Hello, why do you need to store your car with the piston at the bottom and how do you do this? I usually just put 3-4 drops of after-run oil in the carb and pull it over a few times. I have heard this mentioned a few times and thought I better ask. Thanks.
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piston down?
- Thread starter smokin al
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greenwing7
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It's called BDC (bottom dead center). You will see the orientation of the piston of TDC (top dead center) and BDC periodically on these forums. Just letting you know what to look for if you want more of an explanation. To know where BDC is, pull the glow plug, look down the hole as you rotate the crankshaft. When the piston gets to the bottom of the stroke, that's BDC. Then, mark the flywheel so you can tell where BDC is without pulling the plug.
In theory, putting the piston at BDC every time you shut the engine down prolongs the life of the piston/sleeve significantly. There aren't any rings in these engines like normal 2-cycle weed eater engines. The combustion chamber is sealed by a gentle taper in the piston sleeve. As the piston goes up, the sleeve actually pinches it when the engine is cold.
If you had a micrometer, you could measure the inner diameter of the sleeve at the bottom and the inner diameter of the sleeve at the top to see that at the top, it's smaller. Not much, but measurable.
When the engine is in the range of normal operating temperatures (210F-270F), the sleeve expands just enough to not bind on the piston as it goes up and down. When cold, you can (or should) be able to feel the bind by taking the glow plug out and rotating the shaft by hand or slowly with the pull start. As it goes up, it gets harder to rotate. This is what's known as "pinch". When there isn't any pinch when the engine is cold (room temp), the engine is due for a rebuild or a re-pinching. Sometimes though, even though there isn't any pinch left, they still run for awhile.
Hope I didn't bore the crap out of you...
In theory, putting the piston at BDC every time you shut the engine down prolongs the life of the piston/sleeve significantly. There aren't any rings in these engines like normal 2-cycle weed eater engines. The combustion chamber is sealed by a gentle taper in the piston sleeve. As the piston goes up, the sleeve actually pinches it when the engine is cold.
If you had a micrometer, you could measure the inner diameter of the sleeve at the bottom and the inner diameter of the sleeve at the top to see that at the top, it's smaller. Not much, but measurable.
When the engine is in the range of normal operating temperatures (210F-270F), the sleeve expands just enough to not bind on the piston as it goes up and down. When cold, you can (or should) be able to feel the bind by taking the glow plug out and rotating the shaft by hand or slowly with the pull start. As it goes up, it gets harder to rotate. This is what's known as "pinch". When there isn't any pinch when the engine is cold (room temp), the engine is due for a rebuild or a re-pinching. Sometimes though, even though there isn't any pinch left, they still run for awhile.
Hope I didn't bore the crap out of you...
Yep. I would assume so. Maybe you can try marking the side of the flywheel instead of the knurled part?
MustangMan
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You can mark the flywheel anywhere you want as long as YOU know it's BDC. On my RS4 and MT2 with Rotostart I have it marked on the knurl of the flywheel so you can see it dead center in the deck's window.
On my Savage I have it marked on the knurl of the flywheel so that when the piston is at BDC the mark is straight up at 12 o'clock where I can easily see it.
Marking it on the side would work too if your starter box rubs it off. A Sharpie works great. Even had an "HPI Purple" Sharpie so it matches...
On my Savage I have it marked on the knurl of the flywheel so that when the piston is at BDC the mark is straight up at 12 o'clock where I can easily see it.
Marking it on the side would work too if your starter box rubs it off. A Sharpie works great. Even had an "HPI Purple" Sharpie so it matches...
Only useless if you do it like that. Next time, mark the front of the flywheel where it can be easily seen. Don't worry, I did the same thing when I first started.Bouzouki said:
BTW, make sure you put a stripe across the back of your lid. Any neon color tape will do. Doesn't have to be permanent. It'll serve as a warning to the others running with ya. It'll be taken off when your "rookie" status is waived. LOL
c3racing0082
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Diver6127 said:Only useless if you do it like that. Next time, mark the front of the flywheel where it can be easily seen. Don't worry, I did the same thing when I first started.
BTW, make sure you put a stripe across the back of your lid. Any neon color tape will do. Doesn't have to be permanent. It'll serve as a warning to the others running with ya. It'll be taken off when your "rookie" status is waived. LOL
LMAO: There should be a law were rookie 1:1 vehicle drivers has to have bright yellow stripes on there vehicle
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Diver6127 said:BTW, make sure you put a stripe across the back of your lid. Any neon color tape will do. Doesn't have to be permanent. It'll serve as a warning to the others running with ya. It'll be taken off when your "rookie" status is waived. LOL
Did you do this when you were a "Rookie"? And from what I hear you should probably still be wearing a neon stripe. Are you not one of the Malachi bros?
Also what did that actually have to do with marking bdc?
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Dude, sometimes I think you take yourself just a little too seriously, lol.
BTW, you still never said what that had to do with setting the engine at bdc????
BTW, you still never said what that had to do with setting the engine at bdc????
rocknbil
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smokin al said:
They're all correct but it's not that difficult. Rotate the flywheel till you feel resistance from compression, then go halfway back from there.
What gets my attention 3-4 drops of ARO: that is only useful if that's all your crankcase holds.
The reason you use ARO is to displace any alcohol that is left remaining in your engine, because alcohol condenses water from the air and can cause rust to form on your engine internals. The idea is to completely flush out any leftover fuel deposits and you can't do that with a few drops. I use at least a half teaspoon.
More from OS engines site.
I used to use an eye/ear dropper. Glass tube with rubber squeeze bulb. i would suck up about 1 inch of after run oil for my Fanton FR15 and DTX .18, and squirt into the carb opening. I would pick the car up and roll it side to side and forward and back. Then would use my roto start to get it through the engine. I knew it was through when I had red oil on my towel under the stinger. then took a piece of paper towel, rolled it, and stuck it up it's stinger. (ouch) Just my 
AAAAAAh, it was in response as to where to put the mark on the flywheel. Bouzouki said it wasn't worth "doing" since the mark always got rubbed off. He put it on the knurled part instead of the front part that doesn't contact the starting wheel. Hence, the "rookie stripe."NCNitro said:
Pinblaster
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I have a mark on the end of the crank shaft on my losi xxx-nt, Marking the flywheel is good until you have to take it off or if it slips from not being tight enough. It's not likely that you will get it back on in the same position. The tip of the crank shaft never changes orientation to the piston location. Just put a half mark across the tip so you know which side is up or down.
I use RoknBil's method.....that way you don't futz around w/ which end is where.....you just feel it