YS91 Problems?

[cdrking]

I just installed a new YS91 with an SB16 muffler in my Fury Extreme. I ran 3 tanks thru it today. I had a hell of time starting it. I used my Hobbico starter that I have used on my YS80 with no problems. I am using a 12V car/marine battery. Does the 91 have that much more compression? I had to unscrew the plug then start it and screw the plug back in. I will probably go with a 19V battery setup for starting.

The other problem that I had was the front left landing gear bolt that goes vertical down through the aluminum channel and into the skids sheared off. This happened twice. I got a vib somewhere.

I brought it home and took the engine out and checked to see if the crank nut backed off. I seemed tight. The weird part is that when I took the upper collet out, the mating surface between the fan and the collet was scored. Just some metal to metal type abrasion. It seems this would only happen if the nut was loose. I am not 110% sure it was really tight but it sure seemed like it was tight.

When I first installed it I dialed indicated the fan and got it less the 2 thou. I guess I don't have the patience for Dr. Ben's method. I reinstalled the engine and realigned it into the frame/motor mount. It seems the alignment is better now.

I also looked into the engine and no problems. It turns very free with no apparent reason for vibs. It must have had some serious vibs to shear the landing gear bolt.

Any thoughts on the difficult starting and the sheared bolt?

Thanks for the input.

Jeff

[capebob]

Jeff,
The difficult starting is normal for a new engine. I use a Sullivan Dynatron and 24V but a Dynatron at 12 volts is probably enough with a well broken in engine.

Your vibs are probably caused by your fan not being tight. There are not quite enough threads on the YS 90 crank. I had to put another washer between the fan and the nut to get the fan tight.

Bob

[DavidH]

Jeff,
I have never had a problem with the fan being loose on a YS 91.
I use the washer that comes with the engine, between the front bearing and the fan hub. Then the collets, and against the top collet I use an 0331 washer and then the nut. I dial indicate the fan and use a 1/4 inch ratchet to tighten the nut. I don't use any loctite. I just tighten the nut firmly. Using the 1/4 inch ratchet and holding the motor in my hand. I don't believe I am really torquing the nut that much.

David

[cdrking]

Thanks for the info. One other question, do collets wear out? Could the collets be the problem?

The fan is tight for sure this time. No problem with it drawing down on the collets this time. There is no up and down movement at all.

David, I just reread you post. So you put the washer between the engine bearing and the fan AND another washer???? Maybe this is my problem, I am NOT using a washer against the engine bearing and fan. I am only using a washer between the nut and collet.

Jeff

[Blair]

Use a Dynatron on 24v until the motor is broken in. After it's broken in the Dynatron on 12v will be enough.

Blair

[cdrking]

Dang, 24V I really hate to have to use that much juice to start the thing. I am planning on going to two 3000 or 3300 mah NiMh, with 8 cells to give me about 19V but haven't purchased them yet.

So the Dynatron is much better than the Hobbico? Man this tics me off, I just went throught the starter/start shaft shuffle a few months ago.

Jeff

[bob00]

Jeff,

The unthreaded portion of the crank on the YS91 is slightly longer than on the 80. If the fan is installed w/o the washer supplied with the engine the nut will bottom out on the threads before properly securing the fan.

Install it just like DavidH described and you won't have a problem.

Starter - I use an old Hanger 9 HiTorque 12v starter (nothing special) powered by 2x 8-cell 2400mah nicad packs in series - 19.2 volts (http://bob00.d2g.com/gallery/archive.homeweb/images/PA210074.JPG). Starts anything everytime.

- Rob

[capebob]

So the Dynatron is much better than the Hobbico

The Dynatron switch will not hold up to 24 volts. After my switch welded itself closed I removed it and replaced it with a marine push button starter switch. It was a pain to make the mounting bracket but it has held up very well.

Bob

[bighands3d]

If your going to use batts for your starter use the biggest NICADS they will deliver way more current than the NIMH. I would not use the NIMH I know they are lighter but they just don't deliver the JUICE that a NICAD will.

Me pesonaly I have a 800CCA Holly Race batt. and a Powermax 120 from century and it starts every thing. Not very portable for going to the flight line with, but It works on .91s like a 24V system

[DavidH]

Jeff,
There is a washer that came on the YS 91 engine. I leave that washer on the engine and then put the bottom collet in place. I then put the fan on the collet, then the top collet goes next. Then I put 0331 shim washer, then the nut.

I have not known collets to wear out unless they fan spins on them, or the crank spins inside of them.

I use a Hobbico Torquemaster 180 starter that is powered by two 8 cell 2600 nimh packs wired in series. I don't have a problem turning over a new engine. Only time it is a problem it engine is hydro locked, then I don't know of any starter that will handle that problem.

David

[cdrking]

Ok, I just redid the engine with the washer on the bottom and redial indicated it and everything is fine.

I just went out and had a look at my starter, I have the Hobbico Torquemaster 90. Could this be the problem? Maybe the starter itself?

When I went to check to see if it was hydrolocked it was dry as a bone. Like I said though we got it started by backing out the plug.

Back to the drawing board with my start setup. :(

Jeff

[SKYBLUE]

I am having problems with the fan slipping on the collets too which caused the surface of the collets to score badly. The upper collet had the most damage.

Cdrking, which one of your collets had the most damage? The upper one or lower?

I was using the same set up as David described above and my fan still slipped. I will try to add another shim or washer on top of the stock washer or another under the crank nut to see if that would solve the slipping problem.

[cdrking]

The upper collet is the one that had a bit of scoring. I have now solved my problems and it's running great. It now starts easier with two 8 cell NiMh 3300 packs. This gives me 19.2 volts, we'll see how long my starter lasts.

Good luck sorting out your problem.

Jeff