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Discussion Starter #1
Right - trying to rebuild my 1964 Tiger Cub - trying to sort the timing but unfortunately the PO decided to cut extra slots the Auto Advance Unit !!

pictures attached - does anyone have a picture of where the slot in the taper should be so that I can work out which cut out engages with the notch in the camshaft ??? The biker did run quite well with this set up so if I can work out how it should be orientated I'll try and re use it

cheers

Matt
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Discussion Starter #2
Also the ATU unit is stamped 12 Degrees - Greystones on seem to list 5 and 10 degrees - any thoughts ?! tigercub8.JPG
 

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Hi,

ATU unit is stamped 12 Degrees - Greystones on seem to list 5 and 10 degrees
Afaik, Greystones is wrong. If you enter, "lucas auto advance unit", into your preferred internet search engine, it'll return links to several 12-degree references (Google returns a link for a 12-degree AAU from a 650 Bonny ;)); there's also original Lucas documentation kicking around in various www forums. The AAU with the narrower range is for ET ignition.

Hth.

Regards,
 

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Just copy Lucas 54419340 into your search engine, and you'll find a pic of the back of the ATD in a CBS listing, so you'll know the original slot.
HTH
Mick
 

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Discussion Starter #5
Stuart and Mick - thank you for your replies - To be fair to Greystones the list maybe what he has (2nd hand) rather than the complete list - Looking at the parts catalogue it slists part no 54415655 for the t20 - which is 11 degrees !! when I got the Cub it was a non - runner - turned out to be a bent valve - once sorted it was a lovely little bike to ride and me and the girlfriend pottered round Somerset 2 up quite happily - want to get the timing as good as I can, but to be honest, Cubs are no high revving 2 strokes !

thanks again chaps !
 

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Hi Matty, Exactly what model Cub do you have? It looks like 3 wire alternator so you have battery & coil ignition, with conventional round coil?

I have USA model '64 Mountain Cub. T20SM. It has 5 wire alternator with ET ignition. It used to start easy & run great. I took apart to restore bike. Have motor together, in bike & most of chassis is assembled.

I just looked at my points, cam. The cam has no pin to locate AAU! I didn't notice that when I took apart. The AAU is not in cam. I'll have to look in box of parts for AAU. I'll have to dig out the shop manual USA bikes & see what it says.
Turns out early cams with points in timing cover did not have peg for AAU alignment. Just learned that. No telling what parts my bike had in it when I got it. Looked like motor had been apart at least a few times before.

I have KIM the CD man's DVD reprints of original shop manual for '63 & '64. It doesn't address bikes with points in timing cover, but owners manual does... Looks like original AAU was 10deg for battery/coil bike, doesn't show for ET.
However '66 owners handbook shows 12deg for battery/coil bike, 10deg ET.

I'll attempt to dig up the AAU & manual tomorrow.

In the mean time, I think... If you hold AAU up looking straight on at it. Put the large notch in cam about 3:30 o'clock & hold it steady. Now feel what notch on taper is at 12:00 o'clock. That was position of original notch. Try that & see what you get.

That works for unit twins anyway. However if someone put cam on 180 deg out that would not work. That is how you can see if cam is 180 out on twins though.

No matter. You can set AAU/cam by when points open. Per '64 manual the way I see it.
Place AAU loosely in cam where it can turn, but not wobble. Put on points plate. Set gap.
Rotate motor to compression & set piston to timing position. .016b or .063b depending on compression. Turn AAU on its taper until points just open using ohm meter. Turn points plate as needed to set timing. If you lack slot travel. Unlock AAU, mark with marking pin. Pop from taper, rotate AAU as needed & check timing again. Trial & Error. That's what I'm going to have to do.
'66 owners manual shows .016 & .060 which = 8 & 16 deg at full retard. (turning motor by hand).
Don
 

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Discussion Starter #7
Cheers Don

I'm going to trail fit it like you suggest - My bike is a standard T20 - not a sports model etc - its one of the very first points in the side engine so a 1964 Model - Turns out I took a pic on my phone of the ATU when I started stripping it down - the only problem is I can't remember if the engine was at TDC ! Doh ! as I said above it should have a 11 degree ATU (according to the parts manual part no 54415749) I'll fit it and then time it - and yes mine should be the same as what the 66 owners manual shows .016 - 8 degrees -

thanks again

Matt
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Hi Matty, Exactly what model Cub do you have? It looks like 3 wire alternator so you have battery & coil ignition, with conventional round coil?

I have USA model '64 Mountain Cub. T20SM. It has 5 wire alternator with ET ignition. It used to start easy & run great. I took apart to restore bike. Have motor together, in bike & most of chassis is assembled.

I just looked at my points, cam. The cam has no pin to locate AAU! I didn't notice that when I took apart. The AAU is not in cam. I'll have to look in box of parts for AAU. I'll have to dig out the shop manual USA bikes & see what it says.
Turns out early cams with points in timing cover did not have peg for AAU alignment. Just learned that. No telling what parts my bike had in it when I got it. Looked like motor had been apart at least a few times before.

I have KIM the CD man's DVD reprints of original shop manual for '63 & '64. It doesn't address bikes with points in timing cover, but owners manual does... Looks like original AAU was 10deg for battery/coil bike, doesn't show for ET.
However '66 owners handbook shows 12deg for battery/coil bike, 10deg ET.

I'll attempt to dig up the AAU & manual tomorrow.

In the mean time, I think... If you hold AAU up looking straight on at it. Put the large notch in cam about 3:30 o'clock & hold it steady. Now feel what notch on taper is at 12:00 o'clock. That was position of original notch. Try that & see what you get.

That works for unit twins anyway. However if someone put cam on 180 deg out that would not work. That is how you can see if cam is 180 out on twins though.

No matter. You can set AAU/cam by when points open. Per '64 manual the way I see it.
Place AAU loosely in cam where it can turn, but not wobble. Put on points plate. Set gap.
Rotate motor to compression & set piston to timing position. .016b or .063b depending on compression. Turn AAU on its taper until points just open using ohm meter. Turn points plate as needed to set timing. If you lack slot travel. Unlock AAU, mark with marking pin. Pop from taper, rotate AAU as needed & check timing again. Trial & Error. That's what I'm going to have to do.
'66 owners manual shows .016 & .060 which = 8 & 16 deg at full retard. (turning motor by hand).
Don
Hello Don,
Someone else out there may know, but I'd be very surprised to see 10 deg range on an ET equiped machine, the whole ET setup was done to give near maximum flux at the alternator at the ignition point, the range of angle to give sufficient flux is pretty limited. The twins of the time (both BSA and Triumph) all used a 5 deg ATD, which kind of relates to the fully retarded ignition timings based on ET/coil rather than compression ratio. I might, of course, be wrong on this one!
Mick.
 

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Hi Mick, I agree with the 5deg.

Ok, this is odd, my ET cub has 10deg. Mind you this bike has been through the wringer. Was a dirt bike when I got it with lights removed. Seller got it from his uncle that lived in southern California & worked in Triumph dealer... Bike came with boxes of parts. Cub, 650, Bultaco, 3 Cub transmissions. Wide, STD, Close ratios. Several spare clutch parts & all sorts of stuff. Enough to make a street legal bike. I got it inspected, insured & registered, with new legal title, new license plates. Rode in briefly, a few weeks. Started & ran good. The plan was not restore, but a running Cub to ride around. Everything on bike was worn, junk. Swing arm probably had 3/4 side play. Alloy fenders had be hacked back. So I took it apart to very last part. Overhauled all that was wrong. Ran out of time & $$. Bike sat in spare room next to garage since '80 with my '73 Tiger which went in room in '79. The '73 Tiger I bought new & has been on road about 8 years now. The Cub is still in hibernation. I have $ but no time. I want to overhaul Tiger motor first, then maybe move to Cub or not.. We'll see.

I have timing stick that goes down spark plug hole with marks to set timing. I tuned up bike when I got it, but it did start & run. Decently actually. Quite good power.

Back to AAU. I dug the Cub AAU from storage. 10deg on back. So what's it from? Like I said ran good. It is indeed ET bike, ET coil, 5 wire, alternator. I've learned a lot since 1980, yet much more to learn.

The cam has no peg, no hole for peg. Look closely at photos. Someone scratched lines on end of cam. I suppose to line up AAU?? We'll see someday.

I tool AAU apart & lubed it. Not much wear. Looks like springs may have been modified?? I used vibrating pencil to make a not of how the springs were. I see you cannot put the cam on back plate 180deg out due to the long peg one side of cam.

I took some photos today. I made some notes on paper towel. With the keyway (slot) for peg if I had one is at 12 o'clock in photo. Notice no peg in cam. Cam not drilled for peg. Photos should enlarge for close details.

Bike is '64 T20SM mountain cub matching #s. Still has bushing on rod big end & the crank rod oil pump. Oval barrel. The last Cub with square barrel, roller bearing rod, slide block oil pump is the one I'd like to have. Very rare in my area! Actually most Cubs went to scrap yard years ago.
Don
 

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Discussion Starter #10
Hi Don

Previous Owners and ET being the product of the Devil .... as I said I've got a 12 degree and the parts book states for my bike it should be a 11 degree - my bike has the peg in the cam - quoting from an original owner's hand book ( from engine No 101 ) mine being 94630, the following on Ignition timing - "Earlier models have a peg in the camshaft and a slot in the contact breaker (ATU) which serves as a location for the setting but the full procedure is detailed below for later models without the peg ........"

Tiger Cub bible doesn't seem to mention 11 degree ATU's

what engine number do you have ?

I did a part rebuild on the engine 30 plus years ago when I first got it - the ATU or AUU if you prefer is the one with all the notches in it - bike ran well back then - I'm pretty sure I've worked out which notch to use ( if you look at the picture of my ATU you can see a line on the front indicating where the cam lobe is ) I'm going to go with what I've got.

Having looked on the net for other complete ATU's was interesting - there are quite a few listed on ebay USA still in their original boxes - the base plates for the part number listed for my bike looks like the type you have ( a square hole rather than the 2 round holes seen on mine) - some ATU units run clockwise rather than counter wise.

My bike was registered a few days after I was born - we're both 56 years old and both just about running OK.
 
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