GEN III Twin Weber 40 Consumption Manifold Set (Specs)

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As put in and examined on RC003

The final word carb conversion for GL1000/GL1100. Twin Weber 40IDFs…the world’s most tunable efficiency carbs!

Particular because of Don Luther. Don has had his twin Weber-equipped GL1000 on the street for a few years. His bike – “Wang Thang” was the inspiration for this venture. Don supplied a lot early steering on this venture. Thanks additionally to “NiteMare” Pete and “Frenchy” for help. Additionally, Greg Foresi supplied invaluable help in understanding the reasonably complicated math for optimizing the throttle linkage angles for the contra-rotating throttle shafts. These are basically a “Scotch Yoke” mechanism that translate a sinusoidal movement to a linear movement.

You will want to supply your personal Weber carbs elsewhere (they’re straightforward to seek out) together with all the opposite bits wanted to finish the conversion.

Proven painted with high-temp engine enamel (gaskets and {hardware} not included)

Proven with customer-sourced chrome plating (not included). Because of James Jeffrey – Paris, France for picture.

Proven with customer-sourced semi-gloss black powder coat end (not included). Because of Attila Baraczka – Toronto, Canada for picture.

Air Filter Choices

Particulars on sourcing two totally different air filter meeting choices are supplied:

Filter on left can be utilized with out modification… Filter on proper requires slight modification (filter assemblies should not included)

“Rain Hats” enhance climate safety (plans to supply and mount these are supplied)

Efficiency Knowledge

High gear 60-80 roll-on instances had been decreased by 0.4 seconds common. It is a good measure of total energy and tune …a lot safer and gentler than 1/4 mile runs from standing begin. Based mostly on my on-the-road testing and the roll-on numbers, I predicted that I’d discover 5-8 extra max horsepower on the deliberate dyno exams. I additionally didn’t discover any low velocity lack of torque even thought the straight consumption runners are reasonably quick.

Dyno Outcomes

On October 12-13, 2006 dyno runs had been carried out at Ray Worth Harley-Davidson in Raleigh, NC. Ray Worth has one of many prime dyno rooms within the nation. No shock, since Ray Worth himself is without doubt one of the greatest High Gasoline drag racers within the nation.

Jason Clement and Bruce Downs of Ray Worth Harley carried out these exams.

Listed here are the dyno outcomes for the Twin Weber set-up:

Max Horsepower: +8.25 horsepower gained! (+13.8%)

Max Torque: +3.04 foot-pounds of torque gained! (+6.2%)

All these outcomes are relative to the very glorious set of inventory GL1000 carbs in razor sharp tune beforehand on the take a look at bike (RC003). The OEM Honda carbs had been basically inventory. We’d beforehand carried out the “off idle” repair and likewise balanced the CV slides to inside 0.1 gram every on the inventory carbs. They had been completely synchronized.

As predicted, there was no lower in torque at any level throughout the rpm vary with the Webers.

Remember the fact that dynos are notoriously variable from one to the following. Absolute values should not very significant…solely comparative runs on the identical dyno will let you know a lot. Honda was shy about publishing horsepower outcomes for the GL1000, however most magazines on the time pegged it at about 80 hp on the crank. Maintain it thoughts that on a shaft drive bike, parasitic losses within the drive prepare lead to 20-25% lack of horsepower from the crank to the again wheel.

In the event you have a look at the charts, each set-ups present torque curves which can be VERY FLAT and horsepower curve which can be VERY LINEAR. This explains the good street manners for a well-tuned GL1000 with excellent-performing OEM carbs. I’m very impressed with the outcomes that the Honda engineers got here up with on this engine / carb mixture!

Air/ Gasoline mixtures for each setups had been very constant and near-optimal throughout the complete rpm vary as effectively.

The Weber setup confirmed dramatic enchancment throughout the complete rpm vary in each torque and horsepower. Apparently, there’s an particularly vital constructive enchancment in torque on the Weber setup from 3,000 – 4,000…the spot had been most cruising is finished. This “candy spot” explains a part of the very satisfying seat-of-the-pants enhance you’ll be able to really feel with this setup.

For sure, we’re thrilled with these outcomes.

Execs

That is the last word efficiency carburetion setup for the GL1000/GL1100. The one different paths to extra energy can be the expense, complication, weight and warmth technology concerned with superchargers, turbochargers or inner engine modifications.
This setup is roughly 7 kilos lighter than the OEM carb setup!
Very quick, remoted consumption runner design ensures that every cylinder is tuned the identical.
Carb icing won’t be a problem!
Low gasoline mass to maneuver upon throttle demand for nice throttle response.
Most tuning flexibility. Webers are the last word carb for exact tuning! All jets could be swapped in seconds with out carb elimination or disassembly.
Ease of upkeep. These are quite simple and straightforward to take care of carbs. Floats could be adjusted with out carb elimination. Elements are available worldwide. Orifices are a lot bigger on the idle circuits in comparison with the OEM carbs, so there’s much less probability of blocked idle circuits.
Superior float design for glorious gasoline management.
Higher engineered low velocity circuits allow very exact idle regulation and a barely decrease curb idle velocity.
Superior development circuit design gives prompt off-idle response.
Accelerator pumps present glorious transition beneath arduous acceleration.
No choke mechanism required. Accelerator pumps make glorious chilly begin priming machine.
Removing of inventory carbs and airbox frees up appreciable “actual property” beneath the glove field. Hmmm…we predict a nitrous oxide bottle may match there.

Cons

Not really useful for many GL1000 / GL1100 homeowners. Most homeowners can be well-advised to retain their OEM carbs to maximise future resale worth. That is very true when you’ve got a excessive worth collector high quality machine. Most future collectors won’t be overly impressed with this setup. OEM carbs are stellar performers unsurpassed by various carburetion set-ups…aside from this twin Weber configuration.
These manifolds are meant for off-road or competitors use solely. They aren’t authorized for on-road use in lots of jurisdictions. Suitability and compliance to native legal guidelines is your accountability.
This isn’t a “plug and play equipment.” Solely a pair of manifolds, set up ideas, materials lists, provider contacts and baseline jetting suggestions included. Despite the fact that we’ve executed the toughest half for you, you’ll nonetheless want appreciable mechanical means to pick out, overhaul, re-jet and set up the carbs that you simply supply. You will want to have the ability to fabricate an correct, dependable and protected throttle linkage -without slop! Poor throttle linkage will doom your venture!
Baseline jetting suggestions offers you an awesome place to begin, however chances are you’ll must refine primarily based upon different variables akin to air cleaner and exhaust specifics in addition to altitude. You will want some tuning experience.
Baseline jetting suggestions are calibrated for GL1000 fashions. GL1100 jetting needs to be very shut, however you will want to find out your personal calibrations ranging from our baseline solutions.
The air consumption roar from this setup is a bit loud! It sounds completely fantastic…harking back to a Ferrari Dino! Your neighbors will in all probability not agree.
It is a fair-weather setup. It’s not meant for prolonged use in heavy rain. Not included: particulars on putting in rain hats to enhance climate safety (proven above). Rain hats additionally muffle the consumption roar considerably to extra socially acceptable ranges.
Match on later “non-naked” bikes with manufacturing facility fairings has not been verified. Some interference with the fairing can be anticipated.
Spark plug upkeep is a ache in case you retain the OEM plug wires/caps. I strongly advocate you improve to aftermarket coils, wires and caps. Use straight plug caps. Accel and Dyna make glorious excessive efficiency coils and wire units for early wings. Be sure you get coils suitable along with your ignition system.
High shelter covers can’t be pivoted down per regular apply because the carbs placement interferes. Answer: take away the highest shelter cowl decrease pivot pins. Then the highest shelter covers could be secured with simply the big black knobs. The covers could be lifted out vertically for simple upkeep. You’ll want to safe the highest shelter hinge bushings with RTV adhesive or they are going to be misplaced. They nonetheless should be in place in order that the highest shelter covers are positively positioned.
These should not fixed velocity (CV) carbs just like the OEM items. CV carbs have ingenious mechanical logic constructed into them that meters air/gasoline combination considerably in response to precise engine load no matter ham-fisted throttle inputs from the rider. These non-CV Weber carbs take a little bit of refined throttle hand retraining for greatest outcomes. When you get accustomed to the moment throttle response, you’ll prefer it so much.
Riders taller than about 6′ 2″ tall could have clearance points with their left knee. I’m 5′ 11″ and don’t have any clearance points.
Manifolds have been bead blasted and coated with rust preventative oil after fabrication. Since they’re fabricated from metal, you will want to color, chrome or powder coat them to keep away from corrosion. Minor floor rusting could happen throughout storage and transit.
A wholesome clutch is necessary to deal with the facility output.

Recommendation on Choosing Carburetors

Weber 40IDF is the really useful carb. Mannequin quantity is stamped on the decrease carb flange.
Weber 40IDF Mannequin 70 is the popular mannequin. This mannequin is broadly used on VWs and Porsche 356/912s. It ought to have jetting from the manufacturing facility near what you want.
Weber 40IDF carbs with adjustable accelerator pumps are strongly really useful for this software.
Remember that earlier proprietor of your carbs in all probability made jetting adjustments, so confirm your precise present jets, and so on. earlier than ordering extra jets or different calibrated elements.
Weber 36IDFs will work, however these carbs should not broadly accessible within the US. 36IDFs are advantageous as long as the venturis are 28mm. Relying on the mannequin automotive they had been initially destined for, there could also be some non-adjustable idle air bleed jets which aren’t appropriately sized for this software. If yours are improper, they are often soldered shut and redrilled to the proper measurement. Ensure the passages behind the left /proper stability adjustment are clear. They’re “sealed” and arduous to entry on some 36IDFs (in contrast to 40IDFs) Ray Proebstl of Munich, Bavaria, Germany just lately went via this set up with Weber 36IDFs and he was ready overcome these quirks.
Weber 44IDFs or 48IDFs needs to be averted – they won’t be near the calibration you want and can almost definitely have predominant venturis which can be too massive.
Confirm that the carbs have 28mm predominant venturis earlier than your buy. These could be modified if obligatory, however it’s an pointless trouble and expense. Venturi measurement is stamped and visual on the highest, inside floor of the venturi close to the outlet for the accelerator pump nozzle.
Dellorto downdraft carbs are suitable with these manifolds however haven’t been examined. Downdraft Dellorto 36 is mostly equal to Weber IDF40.

I gained’t be publishing the jetting specs. That analysis and testing was very time consuming and costly and is a part of the “worth add.” You’ll faint in case you noticed the invoice for the primary prototype and creation of all the required tooling to provide these!

Keep in mind: Carbs, linkage, air cleaners, and so on. should not included.

My worth consists of solely the pair of manifolds plus a complete set up information (45+ pages) which incorporates step-by-step directions, dimensional drawings, close-up images, materials lists, provider contacts and jetting specs. I additionally embody a set of Viton O-rings to mount the manifolds to the cylinder heads.

Appreciable ability is required to put in these manifolds appropriately. Since I can’t management this essential variable, there is no such thing as a guarantee on these. Relaxation assured that they’re of the best high quality supplies and workmanship.

You will want appreciable mechanical means to pick out, overhaul, re-jet and set up the carbs that you simply supply. You will want to have the ability to fabricate an correct, dependable and protected throttle linkage – with out slop! Poor throttle linkage will doom your venture!

Be aware: Within the curiosity of making a little bit of turbulence to help even gasoline mixtures, the transitions inside these intakes haven’t been overly completed or polished. This intentional “roughness” is helpful and shouldn’t be polished out.

Be aware: DO NOT BUY THESE MANIFOLDS IF YOU EXPECT PERFECT TRANSITIONS TO THE INTAKE PORTS “OUT OF THE BOX.” Be ready to do your personal “porting” work in case you require excellent transitions.

Be aware: The welding on these manifolds might be purposeful, however could not method the creative high quality as proven on the samples above. High quality of the welding is determined by the person ability of the welder chosen by my fabricator for every batch.

Be aware: These Weber manifolds should not marketed for GL1200s regardless that they bolt up advantageous. The issue is GL1200 heads have a lot smaller ports, in order that creates a “step” that adversely impacts movement. Some prospects have overcome this by putting in machined “transition” spacers between these manifolds and the GL1200 cylinder heads. A greater path is to place GL1000 heads (’75-’77 most popular) onto the GL1200 engine. That offers you hotter cams, higher respiratory mixed with the bigger displacement engine and ends in a really highly effective mixture. It normally means changing to a GL1000-style ignition pushed off the left cam within the ordinary GL1000 vogue.

Dyno Chart

GEN II enhancements embody OEM-sized O-ring grooves the place the intakes mate to the cylinder heads. A set of Viton consumption o-rings now included with every order.

Be aware: The provided Directions (45+ pages) are proprietary mental property and are protected by copyright legal guidelines. The images, textual content, baseline jetting specs and different content material might not be copied, reproduced, distributed, saved, or manipulated in any method.

To learn extra opinions on this and different merchandise go to our Overview Website, http://www.randakksreviews.com

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