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    Factory 648 Instructions.
   By Jim Wall
  Special Instructions and Specifications for the 648 Model With Bonneville Motor. 
Breaking the motor in.  

Machines should be run at speeds running from 35 to 55 miles per hour for not less than 200 miles. This "break in" running is for the purpose of obtaining a high polish on the cylinder walls and a positive seal on the piston rings, as well as as to allow all bearing surfaces to "wear in".  More miles of "breaking in" may be necessary if the motor does not feel like it is ready to go.  
Never use heavier than SAE #30 for "breaking in" purposes.  
Never open the motor up until the oil in the tank is WARM.  
Reheat the oil if neccesary, before pouring in the tank.  
Use #50 INDIAN OIL after the engine is broken in and change often.  
Never allow the motor to labor or over peak in high gear.  
Consult instructions on gearing and ignition.  
The spark advance setting is 11/16" for the 648 model; spark plugs fire when the pistons are 11/16" before top dead center on the compression stroke.  
To set the spark timing accurately it is neccessary to remove the rear cylinder head.  Magneto point setting is .015 exactly.  
Use Champoin JA-11 or LA-14 spark plugs.  
 Clearance Chart and Specifications.   
Intake Valve Clearance .010 motor cold. 
Exhaust Valve Clearance .010 motor cold. 
Valve seats 35 degrees
Piston clearance .0075 minimum
Ring gap .018 minimun
Connecting rod lower bearings .0025" -.003"
Connecting rod upper bushing .003"
Flywheel end play .010" - .015"
Drive shaft bearings .0015" minimum
Spark Advance 11/16"
Magneto point setting .015"
Compresion ratio 6 to 1
Cams Bonneville type
Pistons High top - 2 compresion rings and oil ring
Gas tank capacity 4 1/2 gallons
Oil tank capacity 1 1/2 gallon
Indian riders are encouraged to keep records of all meets and events, indicating conditions of course, type of event, speeds obtained, gear ratios used, and weather. Such records will be helpful in the following year or similiar events. Experience is the best teacher.  

The attached chart shows gear ratios for the varios sprocket combinations available on Model 648's (not attached here, but this should be pretty easy to figure out on your own). If a rider expects to compete in all types of class "C" events he should have the range of sprockets shown:   
13, 14, 15, 16, 17, 18, 19 and 20 tooth counter shaft sprockets   

36, 39, 40, 41, 42 and 43 tooth rear wheel sprockets.   

The 18 and 40 tooth sprockes are assembled on the machines.  

The suggested gear ratios for the Daytona race are:  
20-39   4.21  
20-40   4.32  
20-41   4.43  

One mile speedways,  such as Langhorne:  
19-41   4.66  
Time trial:  
18-40   4.80  

1/2 mile dirt tracks:  
15-42   6.06  
15-43   6.21  most popular

These instructions might come in handy when Jim's and Lyle's 648 engine cases are done... :-)  

Expect an update on this project next month. Meanwhile a click on the picture below will take you to the story so far.  
Big Base 648 cases.  
 More racing stuff from Jim here!  
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Intro to Sport Scout Racers.  
All about factory racing tanks.  
How to strengthen your rear  
frame for racing.  
How to narrow your forks.  
All about Indian cams -including  
the experimental "4-cams", which  
you will hear more about soon...