72 sportster misfiring when hot

72 Harley-Davidson XLCH 1000-Sportster discussion forum:


72 sportster misfiring when hot

72 sportster misfiring when hot 
mn said 2007-07-20 15:57 
 
I have a 72 sportster with a Crane Hi4 electronic ignition, a new solid-state regulator and S&S shorty E carb. The bike ran great for 1000 miles after installing the new parts but then started to load up a bit (bogging, then backfiring thru the exhaust). Opening the throttle would blow it out, but the more I rode it (the hotter it got) the worse it ran until I wasn’t sure I could get home. At a steady 2-3K rpm it totally misfires and backfires thru the exhaust. The only way I could get home was to downshift (to up the rpm’s) and floor it. Otherwise, at low rpm it would just pop, spit and backfire. It would still idle when I let off the gas, but roughly, and the rpm’s were very erratic. After letting it sit me for 15 minutes, it started right up and idled ok. I didnt take it on the road, but suspect that it wouldnt have run well until it was totally cooled down. This obviously sounds like a heat related issue, but I’m not sure what component is being affected. Seems like spark, but I suppose it could also be fuel. I have the thermal isolator between the intake manifold and the carb like the carb manufacturer recommended and didn’t have any problems with the carb before all of this started. Has anyone ever heard of coils or electronic ignitions doing this from heat? Suggestions or previous experience is appreciated. 
 
<<Previous          Answer          Discussion overview          Report spam          Next>>

Comments, questions and answersEnter a comment or answer to this message

You can post your question, answer or comment as a guest. Or enter your e-mail to join the forum and get notifcations of new messages.

 
Title 		 
Signature
Optional e-mail
Enter your e-mail to join the forum and get notification of answers and new messages. You can unsubscribe with a single click. Bikez does not display, sell or misuse e-mail addresses.
Message text

Describe technical issues in detail to get quality answers. You can offer or request second-hand parts and equipment as a privat person. Bikez reserves the right to remove any improper or commercial content.
Accept that we store and display the message.  

 

More 1972 Harley-Davidson XLCH 1000-Sportster information

Our discussion forums are intended for short messages. We also welcome more extensive motorcycle reviews.

Bikez also recommends that you check out the technical data and the riders' rating for the 72 Harley-Davidson XLCH 1000-Sportster. You can also rate it yourself. Use our efficient motorcycle classifieds to sell or buy this bike. Your motorbike gets a high quality presentation. Ads are free.