• Don't overlook our Welcome Package, it contains many links to important and helpful information about functions at VHT like posting pictures and sending PMs (private messages), as well as finding the parts you need.

    AD

Ignition Advancer Rebuild Information, all 450/500T Models

Jays100

Veteran Member
Joined
May 29, 2020
Total Posts
720
Total likes
227
Location
Enfield, CT USA
I wrote this and posted it on another site. They're being annoying just now so am bringing that post over here. I believe everyone can benefit from this information. I learned it the hard way. Please feel free to post your experience(s) too.

Part 1 (of 2)

There are three ignition advancers from different manufacturers used on the 450/500Ts, their markings are CB450 (65-72) TEC292 (71-74) and TEC375 (75-76).

The manufacturer (Kokusan or Nippon Denso) determined how the points cam is mounted on the advancer mechanism.

They all mount and identically on the engine but the ignition advance curve varies with the year.

They’re quite simple with typically two fail mechanisms, there are more but primarily two. Btw, depending on your year 450, there are three suppliers of advance mechanism. Their parts do not interchange generally, However, they do interchange on engine.

Failure modes
1. Advancer stuck/points cam results in non-advance and low power output
2. Cam moves but idle hangs, results non-return to idle rpm

Tools needed
Scotchbrite pad, small (1/8” across blade max) flat blade screwdriver, can of brake-clean aerosol cleaner, 3 in1 oil, shop towels/rags, patience and a well lighted workspace, solvent/soap cleaner of choice.

Both failure modes require disassembly to solve.
-Take a before condition pic, both sides. This may be optional to some but future you will thank current you if a piece is lost or you forget how it all goes together.

-Spread the centrifugal weights and remove the cam. If rusted, you’re hosed as they require heat a Herculean effort to remove without damage. If solidified/aged grease, the cams can generally be separated and once they start to move they’re easy. Aside.

-With the small screwdriver, remove the E-clips from the weights pivot post, remove springs, shims (flat and wavy). Keep the shims in order but it’s flat on the bottom and wavy top.

-Remove all grease, clean thoroughly. This is the critical step
Note I’ve found the best tool to remove accumulated, mung, grut, spooge rust and other nastiness (and you’ll find it all) is new Scotchbrite. With adroit treatment of all sliding surfaces, base plate armature, cam inside diameter and the outside too, remove all nastiness encountered. Don’t be shy, it’s hard steel and scratches are no harm (they retain oil). Next, do the pivot posts, get into the corners, bucko, as well as the weight pivot holes.

-Spray brake clean (or use soap and water with an old toothbrush) all parts, do it twice and check if naughty or nice, redoing missed or questionable areas.

-Wash your hands and clean the area, not losing anything. Laying out the dry parts on a clean towel helps inventory, quality inspection and is the gold star of good work practice.

Reassembly in Part 2.
 
Part 2

Reassembly

It’s easy to say just reverse the order of disassembly but there are things you can do to help yourself.
-Dry fit the parts together, all pieces in intimate contact should be a slip fit, particularly the weights. Fit the weights on either post and by feel, try to selectively fit so they’re identical,

-With liberal 3in1 oil or other thin film lube/grease on the pieces, hook one end of the spring to the one weight, repeat for the other. Whether top down or bottom up, it doesn’t matter, just do them both the same.

-If you elected to replace the springs, (I utilized a set from MikesXS from a 650 Yamaha. With some fussing, they will work. I don’t know who else supplies them though)

-Place a thin shim on each of the oiled posts, hook the return spring on the spring anchor post and slip the weight on the pivot post, repeat for the other side. Remember the before photo you took earlier? Refer to it if you don’t remember where stuff goes. Install the top shims on each pivot post, another drop of oil will celebrate assembly.

-The E clips are directional, feel the outside edge - the sharp edge installs up, or away from the weight. Slip it in it’s groove on the pivot post. Pay attention that the middle part of the E is in the groove. They’re quite thin, easily bent and we don’t want them to come loose in operation. Check movement again, all should be smooth from stop to stop, both weights. If not, repeat your cleaning process. It’s critical the weights have absolutely free motion.

-More oil on the base plate armature, or spindle and inside of the cam. Install cam onto the spindle with the slots at bottom. Spread both weights and worry the cam until the centrifugal weight levers engage the cam slots and drop it home.

-Important-ensure the dots, or pips, align. They are located on the end of the cam and armature. If they don’t align, your timing is 180 deg off and your engine will never run. Ever.

-Check the function of the cam. When turned, it should return quickly, even snap, back into its at-rest position. If it does, well done! If not, check springs and any other portion of your cleaning and scouring work. Either install immediately or wrap in a dry, oiled, paper towel and seal in a plastic bag for later use but protected from moisture intrusion or other damage.
 
A question to the forum at large. Is there an outlet that specifically markets the advancer springs?

My daily rider consistently hangs up at 2500-3000 rpm once warm. At cold startup, it barely idles letting me know that the advancer is free to move, it just won't return to the at-rest position for a good idle.
 
No, and they were never offered separately by or through Honda (too many subcontractors, and parts don't always interchange)......
You can clip off one hook and turn up the next half loop on one spring (to form the "new" hook)....
The unit will average out the tension difference and usually it is close to the original "pull".....
On very high mileage units I have had to clip and bend on both springs, but try only one first......
 
A question to the forum at large. Is there an outlet that specifically markets the advancer springs?

My daily rider consistently hangs up at 2500-3000 rpm once warm. At cold startup, it barely idles letting me know that the advancer is free to move, it just won't return to the at-rest position for a good idle.

I don't know of anyone selling them, but I suppose it's possible someone does. I saw someone discussing XS650 springs on HT the other day but I have no idea if they're similar enough to use.
 
Love this - I'm having the 'not dropping back to idle problem' intermittently and I've chased all the regular issues. This is my next stop. Thanks Jays.
 
...You can clip off one hook and turn up the next half loop on one spring (to form the "new" hook)....
The unit will average out the tension difference and usually it is close to the original "pull".....
On very high mileage units I have had to clip and bend on both springs, but try only one first......


Performed this fix with one spring yesterday. I adjusted the idle (1200 rpm) after a test ride with the engine hot. Today it started well - idled at 1K and after a ten minute ride it was falling back to around 12 - 1300 rpm instead of hanging at 2500. I may go in and turn up a half loop on the other spring if it seems to need it, but for the time being it seems to solve the issue.

All the parts on the advancer were clean from my spring tune-up. Carbs are in excellent shape - Idle is rock solid when spraying starter fluid around the intake boots (new), carbs, etc. Throttle cables aren't binding in any way.

This was the final idea on how to attack the hanging idle issue. I've been chasing that for some time.

This seems to have worked.

Cheers and thanks guys.
 
This thread seems like it could help me, but I'm stuck with an advancer that is missing some of the correct shims. Where do I go looking for them, and what specs are they anyway? I'm sure I need both flat and wavy, and I remember that I had to reuse the e-clips because my usually reliable hardware store doesn't have metric e-clips.
 
Unfortunately, Honda only assigned a part number to the advancer itself, not for any parts for it. So, that means you're on your own for finding the correct diameter and thickness shims. Or buy a couple of old advancers in hopes they have a shim or two.
 
Unfortunately, Honda only assigned a part number to the advancer itself, not for any parts for it. So, that means you're on your own for finding the correct diameter and thickness shims. Or buy a couple of old advancers in hopes they have a shim or two.

I'm hoping someone has an advancer in their box of stuff and can tell me the measurements of the pieces.
 
I'm hoping someone has an advancer in their box of stuff and can tell me the measurements of the pieces.

I had two advancers. Disassembled one about a year ago and both of the e-clips snapped. I believe I have all of the other parts. The flat shim is about 0.23 mm thick, the wavy one about 0.06 mm thick with an outer diameter of about 23.9 mm and an inner diameter of about 15.3 mm. Happy to send any/all spare parts to Oakland — excluding the pencil. Feel free to PM.

PXL_20230823_010647458.NIGHT.jpg
 
There are three ignition advancers from different manufacturers used on the 450/500Ts, their markings are CB450 (65-72) TEC292 (71-74) and TEC375 (75-76).

The manufacturer (Kokusan or Nippon Denso) determined how the points cam is mounted on the advancer mechanism.

They all mount and identically on the engine but the ignition advance curve varies with the year.

Btw, depending on your year 450, there are three suppliers of advance mechanism. Their parts do not interchange generally, However, they do interchange on engine.

Am I reading this correctly that the TEC375 advance mechanism is suitable for 5-speed CB450s? Without any other modifications? I recently acquired one that appears in better shape than my original CB450 advance mechanism.

I couldn't find an advance curve in the 500T manual that I have, but the 450 FSM includes the following graphic.

Screenshot_20240315-073846.png

Does anyone have something similar for the 500T? Or, Jay, could you possibly comment on the difference for the TEC375 advance curve?
 
From what I understand, the point at which full advance is reached is around 2300 for the earlier models and creeping up to around 3300rpm on later models / 500T. The graph you posted confirms this. I haven't seen the total advance bandwidth change, just the slope.

From a practical standpoint, the later advancers tend towards better return to idle but they all require servicing at every points change. I'm working on finding replacement springs and will have better information this spring once riding season starts.

As to interchangeability, the advancers are forwards and backwards compatible with all 450/500T models.

You will notice a difference between advancer and engine performance simply idling around town / stop to stop in that the bike will encourage you to keep revs up (at least that's what I've found in my own riding).
 
As to interchangeability, the advancers are forwards and backwards compatible with all 450/500T models.
Thanks for confirming, Jay.

I'm working on finding replacement springs and will have better information this spring once riding season starts.
I just ordered three types of potential replacement springs on eBay. If any of them seem close, I will test them out and report back. It may be a month or so before I get my hands on them.
 
Back
Top Bottom