Author Topic: Spark plug cap resistance and whole lot more  (Read 16864 times)

0 Members and 1 Guest are viewing this topic.

Offline Deltarider

  • Really Old Timer ...
  • *******
  • Posts: 8,121
  • ... but some animals are more equal than others.
Re: Spark plug cap resistance
« Reply #100 on: May 12, 2016, 11:25:56 AM »
Just for the record, if ignition plates needed shims, what brand plates are you guys talking about: genuine Honda or aftermarket (like Daiichi) or both? Could be useful for others to know.
CB500K2-ED Excel black
"There is enough for everyone's need but not enough for anybody's greed."

Offline topperharley

  • Enthusiast
  • **
  • Posts: 134
Re: Spark plug cap resistance
« Reply #101 on: May 12, 2016, 11:32:07 AM »
The text i readed was about the machined groove on block were the plate sit with three bolts. The plate might not sit evenly on there. When you loosen the bolts and set the timing and after that thighten the bolts it shifts a bit and chances the timing. Shimmit so that it sits firmly in radial direction. Lower right bolt is a good place.
It doesnt matter whag plate you use. Its about the groove.

Offline flybox1

  • My wife thinks I'm a
  • Really Old Timer ...
  • *******
  • Posts: 14,301
Re: Spark plug cap resistance
« Reply #102 on: May 12, 2016, 11:35:03 AM »
My points and plate are OE ND, and there is enough play between its 3 mounting posts to need 2-fold of alu can to hold it snug. I also have a spare TEC plate w the same spacing. 


I might suggest this first: don't use a dwell meter when the timing can't be set. The reason: the gaps and baseplate position must be known in order to be able to try to sort out any geometry  problems, and the dwellmeter masks all of this.

Here's what might be happening: the baseplate might be somewhat smaller than those edges that are supposed to hold it on the bike. See if you have "slop" when the 3 screws are loose. If so, try this: insert a shim in the bottom edge of the plate to shift it upward, then set the Points to 0.014" gap. Then adjust the plate to make the 1-4 "F" mark line up at idle, and see where this leaves the 2-3 subplate timing. In the case of the TEC points sets, they usually come right in once this is done.

The FEW and Daiichi baseplates are too small by almost 0.5mm diameter. This allows the whole system to shift timing on the 1-4 side by about 3 degrees: since the 2-3 side then must shift twice that much (6 degrees) to "catch up", and since the subplate only allows 5 total degrees adjustment, it becomes impossible to move the 2-3 set into time. The "fix" for the FEW plates is to center them with a shim or two in the edges of the baseplate at those supports: the Daiichi points themselves introduce another geometry problem that often can't be fixed at all on top of the baseplate issue. That's why I think we're lucky for still having the TEC units available today!

There is no "need" to switch away from points, And the Dyna will just draw more power, without much , if any, spark improvement.   However, if you are unable to make the points system work, it could get you driving.

The points are a simple and basic electrical switch.  When closed they draw current through them, charging the coil.  Open, allows the coils to spark the plugs.  There are only two electrical connections.  One side connects to the engine case, the other connects to the coil.  Pay attention to the wire terminals on the points so they aren't allowed to contact the engine case, and be certain the insulation collar on the post is centered.

Once the connections are confirmed, rotate the crank so that the points are at their most open position.  Ignore the timing marks for now.  Set the mechanical gap to book spec.  If you apply power now, an attached light will shine bright as the lamp filament provides an electrical path around the point contacts.  Now rotate the crank until the light goes out.  This is where the 1.4 F mark should align.  The main plate screws are loosened just enough to allow the plate to rotate.  If the main plate is undersize, the spring pressure from the points can move the main plate in the engine bosses and this can change the gap.  The crank's cam position can alternate which spring is dominant as the crank is turned...which changes the gap setting you just made, because the plate can move with loosened screws.  I like to shim the plate, so it can't move laterally in the engine bosses.  The shims I use are feeler gauge "fingers".  Now, when you rotate the plate, the 1.4 point gap doesn't change, and you can rotate the plate to a position where the light will come on as the F mark aligns with marker.  Lock all three screws of the main plate down tight and do a final check of both max gap on the highest point of the cam on the crank, and that the light comes on when the marks align. You can remove the shim now.  Next move on to the 2.3 point set.  Again rotate the points cam to make the points open their widest and adjust the gap.   Then rotate the crank for 2.3 F mark alignment.  The 2.3 points have their own sub plate, which is moved on top of the main plate, to get the light to illuminate as the marks align.  In most cases, you are now done with point timing.  If ever you loosen the 1.4 plate screws for any reason, you will need the shim for the plate so the plate will hold lateral position, particularly if you attempt to use a dynamic timing light. I've done both, and no longer use the Dynamic to set basic timing, only to verify that the advance is working properly.

If you "run out of range" on either point set, you'll need to pick another of the three engine bosses to place the shims, and start over from the beginning with the 1.4 points.  I have yet to develop a rule about which mount boss to shim.  I think I used the lower left, last time I did this.   Now I just insert shims where ever is the largest before loosening the three screw for the 1.4 plate, 'cause that's where it was needed last time I did the adjustment. No need to do the same work twice.

There is a FAQ entry about shimming the points plate.
[/quote
« Last Edit: May 12, 2016, 12:04:17 PM by flybox1 »
'78 750K (F3 engine) PD42b's, Modified airbox w/K&N  filter, 40/110 jets, 1 needle shim, IMS@ 1 turn out. Kerker + Cone 18" QuietCore

Past Bikes
1974 550K0 (stock), 1973 CB350F (stock), 1983 Yamaha XS400K (POS)
77/78 cool 2 member #3
"Knowledge without mileage equals bullsh!t" - Henry Rollins

"This is my CB. There are many like it, but this one is mine…"

Offline topperharley

  • Enthusiast
  • **
  • Posts: 134
Re: Spark plug cap resistance
« Reply #103 on: May 18, 2016, 06:34:55 AM »

What do you guys think about this spark. Ok or not?

Offline flybox1

  • My wife thinks I'm a
  • Really Old Timer ...
  • *******
  • Posts: 14,301
Re: Spark plug cap resistance
« Reply #104 on: May 18, 2016, 07:01:11 AM »
Picture didnt come thru topper. . .
'78 750K (F3 engine) PD42b's, Modified airbox w/K&N  filter, 40/110 jets, 1 needle shim, IMS@ 1 turn out. Kerker + Cone 18" QuietCore

Past Bikes
1974 550K0 (stock), 1973 CB350F (stock), 1983 Yamaha XS400K (POS)
77/78 cool 2 member #3
"Knowledge without mileage equals bullsh!t" - Henry Rollins

"This is my CB. There are many like it, but this one is mine…"

Offline topperharley

  • Enthusiast
  • **
  • Posts: 134

Offline flybox1

  • My wife thinks I'm a
  • Really Old Timer ...
  • *******
  • Posts: 14,301
Re: Spark plug cap resistance
« Reply #106 on: May 18, 2016, 07:13:05 AM »
That'll do just fine :)
'78 750K (F3 engine) PD42b's, Modified airbox w/K&N  filter, 40/110 jets, 1 needle shim, IMS@ 1 turn out. Kerker + Cone 18" QuietCore

Past Bikes
1974 550K0 (stock), 1973 CB350F (stock), 1983 Yamaha XS400K (POS)
77/78 cool 2 member #3
"Knowledge without mileage equals bullsh!t" - Henry Rollins

"This is my CB. There are many like it, but this one is mine…"

Offline topperharley

  • Enthusiast
  • **
  • Posts: 134
Re: Spark plug cap resistance
« Reply #107 on: May 18, 2016, 07:19:18 AM »
Damn   We leave for a holiday to Greece tomorrow. I lock the garage and come back after a week of sun and beer with loaded batteries. Mystery of the fouled plug continues after that. I hope that there isnt too many episodes left

Offline flybox1

  • My wife thinks I'm a
  • Really Old Timer ...
  • *******
  • Posts: 14,301
Re: Spark plug cap resistance
« Reply #108 on: May 18, 2016, 07:40:23 AM »
Nice!  Have  a great trip.  I have a friend on Kalymnos right now.
Weather looks great.
'78 750K (F3 engine) PD42b's, Modified airbox w/K&N  filter, 40/110 jets, 1 needle shim, IMS@ 1 turn out. Kerker + Cone 18" QuietCore

Past Bikes
1974 550K0 (stock), 1973 CB350F (stock), 1983 Yamaha XS400K (POS)
77/78 cool 2 member #3
"Knowledge without mileage equals bullsh!t" - Henry Rollins

"This is my CB. There are many like it, but this one is mine…"

Offline topperharley

  • Enthusiast
  • **
  • Posts: 134
Re: Spark plug cap resistance
« Reply #109 on: May 19, 2016, 03:10:55 AM »
Thnx fly. We are going to Kos. It looks nice and warm for whole week.

Lähetetty minun SM-G903F laitteesta Tapatalkilla


Offline topperharley

  • Enthusiast
  • **
  • Posts: 134
Re: Spark plug cap resistance
« Reply #110 on: June 02, 2016, 02:38:23 AM »
Hi again. The carbtune gauge arrived and it works well. Carbs are at sync now but one question. I sync the carbs when idle is 900-1100rpm and they are perfectly equal to each other. The question is should they stay nearly in sync when i raise rpm's? cyl4 for example  goes way off sync when raise rpm's but returns when rpm sets back to 900-1100.

I also ordered a main jet kit. Im gonna try the 125# jets.
What could cause the popping, compression sounds and backfiring when engine is warm? Bike runs better when its cold and no popping, backfiring or compression sounds on carbs. Thats one reason to try 125# mains.

Offline PeWe

  • Really Old Timer ...
  • *******
  • Posts: 15,545
  • Bike almost back to the 70's 2015
Re: Spark plug cap resistance
« Reply #111 on: June 02, 2016, 03:13:53 AM »
One important detail is a true TDC. Verify with a piston stop.
(Be careful when rocker arms are mounted and valves might get contact. High CR pistons have higher crowns and stop will hit earlier)

The case mark on my CB750 K6 case has an alternative mark I have done about 3mm clockwise of the std case mark.
T will align with standard mark when the advancer unit is in its max counterclockwise endpoint, lash.

When rotating the crank by the center nut on ignition side can move the advancer clockwise so I use the alternative mark. I checked the TDC before timing a cam but found that the TDC is important for ignition timing. I have timed ignition wrong before with several degrees of too advanced ignition due to wrong TDC mark. Maybe thats why I blew cyl 2-3 pistons back in the 80's. 
Combo of general timing too advanced and maybe forgotten check of 2-3 when adjusting the entire plate for 1-4.
« Last Edit: June 02, 2016, 03:22:56 AM by PeWe »
CB750 K6-76  970cc (Earlier 1005cc JMR Billet block on the shelf waiting for a comeback)
CB750 K2-75 Parts assembled to a stock K2

Updates of the CB750 K6 -1976
http://forums.sohc4.net/index.php/topic,180468.msg2092136.html#msg2092136
The billet block build thread
http://forums.sohc4.net/index.php/topic,49438.msg1863571.html#msg1863571
CB750 K2 -1975  build thread
http://forums.sohc4.net/index.php/topic,168243.msg1948381.html#msg1948381
K2 engine build thread. For a complete CB750 -75
http://forums.sohc4.net/index.php/topic,180088.msg2088008.html#msg2088008
Carb jetting, a long story Mikuni TMR32
http://forums.sohc4.net/index.php/topic,179479.msg2104967.html#msg2104967

Offline PeWe

  • Really Old Timer ...
  • *******
  • Posts: 15,545
  • Bike almost back to the 70's 2015
Re: Spark plug cap resistance
« Reply #112 on: June 02, 2016, 03:21:57 AM »
Thnx fly. We are going to Kos. It looks nice and warm for whole week.

Lähetetty minun SM-G903F laitteesta Tapatalkilla


I and my family will visit Crete later this summer. 2 weeks to endure the clear, blue and not that cold very salty sea, long beaches, buckets of cold beer.. The only thing I can do is to try doing my best without my bike...
CB750 K6-76  970cc (Earlier 1005cc JMR Billet block on the shelf waiting for a comeback)
CB750 K2-75 Parts assembled to a stock K2

Updates of the CB750 K6 -1976
http://forums.sohc4.net/index.php/topic,180468.msg2092136.html#msg2092136
The billet block build thread
http://forums.sohc4.net/index.php/topic,49438.msg1863571.html#msg1863571
CB750 K2 -1975  build thread
http://forums.sohc4.net/index.php/topic,168243.msg1948381.html#msg1948381
K2 engine build thread. For a complete CB750 -75
http://forums.sohc4.net/index.php/topic,180088.msg2088008.html#msg2088008
Carb jetting, a long story Mikuni TMR32
http://forums.sohc4.net/index.php/topic,179479.msg2104967.html#msg2104967

Offline topperharley

  • Enthusiast
  • **
  • Posts: 134
Re: Spark plug cap resistance
« Reply #113 on: June 02, 2016, 03:32:06 AM »
Do you mean that the F mark moves too if the TDC moves?

Offline flybox1

  • My wife thinks I'm a
  • Really Old Timer ...
  • *******
  • Posts: 14,301
Re: Spark plug cap resistance
« Reply #114 on: June 02, 2016, 07:35:23 AM »
I also ordered a main jet kit. Im gonna try the 125# jets.
What could cause the popping, compression sounds and backfiring when engine is warm? Bike runs better when its cold and no popping, backfiring or compression sounds on carbs. Thats one reason to try 125# mains.
At what throttle position is the popping, backfiring?
125's (assuming theyre larger than what you have in there now) are only needed if youve done a WOT plug chop and the plug tips have all come up white  :-\

Refresh us on your current jetting, mixture screw setting, intake/exhaust setup etc...thanks n welcome back. ;D
'78 750K (F3 engine) PD42b's, Modified airbox w/K&N  filter, 40/110 jets, 1 needle shim, IMS@ 1 turn out. Kerker + Cone 18" QuietCore

Past Bikes
1974 550K0 (stock), 1973 CB350F (stock), 1983 Yamaha XS400K (POS)
77/78 cool 2 member #3
"Knowledge without mileage equals bullsh!t" - Henry Rollins

"This is my CB. There are many like it, but this one is mine…"

Offline topperharley

  • Enthusiast
  • **
  • Posts: 134
Re: Spark plug cap resistance
« Reply #115 on: June 02, 2016, 10:26:06 AM »
I have 135#. I had those with 900cc kit. Pilots are std 40#.
It starts after the engine is fully warm. If i idle for a good time like in traffic. Its on its worst in 1/8 throttle and continues on idle but not as that bad. Also in deceleration but only on lower rpm's. WOT is ok and if i try to drive like a Mick Doohan (read high revs) there is no popping or backfiring :)

Offline topperharley

  • Enthusiast
  • **
  • Posts: 134
Re: Spark plug cap resistance
« Reply #116 on: June 02, 2016, 10:27:26 AM »
Jets 135/40 screw 1. Intake open pods. Ex drag pipes no mufflers.

Offline flybox1

  • My wife thinks I'm a
  • Really Old Timer ...
  • *******
  • Posts: 14,301
Re: Spark plug cap resistance
« Reply #117 on: June 02, 2016, 10:36:43 AM »
If its worse at 1/8 throttle, why adjust a jet that supplies fuel at WOT?



You need to be focusing your efforts with mixture screw/pilot jet adjustments. 
Those components are controlling your mixture at 1/8-1/4 throttle.
'78 750K (F3 engine) PD42b's, Modified airbox w/K&N  filter, 40/110 jets, 1 needle shim, IMS@ 1 turn out. Kerker + Cone 18" QuietCore

Past Bikes
1974 550K0 (stock), 1973 CB350F (stock), 1983 Yamaha XS400K (POS)
77/78 cool 2 member #3
"Knowledge without mileage equals bullsh!t" - Henry Rollins

"This is my CB. There are many like it, but this one is mine…"

Offline topperharley

  • Enthusiast
  • **
  • Posts: 134
Re: Spark plug cap resistance
« Reply #118 on: June 02, 2016, 10:40:11 AM »
Cyl 1 and 3 plugs stay in pretty good shape when i drive slowly. Cyl 1 gets fouled much faster if i drive close to wot.
Im planning to get 42 pilots. They have those in our local partshop.

Offline flybox1

  • My wife thinks I'm a
  • Really Old Timer ...
  • *******
  • Posts: 14,301
Re: Spark plug cap resistance
« Reply #119 on: June 02, 2016, 10:43:20 AM »
why 42's?
does your idle plug chop come up with white plug insulators?

Im just trying to save you some $ and time tuning your bike instead of shotgun 'throw some new jets in there' and hope it works approach  ;D
'78 750K (F3 engine) PD42b's, Modified airbox w/K&N  filter, 40/110 jets, 1 needle shim, IMS@ 1 turn out. Kerker + Cone 18" QuietCore

Past Bikes
1974 550K0 (stock), 1973 CB350F (stock), 1983 Yamaha XS400K (POS)
77/78 cool 2 member #3
"Knowledge without mileage equals bullsh!t" - Henry Rollins

"This is my CB. There are many like it, but this one is mine…"

Offline topperharley

  • Enthusiast
  • **
  • Posts: 134
Re: Spark plug cap resistance
« Reply #120 on: June 02, 2016, 11:42:31 AM »
I did a 10 min test on idle and there was little or non change at all in color. Actually only cyl2 had little tanned color on it.

Offline flybox1

  • My wife thinks I'm a
  • Really Old Timer ...
  • *******
  • Posts: 14,301
Re: Spark plug cap resistance
« Reply #121 on: June 02, 2016, 11:46:03 AM »
I did a 10 min test on idle and there was little or non change at all in color. Actually only cyl2 had little tanned color on it.
Just to be clear... all plugs were white, and #2 had slight tan color?
if this is the case, then yes, go to 42's
'78 750K (F3 engine) PD42b's, Modified airbox w/K&N  filter, 40/110 jets, 1 needle shim, IMS@ 1 turn out. Kerker + Cone 18" QuietCore

Past Bikes
1974 550K0 (stock), 1973 CB350F (stock), 1983 Yamaha XS400K (POS)
77/78 cool 2 member #3
"Knowledge without mileage equals bullsh!t" - Henry Rollins

"This is my CB. There are many like it, but this one is mine…"

Offline topperharley

  • Enthusiast
  • **
  • Posts: 134
Re: Spark plug cap resistance
« Reply #122 on: June 02, 2016, 11:54:53 AM »
Yep. Had a photo about the plugs but this is what happened.

I was sitting on sofa and my 3 y old son came and took my cell. I thought that what a heck he cant do no harm there is a sweep lock and all. After a few minutes i noticed an android guy spinning on screen. I took the phone from hes hand and there was a text formating on screen. Yes. All the pics and data gone for past year. Forever.

About the pilots. This aint the biggest problem this popping and backfiring i doesnt piss me of as much as the fouling does so thats why im trying the 125 jets.

Offline flybox1

  • My wife thinks I'm a
  • Really Old Timer ...
  • *******
  • Posts: 14,301
Re: Spark plug cap resistance
« Reply #123 on: June 02, 2016, 12:02:12 PM »
bummer about the photos.  my kids have done the same.
please only change the pilots first.  its easier to see the effect and tune from there.
if you add both new pilots and mains, well, you wont really know where to go next if there is still an issue.
get the idle plugs(pilot jets) right first.  then, move on to the mains.
'78 750K (F3 engine) PD42b's, Modified airbox w/K&N  filter, 40/110 jets, 1 needle shim, IMS@ 1 turn out. Kerker + Cone 18" QuietCore

Past Bikes
1974 550K0 (stock), 1973 CB350F (stock), 1983 Yamaha XS400K (POS)
77/78 cool 2 member #3
"Knowledge without mileage equals bullsh!t" - Henry Rollins

"This is my CB. There are many like it, but this one is mine…"

Offline topperharley

  • Enthusiast
  • **
  • Posts: 134
Re: Spark plug cap resistance
« Reply #124 on: June 02, 2016, 12:07:13 PM »
Will do. Thanks.