ThunderBoat42

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I am setting up a 170 in a sport aircraft .... How important is the fuel tank pick up supplied with the engine. I have 2 engines... 1 'clunk'. I am using large fuel tubing although the Dubro tank has the typical copper tubing.

Also, I purchased these engines a while back... any additional tips on running in from experience? (these are not my first YS engines.. they are all I use... just first 170's) Naturally, I am used to the 'pressurized' system.. so a vented system is unusual and taking some time to absorb.

Any tips, recommendations, input appreciated.

petec

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Not sure I understand the "two engines one clunk", are you building a twin with one tank?

I tried a regular clunk and a header tank, but wound up putting the DZ foam clunk in the main tank after a few flights. YMMV but I strongly recommend the use of the foam clink.

ThunderBoat42

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Soory for not being clear...  I have two engines I am setting up but one does not have the foam tank clunk.   I ordered one last night as I am guessing it has a purpose or wouldnt be recommended/provided.  I am just trying to figure out what makes it so special other than filtering.  I am guessing it holds enough fuel around the pick up for brief bounces out of the fuel during airobatics. 

I was looking at the "Bubbless tanks tetra makes carried by Central Hobbies.  These have worked well on the pressurized system engines... not sure about the vented of the 170/175.

arnstein

My understanding is that the foam clunk is a sort of surface tension filter (STF) (you probably can google this term and find some more info). So it is not really the filtering that is essential. When a STF gets partly exposed to air is will not let air into the fuel feed line due to the surface tension of the fuel, i.e. the surface tension of each “cell” in the foam. For the part of the filter that is submerged in fuel, the differential pressure required to draw fuel across will be less compared with the part of filter exposed to air. Arnstein

ThunderBoat42

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That is correct. witnessed yesterday on the bench... its a fantastic idea they had and exhibits the unique and thoughful engineering that YS continues to provide (and why we pay more for this engine than the others out there.

Yesterday, I could not find my YS in-line fuel filters... I am one, like many, who essentially have a hobby shop at home of parts i 'may need'. Anyway I gradded a sullivan 'final filter' and out in the line, BIG mistake. It woudl lean out over 4000 or so RPM and quit. Turns out, as the fuel draw increased, the filter was letting air in past the joint in the filter and foaming the fuel. One I found a real YS filter, all cleared up. I am so impressed with this engine. Got a gallon of 20/20 VP Powermaster through it them started tuning. uneventful as expected.. perfect idle out of the box.

Break in for first gallon on 18x10 wood... then to carbon fiber.

ThunderBoat42

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QUESTION????  

ThunderBoat42

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A Picture would help!!!

XMANS

Don't know what size prop your running but my guess it's either too big or the prop nuts are not tight and prop is slipping or both.

YS Down Under

ThunderBoat42

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Prop nut is tight...   the wood prop did well but it is lighter.   It appears it eroded the CF though to the wood hub core then stopped.  I have emailed Biela with pictures.  Adding the spinner back plate may help...  but need to see if this is an isolated prop issue.  overall, Thrilled with the engine/prop combo.