Topic: My long-overdue Spark Advancer post...

[dave500]

like this.

[RAFster122s]

Looks like one is a K7 design and the other a K3/K4 design from what was marked on them...

[StockRider]

My advancer was fairly gummed up so I took it apart for cleaning. I did not note the alignment of the cam before disassembly. DOH!

HondaMan's first image shows the alignment mark pointed away from the Hitachi symbol. mystic_1's image (in Reply #7) shows the mark pointed at the symbol.

Which way should the cam be aligned?

Which one do you have? They 'point' to different features on the baseplate, depending on which one.

The "slotted" ones you see in the parts fiche are the -323- series advancers (most made by TEC). They are a larger round-ish baseplate than these, too. The -323- have a different static timing and advance angle (and rate) from the early engines, being made to operate with late-opening intake cams (0 BTC).

The "300" definitely puts them into the pre-1975 engine. The advancers were made by 3 companies at different times, mixed back and forth between New Factory and Old Factory, with the bulk of pre-1972 versions made by Hitachi. This logo looks like 2 concentric circles with a sort of "H" in their midst. The TEC is distinct, and the ND shows up, usually in K1 bikes, pretty often.

The curious part here (to me) is the slots behind the springs. This makes it look like it started out as a 450 twin advancer plate, which may be how it came to be? Those were largely TEC-made. The sandcasts sported many parts that came from the Big Twin. If the bolster in the center were then changed to fit the 750 shaft, that might be their origin?

Cool stuff!

I have the "Hitachi", stamp looks like a compass/cardinal points, weight stops are offset (not centered).

[PeWe]

Both my CB750 have their adv springs cut 1/2 wound to get both correct setting at idle and full advance not too early.  A good mod to get it right thanks to Hondamans recommendations in his written thoughts.

F aligned with TDC mark which is verified with piston stop and also before head was mounted.

My K6 with Dyna-S has a Hitachi advancer (TEC 300 before with HM ignition).
This since I did not want to struggle with the rotor change, on-off when changing ignition. Dyna S has its own advancer.

My K2 has TEC 300 advancer and HM ignition

[StockRider]

So I decided to give it a try with it set up as in the first picture of this topic (cropped image below)..., crank, crank, crank..., crank, crank crank..., crank, crank, BAM..., BAM, BAM! I wasn't ready for how loud those back-fires were! I tried a few more times before I realized I wasn't getting anywhere.

I guess it goes the other way..., or I royally screwed something else up while messing with the advancer/springs. No time left today. I'll pull the plugs to make sure they dry out before giving it another go with the cam rotated 180-degrees.

[Deltarider]

You could have found out rightaway by simply swapping the blue and yellow wires.

[lash]

So I decided to give it a try with it set up as in the first picture of this topic (cropped image below)..., crank, crank, crank..., crank, crank crank..., crank, crank, BAM..., BAM, BAM! I wasn't ready for how loud those back-fires were! I tried a few more times before I realized I wasn't getting anywhere.

I guess it goes the other way..., or I royally screwed something else up while messing with the advancer/springs. No time left today. I'll pull the plugs to make sure they dry out before giving it another go with the cam rotated 180-degrees.
[/quote


Shouldnt the cam “dot” be pointing 180 the other way towards the Hitachi emblem/dot?

[fxef79]

I believe, regardless of which advancer you have, a good rule would be to align the index mark (large side of the cam) towards the 2/3 side of the advancer.  That way, "towards the logo" rule can't steer you wrong since the TEC logo is on the 1/4 side of the advancer, and the Hitachi logo is on the 2/3 side.  And "towards the hole/slot" can't steer you wrong, since that's not true on all of them.  Towards the 2/3 side seems it would always be the right rule... right?

[dave500]

just pay proper attention as you take it apart,simple.