I need help! Pamco timing!

[jgimar]

I am at a loss. Been trying to get my old 77 running smooth and every time we think we’ve got it, something goes south!
Awhile back, my alternator finally gave out and i thought now would be a good time to tear it down and get creative. Most of my work was cosmetic, but we did perform some mods to the function of the bike:
Installed hugh’s pma
Installed a basic pamco
Kicker only(capacitor)
1 1/2 in pipes with torque cones
Pods for air filters.
BS38’s jetted 27.5 pilots, 135 mains, needled clip moved to the top.
Just when we think it’s running smooth, take it out seems to run well, come back and crank it up later, it returns to shit! Backfiring thru the carb, spits and sputters, timing is way off. Cannot figure it out. We have determined TDC, and the only position that it runs remotely marginal now is we have the pamco plate rotated to max advance position. We know this is unacceptable because we are not able to put the right side plate screw in (see attachment).
We just can’t figure it out. One question is, the pamco has no degree marks to set it by. What’s the trick?
Also, when i kick it over, sometimes my counterpart grabs the forks or frame to steady the bike, he gets shocked all to hell and as far as we know we grounded everything electrical.
Totally lost, need help bad! The thing will run but it just won’t run right!

 

[Rasputin]

It sounds very much like you have a HT lead or plug that is grounding out.
If your assistant is getting a shock he/she must be in contact with the HT side of the coil.

 

[jgimar]

It sounds very much like you have a HT lead or plug that is grounding out.
If your assistant is getting a shock he/she must be in contact with the HT side of the coil.

???i mean we have looked at every wire and connection and are baffled. I know i’m grasping at a straw but any suggestions?

 

[jgimar]

???i mean we have looked at every wire and connection and are baffled. I know i’m grasping at a straw but any suggestions?

What about my coil mount. It’s mounted to a bracket we made to fit the frame. Should i buffer that or the bracket with rubber bushings?

 

[5twins]

The Pamco wouldn't have any timing marks on it, they should be down on the alternator. They used to be there on the original but now you have a PMA (PissMoneyAway) so the marks are gone. And timing isn't set at TDC, it should fire about 15° BTDC. Hugh usually supplies a sticker with timing marks for the case. If the Pamco needs to be set fully to one side of it's adjustment slot (or further) to get proper timing, that can be an indication that the timing chain is all stretched out and in need of replacement.

 

[jgimar]

The Pamco wouldn't have any timing marks on it, they should be down on the alternator. They used to be there on the original but now you have a PMA (PissMoneyAway) so the marks are gone. And timing isn't set at TDC, it should fire about 15° BTDC. Hugh usually supplies a sticker with timing marks for the case. If the Pamco needs to be set fully to one side of it's adjustment slot (or further) to get proper timing, that can be an indication that the timing chain is all stretched out and in need of replacement.

The Pamco wouldn't have any timing marks on it, they should be down on the alternator. They used to be there on the original but now you have a PMA (PissMoneyAway) so the marks are gone. And timing isn't set at TDC, it should fire about 15° BTDC. Hugh usually supplies a sticker with timing marks for the case. If the Pamco needs to be set fully to one side of it's adjustment slot (or further) to get proper timing, that can be an indication that the timing chain is all stretched out and in need of replacement.

okay, per the sticker on the pma, currently we can adjust the pamco to get it to fire on the fire mark, but thats with that pamco rotated all the way to the right. it will run in this position but not well. If we rotate the pamco clockwise to a more realistic setting, it’s worse. This is really perplexing. We’ve had that thing running good on two occasions, well enough that i took it out for a spin on the highway and it was running strong. Rode it a couple miles home from where i had it garaged, when i got there, shut it down for a bit, cranked it back up and it went to shit. I am stumped and damn sure don’t look forward to tearing it apart if you think it’s the timing chain. Any further advice or is it time to break out the violin?
Appreciate the help.

 

[5twins]

Well, if the chain is really worn, and it wasn't adjusted properly (set too loose), it's possible it jumped a tooth on the sprockets and now the timing is off. That would account for it suddenly starting to run bad. You can check and see if the cam timing is still correct, that the chain hasn't jumped a tooth on you, with the engine still assembled. There's a locating pin in the cam for the advance unit. At TDC, it should point straight up or down.

It's also possible the advance unit has come loose and shifted from it's correct location. That would throw the timing off too.

 

[Signal]

Are the locating pins in place. The ones that keep the sender unit in the correct position. I only have minimal experiance with Pamco ignitions and sort of remember there are locating pins.
Also is the mechanical advance mechanism in good order.

 

[jgimar]

Well, if the chain is really worn, and it wasn't adjusted properly (set too loose), it's possible it jumped a tooth on the sprockets and now the timing is off. That would account for it suddenly starting to run bad. You can check and see if the cam timing is still correct, that the chain hasn't jumped a tooth on you, with the engine still assembled. There's a locating pin in the cam for the advance unit. At TDC, it should point straight up or down.

It's also possible the advance unit has come loose and shifted from it's correct location. That would throw the timing off too.

One of these days we’ll get this right. And it will from all the great advise i get from especially you, and others. I’ll run it thru the motions and report back.

 

[jgimar]

Are the locating pins in place. The ones that keep the sender unit in the correct position. I only have minimal experiance with Pamco ignitions and sort of remember there are locating pins.
Also is the mechanical advance mechanism in good order.

Thank you along with the others. Add this to the lust of things i need to check. Again than you!

 

[jgimar]

Well, if the chain is really worn, and it wasn't adjusted properly (set too loose), it's possible it jumped a tooth on the sprockets and now the timing is off. That would account for it suddenly starting to run bad. You can check and see if the cam timing is still correct, that the chain hasn't jumped a tooth on you, with the engine still assembled. There's a locating pin in the cam for the advance unit. At TDC, it should point straight up or down.

It's also possible the advance unit has come loose and shifted from it's correct location. That would throw the timing off too.

Just checking, are you talking about the pin in the advance rod or is there another one i need to be aware of?

 

[jgimar]

Well, if the chain is really worn, and it wasn't adjusted properly (set too loose), it's possible it jumped a tooth on the sprockets and now the timing is off. That would account for it suddenly starting to run bad. You can check and see if the cam timing is still correct, that the chain hasn't jumped a tooth on you, with the engine still assembled. There's a locating pin in the cam for the advance unit. At TDC, it should point straight up or down.

It's also possible the advance unit has come loose and shifted from it's correct location. That would throw the timing off too.

Never mind, we figured it out, and the pin was at 6 oclock. So, we should be alright as far as the chain goes.

 

[5twins]

No, not the pin in the advance rod. There is also a pin in the cam that locks the advance unit in place properly timed. There's a notch on the back of the advance unit that locks onto it .....

 

[jgimar]

Never mind, we figured it out, and the pin was at 6 oclock. So, we should be alright as far as the chain goes.

Maybe! With it being at TDC, with the pin in the vertical position, should it be at 12 or 6 or does it matter?

 

[5twins]

Doesn't matter, as long as it points straight up or down. Which position it's in will depend on which cylinder is at TDC on it's compression stroke. If the cam timing was off, with the motor at TDC, the pin would be off to the side, like at 1:00 or 11:00, or at 5:00 or 7:00. If it's pointing down give the engine another full revolution to the TDC mark again and it will now point up.

 

[jgimar]

Doesn't matter, as long as it points straight up or down. Which position it's in will depend on which cylinder is at TDC on it's compression stroke. If the cam timing was off, with the motor at TDC, the pin would be off to the side, like at 1:00 or 11:00, or at 5:00 or 7:00. If it's pointing down give the engine another full revolution to the TDC mark again and it will now point up.

Alright, right now everything checks out. Everything should be as instructed. Lets see what happens!

 

[jgimar]

Okay! Right now sittin still at idle our timing is right on the money. So, i think maybe that problem is taken care of, but still having some backfire problems when i rap it up a bit. Probably still in the pilot jet range. 27.5, needle all the way down, don’t even think we’ve got to a spot to check the main but it’s 135. Any suggestions?

 

[5twins]

Stock '77 carb set? A 135 main may be a bit large for that set, requiring the needle be set at it's leanest (all the way down). A 132.5 main along with the needle set 2nd slot from the top may be better. That worked pretty well on the '76-'77 carb set I tried out. I couldn't run a 135, it was too big. But, I didn't try it with the needle leaned all the way. I wouldn't do that. I don't like running the needles at their extremes (#1 or #5 slot). I stick to the middle 3 slots (#2, 3 (stock), & 4). If it won't run right in one of those 3 slots, I change some other jets so it will.

 

[jgimar]

Stock '77 carb set? A 135 main may be a bit large for that set, requiring the needle be set at it's leanest (all the way down). A 132.5 main along with the needle set 2nd slot from the top may be better. That worked pretty well on the '76-'77 carb set I tried out. I couldn't run a 135, it was too big. But, I didn't try it with the needle leaned all the way. I wouldn't do that. I don't like running the needles at their extremes (#1 or #5 slot). I stick to the middle 3 slots (#2, 3 (stock), & 4). If it won't run right in one of those 3 slots, I change some other jets so it will.

Okay. Did some adjusting, needle is in the 2nd notch from top now, and i switched out the 27.5 pilot for a 30. Smallest main i have right now is the 135’s. Went for a run, it’s runnin but with issues. Got up to about 60 and started getting sputtering and backfiring. That was kinda new. Also between shifts it’s not settling down. I’ll round up the smaller mains and do some testing. Would you suggest i ho smaller than 132?

 

[5twins]

That could depend on your mods. You said you have 1.5" pipes. Straight pipes with no mufflers? They can be difficult to tune for. You also said pods. What kind? If they're the K&N pleated type, they can cause running issues, premature break-up requiring smaller than ideal jet sizes. The 30 pilots you put in now could also be contributing to the break-up, maybe they're too big.

The '76-'77 carb set had the largest needle jets (Z-8) put in any 650 carb set. These limit the jet sizes you can use, especially the mains. You can't go as big as on some of the other 650 carb sets or you make the already rich midrange too rich. The 3 circuits in your carb overlap the one next to them slightly. Larger mains or pilots also effect the upper and lower parts of the midrange .....