Author Topic: Timing change on B33  (Read 1017 times)

0 Members and 1 Guest are viewing this topic.

WayneBergman

  • Blue Star
  • **
  • Posts: 58
    • View Profile
Timing change on B33
« on: 16 December, 2020, 18:37:23 »
Timing question please......I am pretty sure its my timing that has slipped from its correct setting after I have replaced my manual timing adjustment adv/retard cable. I had to pull on the cable and stretch it to fit into the lever assembly on my handlebars as the cable was too short for a new lever I have recently acquired. I have now got a proper length of cable installed so I have the right amount of slack in the system so that is all dealt with. However after this install the bike won't start or run like it did before I got to tinkering with the cable instal. I am pretty sure my timing has somehow gotten itself out of its proper setting. So my question is please......

When I pull extra tight on my manual advance cable is there any chance the mag pinion drive gear could slip on the armature  shaft or could the key stock from the contact breaker assembly perhaps been broken or is there anything that could move my timing settings by pulling too hard on the manual adv/retard cable. My mag has tight line for advance. I have a 1952 B33 with Lucas mag/dyno. I plan to bring it in to a mechanic friend for a look over but this may not be until the new year so at this point I am just curious what may have caused the timing to go funny on me. Back firing pretty good so pretty sure its a too far advanced issue here........thanks in advance.......wayne

idie

  • Golden Flash
  • *****
  • Posts: 771
    • View Profile
Re: Timing change on B33
« Reply #1 on: 16 December, 2020, 19:22:37 »
The timing will not slip because you are pulling the cable tight. You are only moving the cam which will not move beyond the stop. Take the cap off the mag and check the movement of the cam. Otherwise check the timing. Put the mag onto full advance , the points should be opening at 3/8 BTDC on an early engine and 7/16 on a later one. I run both my 49 M33 and 55 B33 on 3/8 BTDC.

WayneBergman

  • Blue Star
  • **
  • Posts: 58
    • View Profile
Re: Timing change on B33
« Reply #2 on: 21 December, 2020, 04:52:08 »
Thanks Idie for the help. I have on order one of the little tools to help find TDC mounted to the spark plug opening. I have done some reading on the timing subject but no real hands on experience with timing a bike so sorry if I have a few weird questions. I think I get the concept of how to do the timing and it all seems to make sense but I do have a few questions please......

1. If I have to pull the mag pinion gear to re set timing I will have the timing side open anyways so I am wondering if there is any value in tring to have a degree wheel somehow mounted to the Half Time Pinion on the Timing side main shaft. I would rather not open up the primary side unless I have to because my stamped cover on the primary is finaly holding oil with out leaking and also its really stuck on there. I can do it but if there is a work around like degree wheel on the timing side main shaft I would be more comfortable trying this, maybe a magnet mount on the shafts lock nut or something comes to mind. ???

2. Also, If I understand things correctly - if I use a degree wheel calibrated to proper practices for finding TDC from piston stops then I dont really have to measure the drop in inches of the piston from its TDC as I am using the degree wheel but I would like to start out with the physical measurment to check to see if the timing is even close before proceeding any further so I am also then wondering if a number from my manual like 7/16" BTDC is suggested for full advance opening of points how does the angle of the spark plug hole factor into this equation. Lets say the piston travels verticaly but my spark plug hole is angled in relation to the vertical travel of the piston.  I am thinking then if the measurement is taking at an angle like some of these spark plug hole tools seem to do, wouldnt that mean one has to use a larger number than the one in the manual. I am guessing this is a moot point but throwing the point out there for clarification?

Hope this makes sense........thanks wayne

paulm

  • Blue Star
  • **
  • Posts: 89
    • View Profile
Re: Timing change on B33
« Reply #3 on: 21 December, 2020, 06:54:32 »
if you take the points cover off and work the lever you can check if the camplate is moving, you may have jammed it if it was so tight

JulianS

  • Empire Star
  • *****
  • Posts: 2417
  • A10
    • View Profile
Re: Timing change on B33
« Reply #4 on: 21 December, 2020, 08:13:02 »
Use a spoke through the spark plug hole and keep it as verticle as possible. But make sure it cannot drop into the cylinder.

WayneBergman

  • Blue Star
  • **
  • Posts: 58
    • View Profile
Re: Timing change on B33
« Reply #5 on: 24 December, 2020, 01:02:58 »
Thanks guys, I am still wondering if I there is a good reason why everyone uses the primary side for mounting the degree wheel. Again I am a neebie to mechanics but wanting to do what I can for maintaining and tunning my new ride. Photo shows what I can see as an easier solution, if I have to open up the timing side anyways for removing the drive pinion gear on the mag why not just mount the degree wheel to the crank shaft with a magnet or something on the timing side. Saves me the grief of removing and re sealing the primary side of things.
Also the photo here is not of my motor, I am still at the head scratching part of this. Waiting for some tools etc to arrive before opening things up.
« Last Edit: 24 December, 2020, 01:05:54 by WayneBergman »

JulianS

  • Empire Star
  • *****
  • Posts: 2417
  • A10
    • View Profile
Re: Timing change on B33
« Reply #6 on: 24 December, 2020, 10:05:08 »
Been there and done it with my A10 with SRM end fed crank.

See first photo.

Still need to accurately locate TDC.

Not suitable for use with a strobe when fitting electronic ignition beause it cuts out oil flow to big ends.

For mag ignition found that bike ran just as well with timing set by rod through plug hole, slight variations in timing not quite so critical with these older machines.

Second photo show SRM timing disc fitted when using strobe.

JulianS

  • Empire Star
  • *****
  • Posts: 2417
  • A10
    • View Profile
Re: Timing change on B33
« Reply #7 on: 24 December, 2020, 11:13:08 »
Rod through plug hole on an A10.

MGI

  • Silver Star
  • ****
  • Posts: 288
    • View Profile
Re: Timing change on B33
« Reply #8 on: 24 December, 2020, 14:24:44 »
To answer one of your questions, there is no reason why you cannot fit the timing disc on the timing side!

Pete C

  • Royal Star
  • ***
  • Posts: 236
    • View Profile
Re: Timing change on B33
« Reply #9 on: 24 December, 2020, 19:27:47 »
I did try timing with a degree disc but found the stick down the plug hole to be quite adequate, even if you can't get it quite vertical.

Timing on the the OHV engines don't seem to  be too critical. I wait until I have the head off for some reason and then settle down with a dial guage to try and get it to within a few thou just for the hell of it.

The sidevalve M series are a bit more sensitive as they tend to run hot anyway and it is worth getting the timing spot on, but these engines have a timing bolt hole in the head just for this purpose.

WayneBergman

  • Blue Star
  • **
  • Posts: 58
    • View Profile
Re: Timing change on B33
« Reply #10 on: 24 December, 2020, 21:12:47 »
OK thanks guys for the tips and confirmation. I will go with a stick or tube down the plug hole and see how it goes......wayne

WayneBergman

  • Blue Star
  • **
  • Posts: 58
    • View Profile
Re: Timing change on B33
« Reply #11 on: 24 December, 2020, 23:24:15 »
I see now that my timing may in fact be too far advanced as I kind of suspected. I am getting a .002" opening at the points at a measurement of 7/16" BTDC of compression stroke - but this is with my advance/retard lever set to full retart not full advance. So when I set the handlebar lever to full advance setting I get the .002" opening at the points at about 7/32" BTDC of compression stroke. I am thinking the timing has somehow slipped from when I first bought the bike a few months back. At time of purchase it started vary easy and ticked over nicely but now back firing when trying to start etc.

Also, it was weird becase when I checked the max opening of my points (should be .012" on my bike) I was surprised to see the lock nut for the points adjustment was not snug and the whole points assembly was kind of rattling around in the breeze so I assumed this was the sole cause of the issue but now that I see that the timing is a little too far advanced I will wait for my mag pinion puller to arrive and do my best to set the timing as recommended in my manual.

Can someone tell me please when I remove the timing cover do you normally replace the gasket? I am guessing I dont have to drain the motor oil out when pulling this timing cover off or is there more oil in this timing case area than I think?.....thanks a bunch ...... wayne

Rog1

  • Silver Star
  • ****
  • Posts: 277
  • M33 Plunger and teles.
    • View Profile
    • The North Bucks Wanderer
Re: Timing change on B33
« Reply #12 on: 25 December, 2020, 01:15:35 »
As I found when my timing slipped, enough oil came out to need a small tray underneath, but I didn't have to drain the oil. I did have to replace the gasket, but as I didn't have one and needed to ride the bike I re-used the old one for a while. It leaked quite well.

WayneBergman

  • Blue Star
  • **
  • Posts: 58
    • View Profile
Re: Timing change on B33
« Reply #13 on: 25 December, 2020, 02:35:17 »
Thanks Rog1, great to know. I will follow suit.I think by my calculations my timing right now is about 6 degrees too far advanced. I may be off with my math and I have been into the ciders as well. Regardless its time to time the machine, enough talking. Oh yes its Christmas eve so I want to wish everyone a good Christmas season, blessings to you all.....wayne

Pete C

  • Royal Star
  • ***
  • Posts: 236
    • View Profile
Re: Timing change on B33
« Reply #14 on: 25 December, 2020, 11:10:12 »
I am assuming that you have not set the timing on your bike before, in which case I woud strongly recommend that you read the guide on the WM20 site at http://wdbsa.nl/ignition_timing.htm.

This relates to the M20 motor but it is exactly the same method as for the B engines.

If the timing has slipped you could check the pinion to make sure it is not cracked on the mating face.