have tryed to fix the bad threds in one sparkplug hole..on the 400 four...got a rep set on e bay..de..20 euro..for 12#1,25 Honda type sparkplug repareir
build a stand to hold and fix the head ..so it vas lined up to the bore of the bad threds..
it is a problem to get cut Deep vitaut to threden the vhole chamber..the cut is angled 30deg..from the one side..hell to get korrekt..got fuzked up the first insert...but faund the rep set is 14#1,25. autside thred..so a standart plug fits inn...if i not find a korrekt rep insert..
i need to file the Sharp egdes..so i not get falce ..glov ignision