points adjustment 1954 SR-1

Information relating to the Matchless G80 or AJS Model 18 500cc Heavyweight.
tbounds
Posts: 10
Joined: Thu Apr 20, 2017 6:20 pm
Location: mississippi , usa

points adjustment 1954 SR-1

Post by tbounds »

I have read everything i could find so far and I am still confused as to setting points. My questions I am new to AJS , but have experience with BMW which I know is different . What order do you give bike a tune up ? what is order in reference to points , timing , valves.
I would guess that timing and points would be first .

2nd I haven;t been able to figure out how to set the points , I have read one article about twisting points on advance to full advance ? clockwise or counter clockwise , then wedge a piece of wood in the to keep them in full advance . Then go to timing gears and remove gear from mag , that is where it gets screwy for me to understand .

3rd setting valves maybe a little more understandable setting them at TDC but no its BTDC by some many degrees/inches/mm.

It seems the that since all of this goes together could someone please explain the sequence of tuning and adjusting all 3 how to do and check them all the most efficient and best way. I sure wish there was a youtube video it makes it lot easier to understand to most of you appears so simple .

thanks sorry for long post.
Tony
Johnobirches
Member
Posts: 155
Joined: Mon Jul 08, 2013 10:19 am
Location: Lancs. UK

Re: points adjustment 1954 SR-1

Post by Johnobirches »

Hi Tony,

You need to get the maintenance manual for your bike all the information will be in there – correct sequence and what to do etc. – with diagrams. You should find it here http://archives.jampot.dk

You time the valves by setting the two toothed gears in the engine's timing cover in correct orientation with the pinion on the end of the crankshaft. The gears and pinion have reference dots to help but it differs from bike to bike.

The points, or contact breaker gap, is set inside the cover of the SR1 by rotating the engine until the points are fully open and checking the gap is right (12 thou for my bike) and adjusting as necessary.

Next you set the magneto [SR1} timing by rotating the crank to the correct position (1/2” Before Top Dead Centre BTDC in my case- with both valves closed i.e. pushrods in lowest position) with the advance retard lever or mechanism set or wedged at full advance now - with the magneto chain case off you put both upper and lower sprockets and chain as a unit into position and tighten the two sprockets on to their centres. When you tighten the mag sprocket the chain may go too tight so you have to loosen, rotate the mag body and platform and repeat.

This isn't gospel as there might be differences for your bike but the manual for mine ‘56 AJS 16MS 350cc had all the steps and pictures I needed to do it for the first time and the bike fired up no problem.

If I've remembered this wrongly others will step in I'm sure.

Good luck.

John
tbounds
Posts: 10
Joined: Thu Apr 20, 2017 6:20 pm
Location: mississippi , usa

Re: points adjustment 1954 SR-1

Post by tbounds »

i looked at the pittman manual and it explains a lot better . I still have a questions that is probably dumb , but it says to check timing on the SR1 automatic advance to rotate ignition control mechanism fully with fingers . questions what is ICM is it the where the points are ,is it on the other side of engine , how to access and rotate ? and which way do you rotate while looking at it clockwise or counter clockwise?
another question it says to remove sprocket from shaft of the armature mag shaft , i think this is the sprocket at top front of chain? when I remove sprocket and the chain is still attached how do you rotate it counter clockwise to check breakers without the piston and crank moving ? Or does the chain come off for this . It say once the slightest break open of points to replace sprocket and tighten.
thanks again.
User avatar
Rob Harknett
Member
Posts: 11236
Joined: Mon Jan 01, 1990 12:00 am
Location: ESSEX UK

Re: points adjustment 1954 SR-1

Post by Rob Harknett »

You are mixing up two things.
One setting the points gap.
Two setting the ignition timing.
tbounds
Posts: 10
Joined: Thu Apr 20, 2017 6:20 pm
Location: mississippi , usa

Re: points adjustment 1954 SR-1

Post by tbounds »

Its is my understanding and it could be wrong that to adjust points rotate engine forward until points open to their widest point which should be between
.010-.012 , if they are not in that range loosen adjusting plate and rotate until with in tolerances.

The time only involves the slightest open of breaker to set timing gear which requires rotating the Ignition advance i don't know what it is for sure or which way to rotate.
User avatar
clive
Member
Posts: 5657
Joined: Mon Jan 01, 1990 12:00 am
Location: LONDON UK

Re: points adjustment 1954 SR-1

Post by clive »

tbounds02 wrote:....questions what is ICM is it the where the points are ,is it on the other side of engine , how to access and rotate ? and which way do you rotate while looking at it clockwise or counter clockwise?
another question it says to remove sprocket from shaft of the armature mag shaft , i think this is the sprocket at top front of chain? when I remove sprocket and the chain is still attached how do you rotate it counter clockwise to check breakers without the piston and crank moving ? Or does the chain come off for this . It say once the slightest break open of points to replace sprocket and tighten.
thanks again.
The ICM or auto advance is part of the sprocket at the other end of the mag from the points. It should be under the bulge in the mag chain cover. It shoud have two springs on it and bob weights which open up as the speed increases. To check/set the timing rotate the unit so that the bob weights come out and jam it open with a bit of wood.

I would not remove the auto advance/sprocket attached to the mag unless you have to. It has a weird inbuilt removal system which I can only get to work with lots of fiddling. Instead loosen the sprocket at the other end (attached to the cam gear). This then allows you to set the timing. I have never managed to get it to work tightening the sprocket at the mag end anyway. Whichever way you do it check once you have set it as it often moves whilst you are tightening it up. Remember to take your bit of wood out once you have double checked it. Leave the chain on throughout.
clive
if it ain't broke don't fix
User avatar
Rob Harknett
Member
Posts: 11236
Joined: Mon Jan 01, 1990 12:00 am
Location: ESSEX UK

Re: points adjustment 1954 SR-1

Post by Rob Harknett »

tbounds02 wrote:Its is my understanding and it could be wrong that to adjust points rotate engine forward until points open to their widest point which should be between
.010-.012 , if they are not in that range loosen adjusting plate and rotate until with in tolerances.

The time only involves the slightest open of breaker to set timing gear which requires rotating the Ignition advance i don't know what it is for sure or which way to rotate.
The topic title is Points Adjustment. So you rotate the engine until the points are fully open, you can see this as the mag cam moves round to its high point opening the points. The gap should be about 10 /12 thou. If not, loose the two points plate screws and move the plate until you have the correct gap. Re tighten the screws, give the gap another check to make sure its correct, job done. Your points are now set at the correct gap.
Timing the ignition involves loosen the AR unit bolt and jamming the unit open. It should be in the shut position, so you can only rotate it one way, that is to open and advance it. When you let go it will shut. If the bike was running ok, do not alter the ignition timing.
tbounds
Posts: 10
Joined: Thu Apr 20, 2017 6:20 pm
Location: mississippi , usa

Re: points adjustment 1954 SR-1

Post by tbounds »

So am I correct in thinking when referring to the auto advanced unit , they are referring the centrifugal mechanical advance unit ? Do u have to loosen nut or just spread the arms ?
User avatar
Rob Harknett
Member
Posts: 11236
Joined: Mon Jan 01, 1990 12:00 am
Location: ESSEX UK

Re: points adjustment 1954 SR-1

Post by Rob Harknett »

I am not sure why you ask this question. If you intend to take things apart with out knowledge of what you are doing, you will create yourself some problems. Do not undo anything on the A/R unit unless the bike needs the ignition timed.
If you remove the timing chain cover. You will see the A/R unit. It will be in the closed position ( fully retarded ) theres a couple of bob weights and springs, and stops. Do not undo anything. Get hold of the thing with your hand, you should be able to turn part so it opens up fully advanced. When you let go it will snap shut again. If it will not turn it may be seized. Pour petrol or similar on it while trying to turn it , keep washing it clean inside until it turns free and snaps shut.
tbounds
Posts: 10
Joined: Thu Apr 20, 2017 6:20 pm
Location: mississippi , usa

Re: points adjustment 1954 SR-1

Post by tbounds »

I ask this question because you said earlier to loosen nut on ar ? I was confused as why i needed to loosen nut on centrifugal advance unit to to spread it?
I do have knowledge of mechanics although I am not a professional mechanic.
I joined and paid for my membership as suggested by members to gain knowledge about doing work on the bike . I have worked on several BMW's , Harley , CZ's ,Hodaka's , Yamaha's , Kawasaki's ,Honda's .
I didn't realize the level of knowledge required to ask questions on this forum . I do apologize for bothering you may I suggest that maybe you should just ignore my posts in the future if you feel I am not worthy enough to ask questions .
Thanks for your help so far and I do appreciate your help
Locked