Valve guide seal replacement without head removal

               
There are lots of valve guide seal replacement details around but I might have an alternative.
One of my seals was crushed, I found some bits of seal when I removed the shim bucket for shim adjustment. I also found minor oiling on the spark plug.
Compressions were good.
Motor is off a 1983 GPZ1100 uni track model in a B1 frame. Under bucket shims.
Special tools I made a valve spring compressor using parts from a V/ compressor kit and a 5mm thick flat bar with nut for height adjustment, used the frame as a pivot point.
Compressor fitting to spark plug hole, 1/4" long sockets to knock the valve guide down (gentle knocks) and another socket to push seal down. Tweezers for collets
Overall time (including valve guide height reset) was 50mins, I assume if I was replacing all seals this time could be cut dramatically. 

1. Put the piston (for valve seal being done) at Bottom dead centre.
2. Remove camshaft.
3. I was lucky to have compressor fittings for the spark plug, using a compressor (approx 90psi) air was pumped in. This prevented the valve from dropping IN, I found that even if the valve went down the air pushed it back up.
4. Using a combination of spring compressor and socket cracked the collets from the retainer.
5. In my case (It was like that when I bought the motor) the valve guide was too far up in the head causing the seal damage on full lift. Others appear ok.
6. Used a socket to gently tap the guide down in the head, in my case I needed just under a mm.
7. Fit new seals springs and collets. 

 

Good work - isn't using "BDC" a little risky though (a loss of air pressure from a "split hose" etc would allow the valve to fall in !!)

Good comment - I have to admit my setup was pretty good but I found the valve would not "just" drop in. Also if on TDC the air would turn the motor to BDC.

I tried the rope in the cylinder years ago and this method was 100% easier and les chance of bending the valve if cracking the collets

Added comment, I used fittings and hose made for my compression gauge, DO NOT USE CHEAP hoses fittings. With the cost saving of pulling the head off etc get good fittings

I have replaced the seals this way some times ,but alway used a rope in the bore.If it is the outer cyl it is not to bad but on intake 2 and 3  it may be tricky .
A easy way to get the valvekeepers back is to use a plastick bag over the valve springplate and keepers and a socket to press down and realease. it can take some attemts but works.

I honestly did not realise how easy this method was. I wish I did this years ago, it was actually my mechanic brother that put me onto this. He uses this method for cars etc. I was supprised when I pushed the valve down it just pushed back up.

Bozo wrote:

I honestly did not realise how easy this method was. I wish I did this years ago, it was actually my mechanic brother that put me onto this. He uses this method for cars etc. I was supprised when I pushed the valve down it just pushed back up.

It's a little easier with cars to do this and leak tests as you can use TDC, put it in gear and apply the handbrake so the motor doesn't spin (with a bike you need a friend to apply the rear brake !!)

Well done, with kind of good solutions and selfmade tools, love it!

( I´ve used this method  to change / renew the valveguide seals on many car engines, like chevy V8, or Pinto 4 bangers....But ever with the piston on TDC,..But be carefull, don´t you "hit" on the top of the valvestem!
If the compressed air missed or failured, the valve can only fell  just a little to the top of the piston,... mostly you can grab it on the stem, bring it back in "close" position, and "pump up" the air again in the  cylinder!
If the valves have a good seat and closes well,.. and if the air delivered compressor works reliable, than there´s allways a good alternative to the work of demounting the head..!

engineering brain is running with this...
i've had a borescope down in the cylinders of the KZ700, and a GS850. I've noticed that when the valves are open, you can see them from the plug hole on both engines.
using an old sparkplug, i wonder if you can make a tool that can slide or rotate into the way of the valve and be locked there for the duration of the work being done.
*thinking noises*

I know of the rope trick. The air pressure trick intrigues me. I have a small pancake compressor that I wouldn't trust in this situation, though. My concern with the air pressure would be if the valve drops far enough, that the air pressure/flow would not be enough to draw it back up.

KeylAmi! wrote:

engineering brain is running with this...
i've had a borescope down in the cylinders of the KZ700, and a GS850. I've noticed that when the valves are open, you can see them from the plug hole on both engines.
using an old sparkplug, i wonder if you can make a tool that can slide or rotate into the way of the valve and be locked there for the duration of the work being done.
*thinking noises*

I know of the rope trick. The air pressure trick intrigues me. I have a small pancake compressor that I wouldn't trust in this situation, though. My concern with the air pressure would be if the valve drops far enough, that the air pressure/flow would not be enough to draw it back up.

This is why my personal preference (and that's all it is) is TDC -  the valve can then only drop a few mm generally. The plug hole tool is interesting but would need to reach the centre of the valve to avoid risk of bending a valve (I'm what the "customer service" world call a "double bagger which I'm sure our American friends are familiar with)

Thanks for your input / replies,  I used this method and like any other method there are risks but done well it is well worth it. Since I had or made most of my tools this was not expensive and simple.

Conclusion, worth doing with good air fittings, Putting the bike into gear and activating the rear brake to ensure the valve can't drop too far (near TDC) is worth considering but like the air hose blowing can be a problem if the brake lets go. REMEMBER both cams should be removed to prevent bent valves.

I have included a picture of my fittings but if I didn't have these I would brazed a compressor hose fitting to a gutted spark plug