LM MK2 Carb synchronization |
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Jools
Senior Member Joined: 19 Aug 2016 Location: Milton Keynes Status: Offline Points: 273 |
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In the old days, racing mechanics would balance the carbs by ear - yes, that's right , by listening to the intake roar from each carb through a piece of tubing.
It's not as far fetched as it sounds either. My late friend Jon had a Triumph Stag with the original V8 engine; there was no facility whatever for connecting up balance gauges, so in the end I resorted to doing the job by ear. Using a piece of tubing, I held it at the intake of each carb in exactly the same place and then made the adjustments, listening to each carb in turn. I kept making adjustments until the intake roar from each carb sounded identical. Despite never having used this method before, it worked very well and Jon swore that the engine had never run smoother afterwards! The human ear can quite easily distinguish different tones, and essentially that's all you're doing, getting the tones to be identical. The advantage of the Stag of course is that the carbs are adjacent to each other, and swapping between them was relatively easy - might be a bit different on a Guzzi unless you use two pieces of identical tubing, one going to each carb. If you have no balance gauges, it's a method worth trying.
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Jools
V1000G5 1972 T150V 1961 Royal Enfield Constellation 1971 Suzuki ACC50 erm... 1963 Philips Panda (and other assorted detritus) |
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red leader one
Senior Member Joined: 07 Oct 2014 Location: Cullercoats Status: Offline Points: 4466 |
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I had twin carbs on a Allegro 1500 years ago and our Superintendent of Works (Transport) tuned my carbs this way everytime I came to Newcastle from Birmingham. Ran like a dream 50mpg easy.
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Jools
Senior Member Joined: 19 Aug 2016 Location: Milton Keynes Status: Offline Points: 273 |
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My dear old Brother had a 1300 Allegro - in chocolate brown. About the only thing remotely yummy about that awful contrivance! We got less than 2 miles from home on setting out for a holiday on one memorable occasion.
We had to return home for my venerable Vauxhall Viva!
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Jools
V1000G5 1972 T150V 1961 Royal Enfield Constellation 1971 Suzuki ACC50 erm... 1963 Philips Panda (and other assorted detritus) |
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TheWrongTrousers
Senior Member Joined: 05 Nov 2018 Location: Somerset Status: Offline Points: 658 |
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The 'All Aggro' as it used to be known. It's interesting to hear Jools going on about doing this sort of thing by listening. Looking at my LM1 handbook that would have come with the new bike, it recommends that the carbs are balanced by standing behind the bike and putting your hands over the exhausts and fiddling with the throttle stops until they both feel the same.
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Dave P.
Senior Member Joined: 12 Jan 2015 Location: Northants Status: Offline Points: 5573 |
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That's how I balance the tick over on my loops.
It's even easier on the RE Bullet! |
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TO LIVE OUTSIDE THE LAW YOU MUST BE HONEST.
1971 V7 Special. 1972 850GT. 1970 T120 Bonnie. 2009 500 Bullet. |
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Jools
Senior Member Joined: 19 Aug 2016 Location: Milton Keynes Status: Offline Points: 273 |
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An RE Bullet? Huh, that's cheating!
I synchronised my Constellation carbs by popping on a Super Meteor inlet manifold - two into one does go! Oddly enough, I was at Newark earlier in the month and saw a Guzzi converted to single carb using a home-made manifold with a Mikuni bolted on.
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Jools
V1000G5 1972 T150V 1961 Royal Enfield Constellation 1971 Suzuki ACC50 erm... 1963 Philips Panda (and other assorted detritus) |
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Brian UK
Moderator Group Joined: 13 May 2014 Location: Surrey Status: Offline Points: 17641 |
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There have been a few of those done. I experimented on the V50 with a home made manifold constructed from 1 inch copper pipe. It worked fine, but I still used one of the Dellortos, and the idle jet outlet is on one side so I could never get the tickover to work.
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Brian.
Better 5 minutes late in this world than years early in the next. |
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Jerry atric
Senior Member Joined: 24 Nov 2014 Location: Wiltshire Status: Offline Points: 3367 |
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A few years ago I met a chap with a Honda 500 four to which he had fitted a beautifully crafted 4 into 1 manifold to an SU carb. All in polished copper, it was such a work of art that I took a photo of it. Something I never do!
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TheWrongTrousers
Senior Member Joined: 05 Nov 2018 Location: Somerset Status: Offline Points: 658 |
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Let's see it Jerry?
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