Harley-Davidson, today, is the holy grail of cruising motorcycles. It’s a legend, it’s a family member for many, and for others, it’s the ultimate dream. It’s almost blasphemous to say anything against the American legend, and that’s a big problem. Not only is it preventing a lot of buyers from making an informed decision, but is also emboldening Harley to get away with things they can fix.
A lot of bikers and Harley die-hards would hate this article.
But, the truth is often bitter. And if that’s going to be the case, let me remind you guys. If you can’t love the something you think you do knowing its imperfections, maybe you don’t love it at all. In this article, we’d be talking about this very common and very worrisome defect with the Harley-Davidson twin-cam V-twin engines.
And it isn’t restricted to a particular model.
Since these engines are found on pretty much every Harley there is (barring the 2018 lineup), these defects exist throughout the range, all the way from the Dyna to the CVO. The notable exceptions are the Sportster Evolution, which has a rock-solid engine, and the V-Rod, which has its own peculiar set of problems. Thankfully though, Harley has fixed a lot of these problems in their all-new Milwaukee-Eight line of single-cam engines, the ones which all the bikes from the 2018 lineup come with.
So, what DOES it do?
Well, it causes your engine to fail. Due to the “shoes” used in the cam chain system, the engine can fail as early as 15,000 miles. The new hydraulic tensioning system, only delayed the catastrophe, but it can still occur at 40,000 miles.
And, why does it happen?
The cam-chain system uses “shoes” which ride on the cam chains. These shoes can wear out pretty fast. These shoes are made of nylon or soft plastic, and rub against the two chains. Once they’ve worn out, a metal-to-metal contact system begins in the system. Pieces of metal grind against each other, and create metal shavings. These metal shavings can get into the engine, and can wreck havoc. The engine case, the crankshaft, pistons, or the cams, they can cause any of these to break. There are no prizes for guessing what happens next. Your beloved Harley’s engine fails, and you’re left with a repair bill that just doesn’t seem fair.
How do you know when it’s happening with you?
When the starter motor is running, you’d notice an unusual sound. The problem is, if you’ve got loud pipes, you’re highly likely to miss it. Other than that, the oil pump passages tend to clog up. But the problem is, that creates no unusual noises, whatsoever. By the time you hear anything because of this clogging, your engine is already being ripped apart to pieces.
Okay, so what can you do to stop it?
Perhaps the best fix is to get a gear set that eliminated the cam chains and shoes altogether. However, that’s an expensive proposition. If you don’t want to do that, I’d highly recommend that you have the system disassembled and the inner and outer shoes inspected thoroughly every 15,000 miles. Actually, just to be on the safer side, I’d personally, make it 12,000! The problem and the fixes to this are well-documented in a number of motorcycle magazines and forums, and you may want to go over them, if you’re nearing that mark on your odometer.
If you’ve got a Harley with a 1999-2006 twin-cam engine, be especially vary. These engines are notoriously more prone to failure. If these engines fail, even a rebuild is not an option. Be prepared to get yourself a new motor, altogether.
The precautions you need to take..
Do make sure that the crankshaft pinion shaft runout doesn’t exceed 0.003″. If you like to ride hard, this runout can very easily cross the 0.003″ mark. If it does, your gears will clash, and cause the catastrophe we’re so worried about. And then in 2011, Harley made the problem a just little more worse. They increased the crankshaft runout balance to 0.012″. Yes, they increased it to four times the previous figure.. This created a runout so massive, that even installing a gear drive kit was no more an option.