RE: Hi Perf Russian 10cc at a bargain price! (Full Version)

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Harry Lagman -> RE: Hi Perf Russian 10cc at a bargain price! (2/25/2008 4:21:55 AM)


quote:

ORIGINAL: Kmot

BTW, and FWIW, there was no crackling sound the first time I ran this engine. I didn't hear it, didn't think about it. The second time there was. I hear it, and thought about it. The only difference being, the prop. I wonder if it is just different prop noise?



Kmot,I think you've nailed it. Correct me if I'm wrong but the first (quiet) prop was made of glass filled nylon (or similar) and the second one was wooden. I have heard wooden props effectively amplify mechanical noise relative to "plastic" type props. I heard an OS Surpass the other day that sounded downright scary with a 13 x 8 wooden prop yet with an MA/APC type 13 x 8 prop, it was very quiet. RPM and thus load were very similar.



daven -> RE: Hi Perf Russian 10cc at a bargain price! (2/25/2008 4:58:05 AM)

Finally got everything "de-gunked", took a while.

Couldn't find a 11x6 in the prop drawer, will break in with a 10x8.

Motor turns over very nice, lots of compression, and the bearings appear to be working well. Carb is still a little tight, but should loosen up with use. Kept the standard straight slot bolts to keep it "Russian" looking.

Highly oiled here with MM air tool oil. Going to mount into my test stand, and hope to get out to the field before it warms up and gets crowded. The motor inside is a little rough, it may need some serious break in.



Kmot -> RE: Hi Perf Russian 10cc at a bargain price! (2/25/2008 5:56:34 AM)

Lookin' good Dave! :D

Hey, check this site out:

http://ruwatches.com/thestore/product_info.php?cPath=27&products_id=38&osCsid=81e004de58be2367f0800ee7d06372ab

Has a photo with a partial view of the factory instruction manual, plus what the tuned pipe looks like.



DarZeelon -> RE: Hi Perf Russian 10cc at a bargain price! (2/25/2008 6:08:18 AM)


quote:

ORIGINAL: DarZeelon

... After removing the prop-driver from the front of the crankshaft (and of-course the piston, sleeve, Etc.) and with the crankcase still cold, pushing back on the front of the crankshaft will get it out (unless the fit is wrong).



quote:

ORIGINAL: Kmot

I used an arbor press on a cold crankcase and the crank came out with the bearing attached.



Tom,


Please note the underlined, bold clause in my quote.

If this was the case, you obviously could not help it, except, maybe, deep-freezing the crankcase before applying that arbor press...


This tolerance issue is not unique to MDS (МДС)... In a MAN engine review for the K&B 6.5, circa 1979-1980, by Harry Higley (or was it Peter Chinn...), it was found that the rear bearing was very loose in the crankcase - so loose, in fact, that it had spun...

That K&B did produce very high performance for its day.



Kmot -> RE: Hi Perf Russian 10cc at a bargain price! (2/25/2008 6:18:01 AM)

Dar, what font do you use for the Russian letter D?



DarZeelon -> RE: Hi Perf Russian 10cc at a bargain price! (2/25/2008 6:30:53 AM)


quote:

ORIGINAL: daven

I had to heat the case to get the CRANK out...



Dave,


Why???

That cannot be!

Did the crankshaft spin freely in its bearings and in the crankcase, or was it held very tightly...

There is no physical contact between the crankcase and the crankshaft in a ball bearing engine.



DarZeelon -> RE: Hi Perf Russian 10cc at a bargain price! (2/25/2008 6:33:48 AM)

Tom,


I'll send you a PM, regarding the fonts.



Kmot -> RE: Hi Perf Russian 10cc at a bargain price! (2/25/2008 6:41:17 AM)

Д Found it!



Kmot -> RE: Hi Perf Russian 10cc at a bargain price! (2/25/2008 6:42:36 AM)

Oh, I just saw I had a PM notice. I was busy searching my character map! :)



Kmot -> RE: Hi Perf Russian 10cc at a bargain price! (2/25/2008 6:48:19 AM)

I 'think' what is going on, is these engines have sat in this tenacious cosmolene witches brew for 17+ years. That and a tight tolernace anyway, makes the rear bearing stick to the crank and get pulled out with it.

FWIW, I polished the journals on the crankshaft where the bearings ride. The rear bearing, after everything was scrubbed clean and the journal polished, would not just 'slip' onto the crank. It had to be pushed hard to be seated all the way to the rear. The bearing then would not just fall into the front case, the case had to be heated to install it.



Kmot -> RE: Hi Perf Russian 10cc at a bargain price! (2/25/2008 6:58:53 AM)

МДС 10 цц КРУ

heh-heh... [:D]



samtech -> RE: Hi Perf Russian 10cc at a bargain price! (2/25/2008 7:18:45 AM)

.... I still haven't got the crank out of the bearings or the case yet..... Cosmoline everyware but there is some sort of adhesive between the outer race and the case. Theres just a little that I can get to on the edge of the case where the outer race is pushed in... Anybody else seen this yet? It's very sticky stuff, unmistakable for anything other than adhesive. I've NEVER seen bearings glued in before. Have any of you? DAR???



DarZeelon -> RE: Hi Perf Russian 10cc at a bargain price! (2/25/2008 7:31:43 AM)


quote:

ORIGINAL: samtech

...I've NEVER seen bearings glued in before. Have any of you? DAR???



Sorry, Sam.

I never did.


When the fit of the bearings is set right, there is no need for any substitution for it...



daven -> RE: Hi Perf Russian 10cc at a bargain price! (2/25/2008 12:45:34 PM)

Samtech,

Mine was the same way. It was gunked up solid, I tapped the crank from the front lightly with a block of wood and didn't feel comfortable tapping it any harder to remove it. I soaked it over night in acetone, dried it off thoroughly, and then had to put in an oven at 300 degrees for 20 minutes before I could tap it free.

At that point, the bearing was stuck to the rear of the crank. Did the same process over (soaked in acetone, and then heated) to remove the bearing from the crank.

Took a good amount of brake cleaner to get all the gunk out of the bearings, but they are working nicely now. Reseated them with heat, and this thing is ready to run.



DarZeelon -> RE: Hi Perf Russian 10cc at a bargain price! (2/25/2008 1:21:27 PM)

Dave,


If properly manufactured, as far as tolerances are concerned, all engines will come apart the same way

The bearing has the given absolute dimensions, since it is of fixed size.

For example, let's take this МДС engine.

The rear bearing is a 6902 (I expected a high performance .61 engine to use a larger rear bearing, but this is what is listed for it), which has an internal diameter of exactly 15 mm (at 15ºC) and an external diameter of exactly 32 mm.

The crankshaft must be held in the inner race of that bearing, so its outer diameter must be very slightly larger, say, 15.005 mm.
Some pressure must be applied to the crankshaft, for it to be slid into the rear bearing's inner race, but this force must not be excessive.

The rear bearing seat in the crankcase must have a tighter fit on the bearing's outer race, so its diameter must be, say, 31.99 mm; maybe even a bit smaller, so the bearing will not come loose, when the engine reaches its normal operating temperature.


So, if an engine is cold and pressure is applied to the crankshaft pushing it back, it should be the only part sliding out.




daven -> RE: Hi Perf Russian 10cc at a bargain price! (2/25/2008 2:22:49 PM)

When the motor was cold, nothing slid.

The only way I could get it out (safely) was heat.



DarZeelon -> RE: Hi Perf Russian 10cc at a bargain price! (2/25/2008 2:42:42 PM)

Dave,


If that is the case, the fit of the crankshaft in the rear bearing's inner race, must be way too tight and the fit of that bearing in the crankcase is way too loose...




blw -> RE: Hi Perf Russian 10cc at a bargain price! (2/25/2008 3:09:26 PM)

Did you check the race for galling? That sometimes happens.



daven -> RE: Hi Perf Russian 10cc at a bargain price! (2/25/2008 3:27:40 PM)

No, the bearings were completey covered in some off shade of green material. It was also under the rear bearing (between the bearing and crank) and it was very sticky which contributed to the difficulties of removing everything. Once cleaned off and 0000 steel wooled, everything fit back together nicely (as it should).

The races looked fine once cleaned, just took a while to get that way. They were nearly completely filled (packed) with that green gunk. Hopefully it did its job in perserving this nearly 20 year old motor.



BTerry -> RE: Hi Perf Russian 10cc at a bargain price! (2/25/2008 4:10:40 PM)

Here is a bit of info on the engine: http://www.rcgroups.com/forums/showthread.php?t=316163

Apparently the carb has leakage problems. Any comments?



bob27s -> RE: Hi Perf Russian 10cc at a bargain price! (2/25/2008 4:51:07 PM)

any chance they chose to use a bearing retaining compound for some reason ??

How did things fit up after reassembly ?



daven -> RE: Hi Perf Russian 10cc at a bargain price! (2/25/2008 5:17:28 PM)

It was a snug fit, but I was able to get the bearing the crank without heat. I heated the whole shebang, bearing and crank to seat the rear bearing which popped in pretty easily.

Things are smooth as silk right now, buts its completely coated in MM air tool oil.



daven -> RE: Hi Perf Russian 10cc at a bargain price! (2/25/2008 5:19:50 PM)

As to the carb leak, I can see that as being a possible issue. It assembles similary to my super tigre 90 carb. I put a piece of wood over the carb and lightly tapped it as tightly as I could against the O-Ring, than held it in place with quite a bit of force as I tightened the nut that holds the thing in place. Seems like a pretty good fit, I will see.



BlackB12 -> RE: Hi Perf Russian 10cc at a bargain price! (2/25/2008 6:31:15 PM)

I just left the bearing on the crank when cleaning it. It spun nice and free, like spin it and it would continue spinning for several seconds before stopping. I didn't feel the need to pull it off the crank so I assembled it still with the bearing on the crank. All bolted back up it has a nice tight feel on the bearings and nice pinch at TDC. Haven't installed the carb yet as I'm still in need of a header pipe before I run it. I'll be installing the engine on a world models skyraider mach 2 to start with. IT's been my engine test plane for several engines.

Mike



Kmot -> RE: Hi Perf Russian 10cc at a bargain price! (2/25/2008 6:46:03 PM)

I always prerss down real hard on an o-ring carb when seating it. That thread on RCG has some interesting comments. I like these:

They make tremendous power for their size,

the tuned pipe made the difference to the power - almost 2000 revs up on the conventional silencer, and it throttled well with near instant pickup

I have several rear exhaust 10cc versions that kick but with a Perry carb & pump.



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