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Re: Lighting no start
Nick H #815056 07/04/20 5:36 pm
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Rode the Lightning around the yard today. Clutch is easy and shifts without any effort or noise.
Had to oil the pistons for compression to start it though. Gasket seal is good but apparently I have leaks past the pistons and rings.
Or the valves still or both. New valves fit the guides better and the head held kerosene overnight, something the old valves didn't do.
Leakdown test was only slightly improved though. I could hear leaking past valves and inside case both.

The bores are 2.95" everywhere with little variation so my standard pistons and rings should be correct.
Ring gaps were .016"-.018". Would it help if I installed +.020" rings and gapped tighter?

Pleased to know my carbs, timing, wiring etc are good though. Big thrill to finally hear it fire up.

Last edited by Nick H; 07/04/20 5:40 pm.

1966 BSA Lightning
(2) 1967 Triumph "Choppa"s
1974 Indian ME125
1960 Harley Servi-Car
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Re: Lighting no start
Nick H #815069 07/04/20 7:33 pm
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Quote
Would it help if I installed +.020" rings and gapped tighter

Not in my opinion .
Larger rings will impart more friction throught all 4 strokes ... not just the power stroke .
ring drag is necessary to seal but it's also a waste of power .
spring load is supposed to be just enough
and
compression and power stroke get behind the rings and add to the rings spring-seal .

Someone else , the engine designers and ring- manufacturers have already done the hard thinking on this .
each oversized is designed to work in a bore-range .

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Re: Lighting no start
Nick H #815074 07/04/20 7:58 pm
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Ok, then I'm thinking i must need a rebore to +.020" and maybe the valve work as well to get compression where it should be.

This project has fought me all the way but I still love the bike and the A65.

[Linked Image from i.imgur.com]


1966 BSA Lightning
(2) 1967 Triumph "Choppa"s
1974 Indian ME125
1960 Harley Servi-Car
Re: Lighting no start
Nick H #815082 07/04/20 8:29 pm
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you can put larger rings in , you wouldn't be the first guy ,
but its not a magic solution .

once the bores get oversized ... they can really benefit from a Machinist
that can return the cylinders to a real geometric cylinder shape .
sometimes they didn't come from the factory cylindrical
... just within whatever tolerance was acceptable .

My old machinist , who is now retired , would show me
how are out of round my cylinders were ...
with the bores first pass as the base line . and they show/tell what he planned to do .

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Re: Lighting no start
Nick H #815086 07/04/20 8:48 pm
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Originally Posted by Nick H
Rode the Lightning around the yard today. Clutch is easy and shifts without any effort or noise.
Had to oil the pistons for compression to start it though. Gasket seal is good but apparently I have leaks past the pistons and rings.
Or the valves still or both. New valves fit the guides better and the head held kerosene overnight, something the old valves didn't do.
Leakdown test was only slightly improved though. I could hear leaking past valves and inside case both.

The bores are 2.95" everywhere with little variation so my standard pistons and rings should be correct.
Ring gaps were .016"-.018". Would it help if I installed +.020" rings and gapped tighter?

Pleased to know my carbs, timing, wiring etc are good though. Big thrill to finally hear it fire up.
It's hard to get a correct measurement on the cylinders unless a somewhat experienced machinist. If your clearance was correct for std pistons, you wouldn't be losing compression and have too large end gap on rings. Just for a ballpark I'd put pistons in and push to one side and measure clearance with feeler gauge. Myself, I leave that part to the shop I use and save myself the heartache. You know all about that by now. Surprising how much one can learn with a battle like this.


Bill
1974 Norton Commando
1966 Lightning
1965 Lightning Rocket
1966 Norton Atlas
1967 Norton Atlas
1948 Panhead
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Re: Lighting no start
Nick H #815091 07/04/20 9:18 pm
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Cool bike,
first thing I noticed , bell mouths with mesh screens,
these screens do very little to clean the air, but they really mess up air flow, get rid , fit air filters, it will go faster, or lose the screens all together and leave the kilt for later, small rocks be damned. Thats why your bores are worn. Do not fit oversize rings, Ive tried, it ran, nothing really bad happened but it used a lot of oil. Big ring gaps are OK , if it runs be happy.


71 Devimead, John Hill, John Holmes A65 750
56 Norbsa 68 Longstroke A65
Cagiva Raptor 650
MZ TS 250
The poster formerly known as Pod
Re: Lighting no start
Nick H #815101 07/04/20 11:59 pm
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It runs and I'm happy but it seems to take an oil bath to get started.

I'm thinking send the whole shebang to Michigan. Sure to be cheaper and better than local.

Thanks for tip about bell mouths. But they look cool! They are stuffed with hardware store air filter material.
I do have stock filters.


1966 BSA Lightning
(2) 1967 Triumph "Choppa"s
1974 Indian ME125
1960 Harley Servi-Car
Re: Lighting no start
Nick H #815104 07/05/20 1:21 am
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Once the back mudguard snaps off it will be time for a rebore.


71 Devimead, John Hill, John Holmes A65 750
56 Norbsa 68 Longstroke A65
Cagiva Raptor 650
MZ TS 250
The poster formerly known as Pod
Re: Lighting no start
gavin eisler #815144 07/05/20 1:25 pm
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Originally Posted by gavin eisler
Once the back mudguard snaps off it will be time for a rebore.
Alright Gavin you want to clarify that comment for me?
Are you saying rear mudguards are prone to snap off?
Time for rebore is now!


1966 BSA Lightning
(2) 1967 Triumph "Choppa"s
1974 Indian ME125
1960 Harley Servi-Car
Re: Lighting no start
Nick H #815148 07/05/20 3:16 pm
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If the rear mudguard loop is absent, the mudguard cracks at the seat loop mounts.
Stand behind the bike while someone revs the motor up and down, the rear lamp can be observed going in and out of resonance like a rattlesnake tail. I agree , time for a rebore.


71 Devimead, John Hill, John Holmes A65 750
56 Norbsa 68 Longstroke A65
Cagiva Raptor 650
MZ TS 250
The poster formerly known as Pod
Re: Lighting no start
Nick H #815245 07/06/20 1:34 pm
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Thanks, didn't realize I was missing a part.

I have read some posts where people have had the same type of piston clearance (.007 or so at the top) and ring gap (.018-.020) as I do and claim the bike runs fine which is why I proceeded with the assembly.

Is there any possiblity that some break in running time will improve the compression issue?

Last edited by Nick H; 07/06/20 1:46 pm.

1966 BSA Lightning
(2) 1967 Triumph "Choppa"s
1974 Indian ME125
1960 Harley Servi-Car
Re: Lighting no start
Nick H #815268 07/06/20 6:27 pm
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There is an old time way to bed in rings, it involves adding some fine abrasive to the inlet, I forget the name of the US brand , in the UK its called scouring powder, used as a last resort.
Someone here did a write up on it , maybe not the BSA forum but some where here.
I have never tried it, and it does sound drastic, but the write up mentioned a surprising success.
One of the US members will know the correct brand name.
I presume the oil is dumped and refreshed immediately after to clear contaminants.

First maybe give it a few hundred miles , if its no better what have you got to lose?

look at some pics of your year model, the rear mudguard loop is a black tube with runs from the top shock mounts and pics up the rear guard at the tailight housing , your rear lamp is not stock, fear not the correct type is not rare and decent repops are out there, the original loop has a couple of additional tabs for the optional grab rail. its a pretty simple affair , a person with some steel and a welder could make a decent copy. or try eBay

If you want to stick with unfiltered air, a shorter bell with no mesh will work a lot better.


71 Devimead, John Hill, John Holmes A65 750
56 Norbsa 68 Longstroke A65
Cagiva Raptor 650
MZ TS 250
The poster formerly known as Pod
Re: Lighting no start
Nick H #815272 07/06/20 7:07 pm
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One thing I’ve found with the shorter bell mouth is they are more susceptible to faltering when it rains, never had this issue with the long velocity stacks... only fun with tuning.


Now let’s all have a beer beerchug

68’ A65 Lightning “clubman”
71’ A65 823 Thunderbolt (undergoing restoration)
67’ D10 sportsman (undergoing restoration)
68’ D14 trials (undergoing transformation)

Re: Lighting no start
Nick H #815312 07/07/20 1:09 am
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The powder is called Bon Ami. I've read about using it for break in.
It's soap and feldspar and they promote it as being good for cleaning vintage car windshields.

But I'm grasping at straws here. Compression is way low. Going for the rebore.


1966 BSA Lightning
(2) 1967 Triumph "Choppa"s
1974 Indian ME125
1960 Harley Servi-Car
Re: Lighting no start
Nick H #815337 07/07/20 8:17 am
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Bon Ami was the go for Vintage bikes in the day when they were new
Back then deglazing the bore & scraping the head were items of routine maintenance.
I would be very weary of doing it to a more modern engine


Bike Beesa
Trevor
Re: Lighting no start
Nick H #818049 07/30/20 2:58 pm
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Update.
Got the cylinder back from the pricey local machinist who did an .020 bore and hone. Ring gaps were .008"-.010", considerably tighter than before.
I assembled with just a smear of oil on the front of the pistons hoping for a quick break in. Well, cold compression was not improved. I'll have to do another leak down to see what's up but this was disheartening.
Bike would not start so I reverted to the old oil on the piston top trick again and this worked. I don't know what this will do to my ring break in process but I'm sure many here will have some ideas.
Bike is not legal so I blasted around the yard in first gear for a while. Hot compression went to 90.
That was yesterday. This morning I started the bike without adding oil to the pistons again. Just a tickle and 3 kicks.
I'm hoping it continues to start easily and compression improves with break in. I don't want to have to go for valve seat work. Head has new valves and springs and holds kerosene for a day or better.

By the way, Gavin's right. Tail light shakes like jello.

Last edited by Nick H; 07/30/20 3:45 pm.

1966 BSA Lightning
(2) 1967 Triumph "Choppa"s
1974 Indian ME125
1960 Harley Servi-Car
Re: Lighting no start
Nick H #818051 07/30/20 3:26 pm
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Your compression after rebore may not be much . Seat the rings in, then check the compression. I would almost bet your problem has finally been solved. Fingers crossed.


Bill
1974 Norton Commando
1966 Lightning
1965 Lightning Rocket
1966 Norton Atlas
1967 Norton Atlas
1948 Panhead
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Re: Lighting no start
Nick H #818096 07/30/20 9:59 pm
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So I decided to strobe the engine. Here is a photo showing my primitive markings.
The left mark at the pointer is TDC and the right mark (looks like a cross) is 34 degree BTDC.
[Linked Image from i.imgur.com]
While it was strobing at idle, the rotor appeared to be frozen at roughly the point it is now in this photo,
except that only the advance mark (cross) could be seen. I could not see the TDC mark at all.
This seems odd to me. Maybe someone can explain.

I have no tach, however as I increased engine speed as far as I dared I could see the timing advance nicely.
I was concerned about this as you may recall I used 2 strong springs on my advance unit.


1966 BSA Lightning
(2) 1967 Triumph "Choppa"s
1974 Indian ME125
1960 Harley Servi-Car
Re: Lighting no start
Nick H #818098 07/30/20 10:17 pm
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“While it was strobing at idle, the rotor appeared to be frozen at roughly the point it is now in this photo,
except that only the advance mark (cross) could be seen. I could not see the TDC mark at all.”

I’m not familiar with BSAs, but why would they set the pointer for TDC rather than the useful advanced timing position (say 34 BTDC)?

Re: Lighting no start
Nick H #818101 07/30/20 10:34 pm
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With a standard points plate assembly you should see around a 25 deg shift in the
mark on the alternator. Just make sure the fully advanced point is at 34 degs BTDC.
That's around 8mm or 5/16 at the piston. That can be tweaked to suit local conditions.
With wear and the 'high precision' assembly of the centrifugal parts, accuracy in
timing before the fully advanced point is somewhat questionable. See Hookes laws
for info regarding spring behaviour etc.

Last edited by NickL; 07/30/20 10:42 pm.
Re: Lighting no start
Nick H #818111 07/30/20 10:57 pm
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So is the pointer/rotor line supposed to mean the same thing as it does on a Triumph (say for strobing)?

Re: Lighting no start
Nick H #818116 07/30/20 11:21 pm
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Yes, the line on the raised segment is the fully advanced mark.
It can be a bit confusing as there is the other hole in the cover
for the pointer, for the ET setup etc.
Just like the trumpet stuff, all Lucas junk.

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Re: Lighting no start
Nick H #818117 07/30/20 11:38 pm
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Thanks Nick, that seems to be the most important thing to know!

Last edited by koan58; 07/30/20 11:41 pm. Reason: forgot the "be"
Re: Lighting no start
Nick H #818118 07/30/20 11:48 pm
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Quote
While it was strobing at idle


Your timing marks won't line up at idle ...
Idle advance is approximately 14° B-TDC ... the engine never fires at TDC.
you can start the stobe at idle and as the RPMs increase ,
the "rotor mark" moves to the stationary-pointer and they will line up , or should line up ... at full advance .

full Advance would be ... 2500 to 3000 rpms... with points
and 5000 rpms with most analog transistor-box ignitions .

Re: Lighting no start
Nick H #818119 07/31/20 12:03 am
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Y'all missed my question. I'll try again. While strobing, the advance mark I made that looks like a cross was visible and roughly in the photos position
at idle, however the TDC mark I could not see at all under strobe light. It became invisible.

It's odd because the strobe should just freeze the motion of the rotor, right? Should appear to be still so one can read "Lucas", etc.
It mostly does this but the TDC white paint mark with black line dissappears!

Don't be confused by my makeshift marks and pointer. Part of the case where the pointer is was cracked and I repaired with JB Weld. Made a pointer from a nail and painted on my marks.[i][/i] Rotor may be on backwards.

Last edited by Nick H; 07/31/20 12:09 am.

1966 BSA Lightning
(2) 1967 Triumph "Choppa"s
1974 Indian ME125
1960 Harley Servi-Car
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