Because the enduro season is about to begin, next weekend, I figured I would go through the XR checking all the items and looking for deferred maintenance.
I changed the brake pads, replaced the rear tire, threw away the stupid aluminum sprocket for a steel one, etc. Then I got a little bug in my arse.
I had read about the Gordon mods but didn't want to lose my snorkel or make the bike any louder. Why do I need the power? I only weigh 150 and the 400 has a lot of power. I decided to do the semi-gordon mod, my own invention. I drilled two of the recommended three 7/32 holes in the muffler endcap for a noticeable but slight noise increase. Then took my snorkel out and cut the heck out of it so that I still have the baffle action of the snorkel to keep mud from landing on top of the filter but I now have more than double the intake area. Both of these were compromises that I could live with but contributed significantly to flow area. The stock carb jets are a 52 slow and 142 main. I popped in a 55 slow and 155 main with the fuel screw at 2 turns. I always have heard that the jet numbers should match, the last two digits that is. Carb stayed in the bike, 2001 non CA XR400R. I already have clean twin air filter.
I don't see a big need to clean the header welds. The new exhaust outlet provides .562 square inches of flow area (15% over stock). Reportedly, the stock header welds only leave a .75 inch diameter opening on each side, .44 square inches each. 2x .44 gives me 0.88 suare inches which is 57% more area than the new outlet.
The bike started much easier than before. It even sounded different as I kicked it over. Once warm I took it for a run around the block and then adjusted the fuel screw a little bit to maximize idle speed.
Rode 43 miles yesterday at an ORV park. Holy smokes the throttle response is much, much better. The front end is much easier to loft up over obstacles. The engine has a very steady idle and wide open throttle runs are better than ever. The whole day was spent ripping around on and off the gas. I couldn't help but whack the throttle open to feel the new kick. Better power and quicker power delivery. I now have to be afraid of giving it too much throttle.
Very nice modification. Highly recommended. 10$ in jets. Why did I wait so long?
I changed the brake pads, replaced the rear tire, threw away the stupid aluminum sprocket for a steel one, etc. Then I got a little bug in my arse.
I had read about the Gordon mods but didn't want to lose my snorkel or make the bike any louder. Why do I need the power? I only weigh 150 and the 400 has a lot of power. I decided to do the semi-gordon mod, my own invention. I drilled two of the recommended three 7/32 holes in the muffler endcap for a noticeable but slight noise increase. Then took my snorkel out and cut the heck out of it so that I still have the baffle action of the snorkel to keep mud from landing on top of the filter but I now have more than double the intake area. Both of these were compromises that I could live with but contributed significantly to flow area. The stock carb jets are a 52 slow and 142 main. I popped in a 55 slow and 155 main with the fuel screw at 2 turns. I always have heard that the jet numbers should match, the last two digits that is. Carb stayed in the bike, 2001 non CA XR400R. I already have clean twin air filter.
I don't see a big need to clean the header welds. The new exhaust outlet provides .562 square inches of flow area (15% over stock). Reportedly, the stock header welds only leave a .75 inch diameter opening on each side, .44 square inches each. 2x .44 gives me 0.88 suare inches which is 57% more area than the new outlet.
The bike started much easier than before. It even sounded different as I kicked it over. Once warm I took it for a run around the block and then adjusted the fuel screw a little bit to maximize idle speed.
Rode 43 miles yesterday at an ORV park. Holy smokes the throttle response is much, much better. The front end is much easier to loft up over obstacles. The engine has a very steady idle and wide open throttle runs are better than ever. The whole day was spent ripping around on and off the gas. I couldn't help but whack the throttle open to feel the new kick. Better power and quicker power delivery. I now have to be afraid of giving it too much throttle.
Very nice modification. Highly recommended. 10$ in jets. Why did I wait so long?
