they were boll*xed


New bearings, pressed and greased

[andydunne]

Next I put all the parts back together, everything timed up etc. I couldnt start the bike at all, it always was hard to start after lying up for a while. So I bought a compression tester and it was only making 80-90psi...a new piston and rings were due.
I wasnt sure which piston to go for, all the debating on here was confusing me , anyway I went for a Wossner kit and it arrived the other morning, it looked great. I was really looking forward to fitting this, seeing as its my first time!
Pretty simple job imo, done in 10-15mins, everything back together, filled with coolant etc I was ready to go. After a small hiccup of the carb not filling, 2nd kick and away she went. GREAT SUCCESS!!
I didnt leave it running too long as the bike is on a stand atm, due to a seal im waiting on for he swingarm. When it arrives ill be able to ride and break her in.
Here is the bike just before I installed the piston


New Wossner piston kit

[andydunne]

Hey guys,
I am thinking about replacing my fork seals as the left fork is leaking ever since day 1 with the bike.
So my question is, are my forks inverted cartridge type forks or dual-chamber style forks? I was looking at 'howto's' from rockymontainatvmc.com on youtube, they have seperate videos for both

[Motorrad]

inverted cartrage 

[andydunne]

inverted cartrage 

Thanks mate. After looking at both videos, Im glad its the inverted cartridge type as they look alot less complicated to work on

[andydunne]

Little update,
Front brakes always felt soft so after looking at the disc it was well worn and beyond the service limit according to the manual.
Stopping power is much improved after fitting new disc, I was gonna go for a fancy wavy disc but money is tight so I chose a stockish brake disc


I also got a 11t front sprocket as I was looking for more torque as I felt the bike seemed to be geared very long.
Current setup is 12/48 and I was looking at 51/52t sprockets but once again money is tight atm so a front sprocket was cheaper than a rear sprocket
The 11t sprocket seems quite uncommon though looking on the net, is a 11t sprocket ok to be running could it do harm , i can always change back to the 12t. I havent rode the bike much so i cant comment on how it feels really!

[andydunne]

Hi guys,
Forkseals really need to be to be changed, left fork is nearly bottoming out when I hit a big jump, its fooked!
Now what fork oil should I use, I was reading a heavier oil would make the forks a little stiffer which would be nice, any advice?

[Spac]

The right quantity of oil (inside the forks, not leaking all over the outside) will fix your problem. Also check the compression adjusters in the bottom of the forks - bringing them in a couple of clicks will help.
If that's not enough, then stiffer springs are the answer.

Heavier oil will tend to make them harsh, and deflect on small, sharp edged bumps.

[andydunne]

The right quantity of oil (inside the forks, not leaking all over the outside) will fix your problem. Also check the compression adjusters in the bottom of the forks - bringing them in a couple of clicks will help.
If that's not enough, then stiffer springs are the answer.

Heavier oil will tend to make them harsh, and deflect on small, sharp edged bumps.

Cheers mate, I am gonna get the seals fixed, im sure it will make a big difference. The oil is prob like water at this stage ha!
I will play with the adjusters then when they are sorted

[andydunne]

Bad wkend for the KX
Went to the local track for a spin, done about 2hours riding, the bike was flying, pushing her pretty hard. Then heard a small noise, thought nothing of it carried on,  around 30secs later the bike died. Got the bike home hoping for the best.
Compression was low, the kickstart had not much resistance. Removed the head, piston and head are both heavily pitted. Removed the barrel, no major damage needs a replate though. The crank seems ok but I am gonna split the cases to be sure.
I will have pics up soon of the damage

Update,
Some of the pitting on the piston


The big end bearing is shot too, whether this caused the damage i dont know. Crank seems ok . this is as far as I got with stripping.
Im gonna send it too a mechanic to have the cases split,crank inspected and hopefully just bearings replaced

[splime738]

Like the look of the rear fender, just bought an 89 this weekend, will fit a similar mudguard when i re-new. Any idea what caused the damage

[andydunne]

Like the look of the rear fender, just bought an 89 this weekend, will fit a similar mudguard when i re-new. Any idea what caused the damage

Ye its cool looking I think, makes it look alot fresher.
No not really, big end bearing wasnt good when i stripped it.
I was also using a plug from my friends KTM 125sx. I had fouled a plug at the track, my friend had a spare plug so threw it in and was flying then, about 3-4hrs later it went boom. Dunno if this would cause damage like this