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HelicopterEngines Plugs Mufflers Fuel › YS91ST, crank or muffler pressure
05-31-2004 11:24 AM  13 years agoPost 1
RotorX

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London

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Hi,

I am wondering what to use on my YS91ST for tank pressure, my MP2 did not have a ready made hole for the nipple, but there is a nipple on the back of the crackcase for the YS91ST - what do ya rek?

cheers

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05-31-2004 11:33 AM  13 years agoPost 2
Davo

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London, UK

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The YS91 uses a crankcase pressurised, regulated fuel system. You need to run a line from the crankcase nipple to the check valve, then on to the fuel tank in order to create enough pressure for the regulator to work properly. Have you looked at the diagram in the instructions?

http://www.yspower.co.jp/pdf/91ST-E.pdf

Also there is usually a tapped hole on the MP2 header for a muffler pressure nipple, you need to block this up with a screw.

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05-31-2004 11:36 AM  13 years agoPost 3
capebob

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Cape Coral, FL

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The YS 91 uses timed crankcase pressure not muffler pressure. The nipple on the back-plate is attached to a 10cm length of fuel line. That fuel line is attached to the one-way check valve that came with your engine and then the one-way valve is attached to the pressure fitting on the fuel tank. Please read the instructions that came with your engine for proper valve orientation.

BTW the muffler pressure fitting on the MP 2 that you won't use is on the header.

Bob

Success is the ability to go from one failure to another with no loss of enthusiasm. Churchill

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05-31-2004 11:42 AM  13 years agoPost 4
MJA

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UK

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The main advantage the YS has is it's "built in"
pressure/regulator system,if you don't use it you may as well have used an OS, as OS uses a decent bolted right through
system to mount the exhaust and doesn't have an oddball crank thread

I don't think the YS will work properly off muffler pressure instead of tank pressure build up through the check valve/crankcase,it may not be enough to make the diagphram/regulator work correctly.It's kind of self defeating too as you'd be back to leaner runs as the tank emptied which the YS setup is designed to stop and does a good job of it too


Martin

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05-31-2004 08:23 PM  13 years agoPost 5
RotorX

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London

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Cool, i will do that, will i need to block the hole that i thought i did not have in the MP2 - uh instructions, i got nothing, as usual Davo is there with what i need - cheers buddy.

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05-31-2004 11:03 PM  13 years agoPost 6
mrNoodles

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Borlänge, Sweden

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Yepp block it with a supplied bolt.

And enjoy your YS/MP2 combo.

/Fredrik
'Hm now I just have to find out where to connect the GV1 sensor to the Jazz80 ESC.

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HelicopterEngines Plugs Mufflers Fuel › YS91ST, crank or muffler pressure
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