RE: YS 91 problem
 

Yes I'm helping out on the forums to assist Dave and Richard while they are working on changing some things in the business. As many know the YS Shop moved in December. There have been some other little changes over the last couple months. I have been helping out filling in for Dave during this time of change over so that he and Richard can concentrate on the new things to come from YS Performance and YS Parts and Service.

The changes are for the better, and the same folks that have been working on your engines at YS Parts and Service will continue to give the same great service. Its just really tough with moving, and some of the other changes to focus on the Internet and the answer forums.

So Here I am. Its actually been fun sharing my knowledge and helping folks enjoy their YS engines.

Troy Newman
Team YS Performance

RE: YS 91 problem
 

Troy
Do you have the HP ratings for the various YS engines.

Doug

RE: YS 91 problem
 

Check the sticky at the top of the page......

http://www.rcuniverse.com/forum/m_2286099/tm.htm

This is on the main forum page for the YS engine support.


actual HP ratings are very subjective, so many things play a role in them. But here are some numbers if you need numbers.

I will say this, the YS engines have equivalent power to most 2 strokes of the same displacement and in some cases they exceed the the 2 strokes for power.


Troy Newman
Team YS Performance

RE: YS 91 problem
 

i have 2 ys 91ac's. i have had problems with both. one is very used but in good cond., just runs bad. so i bought another. raced it about 20 flights. now it idles well and the mid-range is good but top end sucks. almost acts like its too rich. so i tried to adjust it, it leaned out. i adjusted the valves, the same thing happened. i got in a habit of using marvel mystery oil after running. but after reading alot of the above symptoms, it sounds like that wasn't a good idea. please tell me if this sounds like my problem, and what i need to order to fix it. thanks

RE: YS 91 problem
 

I think you have a problem with the oil you chose to use as afterun. The instructions that came with the engine expressly warn about using a after run oil that has no petroleum based oils or solvents in it.

I would say replace all the seals in the motor. While its apart clean all the parts in denatured alcohol.

The regulator diaphram is probably the main culprit but it could be a bad o-ring or seal anywhere in the engine.

Marvel Mystery oil is a petroleum based oil. Just put a piece of silcone fuel line in it for a few day. It will eat it and make is soft and mushy....this is what happens to the silicone o-rings in your engine.


It might be best to send it in to YS Part and Service and have them look the motors over.



Troy Newman
Team YS Performance

RE: YS 91 problem
 

Hi Troy, I have a quick question for you. I just recieved my YS91ac back from the service center about a month ago and flew it yesturday on a Fliton Inspire. I set the high needle at about 2 turns open which may be a little rich, but no one else was at the field to hold the airplane to use a tach. Anyway, it was running fine for about 8 minutes of flight with a lot of transitions as it was the maiden flight and I was just testing it out. I brought it over the runway to do a trial pattern to set up for landing, as it came in I reduced power from about 1/4 to idle in order to simulate a landing, as I re applied power it backfired tossing the prop and spinner (I was not using a lock nut due to a FAI style short spinner, I now have an Ultimate type spinner as I lost the first when it came off so I will be using a lock nut now). I am not very familiar with the YS engine, but it did suprise me in that is kicked the prop off during transition, it had not reached full power. I did not mess with any of the settings from the service center other then the high end, do I need to back the pressure regulator screw out? In other words would this be an indication of too lean in the middle, or does the main needle need to be richened up? I am using a YS 20/20 fuel. Thanks for the help.

RE: YS 91 problem
 

It could be a little lean.

You have to remember what causes you to change a mixture setting. Are you running the same fuel as the folks at YS Parts and Service? I think they use both Cool Power and PowerMaster fuels on the service engines. Not sure about that though. Different fuels make a difference. The next major factor is Gardnerville/Minden Nevada is 6000ft of elevator. This will require the setting to be a little leaner than you in Dallas.

For reference the engine came with a double jam nut.......all 4 stroke engines should use a double jam nut on the prop. It could have backfired as it was getting low on fuel and got an air bubble in it too. This is always an option.

In the mean time here are some instructions on proper setup of the mixture setting on the YS engines.

http://www.probuild-uk.co.uk/factsheets/ys_engines.php

he has very good advice on setting it up.

For safety reasons you should have some way to hold the model when starting it up and flying by yourself.

Troy Newman
Team YS Performance

RE: YS 91 problem
 

Troy
Are these the correct numbers for ordering parts for the YS 63 (Older model with reg. on bottom).
Diaphram ys3055
Gasket Set ys3080
and is this the only way to get the valve cover gasket?
also is a 14 X 4 pitch prop to much for the 63? My max RPMs is 9500 on PM 20/20 fuel.
Correct phone number to order parts? (775) 267-9252
Thanks you for great info.
Doug W.

RE: YS 91 problem
 

Yes I just checked with Central Hobbies website and those are the correct parts.


Diaphram ys3055
Gasket Set ys3080

it looks as though the gaskets come as sets now. Changing all the gaskets is a good thing. One of the major causes of poor performance is air leaksIf the engine is taken apart I usually replace the gaskets.

9500rpm is way too much load for the 63 in my opinion. Especially since you are only running 20% nitro you are really pushing the engine too hard.

For best performance the 53's and 63's should be run at 10,500-11,000 rpm. Since your choice in fuel is 20/20 you need to choose a prop thta gives this RPM.
Not all props are created equal. I think the 14-4W APC might be Ok if running 30% Cool Power Heli but I would look to a 13-6 or 13-4W. With 20/20 you may have to go back to a 12-8 or so.

Just hit those rpms number and the motor will be happy.

Over loading it like you have at 9500 is asking for a mechanical failure. Rod, cam gear, piston, or other propblems.

Ordering parts can be from:

www.centralhobbies.com

or

www.yspartsandservice.com

The phone numbers are on these specific sites to get the stuff.

RE: YS 91 problem
 

Troy
What other parts should be replaced in a yearly check-up besides Diaphram & Gaskets?

Doug

RE: YS 91 problem
 

Really I don't see the need to change a diaphragm on a yearly basis.

The only reason to change the diaphragm is if it gets deformed. This happens when the engine sits for a long period of time and doesn't get run. On the older 91' since it has the plastic like diaphragm-gasket combo...theis can happen quicker than the two piece diaphragm gasket combo of the earlier YS 120's and the 06'-later 110's

However there is no reason to change diaphragm and gaskets just because the engine is a year older.

When the engine sits for a long period time unused....then the diaphragm can become deformed...This is when to do it.

So a preventive little thing is to keep some diaphragms on hand and once a year replace it just to make sure I guess....But its not something that needs to be done on a regular basis just because....

If you fly on a grass or dirt field...you may consider new bearings more often that a guy that is flying on pavement all the time. That doesn't mean every year...I would say grass field a good number is 150-200 flights start to think about a replaced rear bearing. Pavement it can go about double that 300 -400 flights and then its likely time for a new bearing. It all depends on how much use you have on the engine.


Troy Newman
Team YS

RE: YS 91 problem
 

Troy
It appears as though the mufflers and manifold pipes for the 91AC are no longer availible.Isn't the muffler the same for most of the smaller YS engines? Are there any alternatives that are availible and reasonably cost affective?

Doug

RE: YS 91 problem
 

Call YS parts and Service and they can answer this . I would think the header pipe for the standard muffler used on the 110 will work fine. However there may have been some changes.


Call YS Parts and Service. He can tell you the part number needed. Then you can order it from Central Hobbies.

Troy Newman
Team YS

RE: YS 91 problem
 

Troy
I have a 63 and it runs great, high RPMs are 10600, idles 1900 -2000, with APC 13 X 6 prop, PM 20/20 fuel. spool up is pretty slow and I was wondering if the 2 1/4" alum. spinner would cause the spool up problem. Adjustments to the high, low, and reg. don't seem to help.

Doug

RE: YS 91 problem
 

Troy isn't monitoring this forum anymore. But if you start a new thread with a proper topic, someone out there may be able to help you.