View Full Version : Fried Plugs

8th June 2005, 02:27
I just found this forum a couple of days ago so I'm a newbee here.

I have a sweet '83 XL Ironhead that runs real strong and starts first time every time. She smokes a little but only when you first start up cold until she gets good and warm. All stock except for the S&S and pipes.

I usually do all my own wrenching but I've got a problem that I can't seem to fix so I took it in and let somebody else time it, adjust the valves, tune it and adjust the S&S. New battery new coil new plugs new generator brushes new regulator. Same problem.

My spark plugs only last 200 miles maximum. I can always tell when the plugs are going to give out. I'm riding along and she will go from running smooth and strong to a quick loss of power then back fire a couple of times and stall out. All within seconds. Once this happens there is no way she will start again until I put new plugs in - then she runs like brand new again for another 200 miles.

I've tried to clean the plugs after this happens and no matter how clean I get them she won't start on that set of plugs again.

Both plugs look exactly the same when I pull them. Burnt and glazed not wet and no powder - just a hard black and brown glaze.

I've used Harley plugs, AutoLite and Champion. No difference.

The HD mechanics I've talked to around here don't know much about Ironheads and not really interested in them.

Any ideas would really be appreciated. Thanks.


8th June 2005, 02:42

Wile I ride a EVO modle, I do know a thing or two about tuning. From what you have described, it sounds like you are getting a hard glaze build-up, usualy this is a product of poor gas and too much tempature. It could also be from oil getting in the cylnder.

Ok, lets hit the basics, since you had a shop tune it, I will ASSUME they did a good job and set the mixture right, I think the first step I would do would be a leak down test to see if I had bad rings. If it passes, then you may only need to have the valves done to stop the oil burning.
What type of gas are you using? Premium I am sure, but who's? I like to run Chevron. 76 or mobil If that is all I can get, and try to avoid the rest.
Don't use additives, except rocket fuel,(Octane booster) if you get bad gas, better to add this then burn a piston.
I think what you will find is you may need to overhaul the engine, but test first.

8th June 2005, 02:43
BTW, you have a very nice bike.

8th June 2005, 06:34
Sorry i cannot offer further help with your problem. However, i can say "Welcome". I love it whenever another ironhead guy finds us. Seems to happen every week. Great lookin' ride ya got there too.

8th June 2005, 15:53
Sounds like good advice to me. Hope you can get this resolved. I agree-ya got a nice ride Brother! Please keep us posted as to how this problem goes for ya. I always learn new things at this great place. Jump in any time and "post" away. Ride Safe Bro` :smoke

8th June 2005, 16:54
Jeffytune - I use premium gas only and stick with Mobil and Chevron brands. I think the bike is running hot and even hotter since the tune up.
As for rings and valves I can check them out. She smokes when cold but I think that's a Ironhead trait. I never have to add oil between changes. Thanks for your input.

IronMick - I've had this bike for 12 years and will probably never sell it. I like it because it's a generation before the "I gotta have a Harley because it's the in thing to do" took hold in the market place.
I took the picture this weekend after a ride.

My dad was a HD rider and took me for my first ride on my 2nd birthday. Wow, what a ride!
Thanks for the welcome!

Bikerdude - I'll give an update as soon as I find something out. I get lazy because I'd rather ride than wrench. :D She runs so strong and if I just change the plugs every 200 miles or just before then, I don't have a problem. But I do want to find out what the problem is. I'm thinking it's running too hot - that's a start.

8th June 2005, 17:16
Perhaps it's running a bit lean and burning the plugs. That would account for the "running hot" as well.

8th June 2005, 18:36
I'll give an update as soon as I find something out. I get lazy because I'd rather ride than wrench. :D She runs so strong and if I just change the plugs every 200 miles or just before then, I don't have a problem.

i wouldn't wait too long, she may run strong now, but ignoring a problem only insures that it will get worse before it gets better.... good luck.