Working on a Boulevard M50
The Suzuki M50 is a 498cc V-twin cruiser, essentially a rebadged Savage/C50 platform with some cosmetic changes. If you're looking at the Boulevard M50 Manual, you probably already know it shares a lot of DNA with other Suzuki CV series bikes. That means a lot of what applies elsewhere in the lineup applies here too, but there are enough differences that copying instructions blindly gets you in trouble. I've spent more hours than I want to admit wrestling with these. The carburetors on the early models are a particular pain. The factory service manual will tell you the basic steps for syncing them, but it glosses over one thing that actually matters: the idle mixture screws on these carbs are extremely sensitive and they don't like being tweaked past halfway. I learned that the hard way after stripping one. My workaround was simple — I marked the starting position of each screw with a fine-tip marker, backed everything out to two turns, then returned them to the mark and adjusted from there in sixteenths of a turn. Took me three attempts to get it right, but once I stopped guessing and started tracking my movements, the sync came clean.
Boulevard M50 Manual Where to Find It
You won't have much luck getting an official printed copy unless you go through a Suzuki dealership and pay $80 to $120 for it. The real solution is the online versions floating around forums and archive sites. The Haynes manual covers it well enough for a home mechanic, but the factory service manual is the one worth hunting down if you're doing anything beyond routine maintenance. The factory PDF is usually 30 to 40 megabytes and covers everything from valve clearance specs to frame disassembly procedures. Search for "Suzuki C50 service manual PDF" since the M50 uses the same engine and frame as the C50B — just different bodywork and some minor suspension tweaks. Here's something most first-time owners miss. The valve clearance specs in the manual say to check them when the engine is cold. That part is true. But the manual doesn't mention that if you're doing this after a long ride and the engine is warm, the clearances will read narrower than they actually are. I once missed an intake valve that was touching because I didn't account for thermal expansion. The fix was straightforward once I figured it out — let the engine sit for four hours, then recheck. The valve train on these is straightforward to access, but you need to remove the seat and the fuel tank to get proper clearance. It's not difficult, it's just time-consuming and annoying, so plan for it. The rear brake linkage is another area where the manual will get you through the basic steps but leave you confused. The M50 uses a drum brake in the rear. Drum brakes on modern motorcycles are essentially an afterthought at this point, and Suzuki built this one to be adequate, not great. The adjustment linkage has a habit of getting sticky from road grime and brake dust. I found that soaking the pivot points in penetrating fluid and working the lever back and forth repeatedly was more effective than just replacing the adjustment hardware. Most people just swap parts without cleaning the existing ones, which wastes money and time.
Chain maintenance is where people lose patience. The M50 chain tends to stretch faster than the manual suggests if you're riding it hard or hitting puddles regularly. The manual gives you a stretch limit of about three millimeters over a 300-millimeter span. In practice, I'd replace it closer to two millimeters of stretch because by the time you hit three, the sprockets are usually wearing down too. I track this by tensioning the chain to the midpoint specification and then rotating the rear wheel and marking one link with a paint pen. After 500 miles, I measure how far the mark has moved from the center of the final drive cover gap. If it's crept more than a millimeter past where it should be, I'm ordering a new chain and a new front sprocket at the same time. You can skip the rear sprocket if the teeth aren't hooked, but on these engines the torque puts serious wear on the rear sprocket teeth. One thing the manual understates is how important the air filter housing seals are. The M50 has a simple slide-on airbox cover that relies on rubber grommets to seal. When those dry out, you'll get an unmeasured air leak that makes tuning impossible. I spent two weekends chasing a lean condition that wouldn't resolve no matter how I adjusted the carbs. Turned out a small section of the grommet was cracked and the cover wasn't sealing on one corner. The fix cost nothing but cleaning the housing and replacing the grommets. Keep spare grommets on hand. They wear out faster than anyone expects. If you're planning major work like a top end rebuild or timing chain replacement, the factory manual is genuinely the only thing that will walk you through it correctly. The Haynes manual skips some of the more fiddly torque sequences and alignment checks. I recommend keeping both available and cross-referencing them. The factory manual has the precise specs. The Haynes manual has better explanations for steps that aren't obvious. Neither is complete on its own.
Get the Full Details
One last note that probably won't help much but is worth knowing. The ignition timing on the M50 is fixed. There is no adjustable timing. If someone tells you the timing is off and offers to adjust it, they don't know what they're talking about. The only thing you can do is check that the pickup coil is mounting correctly and that the flywheel marks line up when you rotate the engine to TDC. The manual includes a procedure for this, but it assumes you have a timing light and a dial indicator. You don't strictly need either. A mark on the piston via a straw and a socket on the crank bolt gets you close enough for most purposes. Just be careful not to rotate the engine by the front wheel — the final drive ratio means one rotation of the wheel is multiple rotations of the crank, and your TDC mark will be off if you're working from the wrong end. There. That covers the stuff the manual doesn't always make clear. If you run into something specific, post it and we'll figure it out.
