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Can't Get new Enging to Turn Over

Old 05-15-2007, 02:02 PM
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MobileDJ
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Default Can't Get new Enging to Turn Over

Hello All!

I hava a Revo that I just installed a OS .30 engine in.

I also purchased an RD Racing bump box to handle starting duties.

When I went to start the motor for the 1st time....nothing. It wouldn't even turn over. I tried dropping after run oil in the cylinder, then wd40, and finally heated the block with a heat gun to about 200 degrees and still it will not turn over.

I removed the engine and I can turn it over by hand by turning the flywheel......but it is very stiff.

The Bump box is new.....but according to the store owner has been sitting on display for several years.

The battery is also brand new and fully charged.

Could it be a bad battery or bump box?

Any ideas or suggestions?

Thanks in advance.
Old 05-15-2007, 02:04 PM
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jonnymac
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Default RE: Can't Get new Enging to Turn Over

Heat the engine and loosen the glowplug. Once its started tighten the glowplug up.
There is just too much compression for your starter box. Once its broken in it will be much easier
Old 05-15-2007, 09:43 PM
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Default RE: Can't Get new Enging to Turn Over

Jonnymac is right, a buddy just got done breaking one in too, heat it up, preferrably with a heatgun for airplanes ( its what I use ), I done think a hairdryer is enough, and loosen the glow plug just enough to release compression. When it starts tighten it down. Dont run that motor slobbering rich either, it will hurt it. If it dies when you remove the glow starter, its too rich.
Old 05-16-2007, 01:05 AM
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Default RE: Can't Get new Enging to Turn Over

i fail to see how running the engine rich will hurt it, there is no way to over compress one a engines when it's shimmed right for the fuel your using, no matter how rich you run it the engine will flood before it get to that point, and then the only thing thats in danger is your glow plug not the engine, you must run the engine rich during break in because there is a lot of friction during break in from the tight fit of the piston and sleeve that creates a lot of heat, so you need the extra fuel to both lubricate the engines and to keep it cool.
Old 05-16-2007, 05:32 AM
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Default RE: Can't Get new Enging to Turn Over

The cylinder in the OS has a taper and gets smaller at the top. The reason for this is that the top of the cyl gets hotter than the bottom and expands more, so at running temp it's basically straight. They need the temp at the top for break-in, and too rich a mixture wont get it there. Also the Alum piston expands more than the cyl at any given temp so what it tight now will get real bad if run too rich as the cyl cools better than the piston, the result is a low performing engine at best, a broken rod or crank at worst. I suggest you do not allow the engine to run in 4-stroke mode for any length of time.
Old 05-16-2007, 07:05 AM
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Default RE: Can't Get new Enging to Turn Over

every single nitro engine has a tapered piston sleeve instead of piston rings, not just the O.S engines, and the brass and chrome in the piston sleeve expand more then the alloy piston, in an automotive engine (in other words a car engine) with an iron block an alloy piston expands more then the block and causes it to seize but brass expands more then aluminum when heat is applied.

in short, you are much better off running the engine excessively rich during break in then you are running it even slightly towards lean, you need you extra lubrication and cooling of the extra fuel to keep the engine from overheating and so there is as little friction as possible, the temps during break in should, even running very rich get to around 220-240 simply due to the extra friction from the tight fit of the piston and sleeve.

also can you please try to get your information strait, what you have said there go's against just about every moral of a nitro engine, they are not tapered because the top of the engines gets hotter and thus expands more then the bottom, they are a tapered sleeve because they do not have piston rings to keep compression, so they use the tapered sleeve to get enough compression to allow the engine run efficiently.

-edit- [link=http://www.rc-trucks.org/rc-nitro-engines.htm]link[/link] as a reference.
Old 05-16-2007, 09:04 AM
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Default RE: Can't Get new Enging to Turn Over


ORIGINAL: ttoks

i fail to see how running the engine rich will hurt it, there is no way to over compress one a engines when it's shimmed right for the fuel your using, no matter how rich you run it the engine will flood before it get to that point, and then the only thing thats in danger is your glow plug not the engine, you must run the engine rich during break in because there is a lot of friction during break in from the tight fit of the piston and sleeve that creates a lot of heat, so you need the extra fuel to both lubricate the engines and to keep it cool.
Uh huh... I've seen half a dozen stretched out or cracked con-rods at the crank pin. It ALWAYS has happened in the first gallon of fuel, and often during the break-in period. With a combination of having the best possible pinch when new, and the extra volume of space taken up in the cylinder from the extra fuel, you certainly can overcompress an engine. I don't believe its an easy thing to do, but it can be done from the results I have seen.

This is not to say that you should not run rich during break in, because you should! You do need the extra lubrication. I think common sense, as well as the now infamous Steven Bess heat cycling article, would dictate a happy medium between the two opposing sides here.
Old 05-16-2007, 01:46 PM
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Default RE: Can't Get new Enging to Turn Over

Well I always set to factory settings, then lean it out a little so it will idle OK, pull off OK and runs OK if a little slow due to richness, and break in like this. Breaking in at factory settings doesn't get the temps high enough for heat cycling.
It does need to be a little on the rich side but not 'slobbering' rich
Old 05-16-2007, 10:36 PM
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Default RE: Can't Get new Enging to Turn Over


NOT all nitro engines are tapered (ABC ABN AAC), your wrong, do some home work.
Old 05-17-2007, 01:39 AM
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Default RE: Can't Get new Enging to Turn Over

ABC stands for A aluminum piston, B brass piston sleeve, C chrome ware surface.

ABN stands for A aluminum piston, B brass sleeve, N nickel ware surface.

AAN stands for A aluminum piston, A aluminum sleeve, C chrome ware surface.

ABN can also stand for A aluminum piston, B brass sleeve, N nikasil ware surface, nikasil was developed in the 60's for use in wankel engines because it causes much less friction the cast iron allowing the nikasil coated rotor housing and the aluminum rotor to contacted directly without much friction or ware, but ended up being used extensively by Porsche in there high performance 911 models and racing cars, Ferrari and Maserati in a few select limited production cars also by BMW, Jaguar, Honda H sires and in some mopeds.

all types have a taper in the piston sleeve, i'm not trying to start an argument but i'v done my research.
Old 05-17-2007, 06:41 AM
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Default RE: Can't Get new Enging to Turn Over

Not every single nitro engine has a tapered piston and sleeve. Some, [link=http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXVB97&P=0]like this,[/link] are ringed. But, yes, if they are not ringed then they must be tapered to have compression.

The problem with the new OS 30 is simply too much pinch. It's a common problem with new engines and can be very frustrating to get past. If that bump box you bought has been sitting for years then the rubber wheel could have dried out/hardened some and be compounding your problem. You might see if you can get the hobby shop people to give you a new wheel. One method I have used on extremely tight engines is to pull the glow plug out, put several drops of oil in the cylinder and turn the engine by hand a dozen or so revolutions - just be sure to keep it well lubed.
Just take your time on break-in, try not to get frustrated, it will be worth it in the end.
Old 05-17-2007, 06:43 AM
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Default RE: Can't Get new Enging to Turn Over


ORIGINAL: ttoks

every single nitro engine has a tapered piston sleeve instead of piston rings, not just the O.S engines, and the brass and chrome in the piston sleeve expand more then the alloy piston, in an automotive engine (in other words a car engine) with an iron block an alloy piston expands more then the block and causes it to seize but brass expands more then aluminum when heat is applied.

in short, you are much better off running the engine excessively rich during break in then you are running it even slightly towards lean, you need you extra lubrication and cooling of the extra fuel to keep the engine from overheating and so there is as little friction as possible, the temps during break in should, even running very rich get to around 220-240 simply due to the extra friction from the tight fit of the piston and sleeve.

also can you please try to get your information strait, what you have said there go's against just about every moral of a nitro engine, they are not tapered because the top of the engines gets hotter and thus expands more then the bottom, they are a tapered sleeve because they do not have piston rings to keep compression, so they use the tapered sleeve to get enough compression to allow the engine run efficiently.

-edit- [link=http://www.rc-trucks.org/rc-nitro-engines.htm]link[/link] as a reference.
This information is inaccurate. I was on the design team for Kangke’s SK line of engines, as well as several other well known brands.
The reason for cylinder taper IS to compensate for temperature differences from the top to the bottom during normal operating conditions, and almost all air cooled engines do this. The Lycoming IO-360 in my real plane uses taper.
Interference fit engines use more taper than ringed engine to keep piston to wall clearance tighter at the top to assist in sealing near TDC.
The reason an engine that runs too lean will over heat and die is because the piston does expand more than the cylinder, and it’s easy to tell. If the engine dies from lack of lubrication there will be score lines on the thrust surfaces on the piston, if it’s from an over heat, the score lines will be on the wrist pin boss sides.
Cylinder head temps are normally between 215 – 250 degrees but it’s not uncommon for the head of the piston to reach 325 – 350 during normal operation.
The single most common cause of rod or crank pin failure during break-in is 4-stroking, after that it’s a too lean over-heat seize. Many engines use what is know as “piston porting “to control the charge entering the crankcase intake port, or to the cylinder ports to keep a constant exchange of vapor under the piston head, this promotes cooling. Without this porting “pocketing occurs under the piston head resulting in very poor cooling. There are a growing number of engines on the market that do not recommend 4-stroking during break-in. We at SK recommend that you richen the mixture until it just starts to 4-stroke then lean it out until it just cleans up to a 2-stroke mode and start there. But follow the instructions that come with your engine, the factory usually knows what works best.

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