Ingition advancer

If it's broken or just needs tweaked

Moderators: Volker_P, tidd650

User avatar
Ibsen
Posts: 375
Joined: Fri Mar 03, 2006 12:09 pm
Location: Kongsvinger, Norway
Contact:

Ingition advancer

Postby Ibsen » Tue Nov 27, 2007 3:56 pm

The ignition advancer on my 650 have been neglected by the previous owner(s), I suspect it must have been rusty, and it is rattling at idle due to wear. Also the springs for the counterweights are too weak, causing the ignition to advance a little too early. I have bought a replacement advancer, it came from a 1980 CB650 US model, that is in great shape, and so far everything looks good.
However, there is a number stamped on both advancers and they don't match. The original advancer have got the number 426 stamped on it while the one I bought have got the number 460. I wonder of any of you with a 63hp engine, preferably the 650Z European engine, would be so kind and check the number stamped on their advancer. (You only have to take off the ignition cover and maybe turn the engine a little to spot the number.) And it would be nice if those with the 63hp US model engine, and those with the 50hp European engine would do the same.
I wonder why Honda have put an advancer with a different number in different engines, and what the difference might be?

User avatar
Volker_P
Posts: 5508
Joined: Mon Mar 06, 2006 1:53 am
Location: southern Germany

Re: Ingition advancer

Postby Volker_P » Wed Nov 28, 2007 2:04 am

As you probably know, the 426 is the model code number for the RC03 while 460 is the RC05 model code. Identical parts may have different part numbers in the lists of different models. Many years ago the lists seem to have been "optimized" in the sense that each part is identified by exactly one number.
However it is still strange that the number is stamped on the part itself at all. I will have a look, but my CB stands with the ignition cover to the wall for some months. :roll: And I should have a Z-model advancer somewhere. :lol:
From a phone call with an expert last year, I heard that the 50-63hp transition implies a jet change if it should be done really optimized but he did not talk of ignition modifications.
The difference might be a higher advance angle to shift torque somewhat to higher rpm at the 63hp@9000rpm engine.

User avatar
Ibsen
Posts: 375
Joined: Fri Mar 03, 2006 12:09 pm
Location: Kongsvinger, Norway
Contact:

Postby Ibsen » Wed Nov 28, 2007 11:13 am

I must admit, the model number didn't occur to me as an explanation. I have seen the model type stamped on Kawasaki advancers though. Like KZ750 and KZ400 for their 70's twins. And the reason for this is that the advance curve are very different for these two models.
So if Honda stamped the timing advancer with a number for the 79 model and another number for all the 1980-1982 models the reason could be that they are different.

User avatar
Volker_P
Posts: 5508
Joined: Mon Mar 06, 2006 1:53 am
Location: southern Germany

Re: Ingition advancer

Postby Volker_P » Thu Nov 29, 2007 2:18 am

Well, usually all K-Model part numbers (at least following the original intention) should have a "-426-" somewhere in the center. First part of the numbers also have (or at least had) a meaning with regard of their function or location at the bike. At least that's what I heard a long time ago and it fits a bit what I found in lists. So if you ever get a real cheap part of unknown origin with a *-426-* Honda part number and it looks good, collect it as you most probably can use it. :wink:

Back to your item: I had a look on an advancer which is most probably on a 63hp Z-model engine. It carries the "426" stamp. I write most probably because I got it out of a Z-model but the P.O. already replaced the original 50hp Z-model engine by this one. But it has the finned top side covers and a 63hp camshaft (while the bike documents say 50hp) what speaks clearly in favor a 63hpZ-model engine. In case this is of any use for you: the engine number is RC03E-2024815.
I already was able to find the original 50hp engine bottom part too, but the side cover was not accessible that easy. I could try this weekend if this is interesting for you.

Did you try to compare the moving/advancing angle? You could also check whether the T, F and other marks spacing is different. However in any case I would not expect more than a few degrees discrepancy, so it will be difficult to see if there is something to see at all.

User avatar
Ibsen
Posts: 375
Joined: Fri Mar 03, 2006 12:09 pm
Location: Kongsvinger, Norway
Contact:

Postby Ibsen » Thu Nov 29, 2007 10:21 am

Thanks Volker. 8) And no, I haven't taken the old one off yet. It's too cold for wrenching right now.

And I have searched trough the parts lists and this is what I found:

Timing advancer parts # for the 1979-1980 650Z US and European model: 30220-426-174 (replaces 30220-426-164)
" " " " 1981-1982 650, 650C and 650SC US model: 30220-460-771

So it looks like the number stamped on the advancer is the model number. And following this logic it does indicate that Honda made changes to the advancer for the 1891 and 82 models. This is just a guess, but one reason could be that these models have got CV carbs.

The only way to find out if the one I bought works for my 80 Euro model, and if there is any difference, is probably by installing it. :lol:

User avatar
Volker_P
Posts: 5508
Joined: Mon Mar 06, 2006 1:53 am
Location: southern Germany

Re: Ingition advancer

Postby Volker_P » Fri Nov 30, 2007 1:50 am

Interesting, so following your parts list information, all my advancers would be "426" and the advancer of the original 1982 Z-model 50hp engine (with CV carbs) would be my only "460". I will try to check this out some time. :roll:
I think one thing where one might feel a difference first, is a possible shift within the 3-4krpm region where you sometimes get a ringing noise at load.

If it refuses to start with the new advancer, try it backwards. Empty streets and larger mirrors may be helpful during the first time. :lol:


Return to “Technical Discussion”

Who is online

Users browsing this forum: No registered users and 47 guests