BIKES: 600 SRX 850 TRX 600/650 XR 250 TTR 1000 FZR STREET TIRES CARBURETOR  
  The XR Family

 
The least that can be said about the XR's is that it is a big family. No less than 12 different models from Honda bore the name since 1981, when the first model, the 500 XR, was launched. The 500 first grew into the 600 before finally spawning a whole family ranging from 50cc to 650cc and including cousins the XR-L.
This page will focus on the 600cc and 650cc sold since 1991.
 

From Off-road.com
Off-road.com put together a page that sumarizes 16 years of XR's. 21 years would be more accurate as it is only in 2002 that Honda finally decided to release an entirely new model, the XR650R. [go] [cached]

The same Off-Road.com also has burried in his site the specs for both bikes
   XR 600 R [go] [cached]
   XR 650 L [go] [cached]

You can also give a look a the 2000 Honda brochure for both the XR600 and the XR650L [.pdf]

Modifications for the XR 650 L

   XRL Diet Plan and Jetting
At over 47 lbs heavier than the already heavy XR 600 the weight of the 650 really makes itself known when the street turns to dirt. Other than removing its gas cap and rolling a Husaberg underneath, following are a few ways to remove excess flab from your XRL. By replacing the stock headlight with a Baja Designs headlight, the mirrors with Acerbis plastic mirrors, and replacing the stock bend-0-matic handlebars with Renthals you can remove 3 lbs of highly placed weight. Baja Designs Headlight: $88.00 Acerbis Mirrors: $15.00 Renthal Handlebars: $70.00
The unsightly smog pump and carbon canisters can be removed for off-road use to save 2 lbs 4 oz. with a block off kit for $19.95.
The TV set that Honda calls a taillight can be replaced with a 2 lb. lighter and much lower profile unit from Acerbis. Mounts to the stock fender and is fully street legal. See color photos for taillight on XR, DR, and kit parts. DOT Taillight: $38.00 wired and assembled; and $32.00 unassembled.
Removing the steel tank and wings and replacing them with the IMS 4.0 gallon tank or Acerbis 5 gallon tank saves 7 lbs and gives the bike a much greater fuel range. IMS Tank: $190.00 - Acerbis Tank: $185.00
Remove the buddy pegs, and combined with the above modifications, you have removed 16-1/2 pounds of excess pork from your 650L. Remove XRL 650 and replace with XR 600 and Baja Designs Conversion Kit: About $4400. Weight Savings 41 lb. (Sorry - couldn't resist!)

   Jetting the XRL 650
The CV (constant velocity) carburetor on the 650L is very sensitive to changes in intake and exhaust restrictions. Many people, desiring more power from the mildly tuned 650L motor will remove the airbox snorkel and install a decent air filter and a lower restriction exhaust. The bike will pick up 3 to 6 horsepower with these mods, but will run terrible, bogging horribly anytime you whack the throttle hard. Simply rejetting the carb will not fix the problem. After many hours of testing and experimentation, we found that the problem was in the vacuum piston of the CV carb. Baja Designs now offers a simple to install kit that includes the proper jetting and necessary modifications to the vacuum piston and pilot circuit to allow the bike to run properly. XRL 650 Jetting Kit: $21.95 Smog Block-Off Kit for XRL 650 Price: $19.95