Service
SERVICE
JOE MINTON
Break-in blues
My 1978 Suzuki GS550E, with 23,000 miles on the clock, is starting to have an oil-consumption problem and I decided that a re-ring is in order, along with clutch replacement and a valve job.
Two problems have cropped up, however. I don't know a good breakin procedure, and the finish on the engine cases is pitted and worn away in spots. I would like to refinish the cases with a clear lacquer as they came f'rom the factory, but 1 don't know what type of paint to use.
Mark A. Gonion II Illinois
A new piston ring has very little actual contact with the cylinder wad through which it must conduct the heat passed to it by the piston. Until the ring is seated and has fuit contact, it is very vulnerable to high piston and combust ion-gas temperatures. New
piston rings need to have a toad placed on them to ensure that they initially wear (seal) against the freshly honed cylinder wall. On the other hand, they must not he overheated or they will soften and fail prematurely.
You can gel the needed seating pressures without excessive temperatures by accelerating at full throttle from low-to-mid rpm for short periods of lime, say three to five seconds. Each period of acceleration should he foi-
lowed by idiom twice as many seconds of closed-throttle coasting to let everything cool off According to Perfect Circle. a major manufacturer of piston rings, you should repeat this load/ coast cycle 10 times. I have used the Perfect Circle technique for many years with complete success. By the way. don 7 let the engine with its new rings sit around and idle before you do this. You should fully prepare your freshly overhauled bike to be ridden, start it up and go. Do this and you 'll get quick ring seal and very long ring life.
The corrosion on your cases is very hard to remove. You can use cleanser and a brush if it is minor. However, if the cases are heavily corroded, you might as well sandpaper them smooth and paint them silver. Yamaha has a Une of aerosol paints that includes an attractive silver case paint.
I have tried for years (decades?) to find an aerosol dear coat that is anywhere near as tough as the dear that the factories use. If any readers know of a durable clear coat, write to us and we'll pass along the info.
Midnight sack
I am the owner of a 1 983 Yamaha Midnight Maxim 750. The hike has a little more than 14.000 miles, and I'm noticing a bit of sack in the front end. The fork bottoms quite frequently.
I've adjusted the air pressure in the fork to the recommended maximum of 1 1 psi. but the ride is now too harsh. Further. I just can't seem to get the rear end set up properly. My local mechanic suggests I obtain a good set of aftermarket shocks and fork springs. Any suggestions?
Tony Pe penei la
Staten Island. New York
Your mechanic is exactly right. The Maxim's fork springs are both too short and too light in spring rate. Your rear-damper assemblies have low-rate, low-preload springs and probably very little damping left—they didn 7 have much when they were new. This set of problems is very common among lateIb7()s. early-1980s motorcycles.
Progressive Suspension (1112b (l Ave.. Hesperia. CA 92345:619/9484012) has a $56 fork-spring set (part number 1107) that will solve your front-end problem. Several companies
can supply quality shock assemblies, including Progressive Suspension.
By the way. the 11 psi of fork air pressure you use to hold up your bike's front etui also places pressure on the tips of the oil seals. That, in turn, increases friction between the seals and the fork tubes on which they must slide, and results in a harsh ride over small bumps. The Progressive Suspension fork springs will, most likely, eliminate the need for any air pressure at all. and the fork will work more smoothly as a result.
Dull Sabre
I have a 1 984 V65 Sabre with 1 5.000 miles on it. Is there anything I can do to improve its notchy shifting action, especially when it gets hot? Also, is it usual for “shafties” to clunk hard when going into first gear, or have I got a bum transmission?
Lastly, if I undercut fifth and sixth gears to reduce the bike's tendency to slip into a false neutral between those gears, will it help with the gearbox's notchiness, or will I have to modify the shifting mechanism?
Ray Tushingham
Kanata. Ontario, Canada
Most of your shifting problems are due to clutch drag. Your bike has a sprague device built into the clutch that helps prevent rear-wheel hop when you dose the throttle at high rpm while in a low gear. The sprague device lets some of the dutch plates slip when the load conies from the driven (rear wheel) side of the powertrain. rather than from the engine side. Honda no longer fits this device to any of their motorcycles. It worked rather well, but introduced an abnormal amount of dutch drag.
You can fit a Barnett Engineering (9920 Freeman Ave.. Santa Ee Springs. CA 90670: 213/941-1284) clutch-plate set (part number HPK-41. $64) to your Sabre, which will reduce the drag somewhat. The drag in your system, however, is largely due to the sprague device and cannot be entirely eliminated. As for gear undercutting, it is likely that this will make shifting more difficult, though it should reduce the likelihood of the transmission slipping out of gear.
Sob story
Your articles, “Saving Old Standards” and “Keepers; Minton's Guide to Good Ol' Bikes,” in the April. 199I Cycle World were right on. 1 own a 1 978 Honda CB750 with 33,000 miles that 1 intend to keep for the next 20 years. 1 have contemplated upgrading it; thanks to your suggestions, 1 now know what to do, except for one problem.
My bike seeps oil from the head gasket. 1 have been told by several mechanics that this is characteristic of my bike, and that putting on a new head gasket will solve the problem for only 1 5,000 to 20,000 miles. Both mechanics told me that if 1 did replace the head gasket, I might as w'ell have the engine rebuilt. even though it runs great with no chatter of any kind. What do you think of this advice?
Malcolm Jarvis
San Diego, California
Seeping head gaskets were, indeed, a common problem with Honda inline-Fours, all of them. And l agree with the mechanics you have consulted regarding how long a new gasket will last, if. that is. you follow Honda's directions. Fite recommended headbolt torque specs in the Honda shop manual don't work very well, leading to loose bolts. / overtorque the head bolts a full 25 percent. After runningin, the overtorqued nuts will measure the recommended torque value. Many other mechanics have used this trick to help properly seal Honda head gaskets.
/ also recommend that you coat your new gasket with a very thin Jilin of Hylomar sealant, t his is simply the best gasket sealer I have ever used. It was developed by Rolls-Royce for use in assembling its jet-aircraft engines. Used by BM W and Harley. Hylomar is self-healing and remains slightly sticky even after years of use in hotrunning motors. You can get a 100gram tube for $5.30 from Ace Seal Co. (2065 Martin Ave. #113. Santa Clara. CA 95050:408/727-3995).
Before you decide to rebuild the engine, check it out. If it passes a leakdown test and doesn 7 burn oil or show signs of having been overheated, leave it alone. A Honda Four that has run coo! and had its oil changed is capable of going 80.000 miles or more. E3
