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View Full Version : What are the differences between 86/90 and later 91+ Sportster Engines?


Little Mung
16th October 2009, 21:47
Well, I'm not sure there are any pros for these cons. I picked up an 89 883 complete engine with a basket case sportster project, and I'm debating whether or not to look for a 91+ style five speed engine, or to build off the 89 engine. The project will involve your typical stage 2, 1200 build, nothing especially high-end.

So...

What are the internal differences between the early (86-90) and later (91+) engines?


Some obvious things:

-chain-driven
-different carburetor
-6 plate clutch instead of 7 plate
-four-speed instead of five
-different oil pump

Beyond that, my memory is hazy. I seem to recall and American Iron article that discussed later improvement in the cases to prevent oil leaks. Someone also mentioned something to me about a different stator location. Likewise, something is completely different about the cam/lifter/pushrod set-up, but I haven't nailed down the specifics. As a result of these mysteries, there seems to be a lot of parts-availability issues with getting performance (and even replacement) stuff for 86-90 engines.

What sayeth the court? Build it or dump it for something better?

kevmic28
16th October 2009, 22:41
Keep it. Great project to work on and still be able to ride your other bike.

Little Mung
16th October 2009, 23:42
Well, in terms of the engine. What are the primary differences and applications?

I definitely like the chain drive aspect, at least for a "vintage" project. But are they inherently inferior engines? Because the working assumption is that whatever changes Harley made, were made for reasons of improving the evolution design.

I'll keep reporting back on this thread with anything I find.

biknut
17th October 2009, 00:26
Selection of performance cams has become limited.

You can't buy a new stock pinion gear for 88-90

86 and 87 have splined pinion shafts same as iron heads. You can buy pinion gears for those.

The alternator is behind the clutch. A lot of people have trouble with this design eating stators and clutch shell magnets, caused mainly from trap door wear.

The transmission probably isn't as strong, but is easier to repair.

On the plus side you can replace the tappet blocks if they get worn.

Uses the same tappets as EVO big twins.

The cam case breather is slightly better than the head breather design.

The inboard side of the cams use needle bearings.

Motor weights less than a 5 speed.

Little Mung
17th October 2009, 01:16
Ah, that's the stuff! Thanks Biknut!

I still need to look into what people mean about the alternator location, but everything else makes sense. At least now I've got some reference points for deciding whether or not to find a different engine.

I don't know why I didn't find it before, but sportster-org has a good, basic timeline of the evolution-sportster development:

http://www.sportster.org/history/index.shtml#1985

1990:
Keihin 40mm carb with accelerator pump
1991:
Hydraulic lifters replaced with automotive style lifters, oil pump given cast feed lines (integrated with case), breather system moved from crankcase to head (bet this had a huge effect on oil blow-by), primary cover redesigned, introduction of the right-side timing hole, oil filter integrated into case, different rear motor mount (integrated?), one-piece pushrod tubes
1994: derby/clutcth cover changed, quick-release clutch cable, rerouted oil drain line off oil tank, updated all-weather electrical system (sealed connectors, etc)
1998:
Single fire ignition, 1200s dual-plugs
2001:
Pressed-together flywheel

*all info from sportster dot org

Sweet. Now the trick is figuring out what will interchange and what won't. But it kinda sounds to me like they spent all those years getting the engine right. Then right when they finally had it, they redesigned again. But I guess that's why the Harley aftermarket always seems to be a few years ahead of Harley themselves!

racerwill
17th October 2009, 01:27
on my '91, the alternator is on the crank..... part of the flywheel/ front sproket assy...... prior to that it was part of the clutch on the rear sproket....

Ww

xlint89
17th October 2009, 01:41
Here's basicly the same Q you asked, but for a drag XL.

http://www2.ahdra.com/ubbthreads/ubbthreads-5-5-1/ubbthreads/showflat.php?Cat=0&Number=57873&an=0&page=0#Post57873

Little Mung
17th October 2009, 02:39
They make some good points. I've heard of guys who still endorse the four speed, but that still doesn't account for the weaker trap door of the transmission. Good to know that Andrews makes a better replacement trap door though. However, I've also heard of differences between four and five speed gears themselves, such as that fives are dogged or back-cut or somethin like that. Don't remember anything like that when I removed mine on my 94 though. Also, apparently Barnett makes a nine plate clutch upgrade kit, but I wonder how they do so while remaining within the same clutch width spec. Likewise, Andrews has a decent selection of 86-90 cams and valvetrain components.

Anyway, except for the alternator location, I'm seeing fewer and fewer reasons to go with a newer engine, at least for what I'm doing. I did the stage 2/3 1200 pants-on-fire thing, but this time I think it might be more fun to do just a super functional 883 redesign, as weird as that may sound. I recently inherited a Honda S65 of all bikes, and suddenly have a thing for smaller bikes and thumpers. I've never ridden anything less than 1200 cc's, but I was amazed how respectfully an old Honda climbs to fifty-five with a shot glass piston. Be cool to tinker with the tuning and gearing on an 883 to get the same kind of result.

Thanks for the info all! Should do it for now until I split the cases and get a closer look.

roadster
17th October 2009, 04:35
The entire 4 speed is a weak pile from the K model days. Look sometime at the C/S bearing-you can't really upgrade it- and think about running 80-90 HP through something the size of your finger. The C/S bearing is at least as prone to pop as the trap door and grears. When they go the cases are usually blown to bits. The trans can lock up at speed and ruin all the fun.This is a well known historic problem with the 4 coggers.Then there's the alternator which is costly as hell and will fail regularly. (5-speed alt. rotors are pretty bad,too but cheap and V-Twin sells a bulletproof replacement). Aside from the benefit of another gear,the 5 speeds are MUCH more durable.

Lifter bore damage is pretty uncommon so the 4 speeds replaceable tappet blocks are mostly just a potential advantage. Lifter failure is more common on 4 speeds.The rear motor mounts tend to crack on 4 speeds as well but are replaceable. The 5 speeds are integral and only fail if the frame is tweaked badly in a wreck. It's something to look for on a used 5 speed motor,for sure.

H-D really pretty much got the imortant stuff right on the '91 thru '03 XL's. They will take a lot of mods and hold up stoutly under hard use. On the '04 and later rubbers they ditched the trapdoor which is a travesty and substantially upgraded the topend which will retro-fit back to '86 but that's another story.

williamv1203
17th October 2009, 07:16
Nothing much more to say except that the 91 and later engines won't go into an earlier frame without relocating the side stand mount. This is due to the redesign of the primary side of the case to accommodate the relocation of the alternator assembly to the crank.

biknut
17th October 2009, 14:14
Harley always makes changes to improve the design, but the question is for whom. Some changes make the bike last longer, and some changes make the bike cheaper for Harley to make.

I have both a 4 speed and a 5. The four speed in 21 years has lost 1 stator. I've never had a clutch shell failure, but I do tend to stay on top of maintenance.

My 5 speed has already been through about 4 stators since 01. Moving the stator from the transmission main shaft, to the crankshaft output shaft subjects the stator to more heat and vibration, so a better design? I think not. Less expensive to make, and repair? Probably.

Same with the lifter blocks. It's cheaper to just machine them into the block, but if the the bore wears out, it's time for a new block. $10,000 S&S motors use the same lifter blocks, and the same cam geometry as 4 speeds.

Then there's the breather. Moving it from the cam case to the heads didn't make it better. It mainly just made it cheaper to standardize the design with big twins.

The trap doors in 5 speeds aren't any stronger than the 4 speed doors. You just don't find out about it being worn out from alternator failure. Heavy duty trap doors are available for both models for a reason.

Another thing to consider, and this is a biggy, is that a 4 speed (Sportster) is 100 lbs lighter than a rubber mount, and 50 llbs lighter than a 5 speed solid mount. In any kind of, ah hum, street racing enviorment that's very difficult for a 5 speed to overcome. Not that I would do such a dangerous thing. :rolleyes:

So in the end of the day, I think the main reason to consider a 5 speed over a 4 speed comes down to mainly parts availability.

dave76
17th October 2009, 19:18
I was one of the few to have the clutch alternator shell magnets get destroyed. As far as a costly replacement??, not really, V-Twin sells the sealed magnet clutch shell for $350 which is what I went with. Just replacing the trap door with a Zippers billet door with the double row bearing will probably prevent that from ever happening, thats what i did to my dads 88. Anyway biknut gave most of the info, and IMO it's not worth spending the extra money and hassel of having to get rid of the 4 speed to go with a 5 speed. Zippers used to race Ironheads in the 7s with the 4 speed, between them and Andrews you can build a bullet proof trans. If you plan to build a street and strip drag bike, then the 5 speed might look a bit better, but for a building an 80 hp street bike, the 4 speed will be fine.


Clutch shell with granaded magnets
http://i2.photobucket.com/albums/y49/dave76/Picture336.jpg

V-Twin sealed clutch shell
http://i2.photobucket.com/albums/y49/dave76/Picture371-1.jpg

Zippers billet trap door
http://i2.photobucket.com/albums/y49/dave76/Picture337.jpg

Zippers door with gears installed
http://i2.photobucket.com/albums/y49/dave76/Picture343.jpg

Just for reference a stock trap door
http://i2.photobucket.com/albums/y49/dave76/Picture340.jpg

Vanmor
18th October 2009, 07:31
Wow! That was a good argument for the 4 and 5 speed.

I have questions though......

Are the transmissions on the new bikes so good that they could drop the trap door or is it a cheaper way to manufacture the Sportster ?

A solid mount 4 speed is 50 lbs less than a solid mount 5 speed ? And an old 4 speed is 100 lbs less than a rubber mount ? That is almost unbelieveable !

What are the later model bikes using for cam bearings in the engine cases ?

williamv1203
18th October 2009, 07:45
... A solid mount 4 speed is 50 lbs less than a solid mount 5 speed ? And an old 4 speed is 100 lbs less than a rubber mount ? That is almost unbelieveable!

I find it hard to figure out where the weight differences are that substantial also. Not saying I don't believe it though...

Vanmor
18th October 2009, 08:02
Yeah, I'm just trying to figure out where all that weight came from. Fifty and a hundred pounds is a lot of freakin' weight. But I don't want to dispute Biknut. He probably has forgotten more about Sportsters than I will ever know !

Mung mentioned something about smaller bikes. My CX 500 Custom has about 48 hp. It's a heavy little bike for it's engine size, but it has a lot of torque. Four valves per cylinder with two push rods. Honda's only pushrod V twin engine and it revs to 8000 rpm. You gotta admit, it's pretty amazing for a bike made in 1981. I think an 883 only has about 50 hp or so. A 1200 about 63 hp ?

williamv1203
18th October 2009, 08:56
I can understand an 883 being heavier than a 1200 due to more metal in the cylinder, but the larger piston somewhat balances that out. The 5 speed gear set being heavier, I can get. But 50-100 lbs... Possibly heavier gauge steel in the frame. The earlier Sportys did have lighter frames I seem to recall...

DEEP DIVER
18th October 2009, 12:15
My 93 1200 had the same trouble will the magnets comeing loose [the glue HD use is crap]

This is what I did to fix it

http://i405.photobucket.com/albums/pp139/deepdiver53/DSCF2415.jpg

Reglued the magnets in place with Araldite and all the gaps filled with it.
You must have the gaps the same and check the balance after.

You should be able to do this to the clutch hub as well.

racerwill
18th October 2009, 14:31
you guys did an awesome job on this thread..... I know I learned stuff.....

thanks

Ww

biknut
18th October 2009, 14:54
These are the factory published dry weights between the 1988 and 2010 Sportster models. The weight difference is even greater if you consider wet weight. I'm sorry I don't have the factory weights for 5 speed solid mounts handy, but it's fairly commonly known that rubber mounts are about 50 lbs more than a 5 speed solid mount.

It's pretty obvious Sportster's need to go on a diet plan. Isn't it funny that the supposedly sportiest of all Sportster's, the XR, is also one of the most over weight.
WTF was Harley thinking?

1988 XLH 1200 457 lb
1988 XLH 883 463 lb

2010 Nightster 545 lb
2010 XL1200C 562 lb
2010 XR1200 562 lb
2010 883 Iron 548 lb
2010 883 Low 563 lb

I'm happy to report I've dropped over 20 lbs off my bike.

biknut
18th October 2009, 17:01
What are the later model bikes using for cam bearings in the engine cases ?

They run bushings on both sides of the cam, which is not really a problem. They're just a lot harder to replace when they wear out.

dave76
18th October 2009, 17:03
A 1993 5 speed Sportster weighs 477lbs. This was mostly due to the extra weight of the redesigned engine and trans. The 91-93 sportster was lightest 5 speeds available, then as frame redesigns went through weight increased as they beefed the frame in certain areas, the 94-97 models weighed 491lbs then in 96 when the 3.3 tank became standard it weighed even more. In 04 due to the rubber mounting, the frame needed a complete redesign which added 50 more lbs to the frame alone. These are all dry weights.

1991-1993: 477lbs

1994-1997: 491lbs

1998: 500lbs

1999: 507lbs

2000: 518lbs-883, 1200s 529lbs

2001: 540lbs 1200C, 518lbs 883

2003 the same

biknut
18th October 2009, 17:13
A 1993 5 speed Sportster weighs 477lbs. This was mostly due to the extra weight of the redesigned engine and trans. The 91-93 sportster was lightest 5 speeds available, then as frame redesigns went through weight increased as they beefed the frame in certain areas, the 94-97 models weighed 491lbs then in 96 when the 3.3 tank became standard it weighed even more. In 04 due to the rubber mounting, the frame needed a complete redesign which added 50 more lbs to the frame alone. These are all dry weights.

1991-1993: 477lbs

1994-1997: 491lbs

1998: 500lbs

1999: 507lbs

2000: 518lbs-883, 1200s 529lbs

2001: 540lbs 1200C, 518lbs 883

2003 the same

Thanks Dave, that kind of makes my point I made somewhere about Sportster's going into a slow decline in the 90's.

dave76
18th October 2009, 18:21
It's crazy, a wet weight 2010 1200C Sportster weighs over 600 lbs, to me it's not worth it as a standard Superglide weighs about 670 lbs wet and cost only $2000 bucks more, and you get a 96CI bigtwin. I'll stick to my feather 4 speed.lol

Little Mung
18th October 2009, 19:24
Those weight numbers are kind of amazing---then again maybe not. But I wonder how they look across the decades. First time I got on any bike other than a Sporty was my boss' Hyabusa. I couldn't believe how easily you could throw it around between your legs! (All puns welcome) I've never ridden anything besides Harleys, but there's something about the lightweight minimalism of old thumpers. Given today's economics, I wonder if Harley would ever consider going in that direction with the Sporty or a more democratic model (granted, probably without the thumper). People shout blasphemy, but the market is there, and historically that's where Harley started. I wouldn't be at all offended seeing a Buell blast single on a classy, Sporty-like get up... but "more is more" just isn't my mantra.

Sorry for the commentary, but thanks for the info!

dave76
18th October 2009, 19:54
Yeah, I'm just trying to figure out where all that weight came from. Fifty and a hundred pounds is a lot of freakin' weight. But I don't want to dispute Biknut. He probably has forgotten more about Sportsters than I will ever know !

Mung mentioned something about smaller bikes. My CX 500 Custom has about 48 hp. It's a heavy little bike for it's engine size, but it has a lot of torque. Four valves per cylinder with two push rods. Honda's only pushrod V twin engine and it revs to 8000 rpm. You gotta admit, it's pretty amazing for a bike made in 1981. I think an 883 only has about 50 hp or so. A 1200 about 63 hp ?

Alot of people don't understand the Harley engine, yes a Honda will rev to 8000 RPM and beyond, but Honda along with most Japers make an engine with usually an oversquare bore stroke ratio, Harley engines are all undersquare which usually translates to long con rods and log ass strokes, the main reason for the lower revs is basically the piston speed, a safe speed for mass produced engines is usually 4000 FPM (feet per minute). A Sportster engine with the stock 3.81 stroke at 6500 RPM already is up 4132 FPM. Yor Honda having a 52mm stroke can safely rev to 11000 rpm, however the pushrods may limit that. The Honda is an oversquare engine with a 78 x 52mm bore stroke ratio. the Sportster is an undersquare engine with a 88.8 x 96.9mm bore stroke. No other motorcycle produces it's torque at suck a low RPM as Harleys and thats also due to the long stroke, and rods.

Vanmor
19th October 2009, 08:02
Exactly. A long stroke means more torque and thats what gets you moving faster.

Thats why I like old Pontiacs. My old 400ci can get my GTO moving in no time.

I said my CX makes 48hp, but thats at 8000 rpm.

brimic
21st October 2009, 23:27
If you get a Pre-91 evo sportster, prepare to do a lot of sleuthing to figure out what aftermarket parts fit. Most catalogs or online sources list parts for 91 on up. Some of the parts are interchangeable, some are not.

I've found that the lifters that go in a pre-91 evo sprty are very expensive. I spend several days of internet searching and found the range to be from about $28-120 per lifter.

I like the crankcase breather system- my bike doesn't produce any more than a tiny bit of blowby oil, and you don't need any special kits to re-route breathers if you install a different air cleaner.

dave76
22nd October 2009, 03:15
If you get a Pre-91 evo sportster, prepare to do a lot of sleuthing to figure out what aftermarket parts fit. Most catalogs or online sources list parts for 91 on up. Some of the parts are interchangeable, some are not.



Hmm I've never really ran into any issues, except for mabe forward controls. Yes the lifters are different, but you can use the Evolution bigtwin lifers, the heads are slllllllightly different in that the push rod angle is offset just a little then 91-up.

williamv1203
22nd October 2009, 07:02
Hmm I've never really ran into any issues, except for mabe forward controls. Yes the lifters are different, but you can use the Evolution bigtwin lifers, the heads are slllllllightly different in that the push rod angle is offset just a little then 91-up.

It's not the heads that are different. It is the angle that the lifter guides are cut into the bottom end of the 91.
This is critical when installing aftermarket cam sets. If the lift is beyond a certain degree, there will be some clearance issues. This requires some of the material surrounding the guides at the bottom to be removed to allow for the higher lift cams.

Vanmor
22nd October 2009, 07:57
I second the fact that you have to be careful about sfter market parts for early EVO Sportsters. Maybe we need to start a list of parts that fit our bikes. Like this part from so and so will fit even though it's listed for a 90 model.

brimic
22nd October 2009, 17:08
Yes the lifters are different, but you can use the Evolution bigtwin lifers,

Yep, same part number, but still overpriced.

the heads are slllllllightly different in that the push rod angle is offset just a little then 91-up.

Are there any issues with installing later model heads?

biknut
22nd October 2009, 17:30
Yep, same part number, but still overpriced.



I paid $75 for a Jims big axle lifter for my 88 model. How much does a stock lifter cost for a new bike?

brimic
22nd October 2009, 21:40
The new sportsters use the same lifters as the Twinkie engines. Those sell from around $25 ea.
FWIW, I know how much the OEM twin cam lifters cost to the factory, I'm not ethically allowed to say as I have someone on the inside, but they don't cost any more than a chevy tappet bought from NAPA.

xtremraptor
23rd October 2009, 23:09
Great thread. i love it when you guys get going about stuff like this. :clap

Texas_Wild
22nd November 2009, 02:42
GREAT IDEA VAN!!!!

Oh which one haha the one about the parts list that fits our 86 - 90 models!

2+

nos1965
22nd November 2009, 03:52
Did any 1990 1200 XLH's come with belt drives? I just picked one up and it has a belt, would that mean it was converted at some point or did some come that way?

Vanmor
22nd November 2009, 04:36
TW,

What I meant was any Sportster part that will fit out bikes. Anything from a 50 something model to the 2010 model. A list of after market parts would help too.
Something like these pipes fit a 2003 but will fit on a 86 to 90 or something like that.

Vanmor
22nd November 2009, 04:39
I may have messed up but I bought a used set of Ultima lifters for $30. The guy I bought them from ran them for 75 miles in a big twin and then decided to go to solids.

They seem to work OK for now.

Texas_Wild
22nd November 2009, 04:59
TW,

What I meant was any Sportster part that will fit out bikes. Anything from a 50 something model to the 2010 model. A list of after market parts would help too.
Something like these pipes fit a 2003 but will fit on a 86 to 90 or something like that.

I thought I was pickin up what you were putting down but either way yes yes yes someone should. I can copy and past into a format but I dont know nearly enought to be the one in charge of the information and parts realted.

GOOD IDEA!! 1+ :clap :smoke

slumchop
22nd November 2009, 06:45
They make some good points. I've heard of guys who still endorse the four speed, but that still doesn't account for the weaker trap door of the transmission. Good to know that Andrews makes a better replacement trap door though. However, I've also heard of differences between four and five speed gears themselves, such as that fives are dogged or back-cut or somethin like that. Don't remember anything like that when I removed mine on my 94 though. Also, apparently Barnett makes a nine plate clutch upgrade kit, but I wonder how they do so while remaining within the same clutch width spec. Likewise, Andrews has a decent selection of 86-90 cams and valvetrain components.

Anyway, except for the alternator location, I'm seeing fewer and fewer reasons to go with a newer engine, at least for what I'm doing. I did the stage 2/3 1200 pants-on-fire thing, but this time I think it might be more fun to do just a super functional 883 redesign, as weird as that may sound. I recently inherited a Honda S65 of all bikes, and suddenly have a thing for smaller bikes and thumpers. I've never ridden anything less than 1200 cc's, but I was amazed how respectfully an old Honda climbs to fifty-five with a shot glass piston. Be cool to tinker with the tuning and gearing on an 883 to get the same kind of result.

Thanks for the info all! Should do it for now until I split the cases and get a closer look.


working on my 90 883 xl and found this thread quite helpful, trying to upgrade the weak points that have been mentioned around here.

on a side note, my favorite bike I owned was a custom built honda bob thumper, with a 200cc xr engine(stock 17.4 bhp), engine was worked over good, pushing a little over 36hp plus had a NOS kit on it. rolled that bike at 3/4 throttle at 106mph. never opened it all the way, but it was a hell of allot of fun (the fun factor was what made it my favorite, i got my b@lls busted allot on that bike)

xlint89
22nd November 2009, 07:00
Did any 1990 1200 XLH's come with belt drives? I just picked one up and it has a belt, would that mean it was converted at some point or did some come that way?I don't think so.

Pretty sure the belt came out with the 5 speed trans.

Willing to bet yours had the conversion done to it. Only way to know for sure, would be to remove the front pulley and see what splines the output shaft has.

slumchop
22nd November 2009, 07:11
I don't think so.

Pretty sure the belt came out with the 5 speed trans.

Willing to bet yours had the conversion done to it. Only way to know for sure, would be to remove the front pulley and see what splines the output shaft has.

my 90xl final drive is a belt drive also, i had someone say the late year model 90's when they were transitioning into 91, had a few that came off the factory line this way, i am in no way saying this is true at all just something someone said to me.

chris horne
22nd November 2009, 11:04
my 90xl final drive is a belt drive also, i had someone say the late year model 90's when they were transitioning into 91, had a few that came off the factory line this way, i am in no way saying this is true at all just something someone said to me.

In Allan Girdler,s book Harley-Davidson Sportster he writes that the 91 sportster,s had the new belt drive except the basic 883 which kept the chain drive.

The also writes that the moto company did a kit that the dealers could stock so rider,s could convert older evo xl,s to belt drive.

nos1965
22nd November 2009, 12:41
Cool, thanks for the info. I will check the splines.

dave76
22nd November 2009, 16:19
my 90xl final drive is a belt drive also, i had someone say the late year model 90's when they were transitioning into 91, had a few that came off the factory line this way, i am in no way saying this is true at all just something someone said to me.

All 91 5 speed model Sportsters came with the belt drive, if your 90 has a belt drive, someone installed the kit H-D sold. Obviously you could get a 91 as early as August 1990 when the new models start surfacing. The mainshaft output on the 5 speed is about double the size of a 4 speed mainshaft, so the sprockets would never work.