(DIR) Return Create A Forum - Home --------------------------------------------------------- Chainsaw Repair (HTM) https://chainsawrepair.createaforum.com --------------------------------------------------------- ***************************************************** (DIR) Return to: Echo ***************************************************** #Post#: 89782-------------------------------------------------- Echo 621 620 By: Chainsawrepair Date: January 31, 2023, 6:34 am --------------------------------------------------------- Echo CS621 updated compared to CS620 Thought better save this info I read. Different parts are: Cylinder (different porting) Timing map (adjusted to porting) Piston (ventilated, different coating) Piston pin, clips (higher thermal durability) Pin bearing (higher thermal durability) Rings (different size, coating) Exhaust (different internal layout) Although it lost bit of peak power it also gained peak torque so in the end nobody can tell the difference. And the extra weight comes from the same updates the US 590 to 620 got - metal inserts in starter housing, metric screws. Paper specs 13.8891lbs PHO (HTM) https://www.echotools.com/en_us/products/chain-saws/chain-saw/cs-621sx_38 #Post#: 90305-------------------------------------------------- Re: Echo 621 620 By: Cut4fun Date: November 19, 2023, 7:38 am --------------------------------------------------------- Just saving these from different threads. Bore and stroke of 590 620 562 6100 check me on it 6100 47mm X 35mm 620 590 45mm x 37.6mm 562 46mm x 36mm *****************************************************