Hi I hope someone will be able to help me with this one. I have a 2004 Roadstar and I drove the bike around Arizona bike week in Spring of 2009. The bike sat in the garage till yesterday. I tried to start the bike and off course I forgot to disconnect the battery and it was dead. So I charged it, and tried to start it again. It started but I could smell bad gas coming from the exhaust. I checked and sure enough it was bad. So I drained it and filled it with High Octane 91 Started the bike again, but it simply wouldn't idle. If I put the choke on half it runs fairly smooth, as soon as I let the choke off it stalls,wont idle. So I took off the fuel filter and checked it, and it was clear and not plugged. I checked to see if the fuel pump was flowing properly and it was. I checked to see if the petcock is working properly and it is. I pulled the spark plugs and they are perfect I mean a perfect tan color on each of them. Then I checked the plug wires and grounded them to see if the coils are firing and they are. I took off the carb and checked for plugged holes or varnish from the bad gas but the carb is clear and clean. I at a loss, I tried to drive the bike and it drives great off idle lots of power no hesitation, but as soon as I slow down to stop or idle it stalls and the only way I can keep it running is with the choke partly on. I thought I mite have a vacuum leak but I cant see one, I tried to run it without the breather on and same problem. I Tried turning idle screw up to increase the idle and it got worse. Even though the bike will run with the choke partly on the sound out of the tail pipe isnt right I can tell its not runnning correctly. Anyway I am at a loss. Looking forward to hearing on how to fix this

When you say you checked for plugged holes in the carb did you take the jets out and make sure they were clear? Did you pull all 4 spark plugs out and check them? If all that checks out I would try running some Sea Foam through it and see if it clears out.

Your scoot will run better on 87 octane due to the low compression. No sense wasting money on high-priced gas when you can spend it on chrome.

Oh, and

Yes I removed the jets and blew out the holes with compressed air. And funny you mentioned Sea Foam, I did buy a can and added it to the gas and when i took the carb off after running the bike for an hour the carb was clean, but the problem was still there. and like I said lots of power off idle, but from the sound coming from the tail pipes it just didn't sound crisp cant describe sound. The only way I was able to drive it was with the choke on about a quarter pull and I used a tie wrap behind it to prevent it from closing. It got me to around but as soon as I cut the tie wrap it stalled. I checked all 4 plugs and they were perfect nice tan gap correct and no moisture what so ever. Lots of backfiring through carb a couple times a flame. The timing cant be off as the power band off idle is good, lots of torque and no hesitation. Bike has next to 5000 miles on it. I am very versed in fixing bikes but am new to Yamaha.I have to say this one has me stumped. The only thing I haven't adjusted is the pms screw that I am reading about. I will try that tomorrow so I don't piss off the neighbors tonight!!

Hi thank you, and yes your right I could use lower octane, I just wanted to eliminate the possiblity of it being a gas problem once I drained out the old gas. I ran the bike today after running Sea Foam through it and the problem still exists. Having the choke on part way tells me that it was running lean and needed to be richened up... or also tells me there is a vacuum leak somewhere but I checked all the lines going to the carb and they r good and tight. Manifold is not leaking.

You say you cleaned the jets, Did you spray some carb cleaner thru the ports that the jets screw into. If that passage isn't clean all the way thru it won't run. If the carb is "GUMMED" up from bad gas compressed air may not do it. You need a chemicial to break down the varnish deposits. ie: Carb cleaner and not the enviromentilly safe junk.