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Author Topic: Cb360 timing omg help.  (Read 555 times)

Offline MiniatureNinja

  • Posts: 457
Cb360 timing omg help.
« on: Jun 16, 2018, 22:30:07 »
Timing cb360 points, I cannot for the life of me get this right.

What happens is the test light stays in for half the stroke before LF mark, then turns right off after LT. Why are the points open for the entire time?
'75 Honda CB360 - thread

Offline irk miller

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Re: Cb360 timing omg help.
« Reply #1 on: Jun 16, 2018, 23:52:28 »
Make sure you have the cam and advancer right.  Make sure you're testing by rotating counterclockwise.  And, make sure you verifiably at TDC on the left side when it's on the LT mark.  Sounds like you are either rotating the wrong way, or you have the cam flipped.

Offline MiniatureNinja

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Re: Cb360 timing omg help.
« Reply #2 on: Jun 17, 2018, 01:01:28 »
Make sure you have the cam and advancer right.  Make sure you're testing by rotating counterclockwise.  And, make sure you verifiably at TDC on the left side when it's on the LT mark.  Sounds like you are either rotating the wrong way, or you have the cam flipped.

the points cam was backwards on the advancer (180* off)

is it normal for the points to remain on for several degrees after LF ?
'75 Honda CB360 - thread

Offline irk miller

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Re: Cb360 timing omg help.
« Reply #3 on: Jun 17, 2018, 09:52:55 »
the points cam was backwards on the advancer (180* off)

is it normal for the points to remain on for several degrees after LF ?
That means it's out of time.  That's what you're adjusting for.  Your gap and the points plate position affects when it comes on and off.

Offline jpmobius

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Re: Cb360 timing omg help.
« Reply #4 on: Jun 17, 2018, 10:52:49 »
Your dwell angle is incorrect.  This is the duration in crankshaft degrees that the points are closed.  This translates into how long the coil gets electricity and in turn has enough energy to create a spark.  It also determines how long the coil is "off" and gets to cool off.  You control this by setting the gap between the point faces, and this has to be done when the rubbing block is on the highest part of the cam lobe where the points will be open the farthest.  You MUST do this first, before you set the timing.  If you fool with the point gap after setting the timing, the timing will be out and you will have to reset.  Once you set the gap, leave it alone.  You can fool around with the timing all you want and the gap will remain the same.
Mobius


On a long enough timeline, the survival rate for everyone drops to zero.

1973 RD350 Yamaha build  http://www.dotheton.com/forum/index.php?topic=66498.0


Offline crazypj

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Re: Cb360 timing omg help.
« Reply #6 on: Jun 17, 2018, 12:48:45 »
You did set points gap when they were at maximum opening? (0.014")
'you can take my word for it or argue until you find out I'm right'
Best thing I ever overheard
"yep, PJ's my boss, he taught me everything I know, just didn't teach me everything he knows"
Brian Morgan, 1982

CB360's,  http://www.dotheton.com/forum/index.php?topic=11736.0
XS650,  http://www.dotheton.com/forum/index.php?topic=11922.0

Offline MiniatureNinja

  • Posts: 457
Re: Cb360 timing omg help.
« Reply #7 on: Jun 17, 2018, 13:50:53 »
at what what point will the points be open the farthest? is that about 90* after each fire?

I did set the gap but I have never had a vehicle were the points pivot at two parts... so it seams that when I am trying to adjust the gap it pushes the bottom part of the points arm more into the cam throwing everything off.
'75 Honda CB360 - thread

Offline irk miller

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Re: Cb360 timing omg help.
« Reply #8 on: Jun 17, 2018, 13:59:09 »
The cam is eccentric, so the points close at the thickest part of the cam.

Offline MiniatureNinja

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Re: Cb360 timing omg help.
« Reply #9 on: Jun 17, 2018, 14:03:27 »
You did set points gap when they were at maximum opening? (0.014")

ok so this is another example of CMC misleading people.

gonna have to do this right now. LOL

so use the 4 small screws to adjust the gap, and then use the base plate to adjust the timing. right?
« Last Edit: Jun 17, 2018, 14:04:59 by MiniatureNinja »
'75 Honda CB360 - thread

Offline irk miller

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Re: Cb360 timing omg help.
« Reply #10 on: Jun 17, 2018, 14:07:46 »
Brenden at CMC has a good video for this.  He downplays the importance of gap, which I don't agree with, but otherwise it's right on target.


Offline MiniatureNinja

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Re: Cb360 timing omg help.
« Reply #11 on: Jun 17, 2018, 15:38:35 »
Brenden at CMC has a good video for this.  He downplays the importance of gap, which I don't agree with, but otherwise it's right on target.



that's the video I tried to follow yesterday - he says not to even touch the backplate and totally ignore the points gap.
'75 Honda CB360 - thread

Offline jpmobius

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Re: Cb360 timing omg help.
« Reply #12 on: Jun 17, 2018, 15:41:44 »
There is a lot of good material in the CMC video, and there is no doubt that the procedure detailed will result in correctly set timing.  However, this is NOT a good procedure because, as noted it does not consider the point gap, and therefore the dwell to be of any importance.  It is absolutely true that nearly all points ignitions will indeed run with dwell angles wildly outside the specified range so long as the timing is reasonably close.  However, just because one person considers it to be unimportant, that in no way makes it so.  As I previously stated, maintaining the correct point gap is indeed very important - more or less so depending on a variety of factors, but important nonetheless.  For each revolution of the ignition cam, the ignition coil is energized for a percentage of that rotation.  That would be the percentage of rotation that the test light is off.  During this time, when the coil is energized, considerable heat is built up in the ignition coil.  When the light is on, the power to the coil is cut, and the coil is able to cool off.  Heat is the number one enemy of your ignition coils, so that cool off period during each full cycle of the cylinder is important.  The opposite, having too long a cool down period in theory could result in insufficient "charge time" in the coil, but in general this is not usually a concern.

Set the point gap first.  It matters not at all where the timing plate is or where the crank is positioned so long as the rubbing block for the point set you are adjusting is sitting on the highest point of the cam.  Set the timing after both sets of points are properly adjusted.  Your Honda has a single timing plate to which both sets of points are mounted, so in theory, adjusting it for correct timing on one cylinder will result in the other cylinder being correct also.  In practice however, the combination of the precision of all the various parts along with one's precision to set both sets of points to exactly the same gap usually results in very slight variance between the cylinders, so after setting the timing on one cylinder with the timing plate adjustment, you may have to correct the other cylinder timing by adjusting the points adjusting plate for that cylinder.  This is exactly the procedure outlined in the graciously provided manual pages in the previous post.  The info provided there is clear and exactly correct - follow it and your timing will be perfect.
Mobius


On a long enough timeline, the survival rate for everyone drops to zero.

1973 RD350 Yamaha build  http://www.dotheton.com/forum/index.php?topic=66498.0

Offline jpmobius

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Re: Cb360 timing omg help.
« Reply #13 on: Jun 17, 2018, 15:52:52 »
ok so this is another example of CMC misleading people.

gonna have to do this right now. LOL

so use the 4 small screws to adjust the gap, and then use the base plate to adjust the timing. right?

I think it is in fact a bit misleading, but in truth, the point gap is likely to be reasonably close which is probably why he gets (I assume) good results.  It is a result of the fairly limited adjustment range when all the parts are new and properly assembled.  And, the performance requirement is fairly easy - compare to a V-8 car engine with a single set of points - It may redline at half the revs, but has to fire 8 times as often!

And yes, adjust the gap(s), then the timing for both cylinders with the single timing plate.  And as noted in the manual, you can go the extra mile by adjusting the other set of points afterwards to get that cylinder perfect as well if needed.

If you have a strobe light, it is easier, and often more accurate (depending on your static timing setting skills).
« Last Edit: Jun 17, 2018, 15:54:40 by jpmobius »
Mobius


On a long enough timeline, the survival rate for everyone drops to zero.

1973 RD350 Yamaha build  http://www.dotheton.com/forum/index.php?topic=66498.0

Offline irk miller

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Re: Cb360 timing omg help.
« Reply #14 on: Jun 17, 2018, 16:32:17 »
If you go by the manual pages (that's from the FSM) to the letter, and set the gap to .014 (like PJ noted), you will be very happy with the results.  .014 is right in the middle and the perfect gap for this bike. I'm pretty sure .014 is the typical gap for most points based bikes, but don't quote me on that. 

Offline MiniatureNinja

  • Posts: 457
Re: Cb360 timing omg help.
« Reply #15 on: Jun 17, 2018, 16:56:10 »
I think it is in fact a bit misleading, but in truth, the point gap is likely to be reasonably close which is probably why he gets (I assume) good results.  It is a result of the fairly limited adjustment range when all the parts are new and properly assembled.  And, the performance requirement is fairly easy - compare to a V-8 car engine with a single set of points - It may redline at half the revs, but has to fire 8 times as often!

And yes, adjust the gap(s), then the timing for both cylinders with the single timing plate.  And as noted in the manual, you can go the extra mile by adjusting the other set of points afterwards to get that cylinder perfect as well if needed.

If you have a strobe light, it is easier, and often more accurate (depending on your static timing setting skills).

ok thanks.

I was very frustrated and trying to shortcut - because I spent way too long trying to time it with the advancer in backwards before I realized what was going on. I feel pretty dumb but I am chalking it up to sleep deprivation and not having eaten anything that day... I really wanted to finish the bike

found that I am leaking brake fluid too out of the brake pipe which has been used and re-used too many times I guess
'75 Honda CB360 - thread

Offline crazypj

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Re: Cb360 timing omg help.
« Reply #16 on: Jun 18, 2018, 11:32:57 »
The backplate isn't a very good fit in housing so timing and gap tends to vary as timing is adjusted which is very frustrating. It is important to have gap between 0.012" and 0.016". Not adjusting backplate makes it almost impossible to get both sets of points in spec. I had an idea you didn't set gap at high point, seen it happen a lot. Often gap is set at 'F' mark so points never close. Have you downloaded The Hionda Common manual? (fills in the gaps in factory service manuals)
'you can take my word for it or argue until you find out I'm right'
Best thing I ever overheard
"yep, PJ's my boss, he taught me everything I know, just didn't teach me everything he knows"
Brian Morgan, 1982

CB360's,  http://www.dotheton.com/forum/index.php?topic=11736.0
XS650,  http://www.dotheton.com/forum/index.php?topic=11922.0

Offline MiniatureNinja

  • Posts: 457
Re: Cb360 timing omg help.
« Reply #17 on: Jun 18, 2018, 17:12:01 »
The backplate isn't a very good fit in housing so timing and gap tends to vary as timing is adjusted which is very frustrating. It is important to have gap between 0.012" and 0.016". Not adjusting backplate makes it almost impossible to get both sets of points in spec. I had an idea you didn't set gap at high point, seen it happen a lot. Often gap is set at 'F' mark so points never close. Have you downloaded The Hionda Common manual? (fills in the gaps in factory service manuals)

I have that downloaded (I think its the one you linked in a thread)
I didn't set the gap properly, 2 timing videos said it wasn't important and I've had 1 points car ('64 VW bettle) and i don't think I ever adjusted the gap or timing in that thing the entire 8 years I owned it.
'75 Honda CB360 - thread

Offline crazypj

  • Posts: 13157
  • Split personality, I fake being smart
Re: Cb360 timing omg help.
« Reply #18 on: Jun 19, 2018, 11:17:00 »
LOL, 'everyone' has had a Beetle at some time. I still have a 1970 one in a shed in Britain
'you can take my word for it or argue until you find out I'm right'
Best thing I ever overheard
"yep, PJ's my boss, he taught me everything I know, just didn't teach me everything he knows"
Brian Morgan, 1982

CB360's,  http://www.dotheton.com/forum/index.php?topic=11736.0
XS650,  http://www.dotheton.com/forum/index.php?topic=11922.0