Author Topic: timing differences - how bad and what to do?  (Read 1935 times)

Offline cotterpinkid

  • A's Best Friend
  • ***
  • Join Date: Jul 2010
  • Posts: 137
  • Karma: 2
Re: timing differences - how bad and what to do?
« Reply #15 on: 21.01. 2015 20:45 »
I had the same problem, running hot on one cylinder and cool on the other. I initially thought induction bias, but was advised to check the ignition timing. I purchased a bolt on degree disc and borrowed a timing strobe. Sure enough there was a big difference in ignition between each cylinder. The fault lay with the cam ring (which was 'new' replacement) and this was visibly evident just by comparing it with an original cam ring. Having replaced it with a BSA cam ring and re-timed the ignition both cylinders are spot on. Being able to check the timing with a strobe proved to be very worthwhile.
A10 GF Plunger
Velocette Venom

Online mikeb

  • Resident Legend
  • *****
  • Join Date: Dec 2014
  • Posts: 551
  • Karma: 12
Re: timing differences - how bad and what to do?
« Reply #16 on: 22.01. 2015 09:44 »
Triton thrasher - i can get a 0.002 inch feeler in on the sides between the cam ring and housing, but not at the top and bottom. there's a little side play but i guess it has to move.... how bad does that sound???? the ring does stick occasionally but i think this is about groove for the cable end adaptor (the next thing i need to look at).

bsa-bill - i don't quite follow why to the check piston crowns. there a couple in there somewhere and they seem to go up and down, with compression.  can you explain your thinking for me?

Some progress: so i've got the dremel out and have taken a bit of metal off so far. down to a 4-5 degree difference without too much effort at all. I think I'll get a new cylindrical stone in the morning (the current one is uneven) and have another go after that...

cheers

Mike
New Zealand
'61 Super Rocket  - '47 B33 -  '18 Triumph Street Triple RS

Online bsa-bill

  • Wise & Enlightened
  • *
  • Join Date: Mar 2006
  • Posts: 5454
  • Karma: 62
Re: timing differences - how bad and what to do?
« Reply #17 on: 22.01. 2015 10:05 »
Quote
i don't quite follow why to the check piston crowns

Sorry if this is going over old ground , maybe I missed a post as I can't see if you've checked that both pistons are identical, yes they go up and down together but if not of the same make or compression rating the crowns could be of different heights, obvious one is not going to be too high but one could be lower than the other, this will upset timming to a degree (or two - pun intended ) and would also explain in part your blue pipe on one side although I've had a one pipe blues issue before which cured itself, think maybe a stuck valve.
Anyhow I just think if it was mine I would have the head off to check unless I had installed the pistons myself and knew what they were.
All the best with it though
All the best - Bill
1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco

Online mikeb

  • Resident Legend
  • *****
  • Join Date: Dec 2014
  • Posts: 551
  • Karma: 12
Re: timing differences - how bad and what to do?
« Reply #18 on: 22.01. 2015 10:30 »
OK thanks Bill - I get your point. I've got no idea whats in there really (other than some greyish metal bits) and will think this through - see if I can find the time and courage one day. or maybe I'll find a borescope and have a quick oil-free look for a start.

cheers
New Zealand
'61 Super Rocket  - '47 B33 -  '18 Triumph Street Triple RS

Online cyclobutch

  • Wise & Enlightened
  • *
  • Join Date: Aug 2010
  • Posts: 1508
  • Karma: 14
Re: timing differences - how bad and what to do?
« Reply #19 on: 22.01. 2015 11:57 »
Roger at Cake Street did mine with a Dremel.
Various, including ...
'58 Iron Head Flash Bitza


Online mikeb

  • Resident Legend
  • *****
  • Join Date: Dec 2014
  • Posts: 551
  • Karma: 12
Re: timing differences - how bad and what to do?
« Reply #20 on: 17.02. 2015 03:00 »
ok reporting back on this cam ring issue...
i ground it back to near equivalent to the other side with the rotary tool as per triton thrasher's encouragement. did it in 3 or 4 cautious steps, checking each one back on the bike. now within 2 degrees...

started second kick! idles! purrs!

this was easier that i expected especially once i marked up the cam ring so was clear about where to grind.
if your cam ring is similarly worn (and not a housing or shaft issue) I'd say give it a go.

New Zealand
'61 Super Rocket  - '47 B33 -  '18 Triumph Street Triple RS

Online muskrat

  • Global Moderator
  • Wise & Enlightened
  • **
  • Join Date: Jul 2009
  • Posts: 8257
  • Karma: 106
  • Lake Conjola NSW Oz
    • Shoalhaven Classic Motorcycle Club Inc
Re: timing differences - how bad and what to do?
« Reply #21 on: 17.02. 2015 08:41 »
Good on'ya Mike. Split the difference, one side adv 1, the other ret 1.
Cheers
'51 A7 plunger, '57 A7SS now A10CR,  '83 CB1100F, 88 FXST .
Australia
Muskys Plunger A7

Online RichardL

  • Outside Chicago, IL
  • Wise & Enlightened
  • *
  • Join Date: Nov 2007
  • Posts: 5059
  • Karma: 48
Re: timing differences - how bad and what to do?
« Reply #22 on: 04.04. 2015 21:19 »
Using this thread rather than starting a new topic.

Guys,

I might be losing my mind (perhaps reaching that age), but I can't seem to get my timing set for the life of me. Now, I've probably timed my A10 200 times and, at least three times correctly. Today, instead of using my traditional graticule stick down a plug hole I've actually got a dial indicator right on top of the piston. After several attmpts I'm not any to get closer than 70 to 100 thousandths. Usual deal: set the depth, adjust the points till the ciggy paper pulls out, smack the pinion home using a socket, tighten the pinion bolt, recheck BTDC. A couple of other things I do: wood wedge to create friction that stops points from sliding back down the slope when reaching "just open" position, wood wedge or screwdriver between points post and cam ring to hold points tight while tightening pinion bolt (while being real careful about hurting points or cam ring), solvent clean the pinion taper.

Even some consolation would help right now if this doesn't make sense to you, either. But, it HAS to be SOMETHING I'm doing wrong or missing. Just don't get it today, for some reason.

Richard L.
Plan on signing up for the world-wide 2020 DISTINGUISHED GENTLEMAN'S RIDEon September 27, 2020 (if it's not cancelled and we are free to move about by then). Watch website at https://www.gentlemansride.com for details.

Online Triton Thrasher

  • Scotland
  • Wise & Enlightened
  • *
  • Join Date: Feb 2009
  • Posts: 1504
  • Karma: 20
Re: timing differences - how bad and what to do?
« Reply #23 on: 04.04. 2015 21:39 »

You shouldn't have to do anything with a stick at the points end.

Online RichardL

  • Outside Chicago, IL
  • Wise & Enlightened
  • *
  • Join Date: Nov 2007
  • Posts: 5059
  • Karma: 48
Re: timing differences - how bad and what to do?
« Reply #24 on: 04.04. 2015 22:06 »
Maybe not, but all I'm using the stick for is to provide a bit of friction so I can have the points fairly loose from the pinion taper when making the adjustment and preventling backsliding down the cam slope. Do you think it would better if the  pinion is somewhat snugged up while adjusting the points, so the friction comes from the taper?

Thanks for chimin' in TT.

Richard L.
Plan on signing up for the world-wide 2020 DISTINGUISHED GENTLEMAN'S RIDEon September 27, 2020 (if it's not cancelled and we are free to move about by then). Watch website at https://www.gentlemansride.com for details.

Offline duTch

  • Ricketty Rocketty Golden Flashback
  • Wise & Enlightened
  • *
  • Join Date: Oct 2011
  • Posts: 4540
  • Karma: 41
Re: timing differences - how bad and what to do?
« Reply #25 on: 04.04. 2015 22:38 »

 A little ambiguous, but I think I got my head around it- am I missing/forgetting something? I'm not sure why you have the points plate loose on the taper..?
Quote
....., adjust the points till the ciggy paper pulls out, smack the pinion home using a socket,

 I'm assuming that means you've set the points @ ~12thou", and located the points plate relative to the cam ring, so the points are just opening...? (didn't you have some U-beaut doodad where you can hook up a meter to tell when the points are just open?..)

  I suggest maybe if the points plate is not snug in the taper, you may have a false points opening setting.
Also in "smacking the pinion, you may be moving the shaft a bit....I have the gear/nut close, but just free on the taper and push it snug with fingers, hold it in place then let the nut pull it on tight...

  I also took the opportunity to do a rough version of Orabandas slotting mod to make things a bit easier- didn't really take long with a rat tail file...!

Started building in about 1977/8 a on average '52 A10 -built from bits 'n pieces never resto intended -maybe 'personalised'
Have a '74 850T Moto Guzzi since '92-best thing I ever bought doesn't need a kickstart 'cos it bump starts sooooooooo(mostly) easy
Australia

Online morris

  • Wise & Enlightened
  • *
  • Join Date: Aug 2012
  • Posts: 1595
  • Karma: 24
  • Antwerp, Belgium
Re: timing differences - how bad and what to do?
« Reply #26 on: 04.04. 2015 22:56 »
Richard, like duTch I don't think "smacking" the pinion on is such a good idea. If the taper's a good fit, pushing it on with your fingers should give it enough grip for not to move while tightening. Giving it a smack will most probably disturbing it's position
'58 BSA A 10 SA
'52 BSA A 10 Plunger
'55 MORRIS ISIS
The world looks better from a motorbike
Belgium

Online RichardL

  • Outside Chicago, IL
  • Wise & Enlightened
  • *
  • Join Date: Nov 2007
  • Posts: 5059
  • Karma: 48
Re: timing differences - how bad and what to do?
« Reply #27 on: 04.04. 2015 23:33 »
Think you are all correct, because I've now got it within a few thousandths. First step was to be snug enough on the taper while adjusting the points. This made it so they did not slide easily down the slope when getting to the "just open" position. Also, the pinion didn't change positions so much between loose and tight. Then, sneaking up on tightening the pinion while bracing the points block.

Each piece of advice was a good building block to getting my head back in order. Thanks

Richard
Plan on signing up for the world-wide 2020 DISTINGUISHED GENTLEMAN'S RIDEon September 27, 2020 (if it's not cancelled and we are free to move about by then). Watch website at https://www.gentlemansride.com for details.

Online chaterlea25

  • Wise & Enlightened
  • *
  • Join Date: Jun 2009
  • Posts: 3256
  • Karma: 47
Re: timing differences - how bad and what to do?
« Reply #28 on: 05.04. 2015 00:11 »
Hi Richard,
Musky posted a tip some time ago about holding the magneto in the correct position
remove the earth brush holder and fit a wooden dowel in place of the brush and spring
cut the dowel  to length so as it will hold the armature when screwed in partially
(or use a spare holder if you have one)

Once you have the timing set with the dial gauge ,(After fitting the cylinder head)
Make up a timing plug from an old gutted sparkplug tapped for a threaded bolt and locknut, round off the bolt end where it will meet the piston
remove the plug washer and screw it down fully into the head, then adjust the threaded bolt until it meets the piston then tighten the locknut
This tool will then stop the piston in the correct place anytime you wish to retime the engine in future

HTH
John
1961 Super Rocket
1963 RGS (ongoing)

Offline beezermacc

  • Resident Legend
  • *****
  • Join Date: Dec 2011
  • Posts: 993
  • Karma: 39
  • Not for the purist!
    • Priory Magnetos Ltd.
Re: timing differences - how bad and what to do?
« Reply #29 on: 05.04. 2015 09:07 »
A tip worth considering is the points gap, whilst ideally should be 10-12 thou the bike will run perfectly well in the range 9-15 thou. If you have set your timing and find the point of firing is a fraction retarded, opening the points gap has the same effect as retiming by taking the ATD off to advance the ignition, and vice versa of course.
The points gap limits are defined to prevent arcing and hammering. The lower limit is intended to be wide enough to prevent arcing should any fine particles find their way between the points. The upper limit is set to prevent 'hammering' - you have probably seen the impression of one contact on the other when the points faces don't line up very well - this is caused by the gap being too wide and the points crashing together, hence the term 'hammering'. The dwell angle (the amount of time the points are open/closed) is not critical as evidenced by the variety of cam rings for singles, twins and V's which have a variety of lift periods.
Priory Magnetos Ltd - A10 spares, magneto and dynamo refurbs. www.priorymagnetos.co.uk