KentMoney
XS650 Addict
So I recently buttoned up my 1981 rephased engine and had it in the chasis with the throttle hooked up, etc.. I rigged up the ignition to see if I could get it to start for the first time and I ran into problems. I was trying to kick start it and I would get some backfiring, but never could get the engine running.
I am using a Pamco and it is my understanding that there is like 16 different possible configurations for the 277 rephase. I set it up in the one that seemed correct and the aforementioned backfiring occurred. So, instead of just trying a different firing configuration (like I should have) I assumed that I probably had my cam timing wrong. So I took out the engine and set up the following:
I managed to jimmy rig a piston stop, got a dial indicator from harbor freight, printed out a degree wheel and slapped it on some cardboard.
Please tell me if I did this correctly:
Determining true TDC
First I placed the left side piston to somewhere BTDC and then screwed in the piston stop. I slowly rotated it CCW until the piston hit the stop. At this point I set the degree wheel to 0 with the pointer. Then I unscrewed the piston stop, moved the piston to somewhere ATDC, and screwed the piston stop back in. I slowly rotated the crankshaft CW until the piston lightly hit the stop, and took the measurement on the degree wheel. I then divided the difference in half and determined where true TDC was. I marked a reference point.
Determing Valve Timing (is this degreeing in a cam?)
Then I set the valve lash to .012 and made sure the cam tensioner was flush. I set up the dial indicator to detect when the valve started opening. With the refrence point I marked I found true TDC and set the degree wheel to 0. I rotated the crank CW and found that the valve started opening at ~35 degrees BTDC.
So, to me it appears that my cam timing is correct? The Clymer manual says it should open 47 degrees BTDC and apparently the factory owners manual says it should open at 36 degrees BTDC. Which should it be?
If this is the case, then I probably hooked up my ignition incorrectly?
I am using a Pamco and it is my understanding that there is like 16 different possible configurations for the 277 rephase. I set it up in the one that seemed correct and the aforementioned backfiring occurred. So, instead of just trying a different firing configuration (like I should have) I assumed that I probably had my cam timing wrong. So I took out the engine and set up the following:
I managed to jimmy rig a piston stop, got a dial indicator from harbor freight, printed out a degree wheel and slapped it on some cardboard.
Please tell me if I did this correctly:
Determining true TDC
First I placed the left side piston to somewhere BTDC and then screwed in the piston stop. I slowly rotated it CCW until the piston hit the stop. At this point I set the degree wheel to 0 with the pointer. Then I unscrewed the piston stop, moved the piston to somewhere ATDC, and screwed the piston stop back in. I slowly rotated the crankshaft CW until the piston lightly hit the stop, and took the measurement on the degree wheel. I then divided the difference in half and determined where true TDC was. I marked a reference point.
Determing Valve Timing (is this degreeing in a cam?)
Then I set the valve lash to .012 and made sure the cam tensioner was flush. I set up the dial indicator to detect when the valve started opening. With the refrence point I marked I found true TDC and set the degree wheel to 0. I rotated the crank CW and found that the valve started opening at ~35 degrees BTDC.
So, to me it appears that my cam timing is correct? The Clymer manual says it should open 47 degrees BTDC and apparently the factory owners manual says it should open at 36 degrees BTDC. Which should it be?
If this is the case, then I probably hooked up my ignition incorrectly?
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