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REAR CYCLINDER SPARK PLUG CARBON BUILDUP

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Old Sep 19, 2024 | 09:06 AM
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gator91384's Avatar
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Default REAR CYCLINDER SPARK PLUG CARBON BUILDUP

My '02 Fatboy starting running rough and on idle engine quit. It would start back up but felt like it was running on one cylinder. Removed the plugs and the rear was black with carbon build up. Front plug was fine. Air Filter was very dirty. Installed new plug and kept filter off and started up and engine still felt like it was running on 1 cylinder. Pulled rear plug and it those few secs of running carbon was starting to build up. I had spark and wires with volt meter and wires were fine. It has all the symptoms of fuel injection issue but pulled the injectors, tested with volt meter and both between 15.8-16.1 ohms. Cleaned injectors and did not notice any issues with the flow on both injections so I don't think that was the issue. Was thinking it might be a dirty fuel filter but I suspect both plugs would read the same, not just the rear. Any suggestions before I pull the fuel pump and filter?
 
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Old Sep 21, 2024 | 04:26 PM
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From: poway
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Swap injectors.
 
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Old Sep 23, 2024 | 11:13 PM
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Did you clean the rear plug or replace it?....I never clean plugs on Harleys, just replace because once fouled they never come right again.
 
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Old Oct 14, 2024 | 07:19 PM
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Default Intake valve leak

I think I may have found the issue. Did a leak down test on both cylinders. Rear cylinder leaking from intake valve. I was looking through the paperwork the former owner gave me and it looks like he put in a screaming eagle 257 cam which is a race cam and I am wondering if he put in the proper valve springs when he did the build, HD calls for their SE race valve springs when using that cam. Going to pull the heads this weekend and see what is up.
 
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Old Oct 14, 2024 | 08:55 PM
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From: poway
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Hopefully you find more than bent valve, like 10.5 to 1 pistons.. Valve springs and cut guides.

Stock 02 TC88 heads might be able to handle over 0.510 lift but it's pretty iffy..
 
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