HK1012 and Stihl wrist pin

Akutey

Member
Joined
Dec 10, 2018
Messages
32
So I decided to go into a couple of the local chainsaw shop and try to find parts earlier this week. I was pleased to find a German HK1012 caged needle bearing in town and I could order the very last OEM 10x6x35mm wrist pin from Stihl warehouse. So I did and it came today. It runs amazing, I can get to 9300rpm (60Km/h,20inch,36T)
The HK1012 is 4 grams, Stock (Knockoff) uncaged thirteen roller needle bearing is 5 grams, the stock wrist pin was 14grams and lastly the Stihl is 12 grams. Reduced upper end weight by 3 grams increasing top end range slightly and increased reliability. I had to build a tool out of a bolt, nut and two washers to slowly press in the needle bearing. So say the least it is a snug fit and the bearing wont move out of place.
 


JerboaJohn

Active Member
Joined
Jul 29, 2018
Messages
674
ok so now we should all snap up these Stihl wrist pins and the German needle bearing? I always thought a bushing was longer lasting, but then how long would a bearing last?
how much did the upgrade run you?
 

Akutey

Member
Joined
Dec 10, 2018
Messages
32
Yes If you can find a fitting Stihl wrist pin, buy it. German needle bearing on the other hand there still manufacturing.

A bushing could last the longest but there is then friction and its friend heat. This wouldn't be bad if there was better top end oiling or sumped case full of oil. The heat transfer through the piston to rod would most certainly be better. Bronze bushing with graphite pucks should honestly be tryed by someone.
A quality bearing should last in theory if you follow tolerances but the stock ones can move around 2.5mm on either side which can get caught. There also pretty poor to mediocre in heat transfer so piston can't lose too much through the rod.

The Bearing cost 5.65$ (Was in a clearance box) and the Wrist Pin was 20.11$ tax all included.
 

Spare_Parts

Well-Known Member
Joined
Nov 29, 2017
Messages
992
Graphite impregnated bronze bushings don't last in these engines.

Have to look into the wrist pin, thanks for sharing.
 
Top