REF: Extra Models10 - Sportsterpedia

This page is read only. You can view the source, but not change it. Ask your administrator if you think this is wrong.

[[:techtalk:ref:xmodels|{{  :techtalk:gotoxtramodelindex.png|}}]] 
====== REF: Extra Models10 ======
\\
====== XR-750 General Information ======
===== Engine VIN Coding =====
{{:sportster_history:xr-750_engine_vin_chart_by_hippysmack.png?direct&600|}} ((Drawing by Hippysmack)) \\

===== About Factory Original XR-750 Bikes and Parts =====
From Dr Dick of the XLFrum: \\
An original XR is like the original greenback. Who ever had it used it and now it's no longer in original condition even though it's "the original". Breaking out REAL info on old race bikes isn't easy. Take the term, original. It's a term that applies to street models, and not racers. Race bikes, by their service requirements, are useless as delivered and therefore obsolete on delivery. When you're talking XR750s, they were not raced in an IROC situation (eg- they got modded to beat the guys who lined up next to you). So
an original frame is kinda like the original homerun record or the original land speed record. The original record is zero. 
When you have a racer you need to learn the heritage (time line) of the sport at time of machine retirement. Then you self-educate on the who, what, when, and most importantly the why your piece of history is in the dress it's in. That takes place of the street bike "factory original" mind set and mile post. ((https://www.xlforum.net/forum/sportster-motorcycle-forum/sportster-motorcycle-era-specific-and-model-specific/xr-sportster-motorcycle-talk-xr750-xr1000-xr1200/xr-750/165860-xr750-1977-frame?t=1782825)) \\
 
====== Specs / Features ======
===== 1972 =====
New redeigned 750cc engine with aluminum cylinders and heads. Also had new valves, pistons, rods, flywheel assm, "E" cams, carbs and tuned exhaust, 7/8" dia handlebars with an aluminum ball end clutch lever and a fiberglass seat/fender with a foam cushion. 
    * Engine Type: OHV V-Twin
    * Carburetion: Dual 36mm Mikuni carburetors and specially designed air filters
    * Exhaust System: Tuned duals with reverse-cone megaphones
    * Bore and Stroke: 3.125" x 2.983"
    * Displacement: 45cu, 750cc
    * Compression Ratio: 10:1
    * Max RPM: 8000
    * Clutch Type: Multi-plate dry clutch
    * Primary Drive: 25 tooth engine sprocket, 59 tooth clutch, triple row roller chain
    * Rear Drive: 16 tooth transmission sprocket, 40 tooth rear wheel sprocket
    * Overall Drive Ratio: 5.90:1
    * Transmission: Constant Mesh, 4 speed
    * Transmission Gear Ratios:
      * 1st 2.09:1
      * 2nd 1.51:1
      * 3rd 1.14:1
      * 4th 1:1
    * Weight: 295 lbs
    * Tires (front and rear): 4.0 x 19 on aluminum rims
    * Front Forks: Ceriani with 4.40” travel and aluminum fork bracket
    * Rear Shocks: Girling hydraulic racing shocks
    * Gas Tank: Fiberglass construction with 2-1/2 gallon capacity
    * Oil Tank: 3 quarts
    * Electrical: Fairbanks-Morse magneto
    * Color: Jet Fire Orange

\\
\\
[[:techtalk:ref:xmodels|{{:techtalk:gotoxtramodelindex.png|}}]]

Trace: • EVO: Suspension - Sub-01C • REF: Tools - 139 • REF: Oiling & Lubrication - Sub-05H • REF: Tools - 173 • EVO: Engine Mechanicals - Sub-09E • EVO: Engine Control - Sub-03a • EVO: Engine Mechanicals - Sub-09A • EVO: Engine Mechanicals - Sub-04E