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HomeRC & PowerAircraftHelicopterEngines Plugs Mufflers Fuel › YS 91SR Overheating
02-06-2010 09:49 PM  8 years agoPost 1
jutrast

rrApprentice

Henniker, NH

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I have a YS91SR in my TRex 700, and in the last two flights it got hot enough to melt my temp sensor off - ironic, huh?

Today I took it easy doing short little flights, checking the back plate, taking off, pushing it harder, checking again... As soon as i pushed it hard with tic tocs, etc... it shut down and I auto'd in. Checked everything over, and tried again with the same result.

I think I may be losing fuel pressure through a leaky plug - would that cause my problems?

The only damage appears to be some pin-size pitting on the top of the cylinder. Is that anything to worry about?

Any ideas are welcome... I really want to fly this heli and am having a hard time figuring this out...

Toby

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02-06-2010 10:31 PM  8 years agoPost 2
hgh001

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New Zealand

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Hi,

I would suggest replace the check valve and fuel lines for a start.

If you have a header tank installed bypass it temporarily.

The 91SR is very sensitive to a lean runs and over revving of the motor. What is your gear ratio and head speed?

Regards,
Heinz

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02-06-2010 11:50 PM  8 years agoPost 3
Jlerch

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Parrish, Florida

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Fix it now while its cheap! Pin sized pitting leads to this:

James Lerch - Tampa Bay FL

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02-07-2010 12:42 AM  8 years agoPost 4
Darkplague

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Adelaide, South Australia

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That still ok, bit of a rub with emery and shell be golden! :P

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02-07-2010 01:01 AM  8 years agoPost 5
Ironhide

rrVeteran

dexter mi us

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With the engine running pull the feed to the carb . It should be coming out of there like a fire hose !

I had a piece of crap in my one valve and it spun loose , still ran !

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02-07-2010 06:32 PM  8 years agoPost 6
airdodger

rrElite Veteran

Johnston USA

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The engine is leaning out you need to find the reason. You could be lean to start, the valve could be sticking, or more likely the system leaks at high pressure.

Chris

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02-07-2010 09:47 PM  8 years agoPost 7
Jlerch

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Parrish, Florida

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There are two other reasons.

The regulator is having problems (factory adjustment out of whack) or your detonation is the result of high compression and needs a shim. (some do, some don't)

James Lerch - Tampa Bay FL

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02-07-2010 10:12 PM  8 years agoPost 8
tjrhodes01

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walkerton IN. US

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big peice of emery

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02-20-2010 10:41 PM  8 years agoPost 9
jutrast

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Henniker, NH

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I'm having the issue again with over-leaning.

I replaced all fuel tubing, clunk lines and the check valve. I flew it 3 times without issue... I landed several times to ensure the backplate wasn't hot.

On my 4th flight, I could tell the motor wasn't running right. It was bogging and ran very rough when I landed, and it was very hot.

I originally thought it was getting air somewhere leaning it out - maybe it is, but I can't figure out where.

Any ideas?

Toby

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02-20-2010 10:45 PM  8 years agoPost 10
Blink 182

rrApprentice

California

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You might not be getting pressure. Your tank might be leaking air pressure.
Try sealing off the center hole with CA glue.
This has happened to me also.

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