From an thread from a couple of years back. I thought you might be interested.

quote]ORIGINAL: BClem

The '88' was designed by an engineer named James Fueling. He worked in the automotive industry for the most part but was brilliant in a practical sense about engines and their mechanism. He engineered a means for the V twin to reduce the angularity of the valve train including the roller tappets, pushrods and rocker shafts. The design was for the cams to be linked together with a roller chain and then driven as an assembly from the pinion shaft. His inovative design also included an enclosed oil and scavenge pump, the unit assembly of the engine and transmission and totally reconfigured heads without the hemispherical chamber that Harley Davidson always utilized.

Jim Fueling died about three years ago after realizing many success with his endeavors including the design of the twin cam V twin that Harley Davidson adopted for a new series of motorcycles.


BClem
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That sounds accurate. I knew he was the inventor behind the stock twin cam oil pump...which is a gerotor driven pump like his fueling...only not as powerful. Its a shame he passed so early. That guy had a gift for all things motor driven.

 

Both the twin cam and evo are outstanding engines, Its really hard to beat a good evo, but I think if anything will do it, its the twin cam. Sometimes if you go by the posts you read online you would think that nothing made today is any good, but I assure you, for every 1 person out there with a problem with a twincam there are 1000 more that have not had any issues. I know of several twin cams with well ober 100,000 miles on them with relatively no trouble. The evo is a legend, but mark my words, in 15 years we will be looking back at the twin cam with the same love we have for the evo. The twin cam is an outstanding engine and has proven itself time and time again.

 

my evo has over 71000 miles on it, zero problems, so far.

good motor.
i have no clue on a twin cam.

weet

 

Thanks everybody for all the very helpfull information.
You've definitely helped me to make a good decision.

Griz

 

Buy an evo for 1/2 the money, put an S&S 113 in it and go eat TC's all day.

 

I'm not sure what problems have been documented that affect all or most SG's, unless you are referring to the design issues that prioritize style over function. Examples are the minuscule windshield and slammed, uncomfortable rear shocks. It is marketed as a cruiser and is a good bar-hopper, but to be a touring bike the SG needs some work, and this can be done rather easily for a price.

Other than tensioner wear on '06 models and fuel-pump failure on early '08's I can't think of any prevalent repair or reliability issues for the SG or any other modern EG.

Evos were a nearly bulletproof engine. They had some quirks, like leaky base gaskets and extreme angles on the pushrods that sometimes caused odd top-end noises, but they were very solid. I rode one for 106k miles with no engine trouble at all and it is still running today 2½ years later for the happy new owner. That bike still has the original rocker and base gaskets, too, and the heads have never been removed. The big problem with Evos is that to perform decently they had to have ignition and carb/EFI mods at minimum, and cam upgrades ideally. In stock form they produced about 52hp and were not stellar performers, but almost no surviving Evos are totally stock. Add a mild cam, a bit more compression, ignition and carb upgrades, and the bikes ran very well indeed.

Early TC's ('99-'06 FLH's) had flawed engineering in the cam chest and tensioners wear abnormally fast. Some very early TC88's had cam bearing failures, but that was apparently fixed or improved in later years. HD even extended the warranty to 50k miles for this problem. These engines had more restricted heads primarily to meet emissions standards, and that hurt top-end performance. In all, it was a performance improvement over the Evo in stock form, but the cam-chain-tensioner issues that varied greatly from bike to bike was a concern for me and I never owned one. I'm not putting them down, but if I had one I would convert to the new SE hydraulic cam plate and be rid of this problem.

Later TC's are the best of the lot and the best engine HD ever produced, IMO. The new cam setup eliminates excessive tensioner wear, it is equipped with a larger-capacity oil pump, and have newer, more reliable and higher-output (50A) three-phase alternators. The added stroke (88 to 96 ci) results in a meaningful increase in low-end torque, which made more owners happy with the stock performance than any previous design, IMO.

FWIW, Porsche didn't aid HD in the design of the TC engine unless there was some secret project that I am unaware of. However, they did largely design the Revolution (V-Rod) engine. Also, one person wrote that Evos were not rubber mounted, but all Evo FLH's and Dynas were rubber mounted at least those produced in the past two decades.

 

evo has the crankpin that is tapered on both ends, and to true the flywheels, you use a maple wedge or a lead hammer. very caveman approach but it did work. twin cams crank is much different in that an interference fit crankpin is pressed in place. and rarely is there an issue with the cranks. also the tc cranks use a three hole oiling system far superior to what the evo uses stock. another feature is that the twin cam is also oil cooled rather than just air cooled. there is a jet under each piston that shoots a jet of oil to the underside of the piston. twin cams in touring harleys in 07 went to a superior oil pump and cam drive system. it was 06 for the dyna line to get the same improvements. in 09 there was a big difference mainly in the frame of the touring line.
american iron magazine is a good place to learn stuff about your bike. hope you get into a bike soon, and being prepared before purchase is a wise thought. good luck.

 

I used to ride a 1990 Classic and loved but now I have a 2005 Ultra and love it even more. The "05" is fuel injected and when riding two up it makes it up the hills without full throttle. It does seem to be a little hotter on the legs. I also began finding out the older bikes are slightly more difficult to get parts for. EVO is good but I think the TC is better

 

Rubber-mounts go back to the shovel FLT Tour Glide of 1979, made alongside the solid-mount FLH. I think all Evo touring models are rubber mounts, as are Dynas, although they use different systems.