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Post by tuttlemon on Jul 8, 2020 12:41:11 GMT -5
When I went to swap out my stock cam in my 150cc Tao: it had a small flap like gear that when I hand spun the system, didn’t seem to do anything really. There was a metal linkage from one rocker arm to the other that the flap would tip and flip some spring loaded mechanisms, but again, didn’t seem like it did anything. Is this part detrimental? Cause my new A-9 cam didn’t have that metal flap like gear.
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Post by CrankingWithCG on Jul 8, 2020 20:56:15 GMT -5
When I went to swap out my stock cam in my 150cc Tao: it had a small flap like gear that when I hand spun the system, didn’t seem to do anything really. There was a metal linkage from one rocker arm to the other that the flap would tip and flip some spring loaded mechanisms, but again, didn’t seem like it did anything. Is this part detrimental? Cause my new A-9 cam didn’t have that metal flap like gear. Can you post a picture of it? |
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Post by tuttlemon on Jul 8, 2020 21:09:31 GMT -5
When I went to swap out my stock cam in my 150cc Tao: it had a small flap like gear that when I hand spun the system, didn’t seem to do anything really. There was a metal linkage from one rocker arm to the other that the flap would tip and flip some spring loaded mechanisms, but again, didn’t seem like it did anything. Is this part detrimental? Cause my new A-9 cam didn’t have that metal flap like gear. Can you post a picture of it?   |
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Post by CrankingWithCG on Jul 9, 2020 0:04:04 GMT -5
Im not sure honestly. I wouldnt try interchanging them, i think it puts the bearings and lobes in different spaces. Maybe look for a A9 that has that extra little nub? Id wait for someone more experienced to comment, but i think theyre not interchangeable
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Post by FrankenMech on Jul 9, 2020 15:24:42 GMT -5
Probably a decompression valve but I don't know for certain.
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Post by dexameth on Jul 9, 2020 15:28:16 GMT -5
That is the anti kick-back stopper. The starter clutches in these engines are subject to a LOT of force when the engine kicks back during a faulty startup and it can damage the rollers. That little thing stops the cam, which is connected to the crankshaft via the timing chain, and it protects the starter clutch. When upgrading to aftermarket cams, most riders will upgrade to a high strength clutch like Ban Jing. |
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Post by dexameth on Jul 10, 2020 8:42:40 GMT -5
Probably a decompression valve but I don't know for certain. My little Honda Elite 110 had this weird cam looking device on the outside of the cam gear... and it was in fact the decompression lever. Makes me wonder why though... as this engine is 149psi compression from factory and GY6 are like 200psi and they don't need the decompression. The mechanism intrigued me so I researched it and it pushed the valve slightly open until the cam starts spinning, then the centrifugal force pulls the cam away and the lever stops functioning. When the engine shuts off, right before the last rotation of the crank, you here what sounds like a few marbles dropping inside the engine. It's the lever returning back to it's functioning position. That freaked me out before I learned what it was! |
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Post by FrankenMech on Jul 10, 2020 10:49:47 GMT -5
Yeah I had heard of such devices and actually played with one on a 750cc race bike but it has been 30 years since I had messed with it. I don't remember much about it. It did seem to be useful to prevent broken legs.
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Post by CrankingWithCG on Jul 10, 2020 23:39:16 GMT -5
I was just messing with my cam I swapped out....it is a decompression system! Ive been researching these for a week now on 450 dirt bikes and such. It's got a little lobe on the rotating part to keep the exhaust valve open longer. I don't think my 155 has that little arm, but man she's a bitch to start. Gotta damm near jump on it on compression. You may be able to run without it? Just make sure the arm doesn't contact anything, and kick it over with the spark plug removed to ensure the lack of that extra little lobe doesn't do anything weird. Your starter may have a hard time though, I know these 150 starters are already pretty bad. If your scoot had it, I'd try to find an A9 with the extra lobe, but it may work as is
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Post by 3strokeengine on Sept 23, 2020 23:17:33 GMT -5
Its a compression relief so if the motor kicks back while start it holds the exhaust valve open on the first compression stroke the next start. Its not there to stop the engine from spinning backwards, it actually relies on that to "set". Gotta watch that bugger when adjusting your valves  |
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