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Bikernet Tech: The TWEVO Configuration or Stay with an S&S EVO?

What are the Options?

--By Eric Bennett, Lee Clemens, Bruce Tessmer, Grant Hillegass, and Bandit with photos by Wrench

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We ran into a cool FXR recently at Bennett’s Performance, but it sported a S&S Twevo Engine, basically a Twin Cam in a set of Evo mounting cases from S&S. We were intrigued. The bike, moto styled, was built by a customer, James Doerr, and Eric Bennett built the engine. He raced it at the Costa Mesa flat tracks last weekend and came in second. "It's a monster," said Eric Bennett.

This is the last set of S&S Twevo cases on the Planet. Eric Bennett has them locked in the Bennett's Performance vault.
This is the last set of S&S Twevo cases on the Planet. Eric Bennett has them locked in the Bennett's Performance vault.

“Unfortunately, we discontinued our Twevo engines about a year ago,” said Grant from S&S. “In fact, just last week, I scoured our ERP, the warehouse, and all the little nooks looking for Twevo parts. I found nothing.”

This Twevo configuration was the less expensive alternative allowing a builder to go Twin Cam, yet retain a strong Evo 5-speed transmission with a BDL primary system (available for almost any Evo/Twin Cam configuration), although in this case James went with a chain and Rivera clutch. Also, Wire plus wiring (shown here), allows any builder to bolt up a 48 mm Mikuni Carb (with an S&S intake manifold) a DynaTech ignition or any Evo ignition by using a BDL point cover.

Just a handful of parts are needed including a crank position sensor and a map sensor. A coil change is mandatory. All Twin Cams have single fire .5-ohm coils. Evos ran 3-ohm coils with electronic ignitions and 5-ohm with points, mostly dual fire. An Evo stator and rotor will bolt right in.

“With this configuration you should only use an ’06 and below Twin Cam,” Eric Bennett said. “And you must switch out the drive plate to a Screamin’ Eagle larger oil pump and hydraulic cam chain tensioners. The early ’06 and later Twin Cams have stronger sprocket shafts and 2002 was the last year of the Timken sprocket shaft bearings. Eric’s Twin cam is much the same as this one, but with Branch modified heads and all of their internals including Beehive valve springs.
"Timken conversion is highly recommended for any Twin Cam performance application," said Bruce.
Eric running his customer's low-buck hot rod, moto FXR on his dyno. Check out the results.
Eric running his customer's low-buck hot rod, moto FXR on his dyno. Check out the results.

The second alternative is to install an entire Twin Cam driveline in an FXR chassic with some frame modifications. This is more expensive, but will allow you to run fuel injection. It also has some drawbacks if you run a 6-speed, or a later model Twin Cam with substandard parts, which might force you to spit your cases and rebuild the lower end with Zippers or Dark Horse welded, balanced and trued lower end.

To some, the Twin Cam option seems attractive and BDL makes some components to allow a Twin Cam to run an Evo styled ignition, or so you can run a carb.

BDL Components

Part # BDL-CC-200 Cam end adaptor (Included in kit)

Part # BDL-CC-300 Special cam end bolt (Included in kit)
Part # BDL-CC-400 9934 seal (Included in kit)

BDL's Polished Billet Aluminum Cam Cover will need an EVO style counter-clockwise rotation ignition to work properly. All pictures were taken on our cam cover cut away for easy viewing.
Pictured below is how the supplied seal must be installed, flat side of seal facing out.

The stock cam bolt and washer must be removed as pictured left and the washer (inset picture) will not be used.

BDL’s Polished Billet Aluminum Cam Cover can be used with any aftermarket ignition and rotor cup system.

Our Cam Cover is for gear drive cams ONLY.

Here are a couple of alternative wiring systems from Wire Plus to help with your TwinCam into FXR configuration.

There is another alternative, and the more I think about it, the more I like it. This comment from Bruce Tessmer at S&S says volumes in this regard.

When it comes to cams and cam plates and oil pumps, let me say this about that!

You do need to remove that cam plate to check run-out on the (TwinCam) pinion shaft. A 2003 bike is probably not going to have a problem with run- out, but you need to check it. Late model bikes have a much greater chance of having excess run-out since the stock spec is currently .012-inch. Really!

The maximum allowable run out for S&S gear drive cams is .003-inch. When S&S sends out a flywheel assembly the run-out specification is .0005 or less, so you know they are going to be fine.

The less run-out you have, the less problems you will have with vibration and damage to the oil pump and pinion shaft bushing in the cam plate. In fact, you can make more power with a truer flywheel assembly because you can rev the engine higher!

We recommend removing the oil pump any time cams are replaced because you should replace the scavenge port O-ring. Some guys don’t replace it, but we’ve had enough customers with scavenging problems and the resulting oil pukage after a cam change that we now include the O-ring in our cam installation kits.

That O-ring gets stiff from heat and contact with oil, so it may not seal again if it is disturbed at all, so we recommend that you replace it. Of course it’s a good idea to inspect the oil pump for damage as long as you have the cam chest apart. At the end of the day, as long as you have the oil pump and cam plate out, why not upgrade them both?

--Bruce Tessmer

My Mudflap Girl FXR built by myself and the gang at Spitfire motorcycles. It's pure Evo.
My Mudflap Girl FXR built by myself and the gang at Spitfire motorcycles. It's pure Evo.

I reached out to S&S regarding their new line-up of Evo styled engines and Grant Hillegass responded:

Our ”big-fin” V-series engines, like the V111 and V124 are very reliable, bullet-proof powerhouses. TC takeaways like bigger fins, piston oilers, our HVHP oil pump, press-together wheels, the stronger .927 wristpin, bigger TC-style heads and rocker boxes were all improvements to make this happen.

With all of that, I think the TC engine living in the EVO space became more of a novelty when compare to these EVO-styled alternatives. However! There is something to be said about the uniqueness of seeing a TC wedged into and EVO chassis!

It seems to me S&S has addressed any TwinCam improvements and still deliver the best of all worlds, the pure refinement of the V-Twin, the Evo format.

“TwinCam oil pumps work better than Evo jobs,” said Bruce. “They move more oil and filter it while in the engine.” But they can be costly to repair.

On the other hand here’s the info on the new S&S High Volume Evo oil pump:

• 1984-’99 big twins
• S&S V-Series engines


• No thicker than a stock pump
• Gears with fewer, but larger teeth provide increased oil volume for both supply and return sides of the pump
• Supply gears are 9% wider than stock and standard S&S oil pumps • 28% wider than stock return gears ensure proper crankcase scavenging, reduce drag on the flywheels, and eliminate oil carryover
• Increased scavenging capacity results in:
• Less oil in the crankcase
• Less oil carryover
• Equipped with a stock length oil pump drive shaft

Grant sent me complete descriptions of the new S&S engine series:

The new V111 motorcycle engine is designed for torque more than top end horsepower. The short 41/8-inch stroke is equal to the large 41/8-inch bore, which minimizes vibration. The relatively low lift S&S 585 cam and the single coil Sidewinder valve springs minimize valve train noise. This smooth, quiet, torquey engine is ideal for touring applications where vibration and noise can get old on a long ride, and a loaded bagger pulling a trailer can overtax a stock engine.


1984–'99 carbureted chassis
Custom chassis designed for Evolution engines

Features and Benefits

Short stroke produces less vibration and longer engine life
S&S 585 cam and lightweight single coil Sidewinder valve springs reduce valve train noise
S&S forged rocker arms
Shorter than stock height engine makes installation easy
Chrome plated rocker covers, tappet guides, and gearcover

Specs S&S V111

Engine Name: V111
Displacement: 111-inch
Bore: 41/8-inch
Stroke: 41/8-inch
Camshaft: 585
Piston Type: S&S forged
Compression Ratio: 9.8:1


Natural or wrinkle black powder-coat

Carbureted Engines (1984-'99)

S&S Super E carburetor with teardrop air cleaner


1. Intelligent Spark Technology (IST®) ignition system

Knock sensing ignition control prolongs engine life by automatically adjusting timing to eliminate knock by learning and storing ignition requirements of the engine.

Guardian feature ensures proper engine break-in and protects engine with a 3 step break-in rev-limiter for first 24-hours of operation.

Logs engine data, diagnostic test codes and history items, which can be viewed via a PC when equipped with diagnostic cable and software part #55-5075

Extended three-year warranty

2: Super Stock ignition system

Protects engine with a 3-step break-in rev-limiter during first 24-hours of operation.

Logs engine data that can be viewed via a PC when equipped with diagnostic cable and software part #55-1271.

Initially configured for electric start, however, it is kick-start capable.

Two-year warranty


S&S V124 engines are designed to replace stock Harley-Davidson Evolution big twin engines in 1984-’99 chassis. This is a single cam design engine, which has a similar configuration to stock, it’s just bigger and badder. The V124 engine is available for carbureted and fuel injected models, and in natural, black, and polished finish. All V124 engines now feature chrome billet tappet guides and gear-cover, electric compression releases, and show quality chrome plated die-cast S&S rocker covers.

This is my bare 80-inch Evo engine built by S&S for my Mudflap Girl FXR. What a beauty.
This is my bare 80-inch Evo engine built by S&S for my Mudflap Girl FXR. What a beauty.

Carbureted Engines

Engines for 1984-’99 carbureted models include an S&S Super G carb with a teardrop Slasher air cleaner cover and either the S&S Super Stock ignition system or the S&S Intelligent Spark Technology (IST) Ignition. V124 engines with the S&S Super Stock Ignition System carry a one-year warranty. For an extra year of warranty choose an engine with the S&S IST.

Engines purchased with the S&S IST ignition carry an extra year of warranty because we are confident that this ignition will prevent damage to the engine due to knock or detonation, or over revving during the break-in period. Engines with IST feature a special chrome billet gear cover and are available only with billet tappet guides.

Not recommended for kick start applications.

Fuel Injected Engines

Fuel injected V124 engines for 1995-’98 models come complete with a Magneti Marelli style S&S Variable Fuel Injection (VFI) module, single bore induction with a teardrop air cleaner, and the S&S closed loop sensor kit.

Engines can easily be upgraded to S&S single bore tuned induction with a simple bolt-on induction kit. (See Section 5) The VFI system included with each fuel injected engine, comes with closed loop sensors and the complete S&S ProTune II software package.

Base maps for V124 engines with the most common exhaust systems are available on the software CD and from the S&S website. However, it is recommended that the VFI System be fine tuned at an S&S VFI Tuning Center.

Since we have added the S&S Closed Loop Sensor Kit to all VFI equipped engines, tuning is much easier and the amount of dyno time required to fine tune the engine is greatly reduced.

Which Induction System To Use?

Upper curves of this dyno chart show S&S VFI Tuned Induction System. Lower curves show S&S VFI Teardrop Induction System. Although these tests were performed on an S&S T124 engine, the results are identical for V124 engines.

V124 Specs

Bore: 4 1/8-inch
Stroke: 4 5/8-inch
Displacement: 124 inches
Camshaft: S&S 640
Piston Type: S&S Forged
Compression Ratio: 10.8:1

There you have it, and a complete S&S engine you can purchase natural for around 5 grand. It is ready to bolt into your chassis, install one wire, oil lines and a gas line, and you’re down the road to the beach. Polished and wrinkle and chrome motors run about six grand.

S&S is also working on some motors without carbs, intake or ignition systems to help brothers save a few bucks. “You could bolt up a stock carb and go for a ride,” Bruce said. “They won’t perform as well as they could, but you’re back on the road until the funds surface for a better carb or fuel injection.” We will bring you the complete rundown when the factory slips us the envelope.


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