V-Twin Forum banner

why twincams in fxrs? and not just a large evo?

1 reading
31K views 102 replies 28 participants last post by  ecir45  
#1 ·
ive been following the other thread........and it just seems like a lot of work to put a twin cam in a fxr? whats the point! lol.....couldn't u throw a large cc high performance evo in it and get the same result cheaper and easier?

im open to both sides of the argument.....just curious and didn't want to hijack another thread...

didn't come up with much from google
 
#3 ·
This question could open a can of worms, Evo vs TwinCam. The TC platform is a better platform in a number of areas. Just the engine to transmission mounting and rigidity is a bonus. Maintaining a all HD build can be another bonus. Building a larger EVO really requires aftermarket cases or an aftermarket engine. With a TC you can stay all HD and still build a good performer. TC also allows for easy EFI as well as Delphi EFI. There are many more reasons but I think those would be some of the major reasons for me.
 
#4 · (Edited)
ive been following the other thread........and it just seems like a lot of work to put a twin-cam in a FXR? whats the point! lol.....couldn't u throw a large cc high performance evo in it and get the same result cheaper and easier?
Just spitballing here. First and foremost, we're talking about a demographic here that is neither overly concerned about "cheaper" nor "easier" when it comes to modifying our FXRs. We're not a rational bunch. Otherwise, we'd choose a different brand and or model of bike - like one who's parts are not becoming more obsolete and seemingly more expensive by the minute.

Similarly, much of this demographic likes to keep it "MoCo-centric", meaning they want to "keep it Harley" when it comes to the motor.

In addition, within the past several years there's been an infusion of new blood (twenty/thirty somethings) into this group, and with it probably a bigger (and increasing) population that prefers a fuel-injected twin-cam over a carbureted Evo.

The MoCo offered the Evolution motor in only one size, 80c.i. Sure, it can be bored and stroked to as big as 96 c.i., but undertaking that endeavor surely does not to equate "cheaper" nor "easier".

If you are asking "why not install a bigger aftermarket Evo style motor", such as an Ultima, S&S, Rev Tech, etc,? There's still a big portion of this demographic that wants to buy only American, and well, S&S surely ain't cheap. The list goes on...
 
#6 ·
Just spitballing here. First and foremost, we're talking about a demographic here that is neither overly concerned about "cheaper" nor "easier" when it comes to modifying our FXRs. We're not a rational bunch. Otherwise, we'd choose a different brand and or model of bike - like one who's parts are not becoming more obsolete and seemingly more expensive by the minute.

Similarly, much of this demographic likes to keep it "MoCo-centric", meaning they want to "keep it Harley" when it comes to the motor.

In addition, within the past several years there's been an infusion of new blood (twenty/thirty somethings) into this group, and with it probably a bigger (and increasing) population that prefers a fuel-injected twin-cam over a carbureted Evo.

The MoCo offered the Evolution motor in only one size, 80c.i. Sure, it can be bored and stroked to as big as 96 c.i., but undertaking that endeavor surely does not equate "cheaper" nor "easier".

If you are asking "why not install a bigger aftermarket Evo style motor", such as an Ultima, S&S, Rev Tech, etc,? There's still a big portion of this demographic that wants to buy only American, and well, S&S surely ain't cheap. The list goes on...
from my user name apparently I still owned my Suzuki gs1100 drag bike when I joined here , I started riding ironhead sportster in 1985 then shovels then 1987 fxr but to me if you wanna go fast might as well build a metric bike and stop screwing around with vtwin to make big power , yes it can be done but not as easy or cheap
 
#5 · (Edited)
OP-
Your "name" is 800 screws...couldn't you have just used 100 screws to get the job done? It would be cheaper and easier...


TC-
If you are talking big motors, like aftermarket (S&S), you can get bigger cubes and bigger bores with shorter strokes in TC's so you can fit bigger ponies in a stock frame (try putting a 145" tribute EVO motor in a stock, unmodifed frame...lol.... TC offers less drivetrain flex, better pushrod geometry, and with the TC oil tank under the bike, cooler rider temps, more clearance for bigger pipes, (and bigger motors), weight at lower center of gravity, and no hot oil right under your seat.

I've put all kinds of motors in my Harley VIN FXR's-
EVO's? From 60 Hp stockers (cracked the case lip on one due to evo flex and hooligan activities) all the way up to 201 HP.
Twin Cams? From a 60 odd HP crate 88", to my current (and favorite motor) a 172 HP TC.
Never was easier and cheaper in my vocabulary or thoughts.

Leave it stock if thats your thing....This is the FXR way (or any bike for that matter)-do it your way (your way seems to go cheap and EZ), but everyone has their own way to mod their bike-or not.

BTW, what kind of FXR do you have? Whats in it? Post some pictures...Love to see someones bike who makes a post like that-
Cant wait-
 
#7 ·
Holy $&@! What's with the negativity. If u read my original post I stated I'm open to either side. I'm not doing it myself. Just curious. I'm a purest. I like my bikes as original as possible. I was looking for the advantages to putting a twin cam in a bike. I wasn't sure why. Holy hell. Chill out
 
#10 ·
A buddy of mine put a TC in his tricked out Chopper Guys framed FXR. He had a pumped up 96 ci 120 hp Evo with STD cases, heads, and lots of other stuff. All built from scratch by himself, including porting the dual plugs heads himself. That engine was/is a beast as well as a work of art. He is a master builder of 40 years and has his own well equipped shop.

At any rate, this year he built a pumped up 120 ci TC maxed out like his Evo was. It even used S&S cases so no HD VIN. S&S crank... etc. Another masterpiece of craft and backyard engineering.

When I asked him why he went TC he mentioned some of the stuff brought up here but my impression is that he just likes to try new stuff. By the way He hasn't put the new motor on a Dyno but he estimates around 145 hp. I think he is just one of those "go for it" people that is constantly looking over the next hill. I'm proud of him and glad there are people like him around.
 
#12 ·
Damn straight-

Someone once said, "Why climb Everest when there are closer and less difficult (cheaper and easier analogy), mountains to climb?" To which the climber replied "anyone can climb those mountains, but I don't want the easy way out-I choose Everest. It may be harder and more expensive to climb, but those obstacles aren't gonna stop me from climbing a mountain I always wanted to climb-no matter how hard it is. This is my journey, and if you don't understand, then, well, that's OK. You follow your dreams, and I'll follow mine".
 
#13 ·
i just bought a new v111 from S&S... I got a deal on it and it was still pretty expensive. I have seen a few twin cam drivetrains listed recently for around $2k that is for engine and transmission. personally I have never owned a TC and don't really plan to, I am a knuckle/pan/shovel guy and love the evo for reliability. but I could have bought 2 TC drivetrains for what I spent on the brand new crate motor. actually probably 3 after having to upgrade the primary, transmission, starter, clutch, etc. to accommodate the cubes.

I need a drink after thinking about how much I've spent on this bike haha
 
#14 ·
ive been following the other thread........and it just seems like a lot of work to put a twin cam in a fxr? whats the point! lol.....couldn't u throw a large cc high performance evo in it and get the same result cheaper and easier?

I was thinking the same thing. Was surprised to learn that this is evidently an emotionally charged question.

The "all-MoCo" thing seems curious because from what I keep reading, the Twin Cam engine from HD has suffered from a continuing series of issues since it came out. That's the main reason I still have my Evo. I guess you could get a HD Twin Cam and fix all the things wrong with it with aftermarket parts, but then is it really "all MoCo"? And is this really somehow better than a S&S engine? I've seen quite a few FXR's with big S&S engines and it never occurred to me that there was anything "cheap" or "easy" about it. I just though it would be a blast to ride and a really high quality major upgrade.

I guess I can see that some just want to go TC "because". And they have time, desire, money and ability to make it happen. That's all fine for them.

Not to further tick off any members, here. Me, I just see more reasons (for most people) to get big inch power through an aftermarket Evo design engine and be done with it.
 
#15 ·
the big inch aftermarket evo route is for sure the easier way to go
buy an s&s 111" or 124" and have your old motor out and new one installed in a days worth of work (considering the rest of your drivetrain is up to snuff) and you will have more power than the "average" rider will know what to do with for a street driven bike.

To my understanding the TC platform will have more potential to make more power in the end, they come in bigger cubic inches than the evo ever did from the factory and the late model ones with the attached 6 speed looks cleaner (to my eye, i like not having any external oil lines or oil tank since the oil pan is now under the bike)

Are there big hp evo designed motors out there ?
absolutely but i think the potential to make the power off of a factory based drivetrain is better with the TC motor.

You can score yourself a 103" complete drivetrain (engine,trans,primary, and starter) for under $2k
put in a new set of cams, cam plate, and some headwork and lay down a lot more power than your 80" evo will.

Same deal with a 110" drivetrain. Thats a lot of cubic inches for a stock bottom end, stock cylinder engine.

The TC motors in stock form are a little lacking in power but a set of cams will really wake them up and if you up the compression and do a little bit of port work to the heads you really have a nice power output from them.

So i think when you look at it that way the decision is up to the individual

there are pros and cons to both sides.

Im doing a 117" TC swap into an FXR right now and my main reason for it was simply I wanted to do it because I like building custom motorcycles.
I could have easily called s&s and had a 124" evo dropped off in 2 days and had the bike finished in a week - but I wanted to do something a little different with this one
 
#16 · (Edited)
@cbellamore: I've seen and admired some of your work. You're operating at a whole different level than most of the "regulars" here, which I suppose answers the question being pondered in the original post. I'm following your thread with interest, recognizing that there is much more going on there than simply looking for a quantum leap in power. Just wanted to clarify my position.

Meanwhile, I still think that for most riders looking for a big leap in power or their FXR's, that a big Evo transplant would be the first choice.

One issue is the most direct route to a big increase in power for a FXR and that's all. Another issue is a broader approach to more power for a FXR *and* other mods or a more unique mod, or incorporating personal preferences, or things along those lines.
 
#17 ·
@cbellamore: I've seen and admired some of your work. You're operating at a whole different level than most of the "regulars" here, which I suppose answers the question being pondered. I'm following your thread with interest, recognizing that there is much more going on there than simply looking for a quantum leap in power. Just wanted to clarify my position.

Meanwhile, I still think that for most riders looking for a big leap in power or their FXR's, that a big Evo transplant would be the first choice.
your 100% correct with saying that the big evo transplant will suit just about everyone
i personally like that option also especially for the simplicity of it and being able to get it done in a day worth of work.

to me the evo s&s 111" is an awesome all around motor
plenty of get up and go on any street ridden bike
and its smooth as hell

i might even do one of those in the near future on another bike im planning on doing when im done with the TC swap.

really i like both options. I dont think one is a standout better than the other when your talking about an all around use motorcycle
 
#19 ·
your not comparing apples to apples there

the comparison of stock based evo or stock based tc the tc will put down better numbers (when i say stock based im referring to engine cases and mostly stock trim with some bolt in performance parts)

you can build insane powered evo engines for drag racing
but theyre not gonna fit in a stock fxr frame with regards to the height of those kind of motors

i think a lot of swaps you see are relatively stock tc based drivetrains
so in that respect again the tc will do better

there is also an option that is a TC motor but uses all the evo mounting locations for an even easier bolt in application to the fxr
 
#20 ·
Not to get involved in the performance fight of EVO vs TC, there are other reasons one might prefer a TC in a swap.

Everyone here seems to keep thinking performance, Big EVO, how much you can get out of each.

My 1983 bone stock Shovelhead FXRT puts out a whopping 48hp and 50tq. I am more than happy with it. I do wheelies with it virtually every time I get on it. I do however have a TC88 drivetrain and a 89 FXR that I would like to build a TC95 FXR from. With that said my goal is the most stock looking TC FXR I can manage. I would like it to look like a factory built and offered model. Not trying to go for the full custom or top performing hotrod with the largest fastest engine I can build. I want it to look like an FXR that could have come right off the showroom floor with a TC engine in it.

It will still have PLENTY of power compared to my 1983. It will be reliable and ride-able. That isn't to say everyone else's isn't, it is just what I want out of mine. I have zero desire to own an EVO FXR.
 
#21 · (Edited)
Here is what the OP asked-
"couldn't u throw a large cc high performance evo in it and get the same result cheaper and easier? "
He didn't ask about stock EVO vs TC drivetrains in an FXR (and differences, or which is better, of each).

Of course, obviously, both would be fine, and it comes down to personal choice.

The question simply was why not EVO for big CC's?
The HD FXR frame has IMO a low backbone-
The answer to his question is an EVO, after 124" or so, you run out of
real estate. We squeezed a 131" in one, but mods had to be done.
If a 124" is enough, then sure, it's great (I ran one for years in my FXR-
But......
With a TC, you have the bigger bore case options-
http://www.starracing.com/SSSpecialApplicationBigBoreCrankcases.php
So.....you could put a 4.6 bore, for example (I run a 4.375 bore and my 126" has all day clearance everywhere), and with a Standard EVO 124" stroke of 4.625 (which fits in a stock FXR), you could potentially have a 154 CI TC engine in a STOCK HD VIN FXR frame.
Even with a mild 4.375 stroke you would have a 145", which is simply impossible in an EVO without cutting and raising the backbone.
That,
Plus the other areas I mentioned earlier-oil tank relocated for lower center of gravity, no hot oil directly under rider, better pushrod geometry, more room for engine and exhaust, etc.

So bottom line, up to 124" EVO or TC, it's personal choice and what your goals are with the bike-bigger than that, TC wins all day, if strictly just talking cubes-and not the other issues.

Cheap and easy? Lol....
 
#22 · (Edited)
Here is what the OP asked-
"couldn't u throw a large cc high performance evo in it and get the same result cheaper and easier? "
He didn't ask about stock EVO vs TC drivetrains in an FXR (and differences, or which is better, of each)...

He also asked "it just seems like a lot of work to put a twin cam in a fxr? whats the point!"

There is more than 1 part to the question.

springer- said:
This question could open a can of worms, Evo vs TwinCam.
Who knew? LOL
 
#24 ·
The OP's question is a legitimate one. Most of the reasons have been covered. There are others, like a wider selection of cams for the TC, better clutch components with the TC, and with the oil tank below, no puking oil after sitting all winter. Evo or TC, stock or aftermarket, building a bike around the best frame to come out of HD, is a winner no matter how you slice it.
 
#25 ·
The OP's question is a legitimate one. Most of the reasons have been covered. There are others, like a wider selection of cams for the TC, better clutch components with the TC, and with the oil tank below, no puking oil after sitting all winter. Evo or TC, stock or aftermarket, building a bike around the best frame to come out of HD, is a winner no matter how you slice it.

Yup-
 
#28 ·
Evo vs TC, whatever. Big power, whatever. The real reason for the majority of the TC/FXR conversions is economics. The newest FXR is 17 years old, the oldest FXRs are 35 years old. Aside from being work out, there have been so many improvements to the entire drive train of the years that being able to pull a shovel with its shitty primary drive, starter system and trans mission out and drop in a complete TC drivetrain is very attractive. Lots of upgrades, parts are plentiful and low cost, etc.

As for the labor involved, the entire drive train will just about bolt in with very little fabrication work required. A custom oil pan, adapter swingarm bushings and an engine only wiring harness from Wire-Plus can be had off the shelf and will get the bulk of the work done.

Whats left is to fabricate coil and exhaust mounts, possibly a mid-shift. Anything remaining is very minor.

TIME, the FXR crowd falls into a couple of different camps; 1)there are the old crusty guys that will swear the shovel and its tapered shaft transmission are the best thing ever. 2) the guys that just happen to have an FXR because it was a good deal or their dad gave it to them and they really don't know or care. 3) What I will call the FXR fanatics. I fall into this category. Guys that are leveraging as much of the new technology as they can against the FXR frame (without cutting it).

Amongst the guys I ride with it is common to see $1,500 Ohlins shocks, inverted forks, BST wheels, all LED lighting, aluminum swingarms, 12pt stainless hardware throughout, electronic gauges, etc.

The Evo vs TC has been debated extensively and multiple times here. No need to discuss the merits of either engine again, but the physical characteristics that are somewhat unique to the chassis are worth mentioning. The first characteristic is the engine-trans-primary interface. the evo & shovel engine to trans interface is weak at best. The fitment of the primary case to the evo/shovel setup sucks compared to how it fits on a TC drive train. Another worthwhile characteristic of the TC as it pertains to the FXR chassis is the rocker boxes, specifically the rear rocker box. Anyone that has ever removed the rear head of an evo in an FXr will know what I speak of. Add in the TC rocker box and that rear head is not so hard to get to.

There are other features, but suffice it to say the DRIVETRAIN from a TC is very attractive to the FXR Fanatic crowd.
 
#31 ·
TIME, the FXR crowd falls into a couple of different camps; 1)there are the old crusty guys that will swear the shovel and its tapered shaft transmission are the best thing ever. 2) the guys that just happen to have an FXR because it was a good deal or their dad gave it to them and they really don't know or care. 3) What I will call the FXR fanatics. I fall into this category. Guys that are leveraging as much of the new technology as they can against the FXR frame (without cutting it).
At the very least there is a 4th Camp. Those of us that truly appreciate the FXR for what it is and enjoy riding them. Also FXR fanatics.

Camp 1. I have a Shovel FXR with a tapered shaft transmission and know it isn't the greatest thing ever. However with it's 4 speed clutch it is still stronger than the early EVO's primary and clutch until about 1990. Mine's 34 years old and still holding up no problem. So no, I'm not and old crusty guy that's and idiot because I love my Shovel FXR.

Camp 2. By your assessment, if you're not leveraging as much new technology as you can then you are just a idiot that fell into an FXR for no other reason than it was a good deal or your dad gave it to you. Wow what a statement. So no one could just want a Stock FXR because they know what they are?

Camp 3. One could look at this group and classify as a bunch of people that think their FXR is a wannabe Hayabusa and ruined a perfectly good FXR and didn't come anywhere near what a real performance bike will do.

I guess it's all how you look at it. The good part for me is I don't really care what anyone else thinks of my old Shovel FXRT. I get great enjoyment out of riding it. It handles very well with the 2000 FXDX adjustable front end and Progressive 418's on the back. Stopping is much improved over stock with the FXDX front brakes.

To each their own.
 
#29 ·
For some maybe non-rational reason i have never developed the slightest emotions towards the Twin Cam - i think this is not so much because of what i heard about the camdrive issues or
running at higher temperatures vs the Evo, but it just not happend. Although i started off with Ironheads and Shovels in the eighties i feel right at home when jumping on an Evo.
I do not mean to talk the Twin Cam down or something, i just don`t care for it but i think it`s normal to prefer the one engine or bike vs another as the one and only thing bikes are about, is emotions.

So due to my lack of interest for the Twinkie i don`t know much about it, but this thread brought up one thing that i would like to know.
Earlier in my car and bike history i was hunting hp numbers, but what i finally found to be the most interesting for me, is how does torque set in and develop (and how much of it of course).
I once had a Hardcore Chevy SB able to develop big hp numbers, but it was just aweful to drive at about 90 % of the time as i did never take it to a track.

So what i find interesting aside the hp talking is, how do equally big TC`s and Evos (obviously 124" is the limit here) compare torquewise, meaning how does the torque curve look like, at what rpm does it set in, and where is max torque .
500 or 1000 rpm is big difference on a street driven bike, so to me that are main questions i have when getting a new motor.
 
#30 ·
how do equally big TC`s and Evos (obviously 124" is the limit here) compare torquewise, meaning how does the torque curve look like, at what rpm does it set in, and where is max torque.
IMO, that question is just too open ended for a definitive answer. That being said, in similar configurations, size and tuning, I would prefer a TC because of the amount of cooling, engine to transmission rigidity and overall design.

From the theoretical point of view there is little difference. Both are 45 degree, air cooled, pushrod, common crank pin, antique, v-twin engines.
 
#33 · (Edited)
I don't think I fit in any of the fxr owner categories... I've ridden a fxr since 82,,, they are the best bike Harley has ever built,, ride handling smooth and performance wise. In 82 an fxr was the quickest harley made...
Mine is a long story so I'll try to be brief,,,, I'm a Harley wrench, I know every engine from shovels forward,,, the evo is my favorite. Paul has already mentioned all the good qualities of the TC, I just don't like one enough to own one...

I did the 113" S&S evo, and built it the day it arrived. It ended at 137hp...I didn't want to be the biggest or fastest,, just fast enough to keep me from being bored... I have a taper shift baker, the keyway has no issue with the 113,, it is all in how you assemble it, and you need to toss the factory 84-89 clutch. That's half the taper shift problem there...

I built the perfect bike for me,,,, I think that's what everyone else is doing we are all just doing it differently. I can't ride a stock or even an se Harley engine, I keep looking for the pedals to det some speed out of them, if you do build a fast SE motor I think it will cost almost as much as an S&S and not last nearly as long,,,

when I rode the shovel for 25 years, I didn't think it was cool, I had a fortune in it, and it ran incredible for 93", the guy running the dyno the day it made 109hp did not believe it was only 93". I have more money in my 113, and had more money in the shovel than most people paid for their fxr brand new, sad but true, pores is expensive
I had no interest in having a # matching bike, I kept the cases, it won't bring any more unless it is exactly as it left the factory.
 
#35 ·
The clutch itself isn't your problem. It's the clutch hub. It is made of aluminum with a steel insert. The steel insert has a keyway that matches the tapered shaft of the transmission. That key way is weak point and can crack.

If the bike is driven relatively normal it may not crack. However if you be on the bike regularly they usually crack. If you put any significant horsepower to them the transmission should be upgraded for the spline input shaft and matching clutch hub.
 
#36 ·
Ok...The Performance angle didn't work...course ,, what do I know...I ride mostly Shovel's also..tho my '83 has an EVO in it Now..that is temporary. When I finish the Old Shovel mill, it will be back at home. For No other reason than Economics... it came with one, as is Worth more with one.
While Most people don't care...I do. Check how many folks search out a Pristine, Unmolested old Harley...Pay good money for it then someday, for whatever reason they, or their Heirs, try to sell the monstrosity that resulted from "improvements"..
Ever heard it? "Geeze I've got a Jillion dollars into Improvements and can't get even a Half a Jillion offer for the POS"
Semi-Stock...Unmolested= $$$$
Or...YMMV
I can hear someone saying how they happened to find a Sucker...er...I mean sell a Bastard...But, Not Often.
 
#37 ·
I use a Rivera pro clutch....
I do a repair 1 time and forget about it, I've been building High horse bikes all my life, I know what fails, and why,,, im going to catch flak from all the harley purists here but, oh well....factory harley parts are not intended for performance use... the 84-89 clutch is the weakest clutch harley has ever fielded, it doesn't last well in stock bikes, let alone a seriously powerful engine... at 80+ HP it's just a matter of time...
I sell and install a ton of Rivera clutches, everyone is happy with them..

For $500, a Rivera clutch takes its place, no further clutch problems provided your mainshaft isn't trashed from the hub failures...

The failure starts like this, the hub cracks, then the entire clutch assy. begins walking fore and aft, spreading the crack with use, damaging the mainshaft sometimes beyond salvaging, other parts are worn and damaged as well... oem harley parts are outrageous in cost.. doubling in the last couple years.. I use industrial keys, and loctite .
Fix it once or keep messing with it,, I like to ride....
 
#41 ·
Actually...The old Shovel clutch hub can indeed "take it", it is when they [MoCo] made it "Cheaper" that it really sucks.
Then some Brainiac came up with the Splined shaft...and we could Put some real horsepower to that..
of course...I don't go by Dyno results...Just what happens[happened] on the Track! If you understand how the Taper works, and ignore the "key"... you can go pretty well!!
But...that is kinda old news now...