Using honing stones on a 242xp chainsaw cylinder?

[Macpherson]

yeah Spud, any nikasil bore I`ve done has been with wet n dry / oil, I`ve never tried the honing tool in a blind engine cylinder although I do have a smaller version with two prongs, very good for reclaiming master cylinders, I take your point that a light touch is needed. cheers

[kentjames]

Ok so having had the opportunity to look at it again in daylight...

 

Having read up on which acid dissolves aluminium, i read its sulphuric acid, is that correct?

 

Whats the method for doing it with the acid? Just bath it or paste it on the area?

 

I am keen to try the acid and wetNdry first as it would avoid spending money on the hone!

 

Also another question, where is best to get replacement gaskets for this model? Ereplacement parts seem to list them? Or some where else?

 

Any advice much appreciated !!

 

Looking forward to get the saw back together again now, been a fun project.

[peatff]

Ok so having had the opportunity to look at it again in daylight...

 

Having read up on which acid dissolves aluminium, i read its sulphuric acid, is that correct?

 

Brick acid cleans it and that is usually Hydrochloric. It's cheap from builder's suppliers as well.

[spudulike]

Ok so having had the opportunity to look at it again in daylight...

 

Having read up on which acid dissolves aluminium, i read its sulphuric acid, is that correct?

 

Whats the method for doing it with the acid? Just bath it or paste it on the area?

 

I am keen to try the acid and wetNdry first as it would avoid spending money on the hone!

 

Also another question, where is best to get replacement gaskets for this model? Ereplacement parts seem to list them? Or some where else?

 

Any advice much appreciated !!

 

Looking forward to get the saw back together again now, been a fun project.

 

Lightly sand the aluminium transfer, apply the acid with a cotton bud to the effected area, if all is good, it will fizz. Once it has gone black and stopped fizzing, lightly rub with more wet and dry, try more acid and if it fizzes repeat until it doesn't. If it doesn't fizz, all the aluminium has converted to Oxide and can be lightly sanded off.

 

Most acids will attack aluminium, it is something to do with the amount of electrons in the outer shell of the atom, 3 in this case and the acid reacts with the metal to make a salt and hydrogen hence the fizzing - the salt is the black shyte you will sand off!

 

Sulphuric is fine as is Hydrochloric (Muriatic) acid as well as a few others. You want to use non concentrated and it is easier to get hold of - 15% would work fine and the proof is in the fizzing that starts when you put it on the aluminium.

 

Time scales - around 30 mins to do a reasonably caked one but don't leave it without checking regularly and clean it down thoroughly once done - eye protection is a damn good idea!

 

If you get the fizzing along a vertical score, go easy as you may lift the plating - the stuff on old machines is much more brittle than the new plating - found this out when porting!

 

Good luck - the first 10 are the most difficult:sneaky2:

[kentjames]

Thanks Peat and Spud

 

Will most definitely give this a go! The scoring seems slight, you can only just feel it on the finger tip and not very obvious to the eye so hopefully some light sanding after the acid will sort it.

 

Then on to actually buying the new piston as gaskets!

 

Brick acid cleans it and that is usually Hydrochloric. It's cheap from builder's suppliers as well.

 

Lightly sand the aluminium transfer, apply the acid with a cotton bud to the effected area, if all is good, it will fizz. Once it has gone black and stopped fizzing, lightly rub with more wet and dry, try more acid and if it fizzes repeat until it doesn't. If it doesn't fizz, all the aluminium has converted to Oxide and can be lightly sanded off.

 

Most acids will attack aluminium, it is something to do with the amount of electrons in the outer shell of the atom, 3 in this case and the acid reacts with the metal to make a salt and hydrogen hence the fizzing - the salt is the black shyte you will sand off!

 

Sulphuric is fine as is Hydrochloric (Muriatic) acid as well as a few others. You want to use non concentrated and it is easier to get hold of - 15% would work fine and the proof is in the fizzing that starts when you put it on the aluminium.

 

Time scales - around 30 mins to do a reasonably caked one but don't leave it without checking regularly and clean it down thoroughly once done - eye protection is a damn good idea!

 

If you get the fizzing along a vertical score, go easy as you may lift the plating - the stuff on old machines is much more brittle than the new plating - found this out when porting!

 

Good luck - the first 10 are the most difficult:sneaky2:

[Macpherson]

Hi again, although I totally agree with every that`s been said, [and that`s how I would do it ] but it`s worth saying for anyone else reading this, that after I posted on the subject I decided to do a bit of research and re-educate myself, so it seems that the bottom line is that, as said, due to the Nikasil finish being porous it`s an absolute NO using any from of carborundum type stone or hone on it as it may embed, diamond hone only, as for papers... aluminium oxide or silicon carbide are ok as they aren`t easily able to damage the Nikasil, cheers,

I would give a link to you tube but I`m too inept,

[spudulike]

Hi again, although I totally agree with every that`s been said, [and that`s how I would do it ] but it`s worth saying for anyone else reading this, that after I posted on the subject I decided to do a bit of research and re-educate myself, so it seems that the bottom line is that, as said, due to the Nikasil finish being porous it`s an absolute NO using any from of carborundum type stone or hone on it as it may embed, diamond hone only, as for papers... aluminium oxide or silicon carbide are ok as they aren`t easily able to damage the Nikasil, cheers,

I would give a link to you tube but I`m too inept,

 

There are always a number of ways to look at the same thing, I was interested to find more about this and read this PDF which answers a number of questions but does contradict much of what we all do -

 

http://www.mt-llc.com/pdf/98winter_snowtech_article.pdf

 

Firstly the porosity appears to be caused by air holes in the bores aluminium casting and is in fact pitting! Not quite the same as the plating being porous and letting fluid etc through - I couldn't understand how this could be with something so damn hard as Nikasil!

 

Secondly - Nikasil is a basically Silicon Carbide suspended in a Nickel carrier, Silicon Carbide is pretty close in hardness to Diamonds! I knew a bit but this is interesting.

Nikasil also allows coverage of oil on its surface where Chrome doesn't.

 

Thirdly, this article states ball hones should not be used on two strokes due to the balls damaging the ports and recommends FLEX hones which are basically nylon brushes with abrasive material impregnated in to the fibres.

 

It ALSO states that conventional hones shouldn't be used - in reading the article, it is perhaps aimed more at a newly plated cylinder that needs a machined honed finish to complete the process rather than the sort of honing or TBH, glaze busting that we are doing. It also states that it isn't as important to hone a plated cylinder as a cast iron liner!

 

BTW Carborundum IS another name for Silicon Carbide so not sure the difference between SI paper and stone:confused1:

 

So - from my side, after cleaning the cylinder from the aluminium transfer, I will still use my traditional two legged hone - I always use oil and use the hone sparingly just to break the glaze and clean thoroughly afterward.

 

Why will I carry on with this method - each ball hone size only covers a small amount of bore size and the ports may suffer damage - I usually take great care with bevel when porting and have noticed older bores (probably chrome) are pretty fragile and can chip easily.

 

The flex hone seems like a better option, may think about getting one but I have a number of long repaired saws out there using my standard method and have had no complaints or premature failure to date.

 

Matty F had a borderline MS260 that had about the heaviest hone I have ever done - it was still running as his dads "go to saw" one and a half years later:thumbup:Perhaps he can give us an update!

 

We can all get hung up on the technical stuff and each guy will have his own methods or copy others. All I aim for is a repaired bore that will allow the rings to bed in PDQ maximising compression and retaining the longevity of the saw. From experience, I am doing something right!

[Macpherson]

Hi spud, just to say that in no way was anything I said meant to be contradictory or as criticism, I`ve very much enjoyed following your threads since I came across this forum a few years ago, I find the subjects that come up for conversation by yourself and others particularly helpful and interesting and regard the forum as a whole to be an education in many subjects.

Although I`ve used both the honing tools in question for many years my only experience with Nikasil has been whilst working on my own or friends equipment so it`s not for a living and I suppose the great thing is that discussions like this spur you on to investigate subjects more deeply, which of coarse with the internet has never been easier.

cheers.

and, aye, my silicone carbide mistake was realised after I pressed send but when it`s gone, it`s gone as they say:001_smile:

[DCS6800i]

....due to the Nikasil finish being porous it`s an absolute NO using any from of carborundum type stone or hone on it as it may embed, diamond hone only, as for papers... aluminium oxide or silicon carbide are ok as they aren`t easily able to damage the Nikasil....

 

 

Hmmm so your saying iv bollocksed the 2 saws iv honed??

 

The first i did, is running really well (dare i tempt fate and say as good as new!) and the other is almost back together (have had running and all seems well) but i need to order up a few other bits when i get time to finnish the job.

[spudulike]

Hmmm so your saying iv bollocksed the 2 saws iv honed??

 

The first i did, is running really well (dare i tempt fate and say as good as new!) and the other is almost back together (have had running and all seems well) but i need to order up a few other bits when i get time to finnish the job.

 

Relax, I have used a conventional hone to break the glaze on all seized machines over the last couple of years. I took the plunge when I had a MS660 in with three years on it after similar treatment and the bore was good.

 

Nikasil CONTAINS Silicon Carbide, you are putting a little roughness on the bore so the rings can bed in quick. As long as the hone isn't used to REMOVE the transfer, all should be just fine.

 

Lots of methods will work, some may be frowned upon but doesn't mean they are not valid in ones own environment!