TOPIC:

Actually, I even took off the springs from one valve, to see if springs were interfering, and even then, they would not come in.

 

I recomend using assembly lube on the buckets bores and springs.If you will start up the engine soon you can use just oil.To free the bucket try to use some heat from a from a hair dryer or place the head on something that is a little warm.You can also maybe try to use freeze spray or holding a box with startgas or airduster or similar upside down and spray on the bucket .

I will definitely try with some heat. It already moved up a bit by turning it around and a good dose of penetrating oil.
here are two things here. 

1.- I did not lube the bucket as much as you have (I was really trying and expecting to be able to get it out)
2.- There is crude in the buckets. I cleaned them last night with emery paper. even though the head was Vapor blasted, I suspect there is also crude in the “holes”. 

I will disassemble the valves again and clean each of the holes in search of crude 

thank you again guys

That shimbucket may need to be replaced because of overheat .If the bores are not smooth you may use a mini honingtool like for brake pistons to just get them smooth.
Im not an expert maybe some one else knows better

The funny thing (well, not really, but anyway) is that they came out really well with just a regular magnet. So easily, in fact, I don´t have a distinct memory of taking them out... which means they did as they were supposed to.

I will clean everything and go from there. I just looked at cmsnl.com and the cost per piece is almost 60 euro per piece!

I really hope I don´t have to change them!

I think you only need to change out the one that is bad or worn. You can find used buckets on e-bay i think or maybe someone on the forum has some for sale. Do you have a pick how the bore look inside ?

So, finally, the bucket came out. Some heat from a propane torch, penetrating fluid and a soft approach with a vise grip made it happen. No brute force was used, no damage done.

Once all valves are out again (I’m getting really good at it!), I’ve measured both the buckets and the “pits”, for lack of a better name.

my surprise is that the pit’s width is roughly 32,70mm, but there is no bucket that will measure less than 32,80. No wonder they don’t fit well.

my question is: Could have buckets been damaged because of heat (or whatever cause) making them to “expand”? Don’t forget this was a severely mistreated bike in the past.

I’ve found plenty of second hand buckets on ebay in the US. Can they be replaced freely? I was under the impression that the same part
should be used in its original location.

Wow, what you have here is "one of life's little mysteries" the head can't shrink and the buckets can't "expand" any stay there when they have cooled. Have you measured in several places to ensure the buckets haven't become oval. If the buckets have distorted then the solid part at the top should have remained round - have you tried slipping the buckets in "upside down" to see har far in they will go before you feel resistance ?
With regards keeping parts in their original location - ideally yes as the parts wear to each other like your feet and your favourite shoes, however it's common practice to swop shims to run on different cam lobes when adjusting clearances. The head is softer than the bucket so there shouldn't be significant wear on the buckets. Given that new buckets would come in at €480 for a full set, personally if I found the buckets were distorted I would consider "used" parts if the condition was good and they measured up in spec.
I guess the first thing is to establish what is wrong, what has changed since you took it apart and what caused it (not always easy !!)

Was the bores for the buckets blasted?  the surface should be smooth .If i was you i would try to hone the bores super light with a hone like in the picture.I have never done that before and cant guarantie that is safe,but the bores will be smooth at least. I leave this for the experts

Vapour blasting was used, so there is no roughness in the bores. I will take some emery paper as fine as possible to the bores walls and see if any change happens.

As Wookie says, this is a complete mystery to me

cartal wrote:

Vapour blasting was used, so there is no roughness in the bores. I will take some emery paper as fine as possible to the bores walls and see if any change happens.

As Wookie says, this is a complete mystery to me
 

I thought it was normal procedure to mask off bearing surfaces and bucket bores before vapor blasting, given the precise tolerances that need to be maintained in those areas.


 

My understanding is that masking is necessary if you are media (sand, etc.) blasting. Vapor blasting uses water, and does not damage the surface being cleaned.

In any case, if bucket bores would have been eroded by vapor blasting, the end result would be a wider gap, rather than a smaller one; thus making the buckets fit better. 

In any case, I will clean bores tonight well with a good solvent, and then give them a go with emery paper. Planning to use one of these: