Stuck Cylinder Head

[Chakka]

I took the motor out of my 125 in anticipation of sending out for a rebuild. I want to remove the cylinder for easier shipping but one stud appears to be rusted solidly to the head. The other 3 are free. I have been soaking it in penetrating oil now for 4 days but no movment. Anyone have any ideas?

[tomale]

Did I say welcome to the group? Well if not glad you found us.

Have you tried a bit of heat to the nut?  I would think that a propane torch would do the trick. you do not want to get it red hot but if you could raise the temp even to 300-400 degrees that would loosen things up. Two things are a work here. The heat will cause the nut to expand and the heat will also kill the rust, yes I said kill. rust is a bacteria. The head and barrel will act like a heat sink so it will take some time to raise the heat. When you do try to twist it off apply even pressure.... as if it was not rusted on....no bute force, this will only twist the stud. As me how I know....
Steel turns red at about 1600 degrees it should be too hot to touch but not hot enough to turn red. If this is too large of a window to deal with you can go down to a welding store and they have special pens that turn colors at certain temp.
The other option is to use a impact wrench. this is not the same as the brute force method.  An impact wrench uses small quick twists to cause the nut to turn. some of the guys have used this on the flywheel nut that is rusted. My buddy BigMac has used this method several times.
Hope this helps, Good idea to ask questions before diving in head first. you just never know what you will find when you act first and question afterwards. Good job!

Thom Green,I own and ride a 76 250 MC5 MX which I bought new.

[Chakka]

Hi Thom,

Thanks for the tip and the welcome. I have been lurking for some time on this group and finally finished my project list to the point where its time to restore my Pentons, I have the 125 and will be building a 1975 175 from bits and pieces that have been aquired. My plan is to ride with my nephew, he is 18 and an avid mountain biker. Its funny, he rides all the same trails I did as a kid. Me and my friends just did it without all the peddling. He is very excited and wants to try riding dirt bikes and I can't wait to introduce him to it.
I was afraid to use heat on the head, I did not know if it was aluminum or not and was afraid of damaging it. Actually the nuts are off all of the studs. Thats what frustrated me so badly. Its just one pesky stud is firmly rusted to the head. I suppose thats proof that its not aluminum. ( I thought it was galvanic reaction) like I get on my boat. NOw that the motor is out it is much easier to work on. I will try some heat tomorrow and see if that helps. As for asking questions I learned long ago the hard way when in doubt ask people who have experiance, there is no doubt I will have many more before I am done.
Thanks again
Chris

[firstturn]

Chakka,
  I'm a little confused with your situation.  Is this a Sachs engine?  I ask only because you didn't state the engine or the year.

Ron Carbaugh

[Chakka]

Hi Ron,

Its a 1976 125cc KTM motor. You have all my SACHs 125's now! I ebay-ed them back in December after picking up the 1976.

Chris

[tomale]

Did I say welcome to the group? Well if not glad you found us.

Have you tried a bit of heat to the nut?  I would think that a propane torch would do the trick. you do not want to get it red hot but if you could raise the temp even to 300-400 degrees that would loosen things up. Two things are a work here. The heat will cause the nut to expand and the heat will also kill the rust, yes I said kill. rust is a bacteria. The head and barrel will act like a heat sink so it will take some time to raise the heat. When you do try to twist it off apply even pressure.... as if it was not rusted on....no bute force, this will only twist the stud. As me how I know....
Steel turns red at about 1600 degrees it should be too hot to touch but not hot enough to turn red. If this is too large of a window to deal with you can go down to a welding store and they have special pens that turn colors at certain temp.
The other option is to use a impact wrench. this is not the same as the brute force method.  An impact wrench uses small quick twists to cause the nut to turn. some of the guys have used this on the flywheel nut that is rusted. My buddy BigMac has used this method several times.
Hope this helps, Good idea to ask questions before diving in head first. you just never know what you will find when you act first and question afterwards. Good job!

Thom Green,I own and ride a 76 250 MC5 MX which I bought new.

[Chakka]

Hi Thom,

Thanks for the tip and the welcome. I have been lurking for some time on this group and finally finished my project list to the point where its time to restore my Pentons, I have the 125 and will be building a 1975 175 from bits and pieces that have been aquired. My plan is to ride with my nephew, he is 18 and an avid mountain biker. Its funny, he rides all the same trails I did as a kid. Me and my friends just did it without all the peddling. He is very excited and wants to try riding dirt bikes and I can't wait to introduce him to it.
I was afraid to use heat on the head, I did not know if it was aluminum or not and was afraid of damaging it. Actually the nuts are off all of the studs. Thats what frustrated me so badly. Its just one pesky stud is firmly rusted to the head. I suppose thats proof that its not aluminum. ( I thought it was galvanic reaction) like I get on my boat. NOw that the motor is out it is much easier to work on. I will try some heat tomorrow and see if that helps. As for asking questions I learned long ago the hard way when in doubt ask people who have experiance, there is no doubt I will have many more before I am done.
Thanks again
Chris

[firstturn]

Chakka,
  I'm a little confused with your situation.  Is this a Sachs engine?  I ask only because you didn't state the engine or the year.

Ron Carbaugh

[Chakka]

Hi Ron,

Its a 1976 125cc KTM motor. You have all my SACHs 125's now! I ebay-ed them back in December after picking up the 1976.

Chris