850 MKIII Obsessive Amal Throttle Slide Synchronization Gage

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When I wind the twist grip and let go, if I hear two clicks instead of one when the slides hit bottom, I know the cables are not equal in length.
 
I put a TriSpark on my Trident years ago and never looked back. I also added electric start and never looked back. Guess I'm what the British call a braces and belt guy.
Hi Cyclegeezer,
Did your T150 ever kick back whilst starting, and if so ,did the Trispark help?
Sincerely,
Kara
 
Hello fellow Norton Enthusiasts,
Dave, whose moniker in this august forum is Cash, informed me of a fatal flaw in my most elegant apparatus designed in the service of balancing my wayward Amal carburetors. He pointed out that the counterbores into which the throttle slides settle, in the absence of stop screws, are found to vary in their respective depths.
Thus I was measuring a difference of movement from two different beginning apertures. I proceeded to locate a pair of drill bits of an appropriate diameter, and soon found that there was a good .020" difference between the throttle slides, relative to the bottom of the bore, which is truly the important quantity at issue here. Sadly, my apparatus can only be used effectively to verify what feeler gauge technique has already revealed, and with carburetors mounted on the engine, I do not see a way to overcome this limitation.
However, all is not lost. Dial indicators are a valuable tool in the setup of my Trident clutch mechanism and the hard won experience of setting Norton carburetion has prepared me for my encounter with T150 carburetion , whose three carburetors and gantry mechanism at this very moment await me on my bench.
Now, it is a fact that this winter I plan to renew the bushings and bearings in the MKIII gearbox--but I could not bear the thought of not having a single working British motorcycle on the premises. Thus I came up with the idea that I needed a simple and reliable bike to tide me over whilst repairs proceeded on the Commando.
Obviously the only sensible solution was to obtain a 1973 Triumph Trident. I was so bold as to buy a bike from Prescott Arizona, and have some nice people with a truck deliver said machinery here in Vancouver Wa. The bike and I had never met before. Now, the bike looks to be in showroom condition, and the P.O. claimed that the motorcycle ran perfectly . While I believe this statement was offered in good faith, it had overoptimistic elements contained within its scope.
The clutch needs some fine tuning, and appropriate renewal parts are en route from Athens, Greece. It turns out that Tridents are all the rage in Athens. And carburetor renewal parts are in the process of being installed this very day. The third issue is to find a way to stop the three cylinder monster from kicking back during the starting procedure. I have a bruise the size of a coffee saucer on the side of my knee. I am only flesh and bone, and the bike is made of steel . I suspect I may be dumping the Boyer unit in favor of a Trispark soon-- if kicking behavior does not improve.
However, after obtaining appropriate ear plugs I took some rides on the Trident-- before removing its carburetors of course. It is a very different kind of creature relative to the Commando. It is a trippy machine. Many times I have gotten down behind 500ug of high quality LSD , and I can say that riding the Trident is its mechanical equivalent .
Sincerely,
Kara Elizabeth.

I love triples. Bought a new 1969 Trident in Winnipeg. What a thrill in 1969!

Years later a BMW K75RT found its way into my garage. It and the Trident were my two favorite bikes.
 
yeah, well trispark was so named because he cured ignition problems on tridents. tridents, bsa rockets, bonneville 750's and commandos all had their warts back in the 70's. I still have my '71 commando and I think that there's enough support in the community to keep it better than all the rest.
 
On my Norton I have only one carburetor so I don't have to worry, but on other bikes I use several methods. There are simple ways of synching two carbs that require no tools. If you can take the air cleaners off you can just make sure each slide cut away disappears at the same throttle opening. You can do this with your finger or if you can look straight in (you can't on a Norton but you can on a Bonneville) I have a twist grip with twin cables and adjusters near the grip. I have always found that this method gives an excellent result.

On my Vincent it is a nuisance to take the air cleaners off so I just loosen one of the two cable adjusters near the twist grip. I ride along the road with at a normal speed, and adjust the loose cable adjuster tighter and looser until if feels right. If both carbs pick up simultaneously from closed thottle then it is right. I even used this method on by Guzzi V11 that was fuel injected. It had a plastic thumb screw you could use to sync the throttles. I did this on my friends BMW R750/7 years ago. We had switched bikes, I had a 750/5 he had the /7. As soon as I rode off on his bike I knew the throttles on his bike were not synched. I told him I could fix it. He said never mind he was going to take his bike in for a tune up next week. I told him to just let me do it as it would be better, and if I messed it up he was getting a tune up next week anyway. I did it for him by my seat of the pants way and he never bothered to take his bike in for the tune up.

You can synch the idle speeds by ear similarly. If it sounds good it is good. If you can't do it practice it a bit and you will be able to

Nigel
 
As much I have enjoyed the responses to this thread, the serious and the outrageous, I applaud "tinkerbell" for wrenching her own bikes. Even though using twin dial indicators may be a little over the top. Now taking on a Trident, which I happen to own as well, is another learning curve to tackle. Maybe she can get one more dial indicator and sink them on a dining room table as I did, all be it with drill bits. If she decides to adjust her tappets to within .001 or adjust her isolastics and head steady to get the absolute least vibration, good for her. Should "Tinkerbell" show up in Michigan or Barber, I would love to meet her.
 
Hi Cyclegeezer,
Did your T150 ever kick back whilst starting, and if so ,did the Trispark help?
Sincerely,
Kara
Never kicked back, but I went from points to the TriSpark. Old Boyer's are known for going to full advance with a less than fully charged battery, or a weak old battery. That will get you kick back.
 
As much I have enjoyed the responses to this thread, the serious and the outrageous, I applaud "tinkerbell" for wrenching her own bikes. Even though using twin dial indicators may be a little over the top. Now taking on a Trident, which I happen to own as well, is another learning curve to tackle. Maybe she can get one more dial indicator and sink them on a dining room table as I did, all be it with drill bits. If she decides to adjust her tappets to within .001 or adjust her isolastics and head steady to get the absolute least vibration, good for her. Should "Tinkerbell" show up in Michigan or Barber, I would love to meet her.
I used small ball bearings to sync the Trident carbs before I drilled the intakes for vacuum stubs.
 
I used small ball bearings to sync the Trident carbs before I drilled the intakes for vacuum stubs.

I used the ball bearing method on my Trident too, it takes quite a bit of patience to get them to drop at the same time. I also use this method on the Commando, even with the carbs attached to the head. They have never gone beyond the spray tube and easily withdrawn with a telescopic magnet. That said, I usually place some cloth into the manifold just in case. It's a start point for hooking up to the vacuum gauges. It's even easier now with Don Pender's gantry kit.
 
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Can, have you fitted Don’s gantry to the Commando?

Do you reckon one would fit on a T140?
 
Can, have you fitted Don’s gantry to the Commando?

Do you reckon one would fit on a T140?

I've had it on the Commando for over a year. You need to ask Don but it would only be a question of centres if there was room.
 

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2 things to consider with my setup, carb spacings, and clearance. I have one fitted to my current build which is a 650 Yamaha
with Concentrics, I cut and widened the base plate.
850 MKIII Obsessive Amal Throttle Slide Synchronization Gage
 
Thanks both, I’ll have a close look, I think the spacing is different, and I’m no sure about general clearance around there either (tank, OIF, etc)
 
When I install dual Amals I always measure the opening on the motor side using a .040 wire gauge. It gets them very close and a good starting point.
I use a synchronizer tool (forgot the name) that uses steel rods instead of mercury but otherwise very similar. The interesting thing is how much the air screw affects the rods bouncing up and down. That's what I go after first. I know the slides are very close because I used the .040 gauge.
Is there any value to using the cross over tube? I know that when I take off the gauge my idle is too high so it's a headache..l would like to cap off both off the spigots and not bother with the balance tube
 
I used the ball bearing method on my Trident too, it takes quite a bit of patience to get them to drop at the same time. I also use this method on the Commando, even with the carbs attached to the head. They have never gone beyond the spray tube and easily withdrawn with a telescopic magnet. That said, I usually place some cloth into the manifold just in case. It's a start point for hooking up to the vacuum gauges. It's even easier now with Don Pender's gantry kit.
That gantry system is on my list of functional farkles to put on my Norton.
 
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