YS 90 sitting for several years. Start up procedures/precautions?

[edhall]

I have an YS 90 4 stroke, that has been sitting for several years on a Super Stick.

I was thinking of getting it back into the air as a glider tow vehicle.

It seems to turn over, but is there anything I should do before I try and fire it back up.

Can I use a 30% Curtis Young heli fuel at least to test it.

Maybe it should be disassembled before running?

Suggestions?

[invertmast]

whatever you do.. DO NOT disassemble it, and DO NOT put any after-run engine oil in it.

The pump system that YS uses is VERY VERY VERY VERY VERY picky, and if it is damaged or re-assembled in-correctly, you will have to send the motor back.

30% heli fuel is fine. If you are having problems getting it to turn over, squirt some fuel into the cylinder and the carb and turn the engine by hand, repeat this till it free's up..

Again, DO NOT disassemble it and do not use engine run oil as it will swell the silicon pump membrane.

[ACKopter]

I just fired up an old 40 thats been put up for about 8 years. The crank was gummed up and throttle barrel was plain old just stuck but I finally got it freed up and its running like a champ. One of the guys suggested next time( I have another motor in the same cond.) to use Marvel Mystery oil as a soak and leave it at least overnight to free things up. According to him it is the best solution.

[invertmast]

I just fired up an old 40 thats been put up for about 8 years. The crank was gummed up and throttle barrel was plain old just stuck but I finally got it freed up and its running like a champ. One of the guys suggested next time( I have another motor in the same cond.) to use Marvel Mystery oil as a soak and leave it at least overnight to free things up. According to him it is the best solution.


and it is also the exact same oil as after-run engine oil and will swell the diaphragm in the YS fuel pump/regulator system and require the engine to be sent back to YS for repair. Of all the YS engines i have owned, if the pump/regulator system ever goes bad, its a gauranteed trip back to the "shop" of YS, as you can almost never get the things running the way they were before.
YS engines are not like your typical glow motor, their unique fuel system requires specific procedures

[ACKopter]

Wow, no bad advice intended and my situation was on a "typical" glow motor.

[invertmast]

Wow, no bad advice intended and my situation was on a "typical" glow motor.

Sorry, didn't mean for my last post to come across like that.. I've just been bittin by the typical advice for glow motor's on more than 2 YS motors that ended up costing me $80+ to get each one back "right". So i just wanted to make sure, someone else didn't end up following in my foot-steps.

[ACKopter]

No worries invertmast, I didnt take it that way. We are both running a little behind on the OP and I just hope he caught your follow up and avoided my errant input. I would sure hate to have caused any undue harm.

[edhall]

Thanks guys got the message and will watch out on the oil issue for sure.

Been moving the last few weeks so haven't run it yet, maybe early next week.

Thanks for the help

[Pinecone]

I use a heat gun or hair dryer it is won't move.

Fuel works very well to dissolve old oil and re-lube.

Or you can use a more powerful solvent (I use brake cleaner) to clean out the engine, the re-oil with air tool oil or synthetic ATF.

[edhall]

Well it's actually a YS F-91AC.

I removed it from the plane and the throttle is stuck.

Stuck SOLID!

Everything else seems to move freely.

I have dumped some fuel down it, but I doubt it's gonna move easily.

I'll try some heat to see if that frees it up.

Unfortunately, I don't seem to have any air tool oil about.

Trip to Lowes I see.

I should probably check the valve clearances also.

[edhall]

Ok, got throttle barrel pulled out, unstuck, it's not smooth but should loosen up with use.

Only one small problem, the valves are not opening or closing, but the prop turns over nicely?

Continue on, or send into YS for rebuild?

[invertmast]

Ok, got throttle barrel pulled out, unstuck, it's not smooth but should loosen up with use.

Only one small problem, the valves are not opening or closing, but the prop turns over nicely?

Continue on, or send into YS for rebuild?


I would just send it into YS for a service. If the valves aren't moving, but you've turned it over, you could have possible bent the valve pushrod's, or even damaged the cam gear. And if you pull it apart to check those items, the timing will get thrown off as well as the pump/regulator settings.