Ok, So Maybe Not That Worried...Q I I have a brand-new 2006 Honda VT750cc Shadow Aero. It's a 745cc SOHC, three-valves-per-cylinder V-twin. The service manual says to check valve clearance at 600 miles, 0.006-inch intake, 0.008-inch exhaust, two intake valves, one exhaust (stated right on the frame under the seat!). After reading your article on valve adjustment on the Motorcycle Cruiser Web site, I thought I'd give it a try, especially when the dealer told me the adjustment wasn't included in the $60 first service. He also said a valve adjustment would be $250! I can believe it, because to get valve covers off you have to remove the seat, tank, air hoses, etc. My problem is that I'm not sure what the clearance is with the feeler gauges-it wasn't as straightforward as I thought. I think the valve lash is a little tight (maybe 0.004 inch plus or minus), and I'm a little worried, but not $250 worth of worried. Is it common for new bikes to have tight clearances? Particularly Hondas?Dave HunterVia e-mail
A Yeah, Dave, it is normal for a new bike's valves to tighten up a bit. As the new engine is run, the valves tend to pound into their seats; this causes a slight loss of clearance and is entirely normal. For the novice, valve adjustment can be a little tricky, mainly because it does take some experience in using a feeler gauge to develop just the right "feel." Until you develop that feel, I'd suggest using what's called a Go NoGo feeler gauge, available at any tool supplier or auto-parts store, to set the valves. Go NoGo gauges are stepped or graduated. When the adjustment is correct, the first portion of the gauge will slide freely, yet the second portion won't. For example, on your intake valve you'd use a Go NoGo gauge that had a leaf stepped from 0.006 to 0.008. When the adjustment was correct, the 0.006 portion of the gauge would slide freely, while the second portion, the 0.008, would stick. As an alternative you could also double-check the valve using two separate gauges, an 0.006 and, say, an 0.007 or 0.008. If the 0.006 slips in, and the 0.007 or 0.008 doesn't, you're good to go.
>strong>The Four-Stroke Internal Combustion Engine - How-To
Fundamentally, there's not a whole lot of differences between a one-lung lawn mower engine and MotoGP World Champion Nicky Hayden's hand-built V-5 Honda. Both engines employ the same basic architecture and operate according to the same easy-to-understand physical laws. The only real difference is in the details, so once you grasp the basics, the rest is easy. Here's the lowdown on how a four-stroke internal combustion engine works.
One Piece At A Time
Mechanical devices are easier to understand when they're reduced to their components. Hell, even the space shuttle starts as a single bolt, so let's begin by taking a look at a typical four-stroke engine's major components
Crankcase
The crankcase houses the crankshaft and, in a traditional pushrod engine, the camshaft. It also accommodates secondary mechanisms like the oil pump (and water pump if needed), the alternator rotor and stator and sometimes the ignition system. In most instances, the clutch, primary drive and transmission also reside in the crankcase, with the major exceptions being Harley-Davidson FLs, BMWs and Moto Guzzis, all of which have their transmissions bolted to the engine, automotive style.
Crankshaft
The purpose of the crankshaft is to change the reciprocating motion of the piston into rotary motion and to feed energy into the clutch and transmission. Think of a bicycle pedal crank and you'll have a pretty good idea of how one works.