If in fact -- if --- you have 30psi on the rear cylinder and a fubared oily plug, it's possible you holed a piston and the running away was the front cylinder sucking in gutsfulls of oil from the hole in the rear piston via the shared intake manifold. IF your compression reading was really 30psi as you said.
Take a look down the spark plug hole with a flashlight, with the piston at TDC and see what you can see.

 

Man I hate to point fingers, but I've read through this about four times now. And it just doesn't add up. Either the OP isn't communicating things well. or he did something stupid and ****ed up a buddy's ride and is trying to cover it up.

A diesel motor will run away burning it's own oil for sure, but a gas burning Vtwin running away on one cylinder??? Yeah I know I brought up the term "run away" but the bottom line is that just doesn't happen on gas motors. There has to be throttle input, or a major failing in the throttle body. Gasoline engines don't run on oil.

Also the condition of the plug he says is from the rear cylinder...that has been that way for a while. That didn't happen in a momentary incident such as he describes. That motor would barely run if at all with that plug in that condition. At the very least, it would run poorly enough that you wouldn't have it out on the freeway, and it certainly would not be hitting red line on its own.

There is just way to much conflicting data here to not call bullshit.

 

A 2005 is carbureted. EFI didn't come out on Sportsters until 2007.

But the carb motors also have rev limiters.

The most common cause of what he describes is an issue with the throttle cables, specifically a cable with too much slack in it can cause the end of the cable to jump out of the ferrule and get caught in an open position. It usually happens on the carburetor end. Buell got sued over this a long time ago, when it resulted in a guy getting killed while on a test ride. Some guys safety-wire the things in place. But if the cables are adjusted properly, it really can't happen.

Runaway can also happen if anything occurs that causes unrestricted air flow downstream of the throttle plate.

 

OK. I stand corrected. However, I still call bullshit on THIS particular situation. I still think he either did something stupid and is trying to cover his ***, or is trying to get someone to say the engine is toasted so he can buy it cheap.

 

Well I finally got it taken apart yesterday. Had a buddy with a bore scope come out and he was able to see a bolt in the head. So looks like I'll need a new head, and some push rods for sure.

What happened was a bolt in the air cleaner housing came loose and got sucked into the carb. This is what caused the carb to get stuck open and redline the bike. Then it made its way into the engine and caused chaos.

if anyone has a line on a rear cylinder head w/valves for a 04-06, I'd appreciate it.

Thanks everyone for your input.
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It is not an EFI model. It is a carb model. I remember everything correctly, and that is how it happened.

 

BrokeWinger, thanks for your faith in humanity and being a rude commenter. See my follow up post that explains I didn't do anything to this bike to cause the problem. Why would someone post asking for advice and lie about what happened? Sorry for the typo. it should have read that there IS a difference in compression

 

Hey, I can surely admit it when I am wrong. The situation as described just didn't add up, at least not for me. However, no excuses I was wrong. And I sincerely apologize for both my suspicion and my judgement. I am glad you have it figured out and hope you get it resolved quickly and cheaply.

Looking at that picture, I feel like maybe that head could be saved. Can't see the valve seats.If they aren't torn up... Just trying to save you a few bucks. I can't tell is the bolt just laying there or has been it smashed into the head?

In any case good luck with it.

 

We shined a light through the head and can see that the valves aren't seating properly anymore. The bolt was smashed into the head and I had to pry it out with some vice grips. It bounced around a bit and did some damage around the valves. No hard feelings. Thanks for your input.

 

That sucks, was hoping it was salvageable. For what it's worth this situation has spurred me into buying a couple bore scopes (one wireless and one wired).