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HelicopterGasser Model RC HelicoptersOther › Opinion request on my engine
12-30-2009 02:42 AM  7 years agoPost 1
jschenck

rrProfessor

La Vista, NE.

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Hi all - I had a minor ground incursion early this summer with my Predator which sucked the desire out of me for this heli for a while. Then my wife bought me a Trex-700 and I really dove into that, spend my time on it. We also did a bunch of other family related stuff that limited my time - anyhow since the weather has gotten really bad here in the midwest I've had some bench time. Been really wanting to get back at my Predator and today I did just that (house projects can wait).

Basic story on the Predator is I got into a weird condition while flying it where I lost elevator effectiveness. I really felt like an aerodynamic effect more than anything mechanical or controls related. I was flying at a low headspeed downwind at just about the same speed as the wind, nose just settled down and it headed at a light downward angle. I realized I had no elevator so I hit throttle hold and watched it come down. Gained elevator effectiveness about 10' off the ground but had little headspeed left and lots of fwd speed going downwind so it hit *bounced* cartwheeled with blades rabbit eared and clacking together. It came to rest on its side. Unfortunantly it was a freshly plowed field and it was dry. Probably saved a lot of damage but the newly installed velocity stack was sucking dirt in (at idle). I shutdown the engine pretty quick but it did suck in dirt. That was the reason I put it away, I was not looking forward to dealing with this.

So here is where I'm at. Airframe as almost no damage. Blades went onto my Trex and have 5 gallons since. Spindle, main and flybar are straight - tailboom good. Stripped the crown gear and bent a link in the head, look like it.

I pulled the engine out. Nice to have the X frame member cut to allow this without splitting the frame halves. Here are the pictures of it. My question is should I pull it completely apart to clean it out or just send it to Al (@ Hansons) to have him work his magic? This is a "stage 1" Hanson 26 that was bundled with my Predator by Heli-world/Century.

I'm concerned about taking it apart and messing up the crankshaft or creating some other issue. Funny thing is I've taken apart Ford FE engines, Chevy's, Pontiacs and even a Harley but this one concerns me. Same with the carb - messed with Q-jets and Carters but this little carb - well perhaps I just need to dig into it and figure it out. Are my concerned justified, are these engines finicky to build? I'm not expecting it to be a glow engine for simplicity but I'm also concerned that there may be some special tools or knowledge and technique that I don't have to get it back together correctly.

Anyhow what do you think about the condition? It's about 5 gallons or so.

Intake side

Exhaust side

and the top of the piston

btw, anyone have the specs for the three bolts that hold the engine to the baseplate? I had to dremel one of them out

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12-30-2009 05:20 AM  7 years agoPost 2
rbort

rrProfessor

Franklin, MA - USA

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Definately need to clean it out

You don't want to run that engine after it ate some dirt. It may already be damaged from the dirt, you'll have to disassemble and inspect. At least take the head off and look at the cylinder walls and piston ring and piston walls. If you see no scratches then clean up all the carbon with some chemical, I used to use Z-best engine cleaner and that stuff was like magic -- brush it on, wait a couple of hours, and then wipe off the carbon with a bounty paper towel!

If you see scratches in the ring you'll at least want to get a new ring for it, and a head gasket anyways while you got it apart you should replace it. Wash out the lower insides of the motor with gasoline to flush out all and any of the sand grains in there.

That's easy to do, and if its Ok it will get your flying fairly cheaply.

The other alternative is to send it to Hanson. It will cost you probably about $150, but will come back like a brand new motor, all shiny and clean, and with most likely balanced and with a trued crank if nothing else. I know you said it was stage 1, but Hanson (Al) now does much better work than what it used to be when they were sold with the Predators from the previous Hanson owner. You can even get an even lighter piston for it than existed before. That in itself is worth the extra $$$s in my opinion as it will make for a smoother motor, which in turn will make your airframe and electronics last much longer.

Either way it needs attention. If you're short on dollars take it apart and inspect, its not rocket science. If you find something in there you can't fix or don't want to deal with, well then you can always send it in even if you took it apart.

Good luck and welcome back to the gasser world, we missed you around here!

About the bolt, if you need one, I think I got one laying around in an engine box. I don't use them anyways. PM me and I'll send it to you.

-=>Raja.

MA 1005 Hanson 280, 4129 flts
Spectra 27 3DMax, 3187 flts
Whiplash V1 Hanson 300, 1425 flts
Whiplash V2 Hanson 300, 185 flts

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12-30-2009 08:05 AM  7 years agoPost 3
pgkevet

rrKey Veteran

Wales

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Hey, Jschenck

Nice to see ya again! I found some handy Zenoah strip-down youtube vids..mostly car engines but the basics will be the same. It didn't look that scarey.. but for my temperament and for the silly costs and delays in parts I'd probably send it away.. or because of postage costs outbound UK I just bought a new one when my coil died and will use the old one for practice tear-down and possibly spares for my other.

Or take a serious sit-down, think about what you could use any spare electronics for, what you can get for the airframe parts, recall all the pain and think what else you might want instead?

I finally followed your vid on the o-ring mod (some months ago). For me it made absolutely no difference and I still got a vertical click!

I made a post a few days ago.. my elevator crank wore inside it's hub..more century soft alloy.. and that had several degrees of slop that wasn't easy to spot. I also had a proble with poor response in flight..never found a convincing answer but believe it's down to sudden power demand and flight power weakness. I've made changes with dual on-board NIHM power and switches to cut resistance in servo plugs and wire - another stable door shut too late...

Wasn't the nitro easy?

pgk

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12-30-2009 01:23 PM  7 years agoPost 4
jschenck

rrProfessor

La Vista, NE.

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yep - Slime is easy! My Vision frame when I tore it down for the winter rebuild.

So another more specific question - can I take this engine apart enough to clean it without having to pull the magneto or fan off the crank?

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12-30-2009 01:58 PM  7 years agoPost 5
pgkevet

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Wales

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..at least any slime does clean off easy..dip and rinse.. ya canlt get tar spots off that nice.

I suppose if you pull the cyclinder and look under the piston you'll know how much further to go? But to my mind if taking any of it apart ya might just as well do it all.. and think new seals and new/better bearings?

These vids have got to be similar?

They do the whole series.. this is just No2

Watch at YouTube

pgk

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12-30-2009 02:31 PM  7 years agoPost 6
jschenck

rrProfessor

La Vista, NE.

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Thanks for the YT hint, don't know why I didn't think of that I'll take a stab at it myself and if I don't like the results it'll go to Al@Hanson (or maybe Wally? )
ya canlt get tar spots off that nice.
My muffler was a mess of burnt on black goo. On a whim I put a bit of M.E.K. on a shop towel and tried it out. Easily took it off! Muffler looks much better now. Of course M.E.K. stinks a bit, rag went outside when I was done.

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12-30-2009 02:57 PM  7 years agoPost 7
rbort

rrProfessor

Franklin, MA - USA

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Man I don't miss that slime!

Turn stuff always turned me off from nitros, especially when you split the frames you found more gunk inside than was outside!!

Hey what is M.E.K.? Do you have a link for it? I ran out of the z-best engine cleaner and they don't seem to be available any more...

-=>Raja.

MA 1005 Hanson 280, 4129 flts
Spectra 27 3DMax, 3187 flts
Whiplash V1 Hanson 300, 1425 flts
Whiplash V2 Hanson 300, 185 flts

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12-30-2009 03:21 PM  7 years agoPost 8
jschenck

rrProfessor

La Vista, NE.

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M.E.K. = methyl ethyl ketone

http://en.wikipedia.org/wiki/Butanone

Most hardware stores have it in the paint section, it's a good solvent.

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12-30-2009 05:53 PM  7 years agoPost 9
pgkevet

rrKey Veteran

Wales

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I found the wife's ceramic stove top cleaner worked quite well.. also just a bit of automotive cutting back paste... just stuff I had lying around, mixed with some spirit if really foul.

pgk

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12-30-2009 09:58 PM  7 years agoPost 10
AceBird

rrElite Veteran

Utica, NY USA

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M.E.K. = methyl ethyl ketone

Be careful it is a carcinogen. I am suprixed you can buy it anymore.

Ace
What could be more fun?

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01-08-2010 04:14 AM  7 years agoPost 11
jschenck

rrProfessor

La Vista, NE.

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got my package from RHPS with the fan puller so ran off to my shop to spend some quality time with my 26. Turns out with some hints offered by everyone here (Thanks Jack and PK) the engine teardown was not too tough. A few things I needed to make the job easy and not damage things.
1. A good high quality 4mm T wrench. I have a plastic handled 4mm wrench that has proven to be very valuable with this engine and heli in general. It's never touched a glow heli as mine don't have 4mm bolts.
2. Heat. This was a key to the engine teardown. I have a small ceramic heater in my shop that great for applying heat to these endevors.
3. The fan puller. Can't imagine getting the fan off the engine without it.
4. Magneto puller. I made one up out of an old spanner wrench I had laying around. Also figured out I can notch it and use it to install and remove the starter engagement <thing> (what is the proper name for this item, can't think of it now!)

To take it apart I heated up the fan until it was uncomfortable to handle without a towel then applied the fan hub popper tool. easy.
Pretty much the same with the magneto but had to stop it spinning with a screw driver, heat up the crank with a soldering iron and used a chunk of wood to spin the starter <thing> off. Then used my new mag wrench to pop the magneto off.

Man, this engine is in great shape inside. - and it was full of debris! Very glad I took it apart. After cleaning it up with hot soapy water and drying it off with my heater it looks to be in great shape. No sign of any heat damage on the piston and the ring was very free with little oil burn/caked on. There is some loose carbon on the top of the piston which came right off with a bit of soap.

I took this opportunity to sand the exhaust port flat on the cylinder and the exhaust system. Very happy with the results. Basically just put some sand paper on a very flat shelf and pulled the ports across it evenly until I see the sanding marks clean and flat across the entire surface. Back to the bath and they are ready for assembly.

Got the crank shaft/case and cyl back together (with a good dousing of white oil taken from my airtool stash) and put the magneto back on. I spun the starter <thing> back on until it came to what felt like a hard stop.
The end of the crank is flush with the starter <thing> - is this right? IIRC it is

Now I get to mount the fan and clutch.

Bottom line - this engine is not hard to work on, just need the tools to press the magneto off and the fan off. Glad I did it myself

Also before I too much further do I use loctite on the engine bolts? I did not see any evidence of any during teardown. I put them on pretty tight during assembly.

BTW I don't have good pictures to show this but I do see evidence of some radius-ing the ports inside the cylinder and the drill holes in the magneto from balancing. Nice to see the work that Hanson put in there

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01-08-2010 05:40 AM  7 years agoPost 12
rbort

rrProfessor

Franklin, MA - USA

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Nice work!

Hey by the way, two things:

#1, take a dollar bill and fold it 4 fold (in half and in half again) and then put it over the flywheel and between the coil. You need to use it as a spacer for the coil and then push the coil towards the flywheel squeezing the dollar bill and tighten the screws for the coil. When you take out the bill afterwards, the gap between the coil and the magneto will be perfect. Some people say use a business card, but I found that a dollar bill folded 4 times is the right thickness when measured with a caliper.

#2, use new gaskets if you got them for the cylinder and crankcase during reassembly. Alot of times the old gaskets get torn or don't seal well after you rebuild the motor.

-=>Raja.

MA 1005 Hanson 280, 4129 flts
Spectra 27 3DMax, 3187 flts
Whiplash V1 Hanson 300, 1425 flts
Whiplash V2 Hanson 300, 185 flts

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01-08-2010 01:38 PM  7 years agoPost 13
jschenck

rrProfessor

La Vista, NE.

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thanks, good hint on the gap. I was going to ask what the simple way to set that is. The base cyl gasket came out in perfect shape and the crankcase gasket is good also. I was careful not to rip them, didn't leave and material on the metal when I lifted them off. Unfortunately I don't have a spare gasket set.

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01-08-2010 02:37 PM  7 years agoPost 14
AceBird

rrElite Veteran

Utica, NY USA

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Basically just put some sand paper on a very flat shelf and pulled the ports across it evenly until I see the sanding marks clean and flat across the entire surface.
By hand??? This is a lot more difficult then you think. The action of pushing and pulling will take more off the leading edges so you end up with a crown, high in the middle.

Now after you did this, put the muffler and the cylinder together without a gasket and see if you can see light through the joint. That will tell you if you did it right and where the high spots are.

Ace
What could be more fun?

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01-08-2010 02:51 PM  7 years agoPost 15
jschenck

rrProfessor

La Vista, NE.

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I'll do that but I've done this to several mufflers and the results are good. Take a look at the exhaust port on your engine there is way more crown on there as a result of the raw casting than resulting from this. I agree it'd be better to mill it but I don't have access to a milling machine.

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01-08-2010 03:55 PM  7 years agoPost 16
rbort

rrProfessor

Franklin, MA - USA

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Gaskets

If you're reusing the original gaskets you might want to skim coat them with red rtv for added insurance so that they won't leak.

-=>Raja.

MA 1005 Hanson 280, 4129 flts
Spectra 27 3DMax, 3187 flts
Whiplash V1 Hanson 300, 1425 flts
Whiplash V2 Hanson 300, 185 flts

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01-08-2010 04:00 PM  7 years agoPost 17
jschenck

rrProfessor

La Vista, NE.

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That's probably not a bad idea anyway, there was a slight leak around one of them before. I'll pop the flywheel/magneto off tonight and do that.

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01-08-2010 04:08 PM  7 years agoPost 18
pgkevet

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Wales

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I agree it'd be better to mill it but I don't have access to a milling machine.
the poor man' way is to jig it up with a set-square then stick some emery paper on a block and run the block along the bench..like the old smoothing plane. Then set the muffler up in the same way with the same set square. Still not perfect but an improvement.

The lazier way is to set it up as square as possible with the top jaws of your vice and smooth it to them

pgk

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01-08-2010 04:21 PM  7 years agoPost 19
AceBird

rrElite Veteran

Utica, NY USA

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Take a look at the exhaust port on your engine there is way more crown on there as a result of the raw casting than resulting from this.
Raw casting?? Nothing raw on my engines. There were milled from the factory. I suspect the distortion may have come from loose muffler or tightening bolts, heat and a failed gasket or improper gasket.

Ace
What could be more fun?

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01-08-2010 04:22 PM  7 years agoPost 20
jschenck

rrProfessor

La Vista, NE.

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that'd be better also but it'd be tough to get a muffler in a vice. I've cleaned the face of a number of mufflers this way with 220 grit sand paper on a flat surface and pull it across. The first few passes you can see it's effective because it's only taking the high points off the surface. Once I've gotten it down to a clean run across the entire surface I stop. I'm confident this results in a flatter and more square or at least less leak prone surface that what I started with. Doing this to both sides should result in a better seal than what I started with, but a few gallons into it we will all see. I'll post the results and if there is black goo dripping from the joint we will know this didn't work

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