Hello everyone. Long time lurker but this is my first time posting. I have 1975 dt100. I was able to get 1975 mx100 jug and head to put on this bike. The mx100 head I have is pitted pretty badly and will cost me about $200 to get repaired. But dt100 head is fine. I was curious if could use the head from the dt on the mx jug?

My thoughts are it'll be fine. Neither motor are racehorse motors so no high compression & wild porting as such. Happy to be corrected though.

I remember the MX100 from that era to be a race bike...  Cylinder head volume is only about 9cc's and porting was pretty aggressive.

A DT head will likely have a few cc's more volume and would drop compression significantly if used on a true MX cylinder.  (I say "true" because ebay parts are not always what the seller thinks they are.)

Compare the distance from the top edge of the cylinder and the top of the exhaust port...  MX port edge is likely a few mm closer to top of cylinder than DT. 

You can also compare the volumes of the combustion chambers in the heads.

 

MarkT is 'onto it'. Listen to him.
Out of interest or my own curiosity i googled once & this came up, so here's a link incase you want to look.
www.thumpertalk.com/forums/topic/1436395...x100-rebuild-%3F%3F/