Bob,

I have not experienced any issues with the 170 vs 160. I have been running test engines for over 2.5years now and it seems to my experience that they are working the same. The engines are running almost identical to my 160's about 200rpm difference at the very top end and the throttle response down low is a bit better with the 170.

I'm not a paid employee of YS or YS parts and Service so...I can just relay my experience with the prototype engines. I know there were some changes between my engines and the production engines. I have a not yet had an engine that was production with all the changes in it. I think I have all the changes just they are all not in one engine. The case was beefed up a little this would not affect performance. The crank was changed slightly to increase lubrication to the cam area. I have one engine with this new crank and it is working well I don't see a difference in performance. A change was made to connecting rod to make it more robust and provide better lunbrication channels both at the top on the wrist pin and down below on the crank pin. Again not performance related but is relalted to longevity. The case was then changed internally to accomodate this new connecting rod configuration.

There were some minor changes to the pump and I have one engine with the newer pump on it. Performance was the same as the 160pump on that same engine. Again this was a change to make the pump more robust and better longevity. The pump still works the same and has similar style of parts...its just a little different. The 170 or 160 pump work on the same engine and perform the same. For that matter the 140 pumps worked on the 160's too. I would not be surprised if the 160 pump I used was ona 140 at one time.

I just don't see much in the way of difference that could affect idle or reliability.

When the production engines come into the USA I will be going through a comparison of the 160DZ to the 170's The parts changes were to make the engine stronger mechanically not change the way it works.


Troy Newman
Team YS