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Bennett's Performance Evo Engine Rebuild

Re-man Comparison, Twin Cam Debate, and a Slightly Hopped-Up Evo

By Bandit, with photos by Wrench
10/18/2011


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Eric Bennett, of Bennett's Performance, engine builder, Bonneville racer, and lead singer of the Signal Hillbillys.
Eric Bennett, of Bennett's Performance, engine builder, Bonneville racer, and lead singer of the Signal Hillbillys.




We have experienced Harley-Davidson remanufactured engines, JIMS machine remanufactured transmissions and upgrades, and now  something new for an Evo rebuild. We took Dr. Hamster's 200,000-plus miles Evo engine to Bennett's Performance for a solid, aftermarket rebuild.

This article covers a couple of directions. First, H-D's inexpensive remanufacture operation is cool and returns your engine to bone stock configuration, but who wants a stock engine nowadays? Harley's system is all right, but sort of incomplete. Therein lies the benefits of the aftermarket, the flexibility to rebuild an Evo engine in virtually any configuration you choose, from stock to mild upgrade, to big bore, or stroker.

"Evo motors at 80 inches can be great motors when balanced, and put together well," said Dr. Hamster. "Heck, the last one was still going strong at 200,000 miles. So the options became easy and we picked Bennett Performance to do their magic."


The second notion we will cover to a limited extent, is our constant debate over which is the better engine configuration Evo, my favorite, or Twin Cam. Okay, so I'm biased, old school, and cheap. That in itself is simply a tongue-in-cheek debate. We all know the twin cam pattern is more capable of handling performance upgrades; that's a given. But there's a slice of the brotherhood who trust the Evo design, its traditional platform, and its reliability. It is by far the most refined and simple V-twin platform, and virtually every custom manufactured chopper company used Evos as their power plants. We will touch on the plus sides and negative aspects of both configurations throughout this article.


Dr. Hamster was working with a local Santa Monica shop, Venice Custom Cycles, and Javier pulled his engine and dropped it off in Signal Hill at Bennett's Performance, home of the Signal Hill-Billies, the house country-rock band.

"Javier from Venice Custom Cycles pulled the motor, and off it went to Bennett's," said the good doctor, "where they took it all apart. The awesome news happened when Eric from Bennett called and said he could not believe the mileage on this bike. There was minimal wear and tear, and gunk build up."

"Here's what we discuss with any engine rebuild clients," said Eric Bennett, the boss, and lead singer. "We kick around finish options and performance upgrades."

They can have the cases polished, left raw, or powdered almost any color. Then there's chrome, but most of us duck chrome nowadays. Since Branch O'Keefe is right next-door, Eric always suggests headwork by the masters, especially for Evos. Just modifying the heads is a massive performance upgrade, and the manner in which John O'Keefe rebuilds heads, and the high-end quality components he uses add tremendous longevity to any Evo top end. These guys are the Swiss watch masters of headwork.

Eric kicked off the operation by stripping the engine and inspecting each component. He checked the pinion race for true and would follow with lapping and fitting over-sized bearings. The rods were in terrific shape, but the races would be lapped true and the crank and bearings replaced. Plus the Timken set, in the left case, would be replaced.

Eric always replaces the lifters, and the stock breather with an S&S modified breather.

"The breather cavity is a terrific indicator of any crap in the engine," Eric said. "This engine, for the mileage, was exceedingly clean."

If need be, the rocker-arms would be rebushed. All the hardware would be replaced, the oil pump inspected and an S&S oil pump kit will be used to replace all the critical components and gaskets.




For an additional $100, Bennett's has each lower end balanced at 60 percent. Eric uses new stock H-D pistons for a stock compression ratio, modified slightly by the headwork.

All the gaskets would be replace with Cometic gaskets with metal inserts. "This is an all-aluminum engine," Eric explained. "Change the oil often, and make sure to warm it up slowly, since all the components move during the heat cycle."

So let's get started through this 2-3 week process. Keep in mind that any additional machine work will add to the project time.




I meandered into Bennett's pristine shop on the hill over looking Long Beach a couple of weeks later. Eric discovered a problem with the last set of Timken bearings in the left case. He re-welded and machined the groove between the races. John O'Keefe, from Branch/O'Keefe, inspected the heads and rebuilt them. They discovered hairline cracks next to the sparkplug holes, and grooved and welded them. Then Eric installed threaded inserts for the sparkplugs. Those elements took some extra time.

Refurbished heads from Branch/O'Keefe with sparkplug thread inserts installed. The intake valve is .040 over stock.
Refurbished heads from Branch/O'Keefe with sparkplug thread inserts installed. The intake valve is .040 over stock.




Eric lapped and checked the factory line bore through the cases. The heads were originally modified by Bartels' and shaved for additional compression. But the Branch O'Keefe team rebuilt the heads completely with their quality components, including tapered valve guides, new high-quality valves, and springs.

I ran into John O'Keefe while picking up the good Doctor's heads. Their shop is next door to Bennett's and mirrors the cleanliness and organization of Bennett's. It's a sharp orderly machine shop. John took the time to explain the differences between Evo heads and later model Twin Cam components. He pointed out very narrow valve stems and poor quality bottom valve collars that have a tendency to collect oil. Since the valves have dangerously thin stems, they fit very loose in the guides.

Is this getting too techy? How about a break. This photo, by Rogue, just in from a bike show at Biketoberfest.
Is this getting too techy? How about a break. This photo, by Rogue, just in from a bike show at Biketoberfest.




When John rebuilds twin cam heads, he replaces all the moving elements and uses Evo diameter 5/16-inch valves. He also upgrades the valve collars and springs.

"They're just trying to save money," John said of the factory heads.

Most of the special tools Eric uses are from JIMS machine.
Most of the special tools Eric uses are from JIMS machine.



The tool for pressing in the Timken races.
The tool for pressing in the Timken races.







I returned to Eric's shop next door where he was heating the Timken bearings slightly after he trued the flywheels, so they would drop onto the sprocket shaft. The heat prevents any jarring or beating on the shaft that could inadvertently knock the lower end out of true, before the crank had a chance to heat cycle and seat. There is no key-way on the left. The general price for a complete rebuild is $2,500, which includes, lower end, valve job, new pistons, cylinder bore, new fasteners, and gaskets.






Add a cam and performance headwork next door and it usually costs around an additional $850. Next, he replaced the fitted pinion bearing and clip ring, but before he installed the right case he pressed out the old cam bearing and replaced it with the news, longer lasting Torrington cam bearing.




"The heads went over to Branch/O'Keefe to be properly flowed for a "street" porting, matching the performance level to the type of riding I do - 800-1000 miles a day for a week at a time," Dr. Hamster said. "Reliability and good solid performance in the mid range was what I was after. We matched the headwork with the right cam from Andrew's, S&S carb, Compu-fire ignition, and 2-into-1 exhaust from D&D."





Another JIMS attachment to install the sprocket-shaft seal.
Another JIMS attachment to install the sprocket-shaft seal.



Installing the cylinder studs.
Installing the cylinder studs.



He uses an old head bolt turned into a special tool for the operation.
He uses an old head bolt turned into a special tool for the operation.







Eric carefully smeared a light coat of three-bond liquid gasket on the edge of the cases, then installed the right case against the left and tightened the new fasteners from the Gardner Wescott engine fastener kit. Then he torqued them to 22 ft lb. the appropriate level for any 5/16 fasteners.




We peeled out for a night on the town, while Eric kicked off band practice in the studio behind his shop. The next evening, I watched as Eric scrubbed the cylinders in a hot water-based "shit" solvent tank. Then he carefully cleaned them with Simple Green and wiped them down with WD-40 to prevent rust.



This shot shows the hot rod pinion shaft bearings compared to the stock jobs.
This shot shows the hot rod pinion shaft bearings compared to the stock jobs.






Eric started the oil pump installation by replacing the oil pump seal in the return side of the pump body. His S&S oil pump rebuild kit included new keys, snap rings, and seals.



Eric moved around the case and the Garner Wescott fastener kit finding the proper fastener for each hole.
Eric moved around the case and the Garner Wescott fastener kit finding the proper fastener for each hole.



One fastener needed gentle encouragement.
One fastener needed gentle encouragement.




"Oil pump bodies will last forever," Eric said, "as long as debris doesn't gall the interior walls."



The JIMS tool for installing the oil pump seal.
The JIMS tool for installing the oil pump seal.




He used fasteners to hold the pump body and gasket in alignment while he installed the oil pump gear on the inside with the new snap ring. Eric used assembly lube on a lot of the rotating components to protect them until the new supply of oil arrives. He uses the supplied S&S paper oil pump gaskets.

Installing the shaft, key, and retaining ring with some assembly lube.
Installing the shaft, key, and retaining ring with some assembly lube.






"The thicker gaskets mess with the oil pressure levels," Eric explained.






He pointed out that the relief valve opens at 15 pounds of pressure to lubricate the pinion shaft, the crank and lower-end bearings. It's interesting that the lower-end isn't being lubed at an idle, except by the mist being kicked up by the flywheels.




He also pointed out the tappet screen filter. It prevents large chunks of debris from damaging the valve lifters.

The relief valve on top, with the springs, and check ball.
The relief valve on top, with the springs, and check ball.




With the oil pump in place, he could torque the left-handed pinion nut to 45 ft lb. We recently discovered how important the pinion cam drive gear and the pinion nut was, when one loosened in another engine and it sheared the key.



This JIMS tool hold the pinion shaft in place, so the nut can be tightened to 45 pounds without a problem.
This JIMS tool hold the pinion shaft in place, so the nut can be tightened to 45 pounds without a problem.







The key does not drive the gear, but aligns it in a particular position for cam timing. The thrust is handled with the dry surface of the nut and the shaft connection, and then sealed in place with the nut. If that left-handed nut loosens, the key will shear and the engine will quit. Done deal. It's imperative that the tapered shaft be perfectly clean and dry before the nut is tightened.






Eric installed the Branch O'Keefe recommended EV 51, .560 lift cam, with .252 intake duration, and a .256 exhaust duration lobes. Then he worked on setting up the breather gear endplay to .005-.010. and he hooked up the cam with the same endplay tolerances.





The man with the wrenches tightened the cam cover and rolled the engine over. He reached inside the cam chest through the lifter stool holes and checked the breather gear endplay. Then with a JIMS tool bolted to the end of the cam he checked the cam endplay. They were tight, so he switched out shims and tested them again, until they were perfect.

This JIMS tool screws into the end of the cam, so the cam shaft can be pulled in and out to check spacing.
This JIMS tool screws into the end of the cam, so the cam shaft can be pulled in and out to check spacing.




Eric used stock H-D lifters used from '84 to '90 in Evos and from '86-'90 four-speed Sportsters. He primed each one with 20W-50 synthetic oil and installed them in the lifter stools. He used a very cool H-D lifter stool alignment tool to perfectly align each lifter stool before installing the fasteners.





"Twin cams are faster to rebuild than Evos," Eric said, "like rebuilding a four-speed transmission and the faster 5-speed with the trap door."

One of my favorite H-D tools. They hold the lifters up, out of the way, for cam installation. Of course, I don't have a set... Also note the lifter stool guide tool in the corner. It helps align the stool, very cool.
One of my favorite H-D tools. They hold the lifters up, out of the way, for cam installation. Of course, I don't have a set... Also note the lifter stool guide tool in the corner. It helps align the stool, very cool.





I was surprised and we discussed the differences for a half hour, while Eric torqued ¼-20 fasteners to 120 inch-pounds of torque. Then we peeled out to beer-30 and returned the next day at just about closing time to finish the engine.




While I was gone, Eric installed a new cam seal in the cam cover. He pointed out the Twin Cam differences.

"Evos use the cam cover as an integral part of the engine," Eric said. "Twin Cam cam covers are just that, a cover, no fuss, no muss, or messing with endplay."

I still contended that the multiple cams and the cam drive plate added significant time to rebuilds, but what the fuck do I know?

Eric agreed that Twin Cam lower ends lost the quality debate, especially recently with connecting rods without races and push-in straight crank pins and shafts. In an effort to save money the factory late model units are getting sloppy and lower ends don't last much over 40,000 miles.

Measuring ring gap.
Measuring ring gap.



The Harley-Davidson piston.
The Harley-Davidson piston.



The debate continued while Eric set the piston ring gap at .018 or .003-inch per inch of bore diameter. Generally, he sets performance engines wider. The stock pistons come with arrows impregnated into the piston tops to indicate position, since some pistons come with the wrist pin offset to make up for the thrust in the engines during compression strokes. Plus the exhaust eyebrows (half-moon slots) in the pistons are smaller than the intake eyebrows.



Manufacturers include installation instructions with specific recommendation for installing the rings.
Manufacturers include installation instructions with specific recommendation for installing the rings.





Eric also had a formula for positioning the rings. He placed the gap in the second compression ring at 10:00, then the gap in the top ring at 4:00 below the intake valve.



Eric installed the piston in the barrel, then both onto the extended rod, where he installed the wrist pin with assembly lube. He installed one of the keeper rings before slipping the piston into the cylinder. Don't forget, goddamnit.
Eric installed the piston in the barrel, then both onto the extended rod, where he installed the wrist pin with assembly lube. He installed one of the keeper rings before slipping the piston into the cylinder. Don't forget, goddamnit.





"H-D pistons are a bargain at $150 a set," Eric said, "with rings, pins, clips, and they are Teflon coated."




Performance experts recommended that Eric install the gaps in the wrist pin clips at 6:00 or 12:00. He uses .040 Cometic head gaskets. It was time to install the heads, adjust the valves, and wrap up the good doctor's engine. Eric used assembly lube on the head bolts or moly-base lube.

While Eric torqued the heads to 20 pounds, then 32, then 38, and finally 42, which is the SAE torque rating for 3/8 bolts, he recommended heat cycles during break in.




"You should run the motor for just two minutes," Eric said. "Then let it cool down, and do it again for five minutes, let it cool down, then run it for seven-eight minutes. The head temperature should not exceed 150 degrees during this process."




And God forbid, do not lug the motor. That's the worst for any V-twin engine.



Eric spun out each adjustable pushrod before he dropped them through the holes in the heads, then installed the bottom rocker box over Cometic gaskets, then the rocker arms and the remaining rocker box covers. He also installed new pushrod seals and the covers. He checked and rotated the rocker arm shafts.




"They never wear out," Eric said. As he began the torquing process on the rocker boxes, he ran into a stripped 5/16 hole in the rear head. That shut us down for the night. The next day he pulled the head, bored the hole and installed a threaded insert. He assembled the heads, adjusted the valves, and the doctor was good to go.






"All in all, I believe this was the way to go," said the good doctor. "I love the Evo motors for their simplicity, reliability and performance you can get out of them with a relatively small investment.
A sensible way to go instead of spending a ton of money in this day and age. Bessie is coming together and I am looking forward to another 200.000 miles together."



We will bring you a report on the engine's success once the doctor is back on the road. We should break in these Evos and make a run to Bob T.'s place in 14 Palms before winter sets in.


SOURCES:

S&S
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JIMS
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Bennett's Performance
(562) 498-1819


Branch/O'Keefe
Click the image for more info.
Click the image for more info.


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Reader Comments


Page 1 of 2 (8 items)
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Beautiful work!
Can I use late style rocker boxes, drill cylinder heads and plug the crankcase vent hole?

I want to upgrade 1992 breather system to a 1999 style.
Need to do something else?


Pablo Novelli
Martinez, Buenos Aires, Argentina
Monday, February 03, 2014
Editor Response Here's what Eric had to say: Yes he can do that, but I would leave the bottom open, so you would have both. S&S was doing that.
--Bandit
You are very intelligent people when it comes to bikes. Maybe you can help. I am rebuilding a 1992 Heritage Classic 80" 1340. It was my fathers and hasn't ran in years.

I decided this year to bore it .030 over and put semi domed Keith Black 9.5:1 pistons in it. The bike is also getting an Andrews Ev27 cam along with all new bushings and seals, a machined breather gear, Torrington cam, Crane adj. pushrods and tappet roller wheels, polished up heads, ports, and valves, a rebuilt clutch, new compensator sprocket, as well as almost every gasket, seal and o-ring possible, SE intake and exhaust with a re-jetted stock cv carb with a Boyesen twin shot (check them out).

Anyways, my question is, since the new pistons are semi domed, will they work with the stock heads using .030 head gaskets. Dennis Kirk told me the pistons won't be a problem, but I also purchased them from them. Do you have any other info or advice you can give me?

I know this isn't a hotrod of a bike, but I would like a little umph out of her when I get on it. I'm not trying to break the bank here, but if there is something minor I could change or add to "help", then why not, right? You can decide help's definition.

Thanks guys, Glenn Docktor
gdocktor3@gmail.com or 203-305-6771

Could you send some stickers or decals by any chance?
14 Patton Ave. Seymour, Ct 06483

Glenn Docktor
Seymour, CT
Sunday, July 28, 2013
Editor Response I'm going to send your question to Bennett's Performance for a knowledgeable response. And yes we will send you a care package. Hang on.
--Bandit
Very, very helpful, continue your work for the intelligence of the people.

lingsen
jakarta, jakbar, Indonesia
Sunday, July 08, 2012
Editor Response Will do.
--Bandit
Great article, will there be a dyno run when the bike it is done? I can't wait to know the actual final results of this engine.

Luis Rene Ventura
Miami, FL
Sunday, June 03, 2012
Editor Response I'll see if we can't make that happen in the near future.
--Bandit
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