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Author Topic: G-Mot...or not?  (Read 1327 times)
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cd_webb
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« on: June 13, 2014, 06:09:45 PM »

I got this thing from "a certain well known on-line auction site", supposedly never run. I think it's a G-Mot, but all I know is what I've been able to gather here and there, wherever I can find anything to read (mostly here). The guy selling it had no idea what brand it was or what size it might be. There is not one distinguishing mark on it except for the blue anodized rings.

Is there someone here that can tell me what I've got?  Any help here I would certainly appreciate. I hope to gather a few more of these and build something to put them in, so there will be more questions as they arise. Bear with me and my ignorance. It'll get better!  Grin

David
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alset
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« Reply #1 on: June 13, 2014, 09:16:25 PM »

It's a GMOT 120 with what appears to be a somewhat smaller tank than came with the stock 120
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danmellor
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« Reply #2 on: June 14, 2014, 03:52:40 AM »

If it was a GM120, it would have a three point radial backplate mounting. As it appears to be a two point mounting, it's probably a GM63. Similar size to the old Telco and Brown MJ70. That fits with the size of the tank, too.

Cheers,

Dan.
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DaddyO
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« Reply #3 on: June 14, 2014, 04:35:04 AM »

The tank size could indicate use in a CO2 comp model (only 3 cc allowed) Nice motors though. Cheesy
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There cannot be a crisis today, my schedule is already full
danmellor
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« Reply #4 on: June 14, 2014, 07:21:09 AM »

The boxed motor is a GM63, The larger motor is a GM120. The difference in mountings is just about visible!

Dan.
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ILM Tarheel
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« Reply #5 on: June 14, 2014, 08:14:14 AM »

The boxed motor is a GM63, The larger motor is a GM120. The difference in mountings is just about visible!

Dan.

An easier to see difference in this side by side view is the GM63 has 6 fin rings and short crankcase casting while the GM120 has 7 fin rings and a tall crankcase casting. Is this a consistent difference through the entire production runs?
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PeeTee
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« Reply #6 on: June 14, 2014, 08:22:56 AM »

The GM 120 is almost twice the capacity of the 63 and thus larger all over.
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cd_webb
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« Reply #7 on: June 14, 2014, 08:38:09 AM »

Thanks to all! Mine appears to be a dead ringer for the .63 pictured, so that problem is solved. Now, onto the next dark mystery, which in this case concerns what I should see when I remove the cylinder head. Shouldn't there have been a ball seated there for the piston stud to contact? Also the tubing feeding the engine freely spins in the cylinder head. It's not fixed like everywhere else, and I was a little surprised by that. If it's not fixed, it's not sealed, so it's gonna leak some gas, right?
« Last Edit: June 14, 2014, 09:30:13 AM by cd_webb » Logged
danmellor
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« Reply #8 on: June 14, 2014, 09:56:35 AM »

In the cylinder head, there should be visible a plastic seating with the ball bearing in the centre. The tubing in Gasparin/GM motors is not fixed to avoid damage when rotating the cylinder to change throttle settings.

Dan.

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cd_webb
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« Reply #9 on: June 14, 2014, 11:59:07 AM »

In the cylinder head, there should be visible a plastic seating with the ball bearing in the centre. The tubing in Gasparin/GM motors is not fixed to avoid damage when rotating the cylinder to change throttle settings.

Dan.





OK, then there's my first real problem. The plastic seating is there and seated in place, but the ball bearing is missing. I asked the guy if the thing had ever been opened up before and he said he didn't think so, that it was a display model and had never been run. Guess somebody lost their ball bearing and helped themselves. I'll get something figured out. Thanks, Dan! Any idea as to what size ball I'll need?

David
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alset
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« Reply #10 on: June 14, 2014, 12:11:23 PM »

Sorry about my observation that it was a 120.  My (incorrect) understanding was that the 63 had an orange head, the 120 blue, and the 300 black. Thanks to those that corrected that.
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PeeTee
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« Reply #11 on: June 14, 2014, 01:03:24 PM »

David

Dan may be able to tell you the size and where to get suitable balls ( I recall mention of those from ball point pens and gas cigarette lighters but can't remember the context Sad)

Gasparin in the Czech Republic may be able to supply spares, and there are a couple of suppliers in the UK (FliteHook and SAMS), however it may be easier for you to go to a US stockist - the Black Sheep Squadron - here http://www.blacksheepsquadron.com/gmotprices.html  as they do spares kits for $15.

Peter
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cd_webb
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« Reply #12 on: June 14, 2014, 01:11:07 PM »

Thanks, PeeTee. I'll put out some feelers.

The real problem is, I'm an engine lover, and to see one in some state of disrepair is something that I can't deal with. I don't even want to think of the money I've spent repairing nitro engines knowing there's no way I'll ever get my money back out of it. I just can't seem to help myself. I have serious problems!

David
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danmellor
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« Reply #13 on: June 14, 2014, 02:15:46 PM »

A spares kit from Black Sheep for $15 sounds like it may be your best bet. I own something like 20 Gasparin/GM motors and I've never had to use a single spare in maybe 20 years. A spares kit would get you the replacement "O" rings of the correct size for the various joints, too. I'm sorry I can't tell you the size of ball needed. If you get really stuck, I can send you the one from the spares kit in my motor. Ball bearings never wear out in CO2 motors!!

Cheers,

Dan.
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PietenpolAC
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« Reply #14 on: June 14, 2014, 04:38:58 PM »

If you do find a ball bearing, before you add CO2 to the tank the first time, I would loosen the lock ring on the cylinder and screw the cylinder out a little. If someone took out the ball bearing, then they may have unscrewed the cylinder also and screwed it in too far later. You definitely don't want the cylinder screwed in too far or you can damage the motor. Screw it out far enough that there is no binding when the piston moves through its highest position. When the tank is charged (use a gas charge when first setting up) screw the cylinder in about 1/8 -1/4 turn at a time until the motor begins to run. Then continue adjusting with 1/8 turns until you reach the appropriate RPM.

Bruce
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cd_webb
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« Reply #15 on: June 14, 2014, 05:04:19 PM »

Dan, I think you are probably right about the spares kit and where to get it. I'll do that, but I certainly appreciate your offer, which by the way, is above and beyond what anyone could expect. Thank you much!

Bruce, the cylinder was screwed in too far and was causing some binding just into the down stroke. That's the kind of info I'm happy to get. There's a lot of that kind of information that you guys know from years of using these things, that you probably take for granted, but guys like me find invaluable.

One more question and I'll give it a rest. The piston stud pushes up through the hole in the ball seat, right? The ball sits between the ball seat and the cylinder head, right? The full stroke (on my engine) does not push far enough up to extend through the ball seat and touch the ball. Am I thinking of this right, or am I one confused soul? OK, 3 more questions before I shut up!

David     
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danmellor
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« Reply #16 on: June 14, 2014, 05:35:21 PM »

You'll have to get the relevant ball bearing and try it! The previous advice about unscrewing the cylinder and then gradually screwing back until the motor runs is sound stuff. Mr. Gasparin advises against using a liquid charge on his motors, but as long as you make sure the motor is not at TDC before charging, it's fine. If the motor is at TDC and the valve in the cylinder head is open whilst charging, the liquid CO2 can freeze and damage the "O" ring on the piston that creates the compression seal.

Cheers,

Dan.

PS What are the other 3 questions??!!
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cd_webb
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« Reply #17 on: June 14, 2014, 07:55:10 PM »


PS What are the other 3 questions??!!

Well, the last paragraph announced one last question, but in proof reading the post, I noticed 3 question marks. I seldom ask 1 question before 2 or 3 more pop into my head. Besides, while you've got folks willing to share their advice, that's the time to ask, the way I see it.

And when I said I'd shut up, I meant for now. This thread ain't dead by a long shot!

Many thanks to all!!
David
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cd_webb
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« Reply #18 on: June 25, 2014, 07:05:57 PM »

Well, I just received the G24 I ordered today and what a little beauty! Also got a spare parts kit for the Gmot 63 that I was needing, so we're in business. The last thing I need is a way to charge the tank.

Would anyone here happen to know if there is a reason Mike Woodhouse would not be responding to emails? Since the 14th of June I have sent 2 emails and one email order form with no response at all. I used the Free Flight Supplies links for the first email and the order form sent, and the third one was sent straight from my mail provider. Anyone else having trouble contacting him?
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applehoney
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« Reply #19 on: June 25, 2014, 08:47:23 PM »

Quite simply ... Mike may be travelling ....   far afield to contests or on vacation .. or both combined
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