The Art of the Valve Adjust

The Art of the Valve Adjust

LEANINGS

PETER EGAN

WELL, WE FINALLY HAD OUR FIRST really sweltering spring day (58!) yesterday, so I put the battery in my Suzuki DR650 and took that gratifying first ride of the season, a long meandering trip into a sunny countryside dotted with melting lumps of snow. What fun.

I came home toward evening and immediately released my Buell Ulysses battery from the grip of its Battery Tender tentacles and installed it in the bike. I’d planned to take another ride this morning, but the temperature dropped 20 degrees overnight and it started hammering down cold rain at dawn. I went out to my workshop and looked at the Buell.

What to do on a rainy Sunday in spring? Go to the bookstore? No. Not in the mood. Did that too much this past winter. Plug in the Les Paul and practice guitar? Ditto.

I looked around the workshop and my gaze fell on the DR650. An uneasy sense of guilt stirred somewhere deep within my minuscule conscience. The DR now has just over 4400 miles on the odometer, and I’d bought it last year from its second owner when it had about 3400 miles on the clock. I asked if anyone had ever checked or adjusted the valves and he said he didn’t know. Note to self: Check the valves eventually someday when you get time.

Then I proceeded to ride the DR another thousand miles last summer. The valves weren’t noisy, but what if they were tightening up and the two exhaust valves were running a deep cherry red because they didn’t have enough time to transfer heat?

Now, I’m not exactly compulsive about bike maintenance (ask anyone), but I can’t fully relax while riding if I think the bike is hurting itself in some way. For instance, the sound of a tight drive chain makes me tense because I picture the bearings and seal at the countershaft sprocket grinding themselves into a pile of rubber dust and metal shavings. That’s why I’m a slightly loose-chain guy. And a cool-running exhaust-valve guy.

So, I rolled the bike onto my Handy lift and went to work. Took off the seat and gas tank to get at the valve caps on the head. My slim owner’s manual didn’t say a thing about how to adjust

the valves, only that they should be inspected at 600 and 7500 miles and adjusted, if necessary, by a qualified mechanic at your dealership.

Luckily, I just happen to have a factory DR650 shop manual and a Suzuki valve-adjust tool that holds the adjuster in place while you tighten the locknut. These were both given to me by my buddy Mike Mosiman after he sold his DR650 last year. Since then, he’s bought another DR, so I’ve had my phone number changed in case he wants them back.

The shop manual gives very specific instructions: Remove the sparkplugs and alternator cover cap so you can turn the engine over with a socket, remove the timing light/inspection cap to find the TDC marker on the compression stroke, set your intakes at 0.003-0.005 inch and your exhausts to 0.007-0.009 in.

My intake valves were still spot-on at a perfect 0.004, so I left them alone. Both exhaust valves had tightened up to 6 thou, so I adjusted them to 0.008. Moderation in all things.

Like most valve-cap openings, the Suzuki’s are a little tight, but I squeezed in there with my favorite Snap-on gap gauge and then did a final go/no-go check before putting everything back together. The DR fired right up and sounded fine. No funny loud clacking, no backfires; the bike was not engulfed in flame. Done.

It was kind of fun fiddling with the bike, and Suzuki’s valve adjust procedure on this big Single is just straightforward enough to be satisfying on a rainy Sunday afternoon.

Still, during the job, I got to thinking...

Sitting next to the Suzuki were my Buell and Ducati 900SS. The Buell has hydraulic lifters, so the valves never need adjusting, while the Ducati has the fa-

mous Desmo system, where you either need to be a skilled and patient mechanic with a selection of valve shims or take it to a good shop to get the valves adjusted—at considerable expense.

When I was a foreign-car mechanic during the Seventies, I spent half my time adjusting valves—either setting tappets on ohv cars with rocker arms or going through the dog-and-pony show of removing cams and inserting little shims under inverted buckets on dohc engines, then (hopefully) retiming the cams without having the cam-chain tensioner or sprockets move and skip a tooth. Some, thankfully, had shims above the buckets. These days, most of this nonsense is gone—along with the adjustment of ignition points—and the art of the valve adjust is rarely practiced except on the most exotic cars. Or old classics. Hydraulic lifters are the rule.

A lot of bikes, however, still have those shim-under-bucket arrangements, while others use the more home-mechanic-friendly system of overhead cams working on adjustable fingers. Most adjustment intervals are now pretty extended, but it still has to be done.

It occurred to me that, in this age when sportbikes have been a slow sell for many dealers, the $300 or $500 valve adjust is just one more impediment to bike ownership, especially for young people who are facing difficult financing and high insurance costs.

I know that direct cam-on-bucket (and Desmo) valve actuation is light, compact and efficient, remaining precise at high rpm, but is it possible that today’s hard-pressed motorcyclist might be able to live with, say, 100 instead of 110 horsepower? My Buell makes a claimed 103 hp—though, granted, it’s a big ol’ 1200cc engine. Still, it works fine and isn’t too heavy. And that maintenancefree valvetrain is one of the reasons I bought the bike.

It’s also worth noting that any time you don’t have to open a perfectly good engine to the dirt and dust of the outside world—or to the wanderings of the human attention span (like mine)—it’s a Good Thing.

Maybe the art of the valve adjust should be just that—an art, rather than an industry. A special craft we apply to exotic racebikes, lightweight dirtbikes or those old British Twins we love.

Might be time for the valve adjust to join the adjustment of ignition points as a folk ritual for the hardcore racer or the hobbyist who, like me, still has a drawer full of gap gauges that need exercise.