I have seen similar reports of this issue, but have not been able to find a resolution for mine yet.


2001 Sportster 500 HO A01CH50AB. Very low hours, and was stored for a couple years in my shed.


It starts fine and will run great for 5-10 minutes, but will then die out and will not want to start back up unless it sits for a while. Sometimes I can get it to start with an open throttle, and it will run fine if I hold the throttle over 1/4 open, but if I start to let it idle down it will stumble and die.


I have done all the common fixes that I've seen for this problem:


Adjusted throttle cable with 1/8" play
Changed fuel filter and verified fuel flow to and from the pump.
Tank vent not clogged
Air box and connections appear to be sealed and tight.


I got a carb kit and replaced everything. The inside of the carb didn't look bad at all, but I did notice that the pilot jet wasn't tightened all the way so I tightened the new one down. When I got everything back together it wouldn't start and run without giving it 1/4 choke, so I'm assuming that it now also has a lean condition. It's got the Mikuni carb, and haven't found where the mix adjust is yet. That being said, the original problem still exists that after it runs for a while, it will stumble and die out.


At this point I don't think it's a fuel or carb issue. I'm going to replace the spark plug next, not sure if that can be cross referenced with any brand of plug.


I'm hoping someone can give me some more troubleshooting suggestions.


Thanks in advance!

 

Use the BKR5 or BKR6ES plug. The idle fuel screw is under a block off plug and preset from the factory. Most are set fairly close,but you can carefully drill through this block,use a dry wall screw and pull the plug out. If you adjust the settings always check how many turns out from a lightly seated position it was originally set at. Problem may not be fuel or carb related but could be an electrical brake down.On this I'd get the manual so you can go through the trouble shooting and resistance tests. Here's a free supplemental from Polaris that has carb specs and a wiring schematic. Top right hand of the schematic has resistance tests on the stator,pick up coil ,ign coil,etc that may be of help. Type in year,brand and model and the supplemental shows the pdf link you can check out.Download Owners Manuals - By Vehicle Type OR you can get the complete manual for 10 bucks.http://visit.tradebit.com/visit.php/...75/264163430/9

 

Thanks Old Polaris Tech. My current plug is the original BKR6E, should I just go with the same one? I see allot of conflicting info out here about the plugs, but my service manual calls for the BKR5E / 0.036 gap. Looks like the local auto parts has NGK, but is it OK to cross reference a different brand?

 

Stay with NGK,the best plug out there for the money. Doesn't hurt to use either the 5 or 6 as I've used both and so have customers. Rule of thumb if you drive at high speeds,under constant loads that causes engines to be extremely hot,then a colder plug such as the 6 would be preferred. Normal every day use a 5 would be ok. Here's a better description on heat ranges.Heat Range Explanation - Technical Information - NGK Spark Plugs Australia

 

Replaced with the same BKR6E, and that seems to have been the problem. Old plug must have been fouling when it got hot. Adjusted the idle at the carb so I could push the choke all the way in at idle. Still have a bit of a miss sometimes at idle, but at least is stays running now!

Thanks again Old Polaris Tech!

 

Simple things that a lot of people over look can cause a lot of problems.