200 side draft mod
- Thread starter tabrinn
- Start date
HP and CID are the determining factors. I don't agree with everything this guy says but he has some good guidelines.
http://sw-em.com/su_carbs.htm
http://sw-em.com/su_carbs.htm
Practical opinions here. It's easy to get CD type carbs in pairs. Most UK-derived sixes were fitted that way. Triples usually requires you to find an extra carb, and then frequently rebuild it...
However, most British sixes were on the small side compared to the Falcon's 200. So that can be where triples come in handy. You'll never overcarb with a CD type unit - just not make full use of its potential.
Look for isolated float bowls (not integrated) and expect to make some polished or coated heatshields. Quite honestly a riveted sandwich of asbestos tile between two polished alloy sheet faces is the best approach - but asbestos has a bad name these days.
Carbs are mounted by cutting some flanges of 1/4" to 3/8" stock, and brazing them to the prepped log. Then punch through the centres and blend. A simple bolt-in divider for the original carb hole can be made to block 95% of the flow between front and rear carbs (if running a pair).
Yet another reason I'd love an oxy setup...
Regards, Adam.
However, most British sixes were on the small side compared to the Falcon's 200. So that can be where triples come in handy. You'll never overcarb with a CD type unit - just not make full use of its potential.
Look for isolated float bowls (not integrated) and expect to make some polished or coated heatshields. Quite honestly a riveted sandwich of asbestos tile between two polished alloy sheet faces is the best approach - but asbestos has a bad name these days.
Carbs are mounted by cutting some flanges of 1/4" to 3/8" stock, and brazing them to the prepped log. Then punch through the centres and blend. A simple bolt-in divider for the original carb hole can be made to block 95% of the flow between front and rear carbs (if running a pair).
Yet another reason I'd love an oxy setup...
Regards, Adam.
Ak Millers four Kiehn set-up looks like the easiest to set up. That way, you can put it back to stock after you've finished.
I'd say start with four Suzuki GSX600 carbs, and use one wide band oxygen sensor and a stable, large diameter gauge which indicates lean to rich in 10 to 17:1 scales at 0.5 intervels.
Use the stock single 1100 or 1946 or 1908 or Carter carb to get you home, and tune on a quad carbs on loney road. The available needle selection is huge, and all you need to do is limit fuel pressure to less 1.5 psi by an external Holley 2300 float bowl which can supply a similar head of fuel as a stock motorcylce fuel tank. You can then use the stock fuel pump.
A quad carb set-up is easier to dial in a package. It is not a port on port, or isolated runner set-up.
As soon as you go to a non isolated runner design, things then get very simple, and they are largley insensitve to venturi size. Jetting is easier, but still not a walk in the park.
If you are able to do the linkages, and get a quad set-up running well, then go to six carbs.
Six carbs on a sixcylinder engine is an Isolated runner set-up. These instilations are very hard to tune well. The venturi sizes, jets and enrichment circuits get very 'finikity' due to pulse tuning reversion waves. They take a wealth of parts to perfect, but always yield a huge power gain with a small sacrifice in economy id tuned well.
I'd say start with four Suzuki GSX600 carbs, and use one wide band oxygen sensor and a stable, large diameter gauge which indicates lean to rich in 10 to 17:1 scales at 0.5 intervels.
Use the stock single 1100 or 1946 or 1908 or Carter carb to get you home, and tune on a quad carbs on loney road. The available needle selection is huge, and all you need to do is limit fuel pressure to less 1.5 psi by an external Holley 2300 float bowl which can supply a similar head of fuel as a stock motorcylce fuel tank. You can then use the stock fuel pump.
A quad carb set-up is easier to dial in a package. It is not a port on port, or isolated runner set-up.
As soon as you go to a non isolated runner design, things then get very simple, and they are largley insensitve to venturi size. Jetting is easier, but still not a walk in the park.
If you are able to do the linkages, and get a quad set-up running well, then go to six carbs.
Six carbs on a sixcylinder engine is an Isolated runner set-up. These instilations are very hard to tune well. The venturi sizes, jets and enrichment circuits get very 'finikity' due to pulse tuning reversion waves. They take a wealth of parts to perfect, but always yield a huge power gain with a small sacrifice in economy id tuned well.
Would a bolt in divider also work on the 4 carb set up?
Since 6 carbs are finiky, how do you think 6 bike throttle bodies would work? I've seen the ricers do it on hondas. They delete the injector on the body and use a bung on the manifold. You think it might work on our six with a Mega Squirt?
Since 6 carbs are finiky, how do you think 6 bike throttle bodies would work? I've seen the ricers do it on hondas. They delete the injector on the body and use a bung on the manifold. You think it might work on our six with a Mega Squirt?
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