What's on your bench today?

[Mull]

Hedgecutter bearing and gear changes, fabrication of various parts, likewise I found quenching of ally quite ineffective compared to that of steel.

 

 

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Steel will obviously react more because of its heat retention!

[Macpherson]

Looks like a good repair to me,and as long as the plug doesn`t rust in or get kankered up it`ll be fine, seen loads of them , but as dissimilar metals expand and contract at different rates and to different degrees ,a Helicoil is also a good solution as it`s mobile, not being glued in, is stainless and doesn`t like being unscrewed, but it`s a toss up , I never liked short reach plug repairs, only 8 threads ,always a chance to work loose.

And by the way,......remember gettin blasted off by a fizzie , on my 1949 BSAc11g 250 on the way home from school............Cheers.

[spudulike]

I did a bit of research on this a while ago, Steve, but read that carbon steel inserts should not be used in aluminium heads.

 

There seem to be two reasons

 

1, Steel dissipates heat slower than Aluminium, so the plug cannot cool quick enough and may overheat.

2, Aluminium expands about 2.5 times faster than steel, so the insert becomes slack quickly,

 

I was put off using steel because of this. It seems that Anodized aluminium inserts should be used.

 

I have never done either so cannot comment from experience, but will be interested to hear your results.

 

Barrie

 

Life is about learning and have since realised that the wall strength of thin aluminium inserts isn't strong enough. I now have some stainless copper coated smaller ones bit too late for this saw.

 

Time will tell if it lasts but I had a machine in that another person had inserted but come loose, put it back with this loctite and it was still solid months later:thumbup: It was a thin wall steel one!

[spudulike]

Just calculated the difference in thermal expansion of a 16mm hole steel to aluminium.

 

From 20*C to 150*C, the aluminium expands 47 microns, the steel 30 microns giving a differential of 17 microns - a micron being 1/1000 of a mm or one millionth of a meter.

 

A human hair in average is 100 microns so we are talking Gnats danglies here:lol:

 

I think I based many of my earlier views on helicoiled spark plug holes were from a Yamaha FS1E that had been helicoiled that turned sparkplugs in to what looked like a lump of coal in 500 yards - the electrodes melted in no time at all - all because the helicoil was loose and couldn't wick the heat away!

 

It was probably the same FS1E that was blazing past the earlier mentioned BSA 250:lol:

 

A close fitting steel insert will, in theory, act as a larger base sparkplug so any expansion and heat transfer will be very similar to the original.

 

It will be interesting to see how it goes:thumbup:

[MattyF]

A 560 in a box of bits , quite interesting seeing how they work !

[spudulike]

A 560 in a box of bits , quite interesting seeing how they work !

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As I said Matty - the stronger man is one who knows his limitations:001_rolleyes:

 

Give you £40 for it:001_tt2:

 

Think I may be seeing you at the weekend - you can finish those cookies my wife was silly enough to give you last weekend - whilst I split the cases:lol:

[MattyF]

That's possible mate... Very possible

[burrell_]

:lol:

How u getting on with it Matty

[spudulike]

:lol:

How u getting on with it Matty

 

It is in a box of bits, options are local dealer or throwing it at me:001_rolleyes: I have agreed to get the crankcase apart, check the bearings out and to fit the new gasket and reseal.

 

It is up to Matty to rebuild but reckon it may not be the last I see of it:001_rolleyes:

 

A friend in need is a PITA:lol:

[Rich2484]

Kabota 360 has it's new starter motor in. What a PITA that was. Seat out, panel out, and just trying to get my hands in there......

 

Van had a new exhaust. Not mine.

 

Just waiting for the timber grab for the 360 so I can fit that.

 

Ms660 done.

 

Ms200t that went for a swim on Saturday. Very lucky this one, a clean out and a few cups of water from the exhaust and crank case. Clean carb, new spark plug. And runs like a dream.

 

Ms250, sharpen and bar dress.

 

 

Looking forward to the arrival of a Renault b120 4x4.