garymccullen
06-08-2006, 07:33 AM
stock bore 400ex w/stock cam
mods: wb pipe, Air lid off, & K&N filter.
installed 450r carb, expierencing a slight hick-up during idle that will eventually stall, have looked through almost all threads on 450r carbs, jetting & backfiring.
Have tried 42,45,48 pilot jets with adjments to fuel screw from seated to 3 1/2 turns. Stock needle 3rd groove from top. 172 kiehen main jet, also have tried 155, 160, 165 dyno jets for main.
On test rides, best noticable increase in performance using 45 pilot, 3 1/2 turns on screw, and 172 main. On decel slight popping. No bog at any rpm range. Have checked for vacume leaks, sprayed starter fluid when at idle no spike in rpm, hot start hole plugged w/ break fitting good seal. Spark plug checks show between white/grey. Plug reading confirms the lean condition that I get with popping on decel. But still get this hick-up during idle and eventually stalls.
No change w/ 48 pilot up to 3 turns out.
Have tried w/lid on covering portions of airfilter w/duct tape w/ no change in idle problem.
Suspect something in 450r carb, because when I put the stock 400ex carb back on, didnt hick-up during idle, no popping on decel. but unfortunatly throttle response wasnt as good as the 450r carb.
any suggestions would be greatly appreciated.
thanks
mods: wb pipe, Air lid off, & K&N filter.
installed 450r carb, expierencing a slight hick-up during idle that will eventually stall, have looked through almost all threads on 450r carbs, jetting & backfiring.
Have tried 42,45,48 pilot jets with adjments to fuel screw from seated to 3 1/2 turns. Stock needle 3rd groove from top. 172 kiehen main jet, also have tried 155, 160, 165 dyno jets for main.
On test rides, best noticable increase in performance using 45 pilot, 3 1/2 turns on screw, and 172 main. On decel slight popping. No bog at any rpm range. Have checked for vacume leaks, sprayed starter fluid when at idle no spike in rpm, hot start hole plugged w/ break fitting good seal. Spark plug checks show between white/grey. Plug reading confirms the lean condition that I get with popping on decel. But still get this hick-up during idle and eventually stalls.
No change w/ 48 pilot up to 3 turns out.
Have tried w/lid on covering portions of airfilter w/duct tape w/ no change in idle problem.
Suspect something in 450r carb, because when I put the stock 400ex carb back on, didnt hick-up during idle, no popping on decel. but unfortunatly throttle response wasnt as good as the 450r carb.
any suggestions would be greatly appreciated.
thanks