rephase rebuild strangeness

Shakey

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So I'm doing the last bits of my 277 rebuild, specifically fitting the Pamco unit and wanted to 'walk it through' a couple of turns to make sure that all was well. During the build I had set the cam with the left side at TDC and sure enough on the walk through, all looked fine on that side - inlet valve opening as piston descends, closes before the compression stroke, both as per original (checked with a degree wheel).
Here's the weirdness: on the right side, TDC seems to be 277 degrees (all good) but the valve action seems all wrong. Inlet valve opens with the corresponding piston around BDC and stays open as that piston rises on its 'compression' stroke. As it reaches TDC (with me inching the crank round with a wrench) it 'jumps' past TDC on its own. Consequently while ther is goos compression on the left side, there is not on the right.
It's doing my head in and I am beginning to wonder if I put the cam in the wrong way round (is that possible?) or even if the cam was not rephased correctly??
Anyone out there make head or tail of this??
 
cam can go in backwards the threaded side is on the right side.
if so just pull out the cam chain adjuster and lift up the cam a little pull the bearings off one end then pull chain up off the sprocket and pull the cam out to one side then put back in no harm done
 
Yup got the threads on the right cos that's what the advance unit castellated nut attaches to isn't it?
 
Something does sound real weird.

Cams have a certain amount of 'overlap' where the intake and exhaust valve are open at the same time but it's not much on a street engine. The exhaust valve should just barely begin to open just past BDC on the power stroke, remain open as the piston rises on the exhaust stroke, near TDC on the exhaust stroke the exhaust valve should be closing and the intake valve should just barely begin to open, and it should continue to open as the piston drops in the cylinder on the intake stroke.

It almost sounds as though your intake and exhaust lobes are backwards, I don't think that's even possible. Are the rocker arms on the correct lobe for their valves? IIRC the intake valve rocker should be on the inside lobe on the right bank. But if it's not damn if I know why it would be wrong.
 
Sounds like the cam doesn't match your crankshaft. There are two ways to do the crank, rotate the right side three splines to the left, or rotate it three splines to the right. It works the same either way but the cam has to be rotated the same way for it to match up.

If you turn the crank 83 degrees one way and turn the cam 83 degrees the opposite way, it'll be 166 degrees out of time. The intake will open either 22 or 50 degree before BDC, and close at a respective 82 or 54 degrees after TDC.

It sounds like this is your issue. To fix it, you need to either replace the cam with one that matches the crank, or pull the crank out and re-phase it to match the cam.
 
If its "jumping" past TDC it sounds to me as though the cam chain is jumping a tooth..?? Have you checked chain tension & installed a new chain..??
If the cam is installed correctly - advance to the RHS & No #1 cylinder & valve train is timed correctly with a degree wheel - it looks at though your cam has been assembled incorrectly.
What cam is it...??? Some are weld together & some are bolt together, it is possible they are misalligned.

Or what MrRiggs said above.....
 
Thanks for the responses. 1974 I will double check I've got the rocker arms on correctly
Mrriggs I'll check valve events on the degree wheel and see if it matches either of the scenarios you suggest.
Hotdog it doesn't feel like its jump
 
If one or the other is wrong cam or crank.
mrriggs says "It works the same either way but the cam has to be rotated the same way for it to match up.To fix it, you need to either replace the cam with one that matches the crank, or pull the crank out and re-phase it to match the cam. "
it seem to me the part that has to be fixed has to match up with the pamco firing sequence. but maybe just swaping the wires around will work. just a thought Im not sure still tryin to wrap my head around this
 
carbon, im pretty sure the pamco can be set up either way. So if it proves to be a reverse twist, then fix it the cheapest way. Can you get whoever did the work to sort it? Or did you order the cam and do the crank yourself? :)

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killer pete! its good that you put in the homework and make such a varsatile product.
well then yamamans advice sounds good to me.
I must add that I sure feel bad for You:(Bro
 
Bizarrely my post from earlier is only half of what I wrote?!
The crank and cam were done by Jerry at Heiden tuning as a pair, so should be ok. I also sourced the Pamco and a bunch of other stuff from him. I have emailed him to get his take on it and haven't heard back yet. I did have another thought: in Jerry's instructions for installing the Pamco (that he put in with the box of goodies), he suggested getting the right piston up to TDC, then removing the advance rod locating pin and installing the pamco rotor. When I set up the cam and joined the chain, I set the notch at 12 0'clock with the left piston at TDC (as per most of the posts here). Maybe I should have set the cam up to the right cylinder? I wonder if that might cause my symptoms.
I have an idea that I could try and set up three cameras (well, a camera, an ipod and a phone) to record inlet valves, exhaust valves and degree disc through a couple of revolutions, then splice the three together as a movie and post that up on the 'tube with a link. That way you can all see what's going on. I'll see if I have time. If I can solve this with the minimum of unbuttoning that would be good
 
If Heiden built them - you would guess they are correct & something you have done upon installation..??
 
I have to agree. If they did both parts it would be pretty hard to get it wrong. But ya never know... that's why pencils have erasers.
 
Don't know how useful this'll be... I had wanted to get all three camera angles in one frame but couldn't make imovie do it!. So first is the inlet valves with degree wheel and then exhaust. You'll see it turns back against spring pressure at one point (and I drop the wrench at another!). Anyway, here's the evidence...
 
You have labelled your inlet & exhaust movies incorrectly. Silly question - you are not looking at exhaust valves when you should be looking at the inlet valves are you..?? I mean, you havnt got yourself all mixed up with what valves should be opening & are actually looking at the inlet valves when you should be looking at the exhaust...???
 
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