Issue link: https://read.dmtmag.com/i/787665
72 nMarch 2017n www.thunderpress.net THUNDER PRESS Upgrade trifecta Excluding the M-8 (until time tells)… all-alloy OHV Harley engines exhibit traces of three legacy "foibles." 1. Noise coming from the rocker boxes. 2. Oil leaking from the rocker boxes 3. Poor control of the air and oil within that results from positive and negative "pulses" in the rocker boxes, a.k.a. "oil carryover!" It could be argued that Sportsters from 1991–2003 are representative of all three rocker box issues… maybe the most representative. Most Sportster owners (and you know who you are) with bikes from this era have some top-end noises or a leaky bottom box gasket or a little lubricant misting out of the air cleaner. If you don't… you will. Human nature dictates that most of us will wait until things get ugly before taking action. Fair enough! But, when the day dawns that you need to deal with any one of them, why not take care of all three? (I mean—as long as you're in there, anyway!) My friend Paul has a Sportster Sport 1200S with a mere 700 miles from new. Paul isn't much good at living with niggles that can be helped signifi - cantly and yours truly is pretty big on passing that info on, so we decided to address all three issues at once. Whether you DIY or hire it done, here are parts you'll need for '91–'03 XLs: • Two H-D #1039 screws (or equivalent) • One front (#26012-07) and one rear (#26020-07) rocker box breather for '07–on Sportster • Two lower rocker boxes for '07–on Sportster (part numbers vary according to fi nish) • Two lower rocker box gaskets (#17362-07A) • Two "chimney" gaskets (#17695-07A) • Cometic box-to-head gaskets (#RB020 pr.) or equivalent • Rocker Lockers kit (#DK-RL- SPT-8606) • Two middle rocker box gaskets (#17354-86A) or sharp scissors and new (#17354-89) • Lastly… and tricky… is two middle boxes ("D-rings"). You'll either have fi nd some (obsolete '86–'89 style) #17355-86B on eBay, at a swap meet, wherever—or be ready to modify the ones you have. DIY-ers will also need tools and a manual… and perhaps to study the innumerable videos on YouTube that walk you through the actual process. From here on we only hit the high- lights in this little essay. 1. Lid off, rocker shaft bolts out and you should see something like this... 2. You're likely to see something like this as well. The "fi sh lip" crescents towards the head of the rocker shaft bolt are witness marks, left by the back-and-forth rotation of the rocker shaft as the engine runs. Yup… noisy! Moreover, this chattering movement doesn't really speak well for the long-term health of the shaft itself. (Remember, this engine only has 700 "clean oil" miles on it and is immaculately maintained.) The spiral mark is actually from the removal of the bolt. It would be great if this doesn't happen when you remove yours, but some will and some won't… so don't be surprised either way. If there's no other damage, don't worry about replacing them with new ones. 3. As we continue disassembly, inspection of the shaft on this low-miler also tells a tale… although not the one you might think at fi rst. The striations and scuff marks where the rocker bushing runs usually indicate that grit in the oil has turned the bushing into a grinder. Ironically, most of the time the bushing will look and spec "as new," yet the shaft will not. That's because the grit can bury itself in the softer bronze material of the bushing and "sand down" the harder shaft. By contrast, the area of the shaft held by the bolt we just looked at is in fi ne shape even though we know it's rocking back and forth a bit. Might that mean the shaft is harder than the alloy in the rocker box it rocks in, and therefore doing a tiny bit of sanding on the shaft bore in the box? No matter! If your shaft(s) won't pass a fi ngernail test for smoothness, you might want to replace it/them. But most of the time it's just as effective to simply swap them back to front, top to bottom when replacing. That gives the bushing a new, untouched surface to rub on. 4. Once the box is off, you'll need to scrape any clinging old gasket material off. It's important to do it carefully, with the tool of your choice (razor blade or whatever) in order to leave a clean, smooth, unmarred surface for the new replacement.