Problem Starting Last Two Nights

gilx · #1 21st January 2005

I think this is a "Tech Talk" issue, but not sure if this is the correct forum. I have a '04 1200 custom, SE air, dyna kit 180 jet with needle, and SE pipes. Had the dyna kit done last week, runs like a rocket! My problem: last night and tonight my bike was hard to start, refused to idle, and ran rough for about 5-10 minutes before it seemed to stablize. It even backfired through the carb like it did before the dyna kit. However, during the day it ran perfectly. I think I know what might be going on, but want to bounce it off the experience of the group.

Last night and this evening when I came home from work, it was just below freezing, 100% humidity, ice-fog. I think the air-fuel mixture may be icing at the main jet, causing the same lean condition as before the dyna kit. After the motor runs for about 10 minutes, it finally warms enough to warm the carb, thus preventing the icing...I think. In the morning, temps are similar but the humidity seems to be a lot less and I don't have any problem starting or running.

Has anyone else experienced this?

dabronco · #2 21st January 2005

Yes, And no. I had a '74 Charger that would run like s%%t if the humidity was up. It would run rough after starting and even after it warmed up, until I shut it off for a couple of minutes. the engine would warm the carb up and no more ice. The carb never had a chance to warm up with that constant flow of cold humid air rushing thru it. You must be a pilot too!

klown · #3 21st January 2005

How long was it sitting before you started it up? If you are gonna let it sit for more than 10 days or so you should put some fuel stabilizer in the tank to ensure the easy startups.

gordy · #4 21st January 2005

sounds like carb icing make a shield to fit between the air cleaner and the Jugs(cut from a beer can works great) and stick a cap of isopropyl alcohol in the gas tank when you fill up. Works great for me.

Gordy

gilx · #5 21st January 2005

Yeah, I've done some single engine flying...thats what made me think of the carb icing. I commute to work and back. In the morning, it's a cold starter like I have heard Sportsters normally are. I probably let it warm up a lot more in the morning because I'm in my comfy house, finishing off my coffee, and getting my gear on. Usually a couple of times during the day I hop on the bike to run to a meeting. Starts normally and runs fine. The last two nights it may have sat in the parking lot for 4 or so hours cooling before I drove home. Temps about the same as in the morning, but much more moisture. Seat covered in frost, everything else either wet or frost. Drove it this morning with no problems. Gordy, I understand the isopropyl alcohol but not the shield. What is it shielding and how is it placed?