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Post by Goosey on Jul 16, 2010 21:02:34 GMT -5
I got the A9 cam and when I was comparing it to the stock from my old engine I noticed this.  It looks like the tab on the CAM hits the tab on the part with the spring.  The A9 doesn't have that section, and I was looking around and noticed that most of the valve pictures don't show that part either. Some, but not all. Just wondered what it is, what purpose does it serve, and is there any problem without it. |
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Post by Fox on Jul 16, 2010 22:57:23 GMT -5
I've never seen one of those before. (The stock one)
Something to do with the lubrication of the rocker assy. ? :stars:
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Post by Fox on Jul 16, 2010 22:59:32 GMT -5
It triggers something. Do the tabs meet at TDC or just before?
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Post by Goosey on Jul 17, 2010 0:55:58 GMT -5
Hmm, I'll have to check that out tommorow, but I think it's just past the bottom, not top. It's kind of an odd thing, doesn't connect to anything else. Comes off with the valves. The tab on the CAM hits the little lever which springs back and clicks. I hadn't noticed it before, when I did the valves in either scooter, so don't know if it's in the other 2 engines. I hadn't planned to install the CAM till I needed to get to the valves, as you know a complete PITA to get to. Here's how it looks from the other side.  |
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Post by 90GTVert on Jul 17, 2010 3:07:46 GMT -5
It's a stopper plate that would prevent the engine from rotating in reverse. Take a look and you will see that if you rotate the cam one way the lever will move and the spring will make sure it returns. If you rotate it the other way it will just stop. I don't see how it's necessary. All stock 150s don't have them.
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Post by 190mech on Jul 17, 2010 5:36:54 GMT -5
That kinda looks like an automatic compression release,a lot of small engines use them to ease starting,dont know if that is so in this case though.. :stumped:
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Post by 90GTVert on Jul 17, 2010 8:09:49 GMT -5
How could it release compression? It doesn't look like it affect anything that I can see. Wouldn't a compression release open a valve partially or something?
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Post by Goosey on Jul 17, 2010 8:55:59 GMT -5
Yea, it would keep the CAM from rotating backwards now that you mention it. The spring mechanism lets it roll past one way only. I know it isn't shown in the Arrow 150cc manual, and not in very many shots of valve adjustments on youtube. So why would an engine rotate backwards, that it needs preventing? Thanks, I think you solved the mystery and I will not worry about using that A9 now  |
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Post by 90GTVert on Jul 17, 2010 10:46:34 GMT -5
I guess these engines could be started in reverse? If you install the A9 and take off backwards, you must have needed it! lol
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Post by Fox on Jul 17, 2010 11:16:08 GMT -5
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Post by stepthrutuner on Jul 17, 2010 18:03:43 GMT -5
Most curious, Grasshopper.
"Because a man can see, he does not look." — Master Po
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Post by 90GTVert on Jul 17, 2010 18:42:34 GMT -5
BTW, can we add these smileys to the fold Brent?    I added 2 of those. Sorry, but I left the one out. Someone would end up getting their feelings hurt with that one. Trying to keep that stuff outta here. Don't forget the "::" around smiley words ( :word: ). :twisted: = twisted :tongue: = tongue |
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Post by 190mech on Jul 17, 2010 20:25:12 GMT -5
Thought I saw a tab going to the rocker arm,but now I see its a 'stand alone item'.Some engines will burp and run backwards on shut down,makes the cam chain and tensioner do stipid things running backward!Its likely a "perfect solution to a non existant problem"!!
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Post by Goosey on Jul 17, 2010 21:01:04 GMT -5
:idea: :rofl: Good answer  |
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Post by stepthrutuner on Jul 17, 2010 22:20:03 GMT -5
Thought I saw a tab going to the rocker arm,but now I see its a 'stand alone item'.Some engines will burp and run backwards on shut down,makes the cam chain and tensioner do stipid things running backward!Its likely a "perfect solution to a non existant problem"!! That sounds like a plausible explanation. It's just kind of hard for me to imagine a single cylinder 4t trying to run backwards on shutdown. Now if timing events were to be out of whack it's not too hard to imagine. Overheating issues could possibly cause a buck-back I suppose? |
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