Topic: tappets too tight after rebuild

[jonclegg]

Hey guys, first off for all the help during this rebuild. I'm on the home stretch but am having one last problem. I got my cam cover on and went to adjust the valves. The problem is I can't get both the tappets on cylinder 1 or 4 loose with the points at T 1-4. I _can_ get them loose with T 2-3.

This tells me somehow I messed up aligning the cam notch on the right when putting the engine at TDC, but I'm pretty sure I didn't, what could I have messed up here?

-Jon

[jonclegg]

Forgot to add, this is a 78 cb550

[dave500]

remove the cover and check your timing is set correctly,so long as the cam is timed correctly just rotate the engine 360 degrees back to the 1/4 mark and look again.

[jonclegg]

I'm afraid i've done that. 1-4 won't make 1 or 4 loose, only 2-3 does..

[dave500]

remove the cover and recheck your cam timing,if the timing is correct back the adjusters out more.

[jonclegg]

The adjusters all completely backed out.. I'm 99% sure I did it correctly, just wondering if there is some common way to get it wrong.

[dave500]

have the rockers fouled on the valve stems?99% aint good enough,check your cam timing again.

[mcswny]

Sometimes, for me if at T 1-4 and 1 is tight and 1 is loose you need to rotate 360 degrees. And sometimes I need to rotate 360 degrees twice. Not 100 % sure why?

Also, wouldn't it just be easier to adjust your valves while your cam cover is off?


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[iron_worker]

If your adjusters are backed all the way out, you're on TDC 1-4, and you still don't have lash on *any* valve for 1 or 4 (should be able to adjust both valves of 1 cylinder ... then rotate 360 and do the other cylinder's valves) means you aren't on the base circle of the cam.

Check your cam timing again.

IW

[Tugboat]

On a 550 the rockers are in the head cover, so you have to have it in place to adjust your valves.

[mcswny]

On a 550 the rockers are in the head cover, so you have to have it in place to adjust your valves.

Ohhhh didn't know that Tugboat. Only worked on my 750.




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[Dave Voss]

Did you use the rubber band trick to make sure all of the followers were up and out of the way when you reinstalled the cam cover?  You don't actually *have* to use rubber bands, but the important point is that none of the followers bind against the tips of the valve stems while the cover is being secured, or they can become trapped and damaged.  Look through each of the eight valve adjusting holes to make sure, if any are out of position, remove the cover and carefully inspect for damage.

The camshaft being out of time with the crankshaft would make the most sense, and if it is then there should be a spot somewhere in the rotation of the engine where both valves are loose.  If so, this may confirm that the timing is off.  If not, then something else is not right.  You mentioned 'rebuild' but did not elaborate, any chance the cylinder head received an aggressive valve job, and the valves are now seated too deep in the head, eliminating the normal space utilized to set the valve clearances?  This is not a common occurrence, but it is possible.

[dave500]

post a photo of the cam notch when the crank is set at 1/4 T.

[Don R]

The crank turns two times for each rotation of the cam, go around to 1/4 again, it should be loose.  This is where the wasted spark fires.

[jonclegg]

Pulled the cover off, turns out I didn't have the notch as even to the right as I thought. It's actually obvious if you look at the lobs for #4, they should both be totally down, mine were not. I think at the time I was so happy to get the freakin chain on the sprocket I figured it was close enough.

Put it back together and adjusted the valves, seems ok.

-Jon

[Duanob]

Pulled the cover off, turns out I didn't have the notch as even to the right as I thought. It's actually obvious if you look at the lobs for #4, they should both be totally down, mine were not. I think at the time I was so happy to get the freakin chain on the sprocket I figured it was close enough.

Put it back together and adjusted the valves, seems ok.

-Jon

Unfortunately that picture in the manual seems off 180 degrees. The number 1 cam lobes should be pointing down when the piston is at TDC, not up.

When I timed my cam, I had everything set, had the cam in the right place and the #1 piston in the right place at TDC but the cam notch was on pointing towards the rear of the engine ( to the left) not the front (to the right) like in the pic. Try aligning the cam notch towards the rear deck and make sure its aligned perfect.



Too late now that you took the cover off but to verify what I'm saying, set the timing mark on the 2&3 cyls and check the 1&4 tappets, they will be probably be loose. Just a weird thing about the manual.

[Don R]

Did it turn over smoothly while the cam was out of time?  It could bend valves.

[jonclegg]

It turns over ok, it's certainly has more resistance since the rebuild, I'm hoping that's the recut valves, new rings and head gasket. How would I know if I messed up the valves?

[Don R]

If you turned it by hand and didn't feel it catch then turn, it's most likely Ok. If you spun the starter a compression test might tell you.