1901-1953 Indian Motorcycle – Parts – Accessories

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  5. 71 – Crank Case Loading With Oil and Excessive Oil Consumption

71 – Crank Case Loading With Oil and Excessive Oil Consumption


Check oil return line from crank case sump valve to pump for loose connections, which cause air leaks. When cleaning sump valve, make sure that the sump valve plate is assembled to sump housing, that valve is at bottom of sump housing.

This may be assembled two ways, one of them will raise the valve higher on sump housing; automatically raising the oil level in crank case, permitting fly wheels to dip in oil, causing over oiling of motor. Inspect disc valve and screen. Note that screen does not touch return valve disc. This disc must retain its proper seat.

Flush out oil tank every 2,000 miles for cleaner and trouble free lubrication.


The hub bearing lock nut on brake drum side, has a tendency to loosen up (due to not being tight against wheel bearing) allowing this bearing to work out of hub, and transferring side thrust to the needle bearing side, causing ends of needle rollers to wear hollow axle collar.

At the first indication of excess side play in wheels, check this nut up tight and stake it in hub shell. Grease wheel bearings well. When removing hub bearing lock nut on needle bearing side of wheel, be sure and remove lock screw on rim of hub.

Starting with the following motor numbers, all Model 237, Model 337 and Model 437 machines are fitted with a lock screw on the brake drum bearing nut and will not need staking.

Model 237Motor No. BCG 696
” 337” ” CCG 2185
” 437” ” DCG 426


While servicing Indian Motors for cleaning carbon or grinding valves, check bottom of pistons and file the sharp corner off of bottom of skirt, if bottom of skirt has worn to a sharp edge.

This edge has a tendency to scrape oil off cylinder wall on downward stroke of piston. File this edge off round, also check new pistons you have in stock for same condition, and file the edge off before using.


When front or rear or both carburetors on Indian 4 show symptoms of running lean, change the compensator jet, located in float bowl just under the float to jet No. 17, part No. 101309, on rear carburetor, and jet No. 18, part
No . 101420, on front carburetor, which will overcome a lean condition of carburetors when accelerating. Production motors are fitted with a No. 17 jet in front and a No. 15 jet in rear.

Indian 4 Motors run the best with Indian “C” spark plugs, 10 mm, with brass adapters. This plug may be ordered by part No. 41165.

You are advised to use Indian-Edison “C” spark plugs 10 mm in all Indian Motors, where motor performance is expected at higher speeds. Indian “C” spark plug is cooler running than Indian “A” or “B”.


To eliminate discoloration of mufflers and exhaust manifolds, put a 3/4″ rod in tail pipe and knock out the baffles which are located in the front end of the muffler center tubes.


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