stuck case screws

[cdsdorset2]

You can get aerosol shock freeze spray.

[cornishbob]

ive just had a close up look at that bolt. it does look a bit like threadlock doesnt it.

if it is then heat heat heat as dump the trump would say.

many moons ago when i was a greenhorn i had to change a worn out front disc on my older sporty. i broke 2 allen keys attempting it.i then went for a socket. i spoke to the guy in the tool shop and he said a snapon would do it. it cost an arm and a leg butit was sale or return if it didnt...it didnt turned out it must have been a snapoff not a snapon part. he was amazed,

any way.. an old guy i new said 'heat heat heat but not too much'. 5 minutes later the new disc was on

[DAVE BRADY]

Hi,

Even if it is not thread lock it could just be detritus that accumulates over the years.  Bits of sealant and gasket get pushed in to the hole and can easily act like a thread locker.
Once you have all the screws out give the threaded hole a really good clean and run a tap down to ensure all muck is removed. 

Dave.

[cornishbob]

thats absolutely right. the mess in those threads is insidious. even to this day my missus is amazed how muck from the shed gets on the bed sheets

[MadPete]

A handheld electric battery impact driver might work - they have a torque release ratchet that rotates after max torque but still produced some force at the drive head. Unlike mains impact drills that usually just stop (dangerous!) if they can't turn.

Yes, and do get it hot before hand.

[hoogerbooger]

A handheld electric battery impact driver might work

.........

Yes, and do get it hot before hand.

Was a battery impact driver I borrowed....without success.

I don't have a blow torch, but did try a hot air gun focused on the head for 5 mins. No luck and head a bit more mashed

So I've given up for now and have changed the kick start seal and LT lead grommet/boot. Will get it back together and running.

When it's running and hot I can have another go on the top of the 2 ( exhaust might hide bottom one). If it does shift then I will know heat was the missing ingredient. To drill off the heads I think I'd need a local guru to work with ( or there's a garage not too far away that does old bikes)

[iansoady]

Hot air gun is unlikely to get it hot enough - and you need to point whatever heat source you're using at the alloy surrounding the screw rather than the screw itself. The hope is that the alloy will expand faster and further than the steel screw hence releasing it.

[hoogerbooger]

Hot air gun is unlikely to get it hot enough - and you need to point whatever heat source you're using at the alloy surrounding the screw rather than the screw itself. The hope is that the alloy will expand faster and further than the steel screw hence releasing it.

Thanks for the clarification.

I can't see it working for these two screws as it looks like the thread they engage with is distant. With the head drilled off and case cover removed then it would seem easier to heat the necessary area.

[scifi]

The problem with drilling the head off the screw is that the drill bit will bind in the screwdriver slot and snap a 1/8th. or 1/4 inch drill.   Maybe the only safe way would be to gouge the head flat, then centre punch, and then drill.
I suppose you will be looking to replace all these screws with Alan Key screws, maybe stainless..?   I think there is a firm in Cornwall that stocks a good selection of stainless bolts.

[cornishbob]

if i'm reading this right you're trying to heat the bolt?

surely you should be heating the area of the crankcase where the bolt thread is. its that metal that needs warmth.

i have a b&q propane blow torch thats infinately adjustable. i've removed many stuck bolts . its easy to me.