I have a 92 FXR with a mild build evo it is fairly fresh well about a month ago it started knocking like a rod knock, I dont have the Money to pull her apart so its been sitting I dumped the 50wt oil ran some 10-40 thru her, and the sound was the same, I finally snapped and said scew it blow it up...changed to 10-50 castrol ran her half hard about 30 miles, She kicked out a screech at about 10 miles and I figured that was that(During this whole mess no loss of power was noted)I then ran her another 10 miles and bingo no knock no nothing, I am blowing a bit of blue smoke at idle....Maybe a stuck lifter??? or rings are now toast??? Funny thing this bike just plain rips and hauls ***...ANY IDEAS!!!!

 

Something got loose in the chamber it sounds like. Could be anything from the beginning of the intake area (some fastener sucked in)to rings or valves. Top edge of the piston where the ring grove is could havecracked off. Finally speat it out sounds like. Probable didn't help the inside of the chamber or valves rattling around in there. Valves are probably nicked some, top of piston dented at least. But good news is sounds like this, AT THIS TIME, it can can be fixed, just top end. More that likely, and this is just my thoughts, you keep running, and the engine will need a complete overhaul. May distroy itself.

 

I have seen this from carbon knock, spray some water in the air cleaner and let the steam blow the carbon out the exhaust, noise goes away. Do a leak down and compression test to see if it is hurt. Probably just carboned up and worn out.

 

Ouch Rebuild? I was thinking lifter stuck...I fired her up today no sound runs great but it does seem to blow a bit of smoke after hot....Rings may be the deal as you say, Oil pressure and compression are good, plugs look a bit dark but much....I don't have the funds right now to pull her apart if the rings are worn won't the compression go down? I will say it runs very strong but I am worried as I don't know who did the actual rebuild....and will not get a straight answer form the seller I'm sure

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Not rebuild now. May be something, if it is something, limited tojust top end in one cylinder now.
If as King said carbon knock things are OK. If there is a problem it is probably limited to one cylinder now. If the spark plugsare OK may be just carbon. Anything loose would have hurt the spark plug at least enough to notice.
I would stink with 20-50 oil though.
Good Luck with this.

 

I pulled the plugs after a long idle, they look a bit dark but are not coated in oil, I smell very little fuel, It has a big cam and adjustible push rods do you think one could have been moving around or maybe no oil? Its funny it always blew a bit of oil but runs almost as strong as my last S&S motor, she really does move along, I will flush the oil again and go back to Harley oil not the 50wt only though, I am turning 50 tomorrow and my Harley neighbor just said the Harley Gods just did you a favor! Lets hope, I have been off it for a month other than around the block and I really miss this thing....

 

Well I think you may be right, The bike runs good but its smoking a bit at idle when warm, I think rings....So I have a manual how hard is it for the average Joe to pull this motor and do the rings, I have only rebuilt 2 strokes.....

 

You mentioned that compression is 'OK', do both cyls have similar ccp?A careful leakdown test would giveyou more info before you start tearing it down.

VicW.