The Service Dept

THE SERVICE DEPT

JODY NICHOLAS

HONDA 350 TIPS

I own an early 1970 Honda CB350 with steering damper and rubber pads on the tank. After 5000 miles it developed three annoying habits:

1) It became impossible to set the right breaker point gap to the specified setting in the manual without advancing the ignition timing to the point where the engine wouldn't rev above 6000. Changing the points cured this for 1000 miles. Now the largest gap I can set for both points is 0.013 in., with the base plate at full retard. Timing is correct.

2) When the engine is cold and I hold it at 2000 rpm to warm it up, it often makes backfiring noises. After being ridden a few miles it won't make these noises in neutral but will often make them in the lower rpm range—especially as I slow down in second or third gear. I use premium grade gasoline and both mufflers were replaced. The noises started about the same time I began having trouble with the points, although they don't occur in neutral if I warm up the engine on full choke, and they didn't disappear when I replaced the points.

3) Every 500 miles I have to add almost a full quart of oil. There is no excessive smoke coming from either muffler and the spark plugs never foul; both are a coffee-brown color along the top and clean around the gap, which is set at 0.030 in. There is no trace of oil around seals either.

Performance does not seem to be affected in any way-I bought the bike new-but I've enjoyed the 730 0 miles I have put on it and would like to correct these annoyances rather than buy a new bike. Any advice would be greatly appreciated.

Daniel Raines Little Neck, N. Y.

Ignition point gap isn't too critical on the 350 Hondas as long as it's kept between 0.010 and, say, 0.018 in. If you've been replacing your points with those from an accessory company, instead of genuine Honda parts, your trouble may be there. The fiber rubbing blocks on some non-standard point sets are just fractionally shorter than the original equipment parts, and that would give you a smaller range of adjustment. (Continued on page 28)

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It's also conceivable that the contact breaker plate on your machine is slightly "off." A complete breaker plate assembly, including the points and all screws, is available for only a dollar or so more than the points themselves. The Honda part number is 30200-286-004.

While you've got the breaker plate off, it would be a good idea to check the spark advancing mechanism for proper operation. These units will sometimes become sticky after prolonged use and must be lubricated to restore their operation. When checking the ignition timing with a strobe light, ignition advance should begin between 1600 and 2000 rpm, and should be fully advanced between 3200 and 3800 rpm. Although the possibility is remote, it would be a good idea to check the point cam's rubbing surfaces for wear, and always smear these surfaces with a small amount of point cam grease (available at any auto parts store) when installing new points and at regular intervals when you check the timing.

The backfiring condition while warming up is merely a condition of leanness which all internal combustion engines exhibit. By using the choke, this lean condition is corrected so that the engine runs smoothly. If the backfiring continues when the engine is warm, it's possible that the carburetor needles will have to be raised one notch to enrichen the mixture.

If your machine is consuming oil at the rate of one quart each 500 miles, there must be some sign which is easily visible. Either blue smoke will come out of the exhaust pipes, or oil will leak out of the machine, which will be quite apparent. Since your spark plugs are not oily and are the correct color, we can assume that the valve guides and piston rings are in good shape.

When checking the oil level with the engine warm, be sure to wait a couple of minutes after stopping the engine to let the oil from the cambox area drain back to the crankcase. If you don't, you'll get a low reading on the dipstick.

EARLY BSA PARTS

I own a 1961 BSA 500-cc Gold Star and I am having trouble locating certain parts. The local dealers in my area say the machine hasn't been manufactured since 1963, and that parts aren't available from the distributor. Is there any place I can get parts?

William Buckley Boston, Mass.

The best source of early BSA parts we know of is Jim Hunter Motorcycle Repair, 1140 S. Cypress St., Unit A, La Habra, CA 90631. He has been a BSA mechanic and competition rider for years and refuses to let the newer models take precedence in his shop. In fact, his stock of new and used A-7, A-l0, B-33 and Gold Star (B-34) parts is probably the largest in the country.

In addition to his mail order business, any form of repair on these older machines is undertaken in the shop, including lathe and machine work. New and rebuilt magnetos and magdynos are available from stock, and other hard-tofind parts are in abundance.

CHAIN TIPS

I presently own a Bultaco 250 Pursang which I ride in the dirt. I have had to replace my chain quite often, even though I take it off from time to time, wash it in solvent, and let it soak in oil overnight.

Before reinstalling the chain, I always clean the dirt from the sprockets and take extra care to line the chain up. I also adjust the chain to run a little loose with me sitting on the bike. Am I doing something wrong?

One more question: what do the numbers like 428 and 530 which are stamped on the side plates of some chains mean?

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Ernest Hemlock Los Angeles, Calif

No rear chain on a dirt machine is going to last forever. From what you've said, you are going about your chain drill correctly, and the oftener you perform it, the longer the chain will last.

Each joint of a chain is, in essence, a plain bearing which must be kept clean and lubricated for maximum life and optimum power transmitting characteristics. Present day chains are marvels of reliability compared to their counterparts of just a few years ago, and their hardened steel bearing surfaces will carry the transmission's output to the rear wheel with very little fuss.

However, it is essential that there be a film of lubricant between these bearing surfaces, one which is uncontaminated by the dirt and grit that mix with the oil to form an abrasive paste and hasten wear. This film of lubricant also aids in providing a "hydraulic" cushioning effect.

Many dirt riders are now using a spray-on chain lube called "Graphaplate" which is manufactured by Jeeco and distributed' by Webco Inc. This lubricant must be sprayed onto a perfectly clean chain (cleaning the chain in lacquer thinner is recommended, although be sure to use the proper precautions). The spray is actually a form of graphite in a carrier, and the carrier evaporates once the solution has penetrated between the rollers and side plates. The graphite inside forms an excellent low-drag lubricant which doesn't attract dirt and grit, and won't get "wicked out" by dirt like an oil. Many top competition riders are using and endorsing this product, and I have had good results with it myself.

The numbers you see stamped on the side plates of some (mainly Japanese) chains are merely identification numbers which tell you the size of the chain. Some of the more popular sizes are listed below: [Ö]