Topic: Top end rebuild on a cb550, and now bike will not go over 45mph...?

[dergs713]

Hey guys, recently did a top end replacement on my bike due to abnormal wear on my cam chain and head. After doin a valve job and replacing the cam, gear, head, etc. I have now ran into a jam...

 With the same carb setup, same exhaust, and same timing I am now not able to get high into the rpms. And top out at around 45 mph...

Weird I know... but something isn't right. The only thing I can think of is that the cam chain might be a link off on the cam gear....? I don't know if this would do that. Please help, i am suppose to go on a run this weekend for a good cause. I'm lost.

Matt

[Bootlegger56]

I put mine back together one tooth off when I changed to a 650 cam and caught it before I put the valve cover back on.  If you think your off a tooth why not pop the valve cover set the engine at TDC and check the position of the slot in the cam.  Just my thinking.

[alacrity]

Does the 650 cam slot line up differently in the 550 head than the 550 cam?  does it need to be "degreed"?

[dergs713]

I noticed that the tdc mark was a lil off when I had the notch of the cam lined up. That tooth was as close as I could get it. Would this cause an issue like this. I'm just kinda lost where the problems coming from. It's also a stock cam. Thanks for the replies guys. I can take it apart and move it over, but I don't even know if this would cause a prob like this.
Matt

[dergs713]

Bump

[crazypj]

two things,
1. cam timing out
2.  possibly bent valves if you didn't hold up rocker arms when installing cover

[dergs713]

I did end up doing the rubberband trick w the rocker arms. So they were held up ok.

As for the cam timin I guess I might be a tooth off...? Would it still idle and run the way it does. I thought it had to be right on otherwise it wouldn't work at all...

Matt

[dergs713]

Here's where I'm at. Please tell me if this looks wrong to you guys.
Matt

[crazypj]

Cam timing is out.
You need to line up T 1.4, your picture is full advance for ignition timing 

[goldarrow]

+1 on the cam timing.  when notches are lined up to the engine, you should also see both cam sprocket bolts clearly.  in your pic, only one is visible.

[bryanj]

Cam is right, you only see both bolts on the 750, on the 500 you have to rotate the engine to do up the second bolt.

Crank however is WRONG, as said above those are the fully advance mark you need the single vertical line adjacent to the "T" NOT THE ONE NEXT TO THE "F"

[dergs713]

Thanks guys that solved my issue. Bike runs strong. On to another issue now... Getting a tap out of what sound to be the fourth cylinder. Hope a valve arm adjustment might help.

Matt

[Duanob]

+1 on the cam timing.  when notches are lined up to the engine, you should also see both cam sprocket bolts clearly.  in your pic, only one is visible.

I don't that's correct on the 550. I remember thinking why didn't they do it that way? it would be easier to install the cam chain sprcket.

OP:  yeah, cam timing is out one tooth. Put your timing mark on the T1/4 then make sure your cam mark is lined up with the deck. You can loosen the cam sprocket and tensioner and inch-worm the chain around the sprocket easy enough.

[dergs713]

Can't really seem to find out where the tapping is coming from. Used a stethoscope to try to find the noise but nothing really stood out...
Matt

[bryanj]

Check the exhaust are tight, many people spent hours chasing a noisy tappet to find a slightly blowing gasket in the exhaust port

[dergs713]

Ended up being an exhaust leak. Cracked pipe.
Matt