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-   -   ASP/MAGNUM FS400AR Rebuild/Overhaul (https://www.rcuniverse.com/forum/glow-engines-114/6767296-asp-magnum-fs400ar-rebuild-overhaul.html)

Kmot 12-17-2007 12:00 AM

ASP/MAGNUM FS400AR Rebuild/Overhaul
1 Attachment(s)
It was one year ago that I ran my ASP FS400AR radial (hereafter known as FS400) engine on a test stand to begin the break-in process. Over three days, I ran the engine a total of 62 minutes. Then I added after-run oil and left it attached to my engine test stand, put a cover over it, and put it in my shed. Where it has sat untouched for a year.

I decided I wanted to run it again on its one year anniversary. But over the preceeding year I have read some reports of various problems other owners have had. So I decided to pull the back off to have a look inside, and also I was going to adjust the valves before running. Upon first look inside the engine, I was pleased. It looked good. No rust, or evidence of severe metal shavings and such. But there was some grayish residue on the diffuser backplate. And in there I did notice a couple of pepper size specks of something. Then, laying in the ARO, I saw a piece of metal. I removed it, looked at it, and wondered where it came from. Then looking inside the engine I saw it. One of the articulating rods linkpins had broken off in two spots where the circlip attaches. Bummer!

The good news is that I discovered it before serious mechanical damage had occured. So now, it is time for a 1 hour TBO overhaul. :eek:

This thread will illustrate what the process is about, as well as give everyone a look at how the FS400 was manufactured and any goofs the factory may have made in machining and assembling the engine.

My initial impressions of this engine are that it is nicely made. Machined well, and uses decent metallurgy. My concerns are in the area of final assembly, and perhaps a lack of quality control oversight.

The following pictures are not my engine, but those of another owner who had an articulating rod linkpin let go. My engine was very nearly at this stage!

To be continued...

Kmot 12-17-2007 01:54 AM

RE: ASP/MAGNUM FS400AR Rebuild/Overhaul
Here is the inspection report I recored while disassembling the FS400:

1) Slight dark gray residue inside power section. Probably just from wearing in.

2) #2 articulating rod linkpin has flanges broken off. Found one piece inside power section.

3) No rust apparent anywhere.

4) Slight greening to the color of ARO (normally red) in diffuser. Probably due to brass diffuser nozzle.

5) Valve adjustment settings as found:

#1 In: .28mm Ex: .25mm
#2 In: .33mm Ex: .25mm
#3 In: .35mm Ex: .25mm
#4 In: .20mm Ex: .18mm
#5 In: .50mm Ex: .15mm

Specified adjustment: .04mm-.10mm for both In and Ex.

6) One head bolt on #5 cylinder head was not torqued down.

7) One shim on #5 cylinder is warped slightly. Probably due to non-torqued head bolt.

As you can see from the figures above, the valve adjustments were wildy out of specification. All the nuts were tight, so this is how it came from the factory. Perhaps there was some loosening of the tolerances as the parts wore in.

Here is where the engine spent the past year. You can see the fuel tank on the floor, as the rubber bands holding it rotted and broke.


The engine was under this canvas cover to protect it and keep it clean.


The following pictures are as the motor was removed and torn down. You see it just as I saw it.





Up to this point I thought all was fine. Then I found this:



The linkpin at top is the broke one.


Other than that, it looked OK inside!


The rocker boxes all looked good.


It's important to keep all the valvetrain in order as removed, so it can be put back where it came from.


Removing the cylinder heads.


This is another factory goof. It appears the first headbolt someone attempted to install was when the head was not lined up.



And finally down to the main power section and cylinders.


Here are the assorted parts so far.


Again, keeping the valvetrain in order, this is how I stored the tappets.


I am at the point where I need to disassemble the nose from the power section. I tried using heat on the area around the bearing to loosen the case. No luck so far.


Since I do not have a manual, I am guessing at how to tear down this engine. My guess is that the front bearing needs to come out before I can remove the nose piece. Next I will put the whole thing in the oven and see if that will get it to loosen up.

To be continued...

Iflyglow 12-17-2007 07:17 AM

RE: ASP/MAGNUM FS400AR Rebuild/Overhaul
It looks like it was over revved (broken link rod).[X(]

Flyboy Dave 12-17-2007 11:40 AM

RE: ASP/MAGNUM FS400AR Rebuild/Overhaul
....there isn't very much meat on those big end pins. [X(]

Big end pins/lower-end pins/crank pins/bottom-end pins. "Link pins", OK too. ;)


Kmot 12-17-2007 01:21 PM

RE: ASP/MAGNUM FS400AR Rebuild/Overhaul
Link pins, Dave. Maybe on those little girly engines in the motos you worked on they were called big end pins (making up for other shortages, lol) but on the manly P&W radials I used to overhaul the correct nomenclature is link pins. :D

Motorman, max rpm never exceeded 7400 and the engine is rated much higher.

Flyboy Dave 12-17-2007 01:38 PM

RE: ASP/MAGNUM FS400AR Rebuild/Overhaul
....well, allrighty then. :)


gkamysz 12-17-2007 01:51 PM

RE: ASP/MAGNUM FS400AR Rebuild/Overhaul
Is it a fit (lack or clearance) or material issue? It's pretty common to find the heat treated parts too hard or not tempered in the Chinese products. Does the snap ring groove have radii in the bottom? Is everything square? Theoretically the side loading on the link pins should be extremely small so the ring groove needs little strength.

Kmot 12-17-2007 04:35 PM

RE: ASP/MAGNUM FS400AR Rebuild/Overhaul
Greg, once I get the engine completely dismantled I will be able to answer your questions.

From what I can tell so far, the nose case must be removed to then allow the link pin to be removed. I am approaching this disassembly extremely cautiously, for I have no clue where spare parts can be obtained for this engine and I do not want to break anything else during disassembly. I already expect I will have to make my own link pins.

FWIW, after I had heated the nose case I then turned the engine upside down and sort of slammed the crankshaft against a wood 2x4. That was more side loading of those pins and everything else than the engine would ever see normally and no other pieces broke off.

I can't heat the engine in the oven while my wife is in the house. :eek: And I will be out of town for a few days starting tomorrow so it may be awhile till I get the engine completely torn down.

Kmot 12-17-2007 09:11 PM

RE: ASP/MAGNUM FS400AR Rebuild/Overhaul
Okay, the wife went out and I cooked the engine. :D

When I tried to shake the bearing out, the whole nose case actually seperated. Oops! There went my opportunity to see how the engine was timed. [X(]

Anyway, found a little more detritus inside the nose case. Some of it was metallic, the stuff around the tappet bores is just sludge. Seperating the spacer from the nose case was a tough job because of the pin used to align them. So the plastic gasket didn't survive this time.

I removed the damaged link pin and then the piston and connecting rod. I found the piston pin only has a teflon pad on one end. I don't know yet if this is by design or by mistake.

Bake uncovered in a 300°F oven for 10 minutes. :p


Then rap on a piece of wood and the bearing should fall out. Not!


Okay, so now we have come this far let's just tear down the nose case and cam gears, etc.



Here is what the rest of the engine looks like inside:







And finally, here is the link pin. No Greg, it doesn't look like it is radiused for the circlip.


To be continued in a few more days. In the meantime, if anyone knows how to time this engine.................. [sm=drowning.gif]

gkamysz 12-17-2007 09:47 PM

RE: ASP/MAGNUM FS400AR Rebuild/Overhaul


Okay, the wife went out and I cooked the engine. :D

Yeah, just don't get caught. Mine soon to be wife would kill me.

Are those cracks in the crank?!

And finally, here is the link pin. No Greg, it doesn't look like it is radiused for the circlip.

I think the pin is too hard and the lack of radius doesn't help.

Flyboy Dave 12-17-2007 11:07 PM

RE: ASP/MAGNUM FS400AR Rebuild/Overhaul
....the failure on that pin is really odd, when there is no side thrust on it. It should
be dead bolt reliable. [:@]


Kmot 12-18-2007 12:06 AM

RE: ASP/MAGNUM FS400AR Rebuild/Overhaul

Are those cracks in the crank?!
My first thought also. No, that is the crank pin that was pressed into the counterweight and then machined.

FBD: I agree. But take a look at something. Look close at the pins in the photo. See the discoloring? Is that heat treat? Could they have been improperly heat treated and the flanges are too brittle?

gkamysz 12-18-2007 08:10 AM

RE: ASP/MAGNUM FS400AR Rebuild/Overhaul
For some reason heat treating isn't taken seriously or maybe it is not well understood over there. When I was working with RC electric motors a few years ago it took over two years to get a semi-properly heat treated motor shaft. Mean while the product was released and shafts broke right and left. I extremely rarely saw a bent shaft, only broken. Prior to that my experience with electric motors showed only bent shafts, some weak, some strong but never broken, but these were not of Chinese origin.

Kmot 12-18-2007 11:47 PM

RE: ASP/MAGNUM FS400AR Rebuild/Overhaul
Well, I am now sitting here in a hotel room in Northern California. But I have received some good news. I can source parts for this from Just Engines in the UK.

DarZeelon 12-19-2007 01:43 AM

RE: ASP/MAGNUM FS400AR Rebuild/Overhaul

I think you are to have this engine replaced/repaired under warranty.

The cracks in the crank-web alone justify this... It is a major production flaw!
...and the broken link-pin suggests the crankshaft actually flexes, due to these cracks... which produces side-loads on the link-pin retainers.

I believe this crankshaft flaw is the actual cause of this problem.

Send ASP/Magnum those photos!

gkamysz 12-19-2007 08:42 AM

RE: ASP/MAGNUM FS400AR Rebuild/Overhaul
Dar, if you read the posts he said the crank pin was pressed and that is what you see.

I would bet that the flange on the link pin fractured during assembly and wasn't caught or there simply isn't enough clearance for the snap ring without exerting undue pressure on the groove.

BTW, I don't think Magnum really cares about ASP engines or their warranty. Especially if this engine was purchased off the auction site for 500 less than what Magnum charges (I have no idea how Kmot acquired this engine).

w8ye 12-19-2007 09:06 AM

RE: ASP/MAGNUM FS400AR Rebuild/Overhaul
Hobby people have not carried the radial for some time.

I was under the impression that kmot purchased the engine from a Chinese hobby shop that does business over the internet?

DarZeelon 12-19-2007 09:53 AM

RE: ASP/MAGNUM FS400AR Rebuild/Overhaul

I don't see where Tom mentioned eBay, or any auction...

He just wrote he has had it for a bit less than one year, since doing a break-in.

I believe all Sanye made engines carry a two year warranty...
This one is just a bit too expensive to let them get away with any type of production flaw.

The fact the crank-web cracked is a manufacturing flaw.

It means that either the crank-pin insert is too large, or the hole drilled for it in the crank-web is too small...

Parts that are pressed into one-another need to be accurately sized, so pressure holds the inner part in place, but does not break the outer part...

gkamysz 12-19-2007 03:13 PM

RE: ASP/MAGNUM FS400AR Rebuild/Overhaul
Dar, I don't see Tom saying anything about it being cracked?

Send the engine to China then?

SJN 12-19-2007 04:17 PM

RE: ASP/MAGNUM FS400AR Rebuild/Overhaul
Hey Tom.

Thanks for all the pictures.

The manual can be downloaded from the place I bought mine here:

the last 2 pages in the PDF is an exploded view of the engine, and parts list in german

I think the broken pin is number 88, P/N 225536 and it is in stock if you need a new one

Flyboy Dave 12-19-2007 09:00 PM

RE: ASP/MAGNUM FS400AR Rebuild/Overhaul
I'll bet money the so called "assembler" of that engine whacked the pin to get the
circlip seated and cracked the pin in the process....leading to the eventual failure
of the edges of the pin, which are case hardened and brittle....

....any takers ? ;)

The circlip may have had a raised edge, and the assembler whacked it in 3 or 4
places to get it to seat into the groove.


DarZeelon 12-20-2007 12:05 AM

RE: ASP/MAGNUM FS400AR Rebuild/Overhaul

ORIGINAL: gkamysz

Dar, I don't see Tom saying anything about it being cracked?

Neither do I, Greg.

But I do see what appears to be nothing other than cracks...

Not just one, but two of them...

If it walks like a duck and it quacks like a duck (although its owner says nothing about its nature), what would you say it is??

After all, you were the first participant that noticed them...

Kmot 12-20-2007 01:22 AM

RE: ASP/MAGNUM FS400AR Rebuild/Overhaul
LOL, this is funny! :)

gkamysz 12-20-2007 08:30 AM

RE: ASP/MAGNUM FS400AR Rebuild/Overhaul


LOL, this is funny! :)
I agree, you obviously know what you are doing. Let us know what your outcome is.

Kmot 12-20-2007 07:48 PM

RE: ASP/MAGNUM FS400AR Rebuild/Overhaul
Hi fella's! :)

I have just got back home from a trip of a few days (700 miles all in the rain) and so I will have a chance to tear down the engine the rest of the way in the next few days. I will let you know what I find of course.

As for the cracks that are being discussed, I think it is a bit of an optical illusion due to the photograph and a reflection off the crank itself. However, I believe the crank is not cracked but instead what is being observed as a crack is actually a circular clearance created when the counterweight was drilled for the crank pin to be pressed into place. Which was later machined and so the circular line is left evident.

FYI, I purchased this engine in February 2006 for the price of $750 from an ebay seller who imports hobby products from China. Even if it still has a warranty, I will not be boxing it up and sending it back to the Sanye Factory in China. And I would not know how to get the warranty coverage anyway because I did not buy it from an authorized distributor.

Besides, I can repair it better myself, although I will have to pay for the parts. Since I am completely disassembling it, I will be blueprinting it upon reassembly so it should be one of the better running FS400's when I am finished with it. ;)

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