Need help understanding cam

[section1]

So I am working on my JM Star 150 scooter and part of the upgrade was a new head and cam shaft. The old cam and piece that holds it on has some sort of thing that has a small lobe that triggers a spring loaded object. I have no idea what it could be or do. At first I didn't think anything about it but now I'm starting to worry it might be important. The new cam shaft does not have this piece on it.

I haven't ran the engine yet as I still need to get the carb and exhaust back on it.

Here is a pic of the cam. That small disk with a small lobe will turn but stops at a certain place. Any idea what it does would help. It's at the top of the picture if it posts right.

[jeff84]

I believe what that does is hold the valve open slightly to lower the compression a bit so its not so hard to crank over during starting. I could be wrong about that though.

[section1]

I don't know either but that would make since. I hadn't though of that. It should be running this weekend so I hope whatever it did wasn't important.

[snaker]

That is a anti-kickback or anti-backfire mechanism .The movable part jams into that knob if the engine is spun backwards. Not needed, just remove all associated parts.
It has nothing to do with decompression .

[snaker]

On second thought you may have to consider how the parts are installed. I cant recall from memory what it looks like. I found one picture that is hard to see but might have the bracket installed on one or both rocker arm shafts. If you remove you might have too much side play with the rockers.

Can you post a photo of the bracket installation?

[section1]

This is a picture of the rocker arm. That cam lobe thing hits the spring loaded thing on the rocker arm assembly. It would lift it up and the cam turns but it doesn't seem to do anything I can see. I took this pic form a Google search and all rights to whatever legal stuff is theirs but it's just like the one on my scoot. I just didn't want to run out in the dark and pull the valve cover off to get a picture.

[section1]

I did finally find that it is a gy6 camshaft stopper plate. I'm still looking to see just what it does or if it's needed. It doesn't look like it could stop much of anything from where it's located.

[section1]

This is the piece on the rocker assembly that the cam shaft hits.

[snaker]

Yea that plate maybe should stay in place to keep the rocker side play in check.
You could remove any part attached to the plate if it would be in the way or possibly just leave it in place if it isn't going to cause a problem.

What parts above the piston are in your new kit and what is existing?

[section1]

That plate isn't in the way of anything and without the stock cam with that lobe at the end it is just there doing nothing.

It's basically all new, I bought the 61mm drop-in cylinder with piston and the 61mm head. I had the A9 cam that was sent to me by mistake, I had ordered it for my 49cc engine a while back, so I installed that. The rocker assembly is stock. I installed a new valve cover because I thought I needed it to remove the smog stuff but I don't think that was even necessary but I already had it.

I was looking at that lobe thing at the end will only turn one direction, if I try to turn it the other way it locks. I just want to make sure I can run the engine with that A9 cam or if I need to put the stock cam back in. I really don't want to trash this engine by making a mistake and running it if it has to be there and does something important. I'm kinda thinking about taking the new cam out and just using the stock cam as I really can't afford to but everything again.

[section1]

So quick update, I have been running the cam without the added part and I haven't had any problems. With it being so cold here lately I haven't put a lot of miles on it but I have had the scooter out many times and it had run well.

[honda4life]

Compression relief valve relieves stress on the starter when cranking over.