Another timing question!!

[Wenman]

Cb550 1977
Stock points ignition

Can anyone help, I have set the points statically and they are spot on, consider everything else done like valve clearances etc.

When checking the timing with a strobe I have it firing at the 'f'on idle, but when I increase revs the advance marks start to move back towards the fixed timing mark but stops moving around half way (10-15 degrees ish) and won't go any further despite he revs?

What could by causing this???

I've read some posts about advancer springs being warn but this feels like they are almost too strong and not allowing the advance to go far enough!

Thanks
Al

[deltarider]

but this feels like they are almost too strong and not allowing the advance to go far enough!

If that's the case, the advancer must be dissassembled for inspection, cleaning and greasing. We can help you with that. Has the bike been standing for a long period of time?
But first this. The proper way to time the ignition, is to verify/set the breakerpoints gap first. This is crucial. The gap should be 0,3 - 0,4 mm when points are opened at their widest. This is NOT the 'F' position. If the breakerpoints gap is not right, you will not be able to set the timing correctly
BTW, are you sure the screws are set tight (don't overdo it) so breakerpoints and plates are really fixed? See the pic and check if all the little washers and especially springwashers are there. Not every pic shows all the little springwashers. This pic does. Another possibility: your strobe is the sophisticated type that allows to dial an advance and is accidentely set at that. I haven't seen such a strobe in real life but I know they exist.

[K2-K6]

It may be worth getting a look at your advance springs to confirm from someone else on here if they are standard or not. There's quite a bit of advice around to shorten things like this,  so some tinkering could be possible prior to your ownership.

The more advanced timing strobe use the zero position of engine markings to time with,  you point the strobe at tickover and adjust the gun till the F mark is observed to line up and then read off the display on the gun what timing advance you have.

As deltarider says,  worth checking the advance mech moves freely throughout its intended range.

I recall on here recently an assembly error of the advance mech that someone corrected but can't find it, maybe someone will shout it out to cover that off.

[matthewmosse]

I had one on a cb500 where after many long hours trying to get it set right I found the whole mechanism was off a different, unknown bike. It was only when disassembling the advance mechanism next to another to see why it wasn't co operating with the timing light or willing to rev that I spotted that it was different, a double check with a few other spares conformed it was a wrong un and in a rare move for me it was hurled into the bushes as far as I could heft it.

[Wenman]

Thanks for these responses!

Inspecting my ignition plate it has all sorts missing and hardly any washers can be seen. Also looks likee the PO drilled and tapped the points screws.. must have stripped the threads!
I will order a complete plate from DS tomorrow!

The strobe is a cheap £15 one from amazon! It definitely has no display or adjustments on it!😂

The advance mech itself looks good? It's clean springs back and forth doesn't look like it's been tampered with or anything?

Keep them coming!

Alan

[Wenman]

Here's some pics of my advancer!
As far as my research tells me it is the correct one.. I think😬

[deltarider]

Yeah, that's the one, looks OK. No adjustable strobe is good too. Plate must be the culprit. Drilled holes make the adjustment wander. Plate has been messed with too much. That's why I always advocate to avoid adjusting the plates when possible. Back then experienced Honda dealer mecs tought me that they simply adjusted the breakerpoints gaps as that's where all off timing generated. Ofcourse the bikes they dealt with were owned by people that had never touched the plates but had choosen their bikes to be serviced by pro's. I'm sorry you have to go through the full routine again. As you've found out no doubt the trick is to loosen the screws just enough to be able to move breakerpoints and/or plates. If you find the crosshead screws a nuisance, you could replace them by allen screws. As a matter of fact one of the Dutch SOHC4 dealers has them in a kit for € 5,- only. http://shopfourdeel.nl/imbusboutjes-bolkop/72/imbusset-voor-ontsteking-4-cylinders.html I don't know if he ships to other countries.
1. Adjust breakerpoints gap. 0,4mm would be my pick. If you have a dwell meter aim at 46-47^o on a 4 cyl. scale (or 23-23,5^o on a 8 cyl. scale) and check reading remains stable without strong variations.
2. Set timing statically, first 1+4, then 2+3..
3. Check timing at full advance dynamically using a strobe and also check advancer for correct behaviour.
4. For the rest of your life, do not touch the plates no more and correct any future off timing by simply adjusting the breakerpoints gap.
5. If for some reason you have to dissassemble everything (to inspect the advancer) I'm afraid it will be the full routine again.
Note: Once set, timing rarely needs to be adjusted. That is as long the little felt under the cam stays well lubed and you have the ignition cover well sealed (gasket) to avoid that riding in the wet will wash away the grease from the cam in no time.

[Wenman]

Good morning,

Thanks deltraider for that.. I really appreciate the time you have gone to in replying such a comprehensive reply!
When I receive the plate I will go through the process and see where I'm at!
Do I put the new plate on as central as poss and go from there??

One other thing.. the initial problem was the advancer not going far enough! I do worry that my problem still lies here?? Despite the plate being messed around with I'm not sure if replacing this will rectify the advance problems?

Thanks again
Al

[hairygit]

It is possible to assemble the advancer 180 degrees out. Never experienced it myself, but it has been mentioned on here on a few occasions, so that could also be a possibility worth checking.

Sent from my X6pro using Tapatalk

[Wenman]

It is possible to assemble the advancer 180 degrees out. Never experienced it myself, but it has been mentioned on here on a few occasions, so that could also be a possibility worth checking.

Sent from my X6pro using Tapatalk

Thanks, I think that's impossible as there is a small locating lug on the back of the advancer unit making it impossible to put it back in any other way??

Al

[deltarider]

It is possible to assemble the advancer 180 degrees out.

I've checked the pics and his is orientated right. When you're going to replace the plate, you might as well have a look at the advancer. Careful with the 10mm head of the central bolt. It's easily damaged. If possible use a T-handle. After you've had the advancer apart (when fully wide, just lift the cam), on reassembly make sure the little carf in the rim faces the hole (near where it says TEC). I've marked them in white (at five o'clock). Another thing. Don't throw away your breakerpoints yet. If they're original TEC or ND, they're probably better than aftermarket Daiichi points.

[Wenman]

Deltraider

I thought you had it then with the calf! I've had it apart in the past and thought I must have put it back wrong.. however on checking it's actually correct!😩

Reading the manual it says if the timing is stuck in retard it can cause overheating! My engine does get uncomfortably hot so I'm sure there is def a problem here??

Al

[K2-K6]

With it off the bike, you can make a small jig with a piece of wood to bolt the mech to and keep the central static. Then you can mark the zero degrees position with a pen,  rotate the mech to see if the advance marks will reach the zero setting to check the total swing of the parts.

If they are impeded from dropping right back to no advance,  then if you succeed in static timing at that setting it won't be able to reach its max advance.

[Bryanj]

I will add to Delta's advice:-

correct gap is 0.35mm or 14 thou tolerances are for wimps!
after setting static timing re-check gap as moving the plate frequently alters the gap! Keep fettling till both gap and timing on both sides are correct

for somebody new to the job it can take literally hours to get BOTH the gap and static timing exactly right but it is worth it

[Wenman]

Thanks everyone!

Just to confirm am I right in thinking the only thing that would cause this is a faulty advancer? I'm thinking of just sourcing another unit and seeing if there's any difference??