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Old 01-19-2004, 04:29 AM   #226
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yeah... take the plug out to loose the compression.

The rod should be fine to finish the complete running in.

When you "roll" the piston over TDC you should be able to "Feel" the fit through the flywheel. You want it to be smooth but still have a little pinch at TDC. You will feel the difference. A not run in will feel scratchy and stiff as it approaches TDC.
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Old 01-19-2004, 04:32 AM   #227
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Quote:
Originally posted by sparksy
yeah... take the plug out to loose the compression.

The rod should be fine to finish the complete running in.

When you "roll" the piston over TDC you should be able to "Feel" the fit through the flywheel. You want it to be smooth but still have a little pinch at TDC. You will feel the difference. A not run in will feel scratchy and stiff as it approaches TDC.
Great Advice Thanx!
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Old 01-19-2004, 06:43 AM   #228
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Quote:
Originally posted by sparksy
You need to take the glowplug out to do the "is it run in yet" check.. you may find it feels alot closer to finished the run in process with out the compression hindering the "feel" of the piston at TDC.

Dont change the rod until you are finished the run in process... or you are wasting a good rod.
sparksy,
Thank you very much.You are the best!

Fisher,
Just listen what sparksy said.It's correct!
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Old 01-19-2004, 12:35 PM   #229
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Default crankshafts broken

Hi,
this weekend was a bit frustrating for many racers here in Spain. Some friends bought, one or two months ago, the sts dragon D3 from rcmushroom. Everything was ok, the engine works very well, more or less the same performance as the most expensive engines in the market.
Well, with five liters more or less, 4 engines went broken, and we don't know why. And the same for the 4 engines: the crankshaft (you can see the pictures here http://www.cochesrc.com/foros/viewto...r=asc&start=40 ). Do you know why? Is there any trouble with STS crankshafts? I was planning to buy one, but now...
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Old 01-19-2004, 12:50 PM   #230
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Default Re: crankshafts broken

Quote:
Originally posted by tonimccloud
Hi,
this weekend was a bit frustrating for many racers here in Spain. Some friends bought, one or two months ago, the sts dragon D3 from rcmushroom. Everything was ok, the engine works very well, more or less the same performance as the most expensive engines in the market.
Well, with five liters more or less, 4 engines went broken, and we don't know why. And the same for the 4 engines: the crankshaft (you can see the pictures here http://www.cochesrc.com/foros/viewto...r=asc&start=40 ). Do you know why? Is there any trouble with STS crankshafts? I was planning to buy one, but now...
Can you get larger pick of broken side of metal, if I can see metall structure may be able to say something. I general can be two things-wrong steel or wrong temp hardening parameters ( most likely overhardened). It is happened when shaft hardened all the way through with the same Rockwell. Usualy we hardened shaft to 45-48 internal and "skin" to 65-68.
I don't think it is mistake of design, it is more look like mistake of technology.
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Old 01-19-2004, 08:08 PM   #231
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The STS carburettor is made of composite plastic. It will not have overheat problem. Besides, STS's spray bar(mid-needle) has 4 holes on it. Racers can lean it to get extra-power and fuel supply still will not cut off. So it don't have adjusting limit.

Check those broken crankpin,first you will find that it's sign of overheated. Because the pin area is darker and also sign of too lean. That means the lubrication is not enough. And if you measure crankpin you will find it is not round any more. It's oval. The stock crankpin is 4.29mm diameter,just measure the top-bottom and left-right places. When the crankpin has very big play,the conrod will hit the crankcase and pull apart the crankpin.

There is a case I just deal with.Yeah~ Fisher's D3 broken crankpin too. From I studied his crankpin,it is 3.94mm diameter from top to bottom and 4.08mm diameter left to right.(New one is 4.29mm diameter)So 4.29-3.94=0.35mm . That is not only a little play.
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Old 01-20-2004, 03:36 AM   #232
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Quote:
Originally posted by dino.tw
The STS carburettor is made of composite plastic. It will not have overheat problem. Besides, STS's spray bar(mid-needle) has 4 holes on it. Racers can lean it to get extra-power and fuel supply still will not cut off. So it don't have adjusting limit.

Check those broken crankpin,first you will find that it's sign of overheated. Because the pin area is darker and also sign of too lean. That means the lubrication is not enough. And if you measure crankpin you will find it is not round any more. It's oval. The stock crankpin is 4.29mm diameter,just measure the top-bottom and left-right places. When the crankpin has very big play,the conrod will hit the crankcase and pull apart the crankpin.

There is a case I just deal with.Yeah~ Fisher's D3 broken crankpin too. From I studied his crankpin,it is 3.94mm diameter from top to bottom and 4.08mm diameter left to right.(New one is 4.29mm diameter)So 4.29-3.94=0.35mm . That is not only a little play.
Still not ready. Verytight still I can feel what you described sparksy. I went ahead and popped the top and side to look at the progress. The Rod is still very tight to the pin don't know how you assembled it... but didn't try forcing it off the crankpin. Everything still looks beautiful inside my D3? hmmmm.
An observation that I have made during run in is that the motor does not like to run rich. It will die quickly if I have it too rich, tried differant plugs but all the same. Low speed is ok rich but High speed doesn't like fuel. Going to wait a couple days for my new 16/19T Side belts before running more (eating rear tires).
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Old 01-20-2004, 04:20 AM   #233
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Default Re: crankshafts broken

Ouch I currently have STS D3 in shopping basket with rc-muchroom.. Might wait for a reply on this one from STS first

(image from below link in quote)


Quote:
Originally posted by tonimccloud
Hi,
this weekend was a bit frustrating for many racers here in Spain. Some friends bought, one or two months ago, the sts dragon D3 from rcmushroom. Everything was ok, the engine works very well, more or less the same performance as the most expensive engines in the market.
Well, with five liters more or less, 4 engines went broken, and we don't know why. And the same for the 4 engines: the crankshaft (you can see the pictures here http://www.cochesrc.com/foros/viewto...r=asc&start=40 ). Do you know why? Is there any trouble with STS crankshafts? I was planning to buy one, but now...
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Old 01-20-2004, 07:53 AM   #234
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these engines (with crankshafts broken) ran at 90-100 degrees (measured with Exergen), not more
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Old 01-20-2004, 08:05 AM   #235
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these must be a problem with the metal of the crankshafts, or may be a group of engines that went wrong out of the factory. It is not normal. One of the engines is owned by the third classified in Spain nationals (it's not a problem of wrong use)
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Old 01-20-2004, 08:08 AM   #236
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Quote:
Originally posted by tonimccloud
these engines (with crankshafts broken) ran at 90-100 degrees (measured with Exergen), not more

My friend had the same problem and same brake position on last weekend and manufacturer asked us to buy another one because it's too lean.However,its temperature was below 120 degrees .My friend say it may depend on your luck.
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Old 01-20-2004, 08:09 AM   #237
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Quote:
Originally posted by tonimccloud
these engines (with crankshafts broken) ran at 90-100 degrees (measured with Exergen), not more
how many air temperature there?
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Old 01-20-2004, 08:39 AM   #238
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That is why I started this thread on 11-28-2003;check it.
http://www.rctech.net/forum/showthre...threadid=28428

Form the observatory I knew that Madrid is about -2C~13C tomorrow.If air temp. under 10C and the engine running temp. is around 100C. Under the same engine needle setting with air temp. around 30C, what will be the engine running temp?

There is a good tip that Corse-R gave us;

Quote:
Originally posted by Corse-R

With temps between 5 and 15C I'll struggle to not going over 75-85C, the cold air cools too much the engine and gives you false readings. And people starts to lean it

Between 15 & 25C I'm pretty confortable between 95 & 105, 110C as maximum.

Over 25C is happy hour time, but I tune mine engines by ear and check the temperature only to assure myself that nothing is wrong there, doesn't matter if to go happy needs to go at 115 or 140C, each engine is a world apart and each one needs a different temperature. I have one engine that 'awakens' when temp reach 130C, under this temperature is a lemon.

Have seen one engine running happily at 150C.... each one is different. And the fuel you use makes a difference too.
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Old 01-20-2004, 12:12 PM   #239
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Default Broken crank!

Was that crank modified by anyone? If so it could have been weakened !
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Old 01-20-2004, 02:07 PM   #240
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Was that crank modified by anyone? If so it could have been weakened
There are 2 of them, these two still have the crankshaft in one piece

what will be the engine running temp?

one of the broken engines was in Mallorca (20 degrees more or less). Maybe it was a coincidence, maybe not (the engines broke in Madrid, Mallorca, Valladolid...different places separated with a lot of kilometres and very different temperatures)
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