84 flhtc knock
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Stage IV
Joined: Oct 2014
Posts: 4
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From: Maine
84 flhtc knock
Morning,
Was wondering if I could brain pick. Ive got an 84 flhtc and while driving home last night it started with a knock that sounds like its rear cylendar, bottom end.
Here what I know about the bike, as I bought it the day before. 40000 miles. Its got two new(er) jugs. I bought it from a dealer who knew nothing about the bike. I paid short change for it, and everything else is in amazing shape.
The knock seems to be in the 2500 RPM range. At an idle it sounds fine, and not under load it sounds fine. Its also blowing burnt oil smoke out the pipe for that cylendar when I rev it up at idle.
I just lost a sportster to oil pump failure and this is the replacement bike. The dealer sold it as is. I knew I was taking a risk (it sounded fine on the test ride and for the first 150 I put on it before this happened) I warmed it up correcty and haven't run it hard for the most part.
Thoughts?
Was wondering if I could brain pick. Ive got an 84 flhtc and while driving home last night it started with a knock that sounds like its rear cylendar, bottom end.
Here what I know about the bike, as I bought it the day before. 40000 miles. Its got two new(er) jugs. I bought it from a dealer who knew nothing about the bike. I paid short change for it, and everything else is in amazing shape.
The knock seems to be in the 2500 RPM range. At an idle it sounds fine, and not under load it sounds fine. Its also blowing burnt oil smoke out the pipe for that cylendar when I rev it up at idle.
I just lost a sportster to oil pump failure and this is the replacement bike. The dealer sold it as is. I knew I was taking a risk (it sounded fine on the test ride and for the first 150 I put on it before this happened) I warmed it up correcty and haven't run it hard for the most part.
Thoughts?
Outstanding HDF Member
Joined: Apr 2012
Posts: 2,938
Likes: 30
From: North Florida
What does that plug look like?
Run a compression test, then check it wet.
Does it run better on premium?
My preliminary guess would be oil carbon fr unseated rings, and getting a detonation knock.
Run a compression test, then check it wet.
Does it run better on premium?
My preliminary guess would be oil carbon fr unseated rings, and getting a detonation knock.
Seasoned HDF Member
Joined: May 2008
Posts: 21,146
Likes: 12,712
From: South Carolina
It`s knocking and smoking.
There is no benefit in guessing what it might be...
The disassembly process is the same no matter what you suspect.
Remove the rear rocker box first, then the front, if nothing is found remove the cam cover, then cylinder heads and jugs.
There is no benefit in guessing what it might be...
The disassembly process is the same no matter what you suspect.
Remove the rear rocker box first, then the front, if nothing is found remove the cam cover, then cylinder heads and jugs.
Club Member
Joined: Mar 2009
Posts: 66,115
Likes: 51,405
From: Niles Canyon Ca.
What color is the smoke whitish or black and is it leaving an oil residue out the rear pipe ? I'd have a compression check run on both then a cylinder leak down test on that rear cylinder. Without hearing it it's hard to say whether it's piston slap or a rod knock, find a good engine guy and have them put an ear to it for you.
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