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Service

RAY NIERLICH

HEADER DRESS

Q: I am wondering if you could help me out with a mind-boggling thingy regarding my exhaust pipes. I have a Moto Guzzi V7 special and I just changed to a set of matte black Mistral mufflers. I was wondering if you suggest that I wrap the pipes since they are in stainless steel, to help match them with the mufflers, or if I should powder enamel coat them in black instead? Or if you have other suggestions?

ALDO LOMBARDI CYCLEWORLD.COM

A: I generally discourage pipe wrap, as it will keep heat (and moisture) in and shorten the life of the pipes. But if you dig the look, you must. With good preparation, VHT exhaust paint (or similar) has worked well for me. I beadblast the pipes to get a bit of etch on the surface before painting. Cheap and easily touched up. Powdercoating is great on exhaust pipes but might cost more than buying brand-new black pipes.

FEEDBACK LOOP SMOKE TALES

Q: Just getting caught up on some previous issues and read the question about the smoking 2008 Kawasaki Concours (“Dragon Smoke,” May). I had a similar issue on my 2009 Concours while working in California during the summer of 2014. When the bike sat for more than a day it would smoke from under the fairing for a few minutes when first started. It wasn’t a major issue, so I waited until the end of the riding season when I was back home in western New York to look at it further. While I initially thought it might be a leaking valve cover gasket, it turned out to be a slow drip from around the Crank Position Sensor at the front of the engine, with oil dripping onto the headers below.

I replaced the O-ring while doing the valve inspection and other service under the fairing, which took care of the problem. Unfortunately, the problem came back within a year, and rather than replace the O-ring again and end up with the same result I put some black RTV silicone around the seal. I don’t expect the problem to return. If Jack’s problem continues intermittently, he may want to look into this.

DANIEL C. 5TAYNER YOUNGSTOWN, NY

A: Thanks for keeping me humble. Yes, if you see a whiff of smoke from inside the fairing when first starting your bike from cold, most likely engine oil (or coolant, but that stuff is stinky when burned) has dripped on the exhaust when the rubber seals cooled off, got hard again, and leaked. In the Concours 14’s case, it is the exhaust camshaft sensor O-ring that is most likely the culprit. As you say, a dab of high-temp silicone with a new O-ring will do the trick. It’s also worth a quick check to be sure the last tech fully tightened the valve cover bolts. On older bikes with cable-driven gauges, tachometer drives were usually the leakers.

TRUTH ABOUT TEMP

Q: When I got my driving licenses, back in dino-time (oil-wise), I learned the engine wasn’t really warmed up until oil temperature had reached 60 degrees Celsius/140 degrees Fahrenheit. Is this still true? (Or was it ever?) On my Guzzi the oil-temp meter often doesn’t reach that temp until 6 to 8 kilometers, however on my water-cooled Ducati, the “cold” indicator (cooling media) goes out after just 2 to 3 kilometers.

LARS WESTLUND NORWAY

A: Today’s tolerances, materials, and lubricating oils are all much better than in the past. Operating temperatures somewhat outside of the ideal aren’t much of a concern for modern production engines anymore. If your engine runs on the cool side, watch for moisture not getting evaporated out of the crankcase. Water makes a very poor lubricant. If your oil ever seems even slightly milky, change it. If your engine oil runs very hot (say more than 230 degrees Fahrenheit), consider running full synthetic oil and perhaps adding an oil cooler. Excessively high oil temperature will cause carbon buildup in the engine’s hottest places such as piston ring lands and exhaust valve stems/guides.

Also, when oil is excessively heated, its lubricating ability breaks down, which of course will accelerate engine wear. A properly functioning liquidcooled Ducati is less likely to suffer oil-temperature extremes than an aircooled Moto Guzzi, and if the latter is vintage, the crankcase breathing might not be as effective, leading to more moisture buildup if you take a lot of short trips in cool weather where the oil might not get up to a high enough temperature to evaporate the water. Solution? Ride farther and faster!

ASK KEVIN

TRUTH ABOUT GENESIS?

Q: Cycle World journalist Kevin Cameron wrote in his book Sportbike Performance Handbook that early Genesis engines had combustion problems, the chamber “was tight and compromised.” Referring to spark lead, the engines had, as he stated, “a disgraceful 45 degrees in the case of the old Yamaha FZ750.” Yet well-known tuner Jerry Branch, who also assessed the FZ750 engine, described the combustion chamber as having “potential” and said it was “shaped just about right with most of the charge in the middle, underthe plug”-so which one of them is right?

I am in the process of writing a book about the FZ750 and was greatly taken by Nick lenatsch’s article about Brad Dirnberger’s race-winning FZ.

I’d be much obliged if Kevin could take the time to clarify the above, as his detailed Tech Analysis of the FZ750 back in March 1985 is at odds with what he states in his Sportbike Performance Handbook.

MICHAEL BOYLE

NORTHERN IRELAND

A: Saying a cylinder head “has potential” is what you say for public consumption when it doesn’t. Otherwise, why did Yamaha’s chief problem-solver, Masao Furusawa, offer Valentino Rossi four different

testbikes before the 2004 season?

Two had five-valve heads, two had four-valvers, and both 180-degreefiring and 90-degree-firing cranks were offered. Rossi liked best and went quickest on the four-valve 90-degree engine, and it was on an M1 of that type that he won the championship that year. To my knowledge, no one has used a five-valve in MotoGP since. Yamaha's R11,000cc production sportbike was itself converted from five valves to four valves, which it now features.

The piece by Nick lenatsch regarding a restored vintage racebike does not describe a bike that was competitive in US national AMA Superbike racing but rather a nicely prepared nostalgia bike, capable of winning vintage events.

One American builderwho had a lot of experience with the FZ, Steve Johnson, told me with the five-valve the builder had a difficult choice. If he wanted strong acceleration, he could raise the compression, but because that slowed combustion on top-end, peak power was poor. If he built the engine for peak power, with a combustion chamber open enough for combustion-accelerating turbulence to persist all the way through combustion at peak revs, its lower compression ratio reduced acceleration. In his experience, the advantages of the two could not be combined.

Kevin Cameron