Question-------------------------
Followup To
Question -
I have a 1995 Sportster 1200. Last year I cored the baffles out of stock mufflers for better sound. I noticed the bike was runnng a little erratic, but it still ran OK. This year when I got it out of storage I noticed it ran worse. Realizing that changing the exhaust would affect the way it runs I started fiddleing (as much as I could) with the carb. Well, no improvement. So I had a S&S carb from a 1984 Ironhead. So I got a manifold to match the '95 and gaskets , etc. and put the S&S series E on the '95 Sport. Got a breather kit to allow for the different carb and put that in. I also changed the mufflers to Screaming Eagle 2's. Well now it runs even worse than before. I've made all the adjustments (idle& accel. pump) according to the book, but the bike backfires through the carb and the exhaust under load. It idles a little rough, but I can get it to idle at 1000 RPM. I had it running pretty good the other day but then when I put the girlfriend on the back I couldn't get around the block. Misfires, backfires, etc. I'm suspecting vacuum leak, but haven't a clue where it might be. I checked the timing and at 1800 RPM the timing mark is right where it should be. Any help would be appreciated. The local dealer won't touch it because of the modifications. I could put the stock carb back on, but it ran shitty before I changed it.
Thanks
Answer -
Couple of questions. 1. Pull a spark plug and tell me what color it is. 2. Did you rejet the bike after installing the carb or just adjust the air/fuel mixture and pumper?
Mike
The plug tips are light gray and the plug body has some soot on it. I changed the intermediate jet from a .028 to a .0265. I didn't mess with the main jet, so I'm not sure what size is in there.
Thanks
Al
AnswerI would start by checking the intake manifold for a leak. Start the bike and using some carb cleaner, spray a little around the intake where it connects to the heads. If the RPMs go up then you have a leak. If you dont have a leak then you probably dont have the carb jetted right. The other thing is check your timing at idle, not reved up.
Once you check the timing and look for a leak, now go to the carb.
To check the jetting, turn off the pumper.It will give you a false reading. Take the bike for a ride and do not go over 2500 RPM. If the carb spits through the carb then the intermediate jet is to small. If it spits through the exhaust then it to big. Remember to always readjust the air/fuel mixture screw when ener you make a change. After you get the intermediate jet set, not go to the main. Do the same as above, except ride over 3000 RPM. Look for the same signs. One you have the jets set open the pumper abut 1 1?2 turns. Ride the bike and when you shift gears if the bike bogs open it a little farther.
Good luck and happy riding
Mike
