What is Critical Rod Angle and how may it affect your engine wearing out. Smart to know

It's just a simple part of engine design. It affects many aspects of performance, wear and reliability.

[@lifeiswarwarislife1972]

My wife likes a bit of critical rod angle, while my 701 likes a good flogging. Few.

[@BillyWillicker]

On the power stroke in a 2-stroke, the force is against the rear cylinder wall. On case-reed cylinders there is much piston support, on cylinder-reed or piston port cylinders it get to be much less. In the cylinders I machine, the intake side is often worn much more, right where the ring gaps are too. The exhaust port side is where piston support is on the compression stroke - far less rod force than the power stroke. Snowmobiles with engine rotation reverse "gear" have a very low rev limiter in "reverse" because the power stroke force is transferred to the exhaust side during this mode. Maybe a correction video is a good idea.

[@jannep6772]

These KTM/Husky/Gas Gas 250 and 300 two strokes have 125 mm long connecting rod and 72 mm stroke so rod/stroke ratio is 1.736:1. If the motor is pushed for high rpm for a long period of time it definitely will load cylinder walls. I measured my Husky TC250 2018 exhaust port height and it’s just half of the stroke 36 mm height. So if piston top is just level with the cylinder top in TDC then the exhaust duration will be 180 degrees (half of the full rotation 360 degrees).

[@jannep6772]

This 180 degrees exhaust port duration when the exhaust power valve is in open position. I don’t remember how much less duration it had when it was closed.

[@davelambardo6464]

Very neet info! If you understand or are at least aware of the true principles of mechanics it makes you a better geek... / wrencher

[@joelatkinson2080]

Happy 4th!!! God bless America!!!