Compressing Valve Springs In Head

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Has anyone done this on a Commando?

I'm pretty certain one my valve stem seals has popped off the guide.
I think I can make up a tool to compress the springs in situ and I've got a compressor so feeding air into the cylinder to keep the valve up is no problem.
If I go ahead and try this is there going to be room between valve and rocker arm to get the cap and springs out?

Things more difficult because I won't be able to get the adjuster out of the rocker arm (adjusters are non standard large headed type)

Any advice appreciated
 
Rich_j said:
If I go ahead and try this is there going to be room between valve and rocker arm to get the cap and springs out?

I wouldn't have thought so.

Why not just pull the rocker spindle out (taking care to prevent the thrust washer & spring washer from dropping) anyway?
 
By the time you've made a tool the head could be removed and you could do them all whilst on the bench - if you drop a collet whilst doing it in-situ you could end up removing the barrel as well. Chances are it hasn't popped of - how would you know? I reckon it's most probably worn and letting a little oil past. You can easily tell when has happened as those riding behind behind you will soon let you know.
 
Madnorton said:
By the time you've made a tool the head could be removed and you could do them all whilst on the bench - if you drop a collet whilst doing it in-situ you could end up removing the barrel as well. Chances are it hasn't popped of - how would you know? I reckon it's most probably worn and letting a little oil past. You can easily tell when has happened as those riding behind behind you will soon let you know.

Engine spat back and straight after started smoking from RHS, its done this before. I'm a bit suspicious that there's something not right with the groove in the valve guide to locate the seal. I'm tempted to wire lock the seal on this time.

The reason for trying this out is that I don't have a spare head gasket and want to get things running again this weekend, not much to lose, if it doesn't work I can always take the head off after.
 
Probabaly the seal is on there OK. Check the intake guide for looseness in the head. Sometimes you can see a baked on oil streak down the outside of the guide tip and into the intake passage by taking the carb off and looking down the intake with a strong light. If the valve guides were replaced I would be even more suspicious.

If it is the seal I would expect to see a lot of burnt oil on the back of the valve and stem compared to the good side.
 
batrider said:
Probabaly the seal is on there OK. Check the intake guide for looseness in the head. Sometimes you can see a baked on oil streak down the outside of the guide tip and into the intake passage by taking the carb off and looking down the intake with a strong light. If the valve guides were replaced I would be even more suspicious.

If it is the seal I would expect to see a lot of burnt oil on the back of the valve and stem compared to the good side.


No its not, well it wasn't.

I know because I've just taken the head off. Valve seal was half way up the stem as expected.
When the seal comes off its a real off/on switch on a smoking exhaust, guides won't do that, I also only ran for a couple of miles like that so no time for much carbon build up.

I tried the in head way but unseated the pushrod from the rocker while trying to free the collets so admitted defeat.
For anyone trying this in the future you really need ludwig's mechanical stop on the valve. I found the collets stuck and air pressure wasn't enough to keep the valve closed.

Next question, has anyone reused an eyelet gasket? I've got no spare and the old one came off without damage so thinking about using it again.
 
Rich_j said:
Next question, has anyone reused an eyelet gasket? I've got no spare and the old one came off without damage so thinking about using it again.

Yes I did once, only after heating up the engine I had to take off the cilinderhead again. Didn't give me any trouble reusing the same eyelet gasket.
 
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