From the Boutique:

The Harley Tax

L. Maurice Riggins - Jan, 1998

On a new bike, you need to pay "the Harley tax", that is, pay to make the bike the way it should come from the factory if it weren't for a Federal government trying to save us from ourselves. This requires you open up the intake, open up the exhaust, and rejet, not only to adjust for the first two changes, but to compensate for smog jetting as well. And on a factory 1200, if you intend to run it at high revs for max hp, you also need to get rid of the 5,200 rev limit in the stock ignition. There's a little more performance to be had on a nearly stock 1200 in this range at the expense of increased engine wear and tear... only a little if you keep it below about 6,000 rpm (no need to exceed that on a nearly stock 1200) and progressively more as you go up.

You just can't beat the $65 Harley Davidson Screamin' Eagle (SE) air cleaner, which reuses the chrome "ham can" cover. Its filter element has almost twice the surface area of the stock element. There's no other air cleaner on the market that flows nearly as well. Plus, if you ever need to put the bike back to stock, for warranty work for example, you haven't permanently altered the stock components. However, many, if not most, dealers will honor the warranty with the SE air cleaner and slip-on mufflers, particularly if you paid them to install them at delivery or 500 mile checkup for example. Drilling the stock backing plate just gives the dealer an excuse to void your warranty. The SE unit's not much more than a K&N replacement filter for the stock air cleaner ($56) and flows a lot better.

But drilling the stock air cleaner backing plate and using the smaller, rectangular K&N air filter probably flows about as well as the DragTron and KuryAkyn poseur air cleaners which have about the same area. For those who are willing to sacrifice some performance for show, smaller air cleaners like the DragTron show off the chrome pushrod tubes against black painted cylinders excellently and I'd sure be tempted to use one of these on a Custom, for example. Smaller air cleaners like the DragTron also require additional hardware to handle the crankcase venting system, which goes into the air cleaner on a stock or SE setup, and a bracket to provide air cleaner support, which comes from the breather tubes on the stock or SE setup, so the total cost can be much higher than the SE unit. Doing just an air cleaner upgrade, even without exhaust modifications, really requires some jetting changes (see below).

Despite being freer flowing (something like 20%, if I remember correctly) from '97 on, the stock exhausts are pretty restrictive from a performance standpoint, and certainly don't provide the typical "Harley sound" many, if not most, riders want. The most obvious solutions are the HD SE slip-on replacement mufflers at about $120 a pair. I'm told Cycle Shack makes these for HD and that you can get the CS equivalents for about $100 a pair without the Screamin' Eagle script in the rear muffler (which may be an advantage if you're using the tapered ones to keep the bike lookin' stock for law enforcement or other purposes). The SE slip-ons flow something like 300% better than the stock mufflers, are easy to get at the dealership, and with some dealers, keep the warranty intact. I'd guess somewhere between 50 and 90% of aftermarket exhausts sold these days are SE slip-ons. Although some on the list may disagree, the SE slip-ons are more restrictive at higher rpms than some other solutions, like 2 into 1 header systems, such as Bartels, SuperTrapp, and Thunderheaders, and they show this restriction by being a little quieter on a 1200 than an 883 (some people don't like the way they sound on a 1200). But they certainly flow well enough for someone using a smaller than SE air cleaner and/or keeping the stock ignition on a 1200. The SE slip-ons are available in tapered style (which look like stock mufflers), slash-cut (also known as baloney cut) and turn-out. Although there are rumors the slash-cuts perform better and sound louder, the baffles in all three are identical (and removable on the slash-cuts). The main difference is what looks best on your bike. I just wouldn't recommend the turn-outs (or Thunderheaders which hang pretty low) on lowered bikes such as the Hugger and Custom since the turn-outs stick out further, reducing cornering clearance and can drag in a turn... and mufflers don't fold up like foot pegs... they leverage the tires up off the ground (but if you install forward controls, which stick way out, they'll probably drag first, getting your attention). The other thing to watch for is whether an aftermarket exhaust, such as 2 into 1s, will interfere with highway pegs or forward controls, or rearsets, if you intend to use them.

The absolutely worst exhaust solution are drag pipes. They are light, cheap, and if long and properly tuned, provide a few extra horsepower, but at one rpm point high in the rpm range, which is why drag racers use them. They are designed to be run wide-open, not with baffles. The cost to this is approximately a 20% loss (compared to SE slip-ons) in power down in the 2,000 to 3,500 range (where you mainly cruise in fifth), with the loss tapering off above that. This is not only widely published knowledge, but I've seen enough real dyno run results to verify it. Other downsides are the obnoxious noise (which folks with an in-your-face, dare-ya-to-knock- this-block-off-my-shoulder attitude love, especially when they're setting off car alarms :-) and the cheap looks. Most drag pipes are skinny looking and tend to show bluing badly... and they really don't look right with little heat shields tacked on to try to hide bluing or prevent injury. Some try to improve the low and midrange power loss with "anti-reversion" devices such as "power cones" or "torque valves," or restrictions such baffles, or even stacks of washers, to increase back pressure, and while these may gain back a little low end power, they restrict the top end and generally don't work very well... as Chris B. pointed out sometime back... drag pipes are very simple devices which work on acoustic phenomina, not back pressure.

There's no doubt the crossover tube on the stock exhaust header is ugly, and it really hides the pushrod tubes, so most folks would really like to get rid of it. It does provide some power, but for those willing to sacrifice some power for looks, there are plenty of systems besides drag pipes that do away with it. However, many aftermarket systems don't offer heat shields as complete as the stock system and look pretty badly after bluing. Also be careful of horsepower claims, even dyno results. The widely published "BUB" hp gains somehow included cams and other work on the bike running the Bubs that weren't on the engines running the competitor's pipes... imagine that! If looks count, in my opinion, the absolute best looking exhaust system for a V-twin is Vance and Hines StraightShots. They look like fat (2.25") drag pipes, but are really a 1.75" header pipe wrapped with a 220 degree heat shield, so you'll never see bluing. The header pipe turns into a muffler down on the end and the heat shields flow into them so well each pipe looks like one piece from head to end. And you can leave them flat cut or chose from four different end caps, such as slash cut. These aren't cheap, but can be had at a good discount mail-order from Accessory Warehouse (http://www.accwhse.com). They look really classy and sound better than the slip-ons on a 1200, in my opinion. I'd certainly be tempted to get them for a 1200 Custom!

And if you're looking for big hp numbers at high rpm, the black Bartel's racing megaphone 2 into 1 header system is probably the ultimate... but it IS LOUD. Next down the list would be the chrome Bartel's 2 into 1 header with 2 stage muffler, or the widely used, tunable stainless 2 into 1 SuperTrapp system (or chrome RevTech clone maybe... I'm not familiar with it). The Thunderheader comes highly recommended but hangs a little low and out for banking steeply into tight turns. I don't really have any data on the 2 into 2 SuperTrapp unit, but I suspect its benefit would be at extremely high rpms with some loss on the low end, partially due to no crossover. I also suspect decreasing the number of disks may help the low end at the cost of the high end... probably not worth it. I don't have any data on the Vance and Hines 883 racing exhaust resold as an SE unit by HD dealers. But IMHO, it's damned UGLY, and you don't have to do ugly to get hp. Also, Hooker Headers, a long time leader in automotive racing headers is now in the market with a chrome tunable 2 into 1 header (maybe more models... I don't have much info on them).

Knocking or drilling the baffles out of the stock mufflers isn't a good idea... they are louder, but generally sound crappy and this probably would void your warranty. Plus, if you have to put the bike back to stock to resolve a noise traffic citation, which is a lot more likely than having to get any extensive warranty work done, replacement stock mufflers are much more expensive than SE slip-ons.

Then comes rejetting the carb. As Chris Hajer points out, all you really need to do is to drill the cap off the idle mixture screw so you can open it up a little, replace the #42 slow (pilot) jet with a #45 to cure any off-idle stumbles or backfires, and go a size or two larger on the main jet to offset the leanness created by the freer flowing intake exhausts... PERIOD... about $15 worth of parts... all you really need. And actually, you folks who live in Denver or other mile-high places don't need to richen the idle and slow jets... the altitude does that for you... but you do need to rebalance the altitude-compensating main circuit for the air cleaner and exhausts by making the main jet changes. This is a DIY job if you're careful not to bend the floats when you're working around them. ON '96 AND LATER BIKES DO NOT REPLACE THE NEEDLE, as with the '88 1200 needle recommended in World Wide Glide web article. The later stock needles are exactly the same width as the '88 needle in the slow and mid range, but actually fatter (leaner) in the high range (I've measured them)... the opposite of what you're trying to do. Also, don't bother replacing a late model 883 needle with a late model 1200 needle... they were the same at least through '97 and I suspect also in '98. You can drill out the vent hole in the slide to 1/8" to improve throttle response, but this, like changing the needle, requires removing the slide with its rubber diaphram... which can be tricky to reinstall without pinching or puncturing. I DON'T recommend cutting coils off the diaphram spring or even replacing it for two reasons. The spring is what establishes the constant velocity speed in the venturi. While reducing spring pressure allows the slide to come up faster, it also lowers the velocity throughout the entire operating range. Also, there IS such a thing as too much throttle response if the slide opens faster than the mass of the fuel allows it to increase. This will cause a "bog" in power when the throttle is opened. My recommended main jet sizes (for stock needles) are:

       SE air cleaner or mufflers only       Both
883           #165                           #170
1200          #175                           #180

Then there are the "kit" solutions, which give you the basic jetting parts, plus, as Chris Hajer points out, in some cases, add some real "gimmicks" that theoretically make massive improvements. The two most popular kits are the DynoJet kit and the Yost CV2 Power Tube Master Kit, both about $80 at most sources. I used the latter because I like the profile of their needle, which is thin at high rpms, like the late model needles, but also thinner at lower rpms. I found my kit for $65 mail-order, but that's an expensive needle! Like Chris, I really think the "power tube" thing is a gimmick. IF YOU HAVE A '96 OR LATER BIKE, and go with the DynoJet kit, make sure you get #8105 for '96 and later CV carbs, not the older #8102. Also, with late model bikes, avoid the "clone" kits... they are clones of the older DynoJet kit and haven't caught up yet... if you don't want to spend the money on a name-brand kit, just stick with the above jet changes. Finally, the DynoJet or K&N Thunderslide kit... I think this too is just a gimmick... an outrageously expensive one at about twice the price of other kits. In fact in the Autumn 1997 issue of HotXL, in a Thunderslide install article, they were disappointed that their gain on the dyno was only that which DynoJet used to publish for getting the jetting right AFTER the SE air cleaner and mufflers... 2-3 hp... duh! In my opinion, this is about all they should've gotten because all the kit really does is get the jetting right. You have to be careful of claims... a 10hp gain is about what you should get with SE air cleaner, slip-ons, and jetting combined.

Finally, there is the Trock CV carb work. I don't have any data on it, but I'm told the main benefit is in smoothing out the powerband. It's definitely worth researching, but keep a skeptical eye on any claims.

Doing these pays the "Harley Tax" and should result in about a 10 hp peak gain on both 883 (from 40 rear wheel hp stock to 50) and on a 1200 (from 50 rw hp stock to 60... maybe 65 if a 2 into 1 exhaust is used and the rev limit increased to 6,500 or so with a replacement ignition module). This is a massive improvement, especially on an 883 (25%!). However, don't think they will make an 883 equal to a totally stock 1200 which still has tons more power at any rpm below the peak hp rpm.

Other things to consider (or not)....

Factory service manual and even factory parts manual... if you want to understand your bike and/or do any of your own work. Can't beat the prices. These, along with the owners manual, are your BIBLES.

Fuel petcocks... the stock petcock, if in the on or reserve position shuts fuel flow off when manifold vacuum is zero... like when the engine isn't running... or when the engine is under heavy throttle application, at which time the fuel in the float bowl is used until vacuum returns. The stock petcock is a blessing to those of us who have parked with the petcock on and had all the fuel drain out of the tank onto the ground. Despite claims of the aftermarket suppliers, the stock petcock certainly flows enough fuel and/or there's enough fuel in the float bowl for a dyno run or 1/4 mile run... no data I've seen supports the need for more. However, the stock petcock does have one failing... on really long uphill grades with heavy load (like our 300# Pingel evangelist on his 883 :-) and/or heavy throttle application, vacuum may not come back in time to replenish the fuel bowl before it runs out. You can back off the throttle to let vacuum come back and fuel start flowing, but that may not be a good idea if an 18-wheeler's right behind you trying to maintain speed on the grade. So a non-vacuum, aftermarket has at least some merit. The overpriced Pingel is the most popular, and while it doesn't have the no-brainer shut-off and is rumored to be less reliable than the stock unit, it's very common and easy to get rebuild parts for. If you have a late model bike prior to mid/late-97, there may have been a recall on the stock petcock due to oxygenated gas damaging the rubber diaphragm. A dealer trying to use an aftermarket petcock to void the warranty would be on real thin ice.

Beyond the tax... more power!

This section is not intended to be an extremely detailed absolute gospel on high-performance, but to give the new owner a quick look at the next level.

If max performance, be it racing or chasing big hp numbers on the dyno is your thing, you're going to get more performance at higher rpms for many reasons I won't go into here. Just keep in mind that frequent engine rebuilds are part of a racing effort. The harder you ride the bike, the higher you operate it in rpm, and the more often you do either, the sooner something will wear out and have to be replaced. If you want maximum reliability, stop here and keep it under 5,500 rpm. If you want more performance with reasonable reliability, you can find that in the 5,500 - 6,500 rpm range. Just remember, the more often you operate it here, the sooner you're going to see blue-oil smoke coming out of the pipes, and the sooner you'll need to do a top-end rebuild, consisting of boring the cylinders another .010" over and installing new pistons and rings another .010" larger than the last... and doing a valve job while you're at it. This isn't a really big deal in the performance world. If you want even more performance, you can find it in the 6,500-7,500 rpm range, but not only will top-end rebuilds become even more frequent, but you'll also have to start watching and maintaining the bottom end much more. All that being said...

The SE ignition modules for late-model bikes are relatively inexpensive, but due to smog certification (they're CARB approved), don't do anything other than raise the rev limit (they have exactly the same advance curves as stock), which may be desirable especially on a 1200 (but I probably wouldn't bother if running the smaller air cleaners). Single-fire ignitions are expensive, don't make any more power than a dual-fire (unless one of their adjustable advance curves is better than the stock one), but they definitely smooth out idle and low end performance. Most ignition system changes probably void the warranty (the SE disclaimer says it does, but again, few dealers enforce that), but few, if any, require modifications to anything you couldn't put back to stock.

Replacement cams can add varying degrees of power at different points in the rpm range at a cost of rougher idle and some increase in mechanical noise, since they aren't computer-matched to the cam cover like the stock cams. The Andrews N2 cams give a good boost in the low and mid rpm ranges, with a little boost over stock at the high rpm ranges. The higher rpm cams, such as the Andrews N4 and N8, or the SE bolt-in or "big" cam kit (with valve springs), give their most gain in the high rpm ranges with some boost in at least the upper midrange, at the cost of definitely rougher idle, and, unless high-compression heads or head modifications such as shaving are used, a significant loss of low end power. The '98 1200 Sport heads already have the compression ratio to support hotter cams without doing headwork to avoid holes in the midrange. I'm sure most dealers would consider cams, even the SE ones, warranty voiding, but check your dealer.

High performance heads or head modifications usually involve at least polishing the ports, if not opening and reshaping them, for smoother and increased air flow, possibly larger valves (especially on 883 heads being used on a high-rpm, high-hp 1200 conversion), again, for increased air flow, and reducing the combustion chamber volume through shaving (cutting off some of the bottom of the head) or welding in some material to increase compression ratio (to offset the loss of cranking pressure that comes with high-rpm cams). This latter modification is absolutely critical to avoid losing significant power in the low and lower midrange (where most street riding occurs). Jerry Branch, Zippers, and Headquarters are probably the most popular headwork speed shops. There are also many aftermarket performance heads. Probably the most popular replacement heads have been the S1 Lightning heads sold by HD dealers, available either as cast or black painted to match your cylinders. These have stock 1200 valve sizes, but increase compression ratio to offset the loss of cranking pressure of high-rpm cams, such as those sold by the HD dealers. You can now also buy the dual-plugged heads used on the '98 Sport, but I think they are overkill on a modern Evo engine... I'd rather spend the money on higher performance work by one of the reputable shops. Heads are probably also warranty killers, with the possible exception of the S1 heads at some HD dealers.

Replacement carbs... this is probably the last thing you should change... after you've done high-rpm cams, head flow work, and racing exhaust... the stock CV carb flows well enough for Buell to get big hp (85 or so rw) out of it up to 6,000 rpm or more and it's a lot more "driveable" around town than non-CV carbs (it's a sophisticated variable venturi design). But the sacrifice in driveability is worth a few hp on engines modified heavily enough to use their increased flow at high rpms, particularly above 6,000 rpm (and it's also not to say you can't gain some from a replacement carb before doing cams or headwork, etc... you just won't get as reasonable a return on the investment as using the CV carb with cams or headwork). The HD SE and S&S "Super" series carbs (the latter probably _the_most popular replacement carb) are the crudest (butterfly-type fixed venturi) and as a result harder (but not impossible) to tune out the stumbles without some add-on like a ThunderJet. Next in sophistication are the variable venturi designs. The simpliest (and somewhat cruder in the metering circuits) is the Edelbrock Quicksilver II. And the most sophisticated and complex to tune, yet most likely to work correctly "out of the box" without stumbling is the Mikuni. Obviously, it ain't "'merican" but neither are your Showa forks, Yuasa battery, Nippondenso starter and lord knows what else. These are probably warranty voiding as well, but you can go back to stock if you keep the old carb.

And finally, my "don't bothers"...

Replacement ignition coil... the stock coil is fine for all but the most heavily modded high-compression engines and probably works just as well even with these (a single-fire ignition will require a single-fire coil, though). For looks, you can get coils in colors.

Solid lifters, adjustable pushrods... the stock hydraulic lifters are adequate for all but the most extremely high rpm engines... and with hydraulic lifters, you don't need adjustable pushrods (unless perhaps you do some serious shaving on the heads and cylinder bases).

Miracle plug wires (i.e. Nology, et al)... a new set of stock plug wires is better than an old set of miracle wires any day. However, if you use an aftermarket coil, they may recommend specific wires, such as spiral wound inductive suppression wires. Again, if looks matter, you can get wires in colors and wires wrapped in braid of different colors.

Miracle plugs (i.e. Splitfires, including SEs)... and this includes even platinum plugs, which are great for 100,000 mile tune-ups on modern cars where it's difficult to get to them... a new pair of standard plugs every year is about as good as it gets... in fact, I've heard standard copper plugs outperform platinums when new, but this is probably in the range of theoretical.

Real miracles like saw-toothed restrictions in the intake manifold (Turbulators) that do the opposite of polishing the intake, $200 billet crankcase vents (KrankVent) that relieve pressure under the pistons for more power (like the stock venting system? :-), magnetic balls you drop in the gas tank (or devices you put in the fuel line) to "engergize," "magnetize," or "polarize" the gas molecules for big power and mileage gains. Hint: if you don't see the racing teams using it... and these guys are fanatics about little stuff... it probably isn't going to give any significant benefit.

Miracle oil or gas additives... avoid them like the plague! I won't get into the religious war of oil selection, including the petroleum vs synthetic battle... but all you need is a good multi-grade oil... PERIOD! The HD recommended HD 20W-50 isn't cheap compared to automotive oil, but it's certainly not expensive when compared to other good air-cooled motorcycle oils, such as Yamalube, etc. Oil is the life-blood of an air- cooled engine. I change oil and filter every 2,500 miles with the HD oil and change primary lube every 5,000 miles with HD's SportTrans fluid.

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L. Maurice Riggins