Service
SERVICE
We welcome your technical questions and comments, and will publish those we think are of interest to our readers. Because of the volume of mail received, we cannot return any personal replies. Please limit your "Service" letters to technical subjects only, and keep them as brief as possible. Send them to: "Service, ” CYCLE WORLD, 1499 Monrovia Ave., Newport Beach, Calif. 92663.
DRY SUMP/WET SUMP
I own a 1978 Honda 750. All the single cam 750s used a dry sump lubrication system. It seems like a very good system and I was wondering what advantages and disadvantages this system offers and why the manufacturers no longer use it. Joseph Bradley Wabash, Ind.
Dry and wet sump systems both have their good points. A dry sump system allows engineers to design a very compact crankcase because oil capacity is not a consideration, and it ensures oil pickup during hard braking, acceleration and cornering because the oil is pumped out of the bottom of a normally tall reservoir tank rather than out of the sump. The remote location of the reservoir can help cool the oil while it's out of the engine, and the external oil lines make it simpler to add oil coolers, in-line filters, gauges and other competition items.
A wet sump system, on the other hand, has no external lines, so there’s less chance of leakage and failure in the hoses, clamps and other fittings. It requires a larger crankcase, but saves the space needed for a remote tank, leaving the area under the sidecovers for a bigger battery or better access to the bike’s electrics. A wet sump can also lower the eg slightly, as it eliminates the weight of a tank and, usually.
three or more quarts of oil sitting high in the frame of the bike. Oil changes are simpler on a wet sump system because only the crankcase has to be drained, rather than the oil tank and the crankcase. A wet sump also requires only one oil pump, whereas a dry sump system needs a second pump to scavenge oil from the botton} of > the sump and send it back to the oil tank.
As long as there is space for adequate oil capacity, and there is with the wide crankshaft of the average inline transverse Four, and oil cooling is no real problem, there aren’t many disadvantages to a wet sump system.
It’s worth noting that the sohc Honda 750 was introduced in an era when Serious Sport Bikes—Triumphs, Nortons, Harleys, etc.—all had dry sumps and wet sumps were more common on small commuter and playbikes.
OIL SWITCH
A friend and I were talking about the type of oil we use in our four-stroke engines, and I told him I was using Castrol GT two-stroke oil in my engine because I thought it would lubricate better under most conditions and that if the engine ever started using oil, it would burn instead of fouling the plugs. I have other reasons for using two-stroke oil in my four-stroke also. Am I hurting my engine by this practice? I have had no trouble in 12 years of use. Glen Mobly Dowagiac, Mich.
You can get away with two-stroke oil in a four-stroke crankcase, but four-stroke oil is generally cheaper as well as superior in a number of ways. Four-stroke oils contain ash, detergent and various zinc-based additives, all of which are missing in twostroke oils. Ash helps keep contaminants in suspension so they can be trapped by the oil filter or drained out during oil changes. Detergent not only helps reduce sludge and gum buildup, but prevents rust and is slightly alkaline, so it neutralizes acid in the oil. Zinc additives prolong oil life by reducing oxidation, which causes oil to thicken, and they are also essential for reducing wear on cam and lifter surfaces. These ingredients are all critical to good lubrication in four-strokes, but are not found in two-stroke oils because they would either cause spark plug fouling or simply be burned off and wasted with the exhaust.
Some two-stroke oils are worse than others for four-stroke use, however. Outboard and snowmobile oils normally contain light petroleum distillates to help them disburse better in gasoline. These distillates reduce viscosity and bearing life (not good) and then evaporate off to reduce the oil level in the crankcase (also not good). A straight weight injector oil, like an SAE40, would work better, but still contains none of the additives needed for four-stroke operation. It helps if you change it often to prevent acid buildup and oxidation, but it is still missing important additives to reduce valve train wear.
If your engine begins burning enough oil to foul the spark plugs, it will probably be in need of rings or valve guides more than a different type of oil. An engine normally burns oil very heavily before it begins to foul plugs, and then it’s rebuild time. Your 12 trouble-free years with two-stroke oil are probably a testament to careful bike maintenance and frequent oil changes, but you'll get better engine life for less money with a good four-stroke oil.
KZ CAM ADJUST
Referring to the April, 1981, Cycle World article on shimmed valve adjust and my Kawasaki service manual, I set out to adjust the valve clearance on my KZ550. I hamhandedly snapped a camshaft cap bolt while reinstalling the intake cam. I took the bike to the local Kawasaki dealership to have the broken bolt extracted and the camshafts reinstalled. After getting the bike home I rechecked the cam chain timing and found the timing marks on the camshaft sprockets didn’t line up at all like they were supposed to, according to the manual, and as they had prior to disassembly. Calling the mechanic for an explanation, I was told that he had never successfully used the service manual method of counting 43.5 links between the timing marks. His method of reinstalling the cams is to have the notches on the ends of the cams horizontal, pointing in their proper respective directions, exhaust front, intake rear, the engine at TDC on 1 and 4. He doesn’t remove the cam chain tensioner for this operation, only the tensioner cap, which Saves removing the carbs. My bike runs okay, but I’d like to know if this method is a legitimate shortcut or a possible problem.
Kevin Turner
Orosi, Calif.
A Hy-Vo cam chain like that in the KZ550 has a lot more links per inch than a roller chain, so it’s easy to have the sprockets a tooth or two off ' and still have the cam arrows appear parallel to the gasket surface of the cam cover, especially with the chain slack and the cover off '. The bike will run with the sprocket off a tooth, but the engine will sound a bit sour and performance will be off '. If the cams are separated by the correct number of chain links, cam timing will be exactly where it should be when the chain is re-tensioned. Doing it visually with the cam arrows can cause improper timing, so there’s no point in saving the minute or so it takes to count the chain links after you 've gone to the trouble to get the cams out. >
Your mechanic is right in removing the tensioner cap but not the carbs and the tensioner. The shop manual calls for removal of the carbs and tensioner, but it has since been discovered that removing the cap works just as well and is a whole lot easier. Once spring tension is removed, the adjuster wedges will stay in place without Jailing out or slipping into higher tension, as happens on some engines.
THREE INTO THREE
1 have a 1972 H-2 Triple and would like to build a cafe street bike. 1 am having trouble finding expansion chambers for it. Do you know of a company?
Robert Hoeschler New Baden, 111.
The only company we know of still making chambers for the early H-2 Kawasakis is Wir gis Creative Performance, Box 408, Rt. 2, Princeton, III. 61356, phone (815) 875-3354. They make pipes for all Kawasaki Triples, muffled street, unmuffled race or muffled and unmuffled kits. Bassani Mfg., 3726 E Miraloma, Anaheim, Calif 92806, phone (714) 630-1821, also makes Kawasaki Triple chambers for the 750s and 500s, but only for the later 1974 through 1976 models.
XL CAM NEEDLE BEARINGS
Do you know of a company that supplies parts and does the machine work to convert a 1976 Honda XL350 camshaft to use needle bearings?
John T. Snow Valparaiso, Fla.
Mega Cycle Cams, 90 Mitchell Blvd., San Rafael, Calif. 94903, phone (415) 472-3195, virtually invented this type of conversion.
In the case of the XL350 and the earlier XL250, the single-port engines from 1972 through 1978, Mega Cycle will do the machine work on your head—they don’t exchange them—for $50, and has the needle bearings and camshaft, with a choice of six grinds, for $140.
There are similar conversions for the Honda SL100, XL/TL125 and XL 175. Mega Cycle has straight conversions, drop-in needle bearings and cams with no machine work needed, for the twin-port Honda XL/XR250 and 500. And they have kits for Honda CB350, 450 and 500 Twins, Yamaha Virago and 920, Kawasaki KLX250 and Suzuki DR/SP370 and 400. Details are free for the asking.
MORE MZ!
You were looking for a parts source for MZ motorcycles (March, 1982 CW):
1) Jim Carrier, Standard Fittings, P.O. Box 1268, Opelousas, La. 70570, phone 1-800-551-9060, or,
2) Ted Parrish, Duquesne Cycle Sales, 2525 Duquesne Rd., Joplin, Mo. 64801, phone (417) 624-4929.
1 was talking with Ted Parrish and he told me he was going to import MZs this year. MZ has a new street sport Model ETZ250, which comes with disc or drum brakes, premix or oil injector and has a five-speed trans.
Jeff Wenzel Washington, D.C. E8
