i am looking to do a valve adjustment and when I remove the cover to access the marks for TDC, it looks as if they are home made. All the YouTube videos, shop manuals and forums show what looks to be a different stator with a plate having both the TDC and firing marks. I am not sure if I should trust what looks to be home made marks? Why does this look different than all the other pics, do I need to remove the bronze color disk also (not mentioned anywhere)? Also when rotating to turn the engine the nut seems loose and unscrews when you turn it counter clockwise? Thanks for any tips and pointers as to what I have.
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TDC on '78 Special
- Thread starter Duck749
- Start date
You have an aftermarket PMA. The reference material you are drawing from is for the stock/OEM. First you will need to torque the nut back down. Then with a straw or wooden dowel find TDC and see what marks corespond to that. You shouldn't need to remove the rotor(bronze colored disc).
peterg
XS650 Addict
I found this video helpful for valve adjustments. It doesn't require that you find TDC.
mike in idaho
XS650 Addict
Easy way to do it is to roll the engine over until one of the exhaust valves is all the way down(open) and adjust the valve on the other side( it will be on the camshaft base circle). With that valve adjusted, turn the engine over until that valve is all the way down and adjust the other side. Move to the intake side and repeat. That's how we did it on the Britt twins, works on any engine with a 360° crank.
You might want to check just where TDC is by checking piston position. As I recall that mark lined up with the notch is the max advance mark. If it is, then TDC will line over toward the right where that flat area above the notch comes to the circle where the cover goes on. And idle timing will be about 1/4 to 3/8 inch to the left of TDC.
It all depends on how the person making those marks set it up. Have you tried contacting the person who did the install and set up to ask what the marks mean?
Doing a bit of research on PMA installs on these bikes May help you understand the timing marks.
Leo
It all depends on how the person making those marks set it up. Have you tried contacting the person who did the install and set up to ask what the marks mean?
Doing a bit of research on PMA installs on these bikes May help you understand the timing marks.
Leo
i am looking to do a valve adjustment and when I remove the cover to access the marks for TDC, it looks as if they are home made. All the YouTube videos, shop manuals and forums show what looks to be a different stator with a plate having both the TDC and firing marks. I am not sure if I should trust what looks to be home made marks? Why does this look different than all the other pics, do I need to remove the bronze color disk also (not mentioned anywhere)? Also when rotating to turn the engine the nut seems loose and unscrews when you turn it counter clockwise? Thanks for any tips and pointers as to what I have.
Hi Duck and welcome,
Like they said, your bike looks different to the book diagrams because it's stock alternator has been swapped for a PMA.
And that's just the start of your electrical adventure.
Most likely the dreaded PO has also swapped the points for a Pamco system (which is a good thing if it's done right)
and may even have ditched the battery in favour of a capacitor (always a bad thing, regardless)
