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'69 A65L, my best tickover yet #38328
05/01/08 12:55 am
05/01/08 12:55 am
Joined: Mar 2006
Posts: 1,011
Canada
Gunk Offline OP
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Gunk  Offline OP
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I've declared victory so many times. Only to find it can still run better. I am pretty happy with it.
What do you think?

Tickover video


"he who laughs fast, laughs first"~Gunk
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Re: '69 A65L, my best tickover yet #38329
05/01/08 1:39 am
05/01/08 1:39 am
Joined: Nov 2004
Posts: 1,694
georgia
T
trumpetloon Offline
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georgia
Having followed your carburetion odyssey; I have this comment. You have a clearly obsessive/retentive personality; and an uncanny genius for making really old British bikes run unbelievably smoothly (at least at idle). Please condense and present your journey to this point as a synopsis here, and congratulations on making your BSA idle like a Honda. :g:


1974 TR5T
Re: '69 A65L, my best tickover yet #38330
05/01/08 2:18 am
05/01/08 2:18 am
Joined: Mar 2006
Posts: 1,011
Canada
Gunk Offline OP
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Gunk  Offline OP
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Canada
I owe it all to Britbike.com
hard work and and no drugs.


"he who laughs fast, laughs first"~Gunk
Re: '69 A65L, my best tickover yet #38331
05/01/08 9:19 pm
05/01/08 9:19 pm
Joined: Sep 2007
Posts: 57
Smurdley Offline
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I'm glad to hear your's makes all that top-end racket too.

I just got mine running decently, and I had some concerns about that...


OVBSAOC #4062
1968 BSA A65L Lightning
2005 Triumph Bonneville
Re: '69 A65L, my best tickover yet #38332
05/01/08 9:57 pm
05/01/08 9:57 pm
Joined: Mar 2006
Posts: 1,011
Canada
Gunk Offline OP
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Gunk  Offline OP
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Loud valves save lives!
There's no desmo drive in that motor.
Guess that's why they are called tappets.


"he who laughs fast, laughs first"~Gunk
Re: '69 A65L, my best tickover yet #38333
05/03/08 1:29 am
05/03/08 1:29 am
Joined: Aug 2001
Posts: 3,884
Cape Carteret, NC
M
Mr Mike Offline
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Cape Carteret, NC
New carbs with proper set and they will idle nicely. I can turn mine down to 500-600, but usually keep it at 800-1000 for the better oil pressure. Before the new carbs I could never get it right. By the way the it sounds just like mine.... a little clack up on the top end.

Mr Mike

Mr Mike

Re: '69 A65L, my best tickover yet #38334
05/03/08 1:38 am
05/03/08 1:38 am
Joined: Feb 2006
Posts: 307
Saint John, New Brunswick
BSACafe Offline
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Saint John, New Brunswick
Wow!!! Nice work Gunk. Now come to NB for a vacation and set me up!!! Once you are here, I'll take care of your room and board....and you won't run out of work. Sound good?


Jer

http://www.caferacer.ca

1968 BSA Lightning Cafe
1968 BSA Thunderbolt
1969 BSA Royal Star
1972 BSA Thunderbolt
Re: '69 A65L, my best tickover yet #38335
05/03/08 10:56 am
05/03/08 10:56 am
Joined: Mar 2006
Posts: 1,011
Canada
Gunk Offline OP
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I'd like a spot near the river.
How in the heck did you end up in Saint John?

These are original carbs. No sleeves.
I just worked on increasing the vacuum seal with the manifold side by lapping the slides in with fine carbide grit.
I did 4 carbs with 3 great results. If there is little (<.005) side to side play, they can be saved.

Or, you can buy new carbs.


"he who laughs fast, laughs first"~Gunk
Re: '69 A65L, my best tickover yet #38336
05/03/08 12:33 pm
05/03/08 12:33 pm
Joined: Mar 2005
Posts: 568
the dungeon, in N.W. Ohio
Mitch C. Offline
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the dungeon, in N.W. Ohio
So how did yuo lap in the vacauum side anyway... I would like to do so, it has me interested.

Re: '69 A65L, my best tickover yet #38337
05/03/08 1:06 pm
05/03/08 1:06 pm
Joined: Sep 2007
Posts: 1,134
Ottawa, Canada
gREgg-K Offline

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Good work, Gunk.

Let me see if I understand what you did: you had Concentrics with the classic worn & loose slides, but you were able to reclaim them by lapping the engine side of the slide to the body?

... Gregg


Spyder Integrated Technologies
Lucas, BTH, & Miller Magneto & Dynamo Restoration
SMITHS Chronometric Restoration
magneto@spyder-it.com
Re: '69 A65L, my best tickover yet #38338
05/03/08 2:22 pm
05/03/08 2:22 pm
Joined: Mar 2006
Posts: 1,011
Canada
Gunk Offline OP
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Gunk  Offline OP
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Yup.
I welded a piano wire with a threaded end to the tip of an old jigsaw blade.
Then I clamped the carb body into my vise with a heavy layer of soft foam, the intake flange faced up.
The slide was painted with layout blue, steel blue, layout dye... whatever you call it.
The slide was fastened to the end of the wire with low profile nuts (necessary to avoid crashing into the brass jet tube).
The blade with wire was attached to my variable speed jigsaw and the saw was clamped to my bench, raised appropriately to align the blade horizontally with the slide inserted in the slide bore.
The assembly was adjusted until the slide just bottomed out in the slide bore. The wire was sufficiently long to act as a spring, preventing the slide from slamming on the bottom of the bore with force.
Now the jigsaw acts to move the slide up and down in the bore at variable speeds.

Now the mechanism is operated with vacuum from a shop vac applied to the intake flange.
After a few dozen strokes, the slide is removed and will display a wear pattern, revealed by the removal of the layout blue. This will give an immediate visual indication of the amount of lapping to be done.

Caution!!!!!!
Before proceeding be aware, use of a highly flammable solvent in this procedure WILL RESULT IN AN EXPLOSION AND FIRE.
You must avoid using flammable aerosol spray lubricants in lapping the slides with a shop vac. Use only light machine oil.

Starting with a 280 carbide grit, drop a pinch of grit onto the slide through the flange opening.
Wet the grit with light machine oil.
Operate the jigsaw, at slow speeds first until you achieve free movement, then increase speed gradually, you should begin to hear a tapping as the slide touches the bottom of the stroke.
When it is operating properly, apply vacuum from your shop vac to draw the slide to the manifold opening.
Replace the grit and oil every few minutes or so as required, some will be drawn into the vacuum.

The layout blue is very resistant to oil and will begin to show indications of the surfaces mating properly. At the 80% mark, wash the slide and body thoroughly and repeat with 400 grit.

At the 90 % mark wash and replace with 600 grit.

Each operation should take less than 1/2 hour.

If the slide is very worn, this will not work.

You may speed the procedure by pushing the intake side of the slide with your finger while lapping.

Obviously, every part of the carb must be washed and flushed repeatedly after this procedure to remove all traces of grit.

There are contact points on the inside lip of the slide at the intake side at each side of the cutaway. These may interfere with the lapping and should be ground down VERY SLIGHTLY (.002) before beginning.

Remember, this is just a story about what I did, not a recommendation or endorsement of a method.
I judge this to be effective in many, but not all cases.
I would have to do many more before perfecting this method.

This was inspired by a single statement on the television show "Tank Overhaul", where the restorer said "British machining was nowhere near American standards at this time, and as a result, many parts required hand-fitting."

I included a video with no padding around the carb just for clarity.

I got the carbide grit from Lee Valley Tools, who operate a mail order.

The single-most important factor in obtaining a smooth low speed idle is IMHO obtaining maximum manifold vacuum.
Short demo video

This procedure will remove very little metal if done correctly, The overall gap will increase, and the slide will not be perfectly round, however air leaks around the slide will have little effect on greater than 1/8 throttle openings.
Total slide to bore clearances should not exceed .005"
When you think you are done, clean everything thoroughly and retry the slide with just layout blue. The wear patterns should be even, and show a nice football shaped pattern with clean sharp edges.

Cheers! going riding now.

Gunk


"he who laughs fast, laughs first"~Gunk
Re: '69 A65L, my best tickover yet #38339
05/03/08 11:57 pm
05/03/08 11:57 pm
Joined: Aug 2001
Posts: 4,256
argyll. scotland, uk
gavin eisler Offline
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argyll. scotland, uk
Gunk ,you are a brave man , carborundum grit and soft alloy is bad news, some will inevitably be left behind embedded in the alloy. Your slides didnt fit because the carb bodies were distorted.
I think it is better to remove the body distortion by replacing or mechanically removing the oval than extremme lapping in.
I have done something similar with blue and wet and dry to a visitors bike when the throttle was jamming at wide open but purely as a get home safely bodge.
On the plus side your slides wont jam at full throttle because they are loose, on the negative side they will wear rapidly and have air leaks, they are also responsible for the some of the clatter at tickover, try taking the filters off and pushing the slides tight to the inlet side when ticking over , some of the "tappet " noise will disappear.They are rattling loose in the carb.
Cheers
pod


71 Devimead A65 750
56 Norbsa 68 Longstroke A65
Cagiva Raptor 650
MZ TS 250
The poster formerly known as Pod
Re: '69 A65L, my best tickover yet #38340
05/04/08 12:57 am
05/04/08 12:57 am
Joined: Oct 2004
Posts: 1,058
San Francisco
Redman Offline
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San Francisco
Mine are sleeved Monos......I may take them off and check them with blu-ing.......I have had problems with one side at idle and just above for a while now.Hmmm....Buster is down waiting for parts anyway....


Life is short but very wide.
Re: '69 A65L, my best tickover yet #38341
05/04/08 1:46 am
05/04/08 1:46 am
Joined: Mar 2006
Posts: 1,011
Canada
Gunk Offline OP
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Gunk  Offline OP
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Canada
Hey Pod.
You have much more experience than I and I respect that. But try and give me a little credit.
My carbs are not badly warped, I straightened them out 2 years ago. Recently I tried to address the problem of fitting the slides better by purposely forcing the lower 1/3 of the bore to fit the slide profile better. Still, I was getting too much air leaking around the slide at the sides. A .002 feeler passed easily at both sides of the slide from the manifold side to the intake side with finger pressure forcing the slide tight to the manifold side. This cannot support vacuum.
Over the past two years I have read stories of carbs working perfectly even as slides were worn paper thin (look up paper thin using the search tool.) JH says the normal clearance is .0035-.004
I have exceeded this by .001 on only one side.
I performed this experiment on 4 carb bodies with only one failure. I decided not to proceed on the last one since the clearance would exceed .005.

This is a game for me. A distraction.
But there is no excessive play.
The slides are not rattling around. Frankly it would be more interesting if I could make that happen. I've tried to simulate the effect that would fracture the slide by attaching it directly to the intake on my 2 hp compressor pump, sadly I could not break the slide.

I've conquered the beast and decided the AMALs are just a crappy carb, no big news of course.
If there is carbide 600 grit imbedded in there,it will only serve to provide a high polish.
The purpose of stepping through the grades is to prevent exactly the problem you speak of, and is a proven method for polishing.
Stepping from 280 right to 600 would be a problem.
Proper polishing REQUIRES a progression of grits.
But a cylindrical slide in a cylindrical bore is a pitifully bad design. That's why nobody makes them like that anymore, except those that are produced from 30-40 year old designs.

And the 1/8" microphone diaphragm in the camera I used for the video is naturally more responsive to tinny noises. The bike does not sound "clicky" like that in person.

They will get me through the season. Then it's the Keihin carbs for me. If business had been better last year I would have bought them instead of trying this.
Anyway, I've got all summer to prove the method is a failure, and I won't hesitate to let everyone know if things fall apart. Stay tuned.

And remember, it's just a story. I'm telling all of you. If you do this you will probably regret it.

Or maybe not.

By the way, I stole a lot of my method from a fellow who was rebuilding carbs for an airplane engine. He seemed to know what he was doing.


"he who laughs fast, laughs first"~Gunk
Re: '69 A65L, my best tickover yet #38342
05/04/08 1:21 pm
05/04/08 1:21 pm
Joined: Aug 2001
Posts: 4,256
argyll. scotland, uk
gavin eisler Offline
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argyll. scotland, uk
Hi Gunk.
didnt mean to sound so disparaging, youve obviously been very methodical and used best practice, mare power to your elbow.
My own lighting, which runs with no air filters , gets noticeably quieter when I fit new slides.
I like concs because they are easy to work on, but I treat them as consumables, after the 2nd set of new slides I change the bodies out, still on the original float bowls, floats and lids though.
Like my favourite hammer, only had one new head and three new handles.
Cheers
Pod


71 Devimead A65 750
56 Norbsa 68 Longstroke A65
Cagiva Raptor 650
MZ TS 250
The poster formerly known as Pod
Re: '69 A65L, my best tickover yet #38343
05/04/08 10:10 pm
05/04/08 10:10 pm
Joined: Mar 2006
Posts: 1,011
Canada
Gunk Offline OP
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Gunk  Offline OP
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LOL
Good on ya.
I think you have a healthy approach to these gizmos.
I'll save them in the box that goes to the next owner.

Ciao!


"he who laughs fast, laughs first"~Gunk
Re: '69 A65L, my best tickover yet #38344
05/05/08 12:28 am
05/05/08 12:28 am
Joined: May 2008
Posts: 1
Oakville, Ontario Canada
G
George Chisholm Offline
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Oakville, Ontario Canada
Hi Gunk,
You have the best starting and idling BSA I have ever heard.
I live in Oakville, Ontario and own a 72 BSA Lightning.
Where do you live in Ontario?
Regards,
George

Re: '69 A65L, my best tickover yet #38345
05/05/08 7:07 am
05/05/08 7:07 am
Joined: Aug 2001
Posts: 1,719
BC Canada
441/R3cafeSteve Offline
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Gunk it is awesome sounding, would like a crack or two on the throttle though.
I think the suction really makes the front face the essential surface but as many of use have seen a lot of bikes that are just idled have the tell tale damage to slide in the form of a smile or cresent ridge. This once put to use actually moving up and down damages the body top inlet edge by skipping as the ridge pasess and wearing it faster under load. I have only cleaned slides and buffed them on lathe. I think the more metal you remove the less time you have to use the carb. High polish on the slide like a mik slide appearance will stop a lot of sticking issues. You can't see it but that grey patina is thick and not a good sliding surface. I have not had slide issues in ten years polishing mine each season.
Steve
-the next step is to autosol the slide and silvo clean the body (less abrasive chemical peel LOL!) then both slide and seall well imo.


The 441, most versatile BSA of the 60's
Re: '69 A65L, my best tickover yet #38346
05/05/08 12:14 pm
05/05/08 12:14 pm
Joined: Mar 2006
Posts: 1,011
Canada
Gunk Offline OP
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Burlington George. We are neighbors.
And thanks.
The bike was warm already when started for the video.
It's actually quite cold blooded. Takes about 2 minutes to really warm up and start running well.
It's easy enough to start cold tho.

I'll post a new video shortly to show it revs too.
And I'm going to grab a can of Silvo and try it Steve.


"he who laughs fast, laughs first"~Gunk
Re: '69 A65L, my best tickover yet #38347
05/08/08 1:37 am
05/08/08 1:37 am
Joined: Apr 2006
Posts: 1,709
Virginia, USA
SBoyd Offline
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Gunk
Excellent
Enjoyed the idle music and more.

Now, help me understand.
Your lapping method, with vacuum on the intake and the slide going up and down, seems to emulate normal usage.
That is to say, we have engine vacuum holding the slide in place and vertical throttle-action just as your lapping machine. So, I am thinking that normal use would lap the AMAL Concentric into better sealing just as you are achieving with your method.
Your method seems to suggest that normal use will improve sealing and idle performance.
Please re-explain.
Thank you
>>sb


Stop the insanity.
Re: '69 A65L, my best tickover yet #38348
05/08/08 3:32 am
05/08/08 3:32 am
Joined: Mar 2006
Posts: 1,011
Canada
Gunk Offline OP
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Canada
The normal wear can improve, or maintain some.
There are posts that relate experiences that support this notion.
The normal wear could not compensate for the distortion of the body from over-tightening the flange nuts though.


"he who laughs fast, laughs first"~Gunk
Re: '69 A65L, my best tickover yet #38349
05/10/08 1:44 am
05/10/08 1:44 am
Joined: Apr 2006
Posts: 1,709
Virginia, USA
SBoyd Offline
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Virginia, USA
I think we are onto the same thing here.
I think I've been able to eliminate the "bad wear" on my concentrics, bringing them right into the 21'st century.

The 82 Bonneville came with Bing CV carbs with which I cannot abide. Having freedom of choice, I went with my first love....AMAL concentrics.

I was able to rubber-mount them by using MAP manifolds in the reverse of their intention. (you need to port the manifolds out with a die grinder)

Now, I've wound-up with concentrics that are not subject to vibration wear on the needle-jet, etc, and not subject to distortion since there is no need for the O-ring (a gasket is used) and no body distortion can occur.

The only wear is the beneficial lapping ala Gunk.

Don't know of anyone else who has hose-mounted concentrics. but would like to hear about it. [img]http://i85.photobucket.com/albums/k65/ducboy99/amal1.jpg?t=1210383614[/img]
[img]http://i85.photobucket.com/albums/k65/ducboy99/amal2.jpg?t=1210383702[/img]

Idle is great, and now I know it will only get better.


Stop the insanity.
Re: '69 A65L, my best tickover yet #38350
05/10/08 2:00 am
05/10/08 2:00 am
Joined: Sep 2007
Posts: 1,134
Ottawa, Canada
gREgg-K Offline

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Ottawa, Canada
An anti-vibration mounting is a good idea for any carb. Even Weber DCOEs can be vile unless you mount them on rubber couplings.

Aside from protecting your carbs from the damaging effects of vibration, a rubber mounting also gives you a nice thermal break.

.. Gregg


Spyder Integrated Technologies
Lucas, BTH, & Miller Magneto & Dynamo Restoration
SMITHS Chronometric Restoration
magneto@spyder-it.com
Re: '69 A65L, my best tickover yet #38351
05/10/08 12:04 pm
05/10/08 12:04 pm
Joined: Aug 2001
Posts: 4,256
argyll. scotland, uk
gavin eisler Offline
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argyll. scotland, uk
Ive used hose mounted MK1 concs for years.
Benefits , no vibration, easy dismount, longer inlet tract.
Drawbacks, stock air filters wont work on OIF, carb top to fuel tap clearance issues,
carbs sag on the rubbers after a while, looks a bit down at heel , rubbers perish.
Keep a spare pair on the shelf or use radiator hose off cuts at a push.
Pod


71 Devimead A65 750
56 Norbsa 68 Longstroke A65
Cagiva Raptor 650
MZ TS 250
The poster formerly known as Pod
Re: '69 A65L, my best tickover yet #38352
05/10/08 1:17 pm
05/10/08 1:17 pm
Joined: Apr 2006
Posts: 1,709
Virginia, USA
SBoyd Offline
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Virginia, USA
Pod
What do you use for the manifold? I am looking for a machinist who can somehow machine-off the mounting ears of a MK1 and create a spigot.
That would make things more compact and less weight hanging on the hose.
MK1.5's don't have a tickler.


Stop the insanity.
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