Topic: Degree wheel for CB550K timing - ideal wheel size?

[Erny]

I'm preparing to install Megacycle 126-00 cam info my CB550K1 engine.

It will be my first timing, so excuse me if I ask something stupid
I understand the principe however (some details I still need to re-read as english is not my native language).

If I understood properly recommended is to use alternator side to place degree wheel (10mm bolt on rotor).

I'll do my own custom wheel, I found great tool to create your own wheel here: https://www.blocklayer.com/degree-wheel.aspx

Now the key question, size: due to protractor resolution and precision, wheel should be the bigger the better, but still what is reasonable biggest size to work with?
I can print on 1 A4 sheet max approx 190mm OD. Looks already giant 

Any practical recommnedation from you folks who did it already?

Attached example

[turboguzzi]

mine is 180mm
recommendations:
-glue it to some thin plexiglass if you want it to last
-craft some sort of good indicator to get the reading, i attached a thin metal strip with an arrow at the end to one of the starter mount bosses
-build yourself a piston stopper to from an old plug to find accurate TDC, google "piston stop TDC" if you dont know what im talking about...
-think well about what you are doing when you use the piston stop, easy to bend a valve if you turn the engine in wrong direction...
 

[MRieck]

10" is pretty standard though, as you alluded to, the larger the wheel the better the resolution.

[fantino]

I just finished doing this from the same online template - I used a 10" wheel, any smaller I personally would have found a bit tough to accurately discern reliably down to half a degree, depending on how precise you're trying to be.

As TG suggested, putting it on a piece of plexi is very helpful. I was feeling extra and printed an indicator to attach to the side of the case because I kept bumping into the piece of bailing wire I had been using and found it a little ambiguous depending on the viewing angle.

Next time I will face the wheel towards the inside of the motor as there was a lot of leaning over to look at the marks on the wheel while turning the motor from the points side.

Idk if this is more or less accurate than a piston stop, but I already owned this little sliding TDC gauge to use on a 2-stroke scooter I have, so I put a dial gauge on the end of it and found TDC by comparing the piston lift at +\- 30deg TDC - but you definitely have to pay attention to backlash from the cam chain with this method (esp if chain is not new) or only turn the motor in the correct direction of rotation.

[turboguzzi]

while its true that bigger is better, in the case of a timing wheel, IF you use it also for dynamic ignition timing with a strobe gun, a bigger wheel tended to loosen up when i revved the motor, a smaller one was easier to keep fixed on the crank. if its just for setting the cam, then yes, bigger = more accuracy.

fantino, put a mirror next ot the wheel if you dont want to run to the other side of the bike all the time

is that project of yours running? remeber it from eons ago.

[MRieck]

I just finished doing this from the same online template - I used a 10" wheel, any smaller I personally would have found a bit tough to accurately discern reliably down to half a degree, depending on how precise you're trying to be.

As TG suggested, putting it on a piece of plexi is very helpful. I was feeling extra and printed an indicator to attach to the side of the case because I kept bumping into the piece of bailing wire I had been using and found it a little ambiguous depending on the viewing angle.

Next time I will face the wheel towards the inside of the motor as there was a lot of leaning over to look at the marks on the wheel while turning the motor from the points side.

Idk if this is more or less accurate than a piston stop, but I already owned this little sliding TDC gauge to use on a 2-stroke scooter I have, so I put a dial gauge on the end of it and found TDC by comparing the piston lift at +\- 30deg TDC - but you definitely have to pay attention to backlash from the cam chain with this method (esp if chain is not new) or only turn the motor in the correct direction of rotation.

Turn the wheel around and read it from the right side of the engine. Much easier turning the spark advancer and reading the numbers. You also don't have to worry about disturbing the wheel which can happen by using the rotor bolt.

[fantino]

fantino, put a mirror next ot the wheel if you dont want to run to the other side of the bike all the time

is that project of yours running? remeber it from eons ago.

Haha yeah, I definitely learned my lesson this time. I'll do either what you or Mike suggested.

My CB500 project took an extended hiatus. I picked up a couple major house restorations in addition to my day job over the last few years which consumed all of my spare time and money. Those are finally wrapped up and rented out, so I'm back to it. Not getting my hopes up too much to be going on any long rides on it this season, but it'll at least be running and starting to work on tuning at the current pace

[Erny]

Thanks for advices, gents!

In my case, I'm going to perform timing with engine in the frame - wondering if I can still use 10'' wheel w/o being in conflict with something