loud knocking after 4-5 miles
Thread Starter
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6th Gear
Joined: Jul 2007
Posts: 10
Likes: 0
loud knocking after 4-5 miles
I have a 1981 FLH with the 1340 shovel on it that I am about to strap a bomb too. I have been working on this thing off and on for about 6 months now. I can crank the bike when cold it runs great sounds great, let it warm up and take off up the road on it and 4-6 miles into the journey it will start this god awful banging, every now and then it will quit for a second or two then come right back. so i turn around go back to the house of course now its running like ****, sputtering and not really wanting to take the gas. get to the house cut it off let it set for a minute or two fire it back up and it runs fine for a minute or two then starts that god awful racket again. heres a list of what I have done to try and find this thing:
heads and rocker boxes rebuilt
adjusted the lifters a million times in a million different ways
new plugs with different heat ranges 4 times
new rings
new coil
new wires
timing is set to factory specs
new lifters
carb was rebuilt too
Have checked the cam and it and bearings look good and are nice and tight
if you heard this thing you would swear the crank or one of the rods was getting ready to take a **** on me, but this thing comes and goes and I wouldnt think that a rod or crank would come and go would it???
I think it is coming from the back cylinder rocker box but everything looks normal in there. any help would be greatly appreciated and if your aroundspartanburg sc or charlotte nc drop by have a beer and tell me what the hell to do. thanks ahead of time
heads and rocker boxes rebuilt
adjusted the lifters a million times in a million different ways
new plugs with different heat ranges 4 times
new rings
new coil
new wires
timing is set to factory specs
new lifters
carb was rebuilt too
Have checked the cam and it and bearings look good and are nice and tight
if you heard this thing you would swear the crank or one of the rods was getting ready to take a **** on me, but this thing comes and goes and I wouldnt think that a rod or crank would come and go would it???
I think it is coming from the back cylinder rocker box but everything looks normal in there. any help would be greatly appreciated and if your aroundspartanburg sc or charlotte nc drop by have a beer and tell me what the hell to do. thanks ahead of time
Stellar HDF Member
Joined: Dec 2006
Posts: 2,906
Likes: 11
From: Grottoes Va.
RE: loud knocking after 4-5 miles
have you got the right grade oil filter? sounds silly, but i read on here somewhere about a too fine of a filter would cause problems similar ti yours, knocking, running like poop. after the scoot sat for a few minutes, would run ok till the oil filter slowed it down again. something about oil sumping or something like that. I'm no wrench so take it for what it's worth.
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Seasoned HDF Member
Joined: Jan 2007
Posts: 20,616
Likes: 4,440
From: anacoco, la
RE: loud knocking after 4-5 miles
are you running straight weight oil? i've heard that on the older bikes, multi-grade viscosity oils tend to be too thin and allow the lifters to bleed down.
just thinking
just thinking
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Joined: Aug 2006
Posts: 60
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RE: loud knocking after 4-5 miles
Is it an engine knock orignition knock? One other possibility is vapor lock in the fuel system which will cause the engine to start skipping or cause it to stall as fule is not entering the carb. If this is possible check the fuel line routing to see if they are too close to the exhoust, heads, etc.
Thread Starter
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6th Gear
Joined: Jul 2007
Posts: 10
Likes: 0
RE: loud knocking after 4-5 miles
16000 miles on the bottom end. everything in the bottom end was in check according to this old *** harley manual. when I listen to it with a scope it sounds like its coming from the back rocker box. i am running 20 50 in it now. i will have to check what kind of filter that is on it in the morning. I am thinking and from the way it sounds it is a metal on metal knock of some sorts. I am about ready to strap on a bomb and shoot at it until it blows up. I have just never heard of a rod knock doing like this but I am a old mopar and chevy man so who knows?
thanks for all the help guys......if i ever get it fixed i am writing a book lol
thanks for all the help guys......if i ever get it fixed i am writing a book lol