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Post by carasdad on Jan 18, 2014 21:34:25 GMT -5
One thing I have not seen anyone post about here are commonly mismatched parts.. The number one most common one I see on folks Scoots are replacement pistons that are not correct for the cylinder. I have though seen posts and incidents in person where someone orders a new piston and performance degrades from even worse than the worn original piston and rings. It seems we fail to remember that the piston ports must match the cylinder they are going in. Below are a few pics of different style pistons. Take note of how large and how small the piston ports are..how high up or low down they are from the piston skirt. If they don't match the cylinders porting..performance degradation will occur. The last pic shown here is of a new Athena Aluminum 2 ring cylinder kit I have. Note not only how small the cylinder port is in comparison to most kits..but look at the piston port. It is only a notch at the bottom of the piston and not 2 elongated holes in the piston like many kits. I myself have simply bought new piston kits..tossed them in..then wondered why it was hard to tune and performance stunk.. Now I match the old piston to the replacement one before ordering and have found the performance was back to its original power output. Just some food for thought..something to ponder..and a chance for you 2T gurus here that build some of these monster machines we see on this site..to possibly explain and enlighten us regarding this vast array of piston designs we see..and how each affects us. So please input as much as possible. I think this has been an overlooked and never discussed issue with our Scoots.. Thanks, Glenn P.S. I don't have a photo account anywhere to post the pics from..so here is a link to my post with pics on another forum.. 49ccscoot.proboards.com/thread/7886/commonly-mismatched-parts |
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Post by ramblinman on Jan 19, 2014 6:51:36 GMT -5
my 50mm bbk doesn't perform as well as i would like. i just lack the knowledge and experience to gain more power out of a 50cc. i do my best just to keep the thing running.  little tip for you. if you right click the pic you want to post, then click copy image url. goto your post, move your cursor over the box titled insert image. click that box and right click/paste in the image url. hope i explained that well enough. you do it once and then it's easy. |
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Post by carasdad on Jan 19, 2014 10:51:27 GMT -5
Slow down on all the replies..I can't keep up..lol All these views but not any input..so maybe I worded it wrong? Or possibly it is common knowledge and I am just a late bloomer?..  |
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Post by urbanmadness on Jan 19, 2014 13:24:59 GMT -5
The thing to remember is that port size, placement and shape work like a cam on a four stroke. It's going to control duration, and timing for intake and exhaust scavenging. The piston has to work with the ports since it's like the valves on a four stroke. The piston opens and closes those ports. A lot of the work done with the head and cam on a four stroke is done with the piston and cylinder ports. 2 strokes are simple and complex at the same time!...
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Post by carasdad on Jan 19, 2014 15:08:44 GMT -5
The thing to remember is that port size, placement and shape work like a cam on a four stroke. It's going to control duration, and timing for intake and exhaust scavenging. The piston has to work with the ports since it's like the valves on a four stroke. The piston opens and closes those ports. A lot of the work done with the head and cam on a four stroke is done with the piston and cylinder ports. 2 strokes are simple and complex at the same time!... Bingo Sir. Exactly what I was getting at. Each of these pistons are one on Ebay and from Vendors here that folks buy. But since each one is so different..I can now see why their new rebuild when buying a piston kit..more often than not runs worse that it did with the worn components. I then noted folks just buy any piston kit that is 47mm and install it with the cylinder they have...only to be disappointed. One of my questions by looking at each piston..since they are like 4T cams..is that which would give more top end output..which would give more low end. i.e. the small ports higher in the piston..the long ports in the piston..or lastly the bottom pic where it is not a hole for a port..it is just a notch. Hoping to get some input.. |
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Post by carasdad on Jan 20, 2014 7:34:34 GMT -5
Does this mean this site is only for things like.. "Scoot died won't start".."My battery won't charge".."Will a 34mm carb work on my stock 50 and give better performance".."How do I make a 50cc GY6 go 60 mph?"..and repeated things of that nature.. I was hoping somebody could explain the port differences and what they do..since we know that installing the wrong piston kit has Ill effects on the engine..
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Post by scooter on Aug 23, 2014 9:38:18 GMT -5
Does this mean this site is only for things like.. "Scoot died won't start".."My battery won't charge".."Will a 34mm carb work on my stock 50 and give better performance".."How do I make a 50cc GY6 go 60 mph?"..and repeated things of that nature.. I was hoping somebody could explain the port differences and what they do..since we know that installing the wrong piston kit has Ill effects on the engine.. I am really lost here. Ports on the piston, did you say? Does this diagram address any of your questions?  |
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New Rider
Currently Offline
scooting in michigan...
Posts: 17 
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Joined: Mar 7, 2014 23:09:41 GMT -5
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Post by lanternscooter on Aug 23, 2014 23:25:06 GMT -5
Does this mean this site is only for things like.. "Scoot died won't start".."My battery won't charge".."Will a 34mm carb work on my stock 50 and give better performance".."How do I make a 50cc GY6 go 60 mph?"..and repeated things of that nature.. I was hoping somebody could explain the port differences and what they do..since we know that installing the wrong piston kit has Ill effects on the engine.. I am really lost here. Ports on the piston, did you say? Does this diagram address any of your questions? he is talking about 2t pistons |
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Post by rockynv on Aug 24, 2014 8:37:12 GMT -5
On a simple 2 stoke engine to simply put it the piston is the valve and the cylinder is the valve seat with ports that allow intake and exhaust as the piston passes over them: Cylinder ports:  2 stroke windowed pistons:  2 stroke basic diagram:  More info: www.2-stroke-porting.com/Home.html |
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Post by scooter on Aug 28, 2014 15:49:01 GMT -5
On a simple 2 stoke engine to simply put it the piston is the valve and the cylinder is the valve seat with ports that allow intake and exhaust as the piston passes over them: That's neat. I used to mess around with 2 stroke R/C engines but I don't recall seeing ports on them. |
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Post by rockynv on Aug 28, 2014 21:19:55 GMT -5
On a simple 2 stoke engine to simply put it the piston is the valve and the cylinder is the valve seat with ports that allow intake and exhaust as the piston passes over them: That's neat. I used to mess around with 2 stroke R/C engines but I don't recall seeing ports on them. Here is a Cox .049 cylinder with one of the ports showing:  Really two stroke diesels. |
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Post by scooter on Aug 29, 2014 0:51:44 GMT -5
Here is a Cox .049 cylinder with one of the ports showing: Really two stroke diesels. Yes. Those were fun. I have held them in my hand and cranked them up. A little scary. They have a lot of power in a tiny package. |
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Post by rockynv on Aug 29, 2014 22:46:19 GMT -5
Really two stroke diesels. Yes. Those were fun. I have held them in my hand and cranked them up. A little scary. They have a lot of power in a tiny package. My kid brother does competition flying and machines his own engine mods with a MiniMat machine. Says some of the best engines he's got come from Italy. |
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Post by scooter on Aug 30, 2014 4:35:08 GMT -5
My kid brother does competition flying and machines his own engine mods with a MiniMat machine. Says some of the best engines he's got come from Italy. Nice! I just did it as a hobby but my thing was designing the air frames. I didn't know much about the engines except the basic theory of how they functioned.  Kind of like my scoot. |
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Post by rockynv on Aug 30, 2014 11:10:47 GMT -5
Nice! I just did it as a hobby but my thing was designing the air frames. I didn't know much about the engines except the basic theory of how they functioned. Kind of like my scoot. He does the airframes too and is pretty fast at knocking off practice frames for testing out engine mods or trying out new routines before doing them with his competition show pieces. |
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