HobbyKing.com New Products Flash Sale
Reply
Thread Tools
Old Sep 29, 2006, 11:05 AM
Deported Village Idiot
TheSaint's Avatar
A roamin' in the gloamin again
Joined Jun 2006
517 Posts
Help!
YS-91 Engine Fuel/Tank/Fill/Vent Line Hook-Up (Again)

Folks

A few weeks ago I posted about hooking up the fuel lines for a YS-91 4-stroke engine.

As you may recall the engine setup has a fuel pump in the line between the tank and the carb and a check valve in the return/tank pressurization line. Per the YS manual the return line is supposed to go directly back to the tank.

The problem therefore is how to fix up the fuel fill line and more particularly the vent line, as the check valve in the return line prevents using this to vent during filling.

One suggestion posted was to put a tee in the return line between the check valve and the tank and to fit a removable fuel barb in the end of the branch line. The barb is removed for filling, then refit the barb for flying, so that the tank remains pressurized.

Another variation was to fit a gas conversion stopper and run the third (vent) line to aa barb as above.

Questions:

1, if the engine has a fuel pump (claimed "supercharger" by YS) does the tank reallly need to be pressurized?

2, Has anyone used a Robart #205 Ultra-Fueler Connection in a situation like this? Robart image suggests this could solve the problem.

I also have a similar problem with a smoke fuel setup. I'm using a Sullivan electric pump to feed smoke fuel from a separate tank to the nipple on a Slimiline Pitts muffler. I presume this tank doesn't need to be pressurized (there is a pump after all) but it does need to vent. I was thinking of using a Robart/DuBro in-line fuel filler between the tank and the pump and simply running a vent line out through the bottom of the cowl. Thoughts?
TheSaint is offline Find More Posts by TheSaint
Reply With Quote
Sign up now
to remove ads between posts
Old Sep 29, 2006, 11:27 AM
And You're Not
Timbuktu, Mali (Happy?)
Joined Oct 2002
6,514 Posts
There is no pump on a YS .91. The crankcase pressure pressurizes the fuel tank, the check valve keeps the tank pressure from going back into the engine. The tank must be pressurized for the engine to run. What you might be mistaking for the pump is a pressure regulator, it simply meters the pressurized fuel going to the carb.

The easiest and best way is with a T in the line between the tank and check valve on the "vent" line and anywhere in the pick up line. I don't like the fuelers, a YS doesn't just need "some" pressure, it has to maintain "exact" pressure or the regulator won't function properly. Even a miniscule leak in the fueler will cause headaches, the simplest method is the best (I don't even use the T, I just disconnect the hose from the check valve to let the pressure off to fill the tank).

Oh, and the "supercharger" has nothing to do with the pressurized fuel system. The YS can keep a slightly higher than atmospheric pressure on the intake tract by using a disc induction and a carb that's divided in 2 parts separated by an o-ring on the carb barrel. Again, it's just a clever way of using crankcase pressure, there is no actual "supercharger" mounted on the engine, just like there is no discreet "fuel pump".
Jeffery is offline Find More Posts by Jeffery
Last edited by Jeffery; Sep 29, 2006 at 11:36 AM.
Reply With Quote
Old Sep 29, 2006, 11:45 AM
Deported Village Idiot
TheSaint's Avatar
A roamin' in the gloamin again
Joined Jun 2006
517 Posts
So a tee between the tank and the engine to fill and another tee between the check valve and the tank to vent, plug both before take-off is the best way to go? The engine is under a cowel, so disconnecting lines will be a pain, BTW.
TheSaint is offline Find More Posts by TheSaint
Reply With Quote
Old Sep 29, 2006, 11:57 AM
And You're Not
Timbuktu, Mali (Happy?)
Joined Oct 2002
6,514 Posts
You got it. Get some of those fuel dots in 2 different colors so you know to unplug the "vent" line first. If you accidently unplug the fill line, you will get a glow fuel shower. Most YS users have done it by accident one time
Jeffery is offline Find More Posts by Jeffery
Reply With Quote
Old Oct 01, 2006, 08:35 AM
Warbird Pilot
Richard L.'s Avatar
Puget Sound, WA
Joined May 2004
437 Posts
Quote:
Originally Posted by TheSaint
The barb is removed for filling, then refit the barb for flying, so that the tank remains pressurized.
The tank doesn't need to remain pressurized while fueling. You need to let pressure out before you fill her up anyway. After the vent line is plugged up, a few flips of the prop will pressurize the tank again.

I like to keep things simple and use 2 tee's and 2 fuel dots as my engine is also inside the cowl. Note the color coded fuel lines (red = press, blue = fuel):


______________________________

http://www.WarbirdObsession.com/
Richard L. is offline Find More Posts by Richard L.
Reply With Quote
Old Oct 02, 2006, 08:38 AM
Deported Village Idiot
TheSaint's Avatar
A roamin' in the gloamin again
Joined Jun 2006
517 Posts
Richard,

That looks like the way to go - got any brand names and/or part #s for Tower Hobbies etc. so I can order?

BTW I bought the Robart gizmo on spec at the weekend and it won't work because (I think) the vent line is permanently open (unless it's capped externally by me).

I've got a spare easy-fueller (the single line w/ probe type) which I'll keep for the smoke tank.
TheSaint is offline Find More Posts by TheSaint
Reply With Quote
Old Oct 02, 2006, 08:51 AM
Warbird Pilot
Richard L.'s Avatar
Puget Sound, WA
Joined May 2004
437 Posts
I really like the fuel dots from PSP: http://www.pspmfg.com/FuelDotsRegular.html

As for metal tee's, Central Hobbies has them.


______________________________

http://www.WarbirdObsession.com/
Richard L. is offline Find More Posts by Richard L.
Reply With Quote
Old Oct 09, 2006, 08:57 AM
Deported Village Idiot
TheSaint's Avatar
A roamin' in the gloamin again
Joined Jun 2006
517 Posts
Quote:
Originally Posted by Richard L.
I really like the fuel dots from PSP: http://www.pspmfg.com/FuelDotsRegular.html

As for metal tee's, Central Hobbies has them.


______________________________

http://www.WarbirdObsession.com/
Ordered both last week (Wednesday?) and they arrived UPS over the weekend. Stuff looks good. Thanks for the tips.
TheSaint is offline Find More Posts by TheSaint
Reply With Quote
Old Oct 12, 2006, 02:34 PM
Registered User
Scotland
Joined May 2006
23 Posts
Great pics Richard L,super neat installation, was wondering how you guys run these engines dry after a days flying, am kinda used to pulling the pipe to the carburettor, not so easy on my YS 63-S, any hints?
teuchter is offline Find More Posts by teuchter
Reply With Quote
Old Oct 12, 2006, 03:54 PM
Warbird Pilot
Richard L.'s Avatar
Puget Sound, WA
Joined May 2004
437 Posts
Simple, just drain the fuel tank via the blue tee, close both fuel dots, and run the engine dry. No need to pull on any fuel lines.


______________________________

http://www.WarbirdObsession.com/
Richard L. is offline Find More Posts by Richard L.
Reply With Quote
Old Oct 25, 2006, 11:09 AM
Deported Village Idiot
TheSaint's Avatar
A roamin' in the gloamin again
Joined Jun 2006
517 Posts
Another question -

The manual says use a fuel with 15-20% nitro with 15-20% oil (castor, synthetic or mixture) to break in. It says not to use 4-stroke due to low oil content

Does this mean use 2-stroke to break in the engine, say 3 or 4 tank fulls, then switch to 4-stroke?
TheSaint is offline Find More Posts by TheSaint
Last edited by TheSaint; Oct 25, 2006 at 11:27 AM.
Reply With Quote
Old Oct 25, 2006, 11:22 AM
And You're Not
Timbuktu, Mali (Happy?)
Joined Oct 2002
6,514 Posts
You don't want to run conventional 4 stroke fuel in a YS at all, really. It has a lower oil content since some of the unburned blow by oil goes back into the crankcase to provide lubrication (this is why there is a vent on a normal 4 stroke spitting out fuel/oil). The YS is like a 2 stroke, all of the lubrication the low end gets is from the oil in the unburned fuel. You see quite a few fuels labled " YS 20/20", this is 20% nitro, 20% oil. Helicopter fuel also generally has a higher than normal oil content so it is OK to run in a YS. As long as the fuel has 20% oil, you'll be fine.
Jeffery is offline Find More Posts by Jeffery
Reply With Quote
Old Oct 25, 2006, 11:25 AM
Warbird Pilot
Richard L.'s Avatar
Puget Sound, WA
Joined May 2004
437 Posts
Quote:
Originally Posted by TheSaint
Another question -

Does this mean use 2-stroke to break in the engine, say 3 or 4 tank fulls, then switch to 4-stroke?
Go with what the manual suggests. When it says "not to use 4-stroke fuel", it means do not use 4-stroke fuel and do not switch to 4-stroke fuel, even after break in. Use YS 20/20 fuel for best results.


______________________________

http://www.WarbirdObsession.com/
Richard L. is offline Find More Posts by Richard L.
Reply With Quote
Old Oct 25, 2006, 11:28 AM
Deported Village Idiot
TheSaint's Avatar
A roamin' in the gloamin again
Joined Jun 2006
517 Posts
Cheers guys - guess I'll use the 4-stroke for bar-b-que lighting or maybe add some "homebrew" castor oil?
TheSaint is offline Find More Posts by TheSaint
Reply With Quote
Old Oct 25, 2006, 11:52 AM
And You're Not
Timbuktu, Mali (Happy?)
Joined Oct 2002
6,514 Posts
Quote:
Originally Posted by TheSaint
Cheers guys - guess I'll use the 4-stroke for bar-b-que lighting or maybe add some "homebrew" castor oil?
I'd go easy on the castor, but there wouldn't be any problem adding a little synthetic 2-stroke oil, I've used Klotz Techniplate Synthetic (it's even pink) to fuel. Lot of guys swear by castor, and I like a little in a 2 stroke, but you can get nasty carbon deposits on the valves of a 4 stroke if you run a lot of it. But sure, no need to waste the 4 stroke fuel you have, just realize that adding oil will reduce the relative nitro content. As long as the engine runs on it, it should be fine. You'll be in for a treat when you do use it up and get some regular 20/20
Jeffery is offline Find More Posts by Jeffery
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Help! saito 50 4 stroke fuel tank hook up itchntofly Engines 3 Dec 25, 2006 01:59 PM
Sold FS lite machines vmaxx 7 engine and fuel tank kirtdog Aircraft - Fuel - Engines and Accessories (FS/W) 1 Sep 06, 2006 09:52 PM
Fuel tank fill line q's ctoms Fuel Plane Talk 3 Sep 23, 2004 09:32 AM
Using crankcase vent to pressurize fuel tank Trek2120 Engines 8 Sep 28, 2003 07:40 AM