Cam timing 180 off from points ???

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23 Oct 2012 11:18 #555352 by KZB2 650
Cam timing 180 off from points ??? was created by KZB2 650
Rebuilt my KZ650 top end this summer did'nt split the case and left the points in and are still timed right and have it all buttoned up. Fell good about everything except...

When putting in the cams I rotated the motor clock wise 3 times or so to be sure the slack is taken up then went to tdc on the 1/4 mark just like it said and set the cams in.

Went well lines on the sropokets are right where they should be and I checked the 36 pins about a half a dozen times after getting the tentioner right and rotating so I'm sure thats good but can I be 180 degrees off ???

Have spun it over and it has a solid 145-150 comp on a un started motor. Like I said I have not tryed to start it yet and want to be sure.

All I can see on both manuals is where it say set it to tdc at 1/4 and set the cams there no mention on how to be sure that the 1/4 tdc setting I started at is where the points fire for 1/4 at that position?? Does this make sence on what I'm trying to ask?

Please let me know I'm running out of warm weather and am to chicken to try and stert this until I'm sure I'm good on this.

1978 KZ650 b-2
700cc Wiseco kit 10 to 1.
1980 KZ750 cam, ape springs, stock clutch/ Barnett springs.
Vance and Hines Header w/ comp baffle and Ape pods, Dyna S and green coils, copper wires.
29MM smooth bores W/ 17.5 pilots, 0-6s and 117.5 main
16/42 gearing X ring chain and alum rear JT sprocket.

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23 Oct 2012 14:34 #555376 by steell
Replied by steell on topic Cam timing 180 off from points ???
If it's 180 degrees off just rotate the crank one more time and it will be perfect :)

Cam turns 1/2 turn for every full crank turn, or cam turns once for every two crank revolutions.

KD9JUR

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23 Oct 2012 15:01 - 23 Oct 2012 16:45 #555385 by KZB2 650
Replied by KZB2 650 on topic Cam timing 180 off from points ???
Thanks Steell for the reply. I'm so confused right now I hope I make sence. I feel good about how I have the cams and cam chain set. Right on the money both arrows and at at tdc 1/4.

I quess what I'm wondering is do I have them set right to the point firing. As long as I had the points and timing right before the bebuild if I set the mark at tdc 1/4 and do the cams like it says in the book I will have the correct firing of the plugs. Right?

Should the points be open and ready to fire on the number 1/4 mark when I set the cams in and get them all lined up like this for the first time?

Thats what I can't remember if the 1/4 points were open and ready to fire or were they closed for the compression stroke when I set the cams in and set them. Could this throw things 180 degree's off.

Edit........Just went out and seen that every half turn on the points from the 1/4 to 2/3 mark then back to the same opens the points each time. Does it make a difference on which 1/4 mark you have it on when you set the cams in, I mean could I have turned it one turn more than I have it now on the same 1/4 tdc mark and it would bring the same result and be correct?? I worry to much for another rebuild trust me.

1978 KZ650 b-2
700cc Wiseco kit 10 to 1.
1980 KZ750 cam, ape springs, stock clutch/ Barnett springs.
Vance and Hines Header w/ comp baffle and Ape pods, Dyna S and green coils, copper wires.
29MM smooth bores W/ 17.5 pilots, 0-6s and 117.5 main
16/42 gearing X ring chain and alum rear JT sprocket.
Last edit: 23 Oct 2012 16:45 by KZB2 650.

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23 Oct 2012 17:13 - 23 Oct 2012 17:19 #555409 by bountyhunter
Replied by bountyhunter on topic Cam timing 180 off from points ???
It's a wasted spark ignition which means it fires on every TDC stroke (intake or exhaust). If you get the ignition timing 180 off, it is firing on the BDC (bottom) of the stroke. That happens if the timing advancer is installed 180 off. I think on the fours it can also happen if the wires coming from the sensors are reversed going to the coils (?)

As Steell said, the cam alignment can be set on either TDC stroke (intake or exhaust) for the correct piston set since the cams don't care which TDC stroke it is. What can be alarming is that you can rotate the engine to the next TDC and it looks like the cams are pointed 180 wrong, and you freak out. Everybody has done that at least once. That's because the crank turns two revolutions for each camshaft revolution.

1979 KZ-750 Twin
Last edit: 23 Oct 2012 17:19 by bountyhunter.

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23 Oct 2012 17:40 #555413 by KZB2 650
Replied by KZB2 650 on topic Cam timing 180 off from points ???
Thanks bounty hunter, been thinking I was right but woke up at midnight worrying about it and have had a sour stomach over it since. Looks like tommoro will be the day I finally fire her up. ;) I just hope I can finally relax about this and all else now.... first fire up is suppose to be a good day not a day to worry about. LOL.

1978 KZ650 b-2
700cc Wiseco kit 10 to 1.
1980 KZ750 cam, ape springs, stock clutch/ Barnett springs.
Vance and Hines Header w/ comp baffle and Ape pods, Dyna S and green coils, copper wires.
29MM smooth bores W/ 17.5 pilots, 0-6s and 117.5 main
16/42 gearing X ring chain and alum rear JT sprocket.

Please Log in or Create an account to join the conversation.

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