I was wondering what others are running on their mc5 250's for jetting. I looked up what the book says and it is leaner than what I am running. The other day I was changing a throttle cable and found that the needle was on the bottom groove, I had moved the needle to the middle groove and the bike ran worse. I consulted the book and it seemed to suggest that the correct setting is the bottom groove. I moved it back to the bottom groove and found as well that the air mixture screw was turned almost all the way in. I changed the pilot to the next bigger and was able to adjust the air mixture screw closer to what it should be( 1 & 1/2 turns out). what I found though is that I am running a larger pilot and a larger main than stock. this may be due to the aftermarket pipe. I am wondering what others are running and why. living here in the great northwest I am only 4-5 hundred feet above sea level and cooler temps. I guess I am not too worried since i am running richer than stock and not leaner. but it would be nice to get the carb spot on. I would still like to put a mikuni on but because of money that will have to wait. Fortunatly I do have a few jets for the bing.
anybody need a 35 pilot I have two. I am running a 40 pilot and a 280 main. as far as I can tell everything else is stock. To be sure I will have to tear it down again, which I may be doing anyway.
Thom Green,I own and ride a 76 250 MC5 MX which I bought new.
Thom,
the pipe would change the jetting.
try a larger needle jet and keep going larger on the main till the bike runs rich.
then back off on the main jet size. i try and get a needle jet that will let me run in the middle. its not always possible but that gives me some room if i go to a place where the air temp and altitude dictate a change in my jetting.
Just like you did with the idle jet. 1 to 1 and 1/2 are a good place to be on the setting.
John