Engine knocks after oil change '85 GS550L

[Guest]

Hi all,

New to this forum and motorcycles in general. Bought my first bike about 2 months ago, a 1985 GS550L, mostly on a whim. I love it, and ride it as much as possible.

On Friday, I was riding and all sounded normal. I gave the bike its first oil change on Monday. Used the filter the shop down the street sold me and 3.3 quarts of Castrol 20W-50 (non synthetic). Ran the bike for a minute, checked the levels, and it all looked good. The oil is a little high, but I can still see the top level in the window.

Rode it into town, and then I started noticing a knock in the engine. This is definitely a new sound that wasn't there last week. Over the last couple of days, I've figured out the pattern. The engine has to be warmed up, and at idle. I don't hear the knock early in the ride or if the engine is running over about 1200 RPM. Of course I can't hear anything at speed, but if I rev the engine at a stoplight, I don't hear the knock; it's only at idle. It's a very regular knock, about 3-4 per second.

I called up the guy I bought it from and asked what oil he used; he said he never changed it. He bought it from another gentleman before he sold it to me, and said he never got a chance to even change the oil before I bought it.

I've heard that going from synthetic to non, or vise-versa can cause some issues, although I haven't seen specifically what they are. I've also heard that running low octane fuel can cause issues, so I've been running premium for about a month. So, I really don't know what could have caused this, but there's no doubt in my mind that my oil change caused it. Any ideas from the community?

[Steve]

First of all, Welcome.

Now, let's address your questions.

Bought my first bike about 2 months ago, a 1985 GS550L, mostly on a whim.

Nice little bike, but you will catch some flak from some of the "L" haters. Ignore them.

On Friday, I was riding and all sounded normal. I gave the bike its first oil change on Monday. Used the filter the shop down the street sold me and 3.3 quarts of Castrol 20W-50 (non synthetic).

Why such thick oil? 10w-40 will be sufficient for all uses except racing across Death Valley. The thinner oil will flow easier through all the small passages, actually giving you better protection in most cases.

Rode it into town, and then I started noticing a knock in the engine. This is definitely a new sound that wasn't there last week. Over the last couple of days, I've figured out the pattern. The engine has to be warmed up, and at idle. I don't hear the knock early in the ride or if the engine is running over about 1200 RPM. Of course I can't hear anything at speed, but if I rev the engine at a stoplight, I don't hear the knock; it's only at idle. It's a very regular knock, about 3-4 per second.

Sounds like what many of us call "cam walk". Once you verify that is what it is, you can ignore it. My wife's bike had that sound when we bought it 7 years ago, it still has it, 25,000 miles later. It's no better, but it's no worse, either.

I called up the guy I bought it from and asked what oil he used; he said he never changed it.

How long did he have the bike, or how much did he ride it?

I've heard that going from synthetic to non, or vise-versa can cause some issues, although I haven't seen specifically what they are.

Oil discussions can get rather heated at times, but switching to or from synthetic is no more involved than opening a different bottle and pouring it in. No problems going either way.

I've also heard that running low octane fuel can cause issues, so I've been running premium for about a month.

Fuel discussions can also get heated at times, but, basically speaking, you have probably been wasting your money for about a month. The bike is designed to run on "regular" gas. Running "premium" (the only thing "premium" about it is the price) can actually hurt the engine at times.

So, I really don't know what could have caused this, but there's no doubt in my mind that my oil change caused it. Any ideas from the community?

Yes, the oil change probably "caused" it, but only because it has fresh oil and is able to move around and "do its thing".

By the way, these engines are not quiet, you will get used to the noises it makes.

.

[volvo64]

Nice little bike, but you will catch some flak from some of the "L" haters. Ignore them.

What's wrong with the L's?

Why such thick oil?

I read a lot of discussion about which oil to use, and had decided on Rotella-T semi-synthetic 5W-40. Then I bought the oil filter from a bike shop, started talking to the guy who ran it, and he said he's been using 20W-50 on every bike that came through for the last 20 years. So I listened to the guy who sounded like an authority on the subject.

Sounds like what many of us call "cam walk". Once you verify that is what it is, you can ignore it.

How can I verify that? I've always been slightly mechanically minded, but my profession is IT, so I get no exposure past what I do in my own garage.

How long did he have the bike, or how much did he ride it?

He only had it for a few weeks or less, I believe. He bought it from a guy, presumably just to resell it. I think I bought it before he had a chance to really do much to it.

Oil discussions can get rather heated at times, but switching to or from synthetic is no more involved than opening a different bottle and pouring it in. No problems going either way.

That's reassuring.

The bike is designed to run on "regular" gas.

I'll go back to regular for a while and see what happens.

[hampshirehog]

Could also be the clutch making that noise. Loads of them do it - a carb balance can help.

[volvo64]

Could also be the clutch making that noise. Loads of them do it - a carb balance can help.

But would the oil change bring that on? There's no doubt in my mind that the oil change did something to trigger this knock.

I can feel the knock in my handlebars and on my gearshift. I just took it out for a spin to check how the clutch played in: it knocks in gear and in neutral, and with the clutch engaged and disengaged.

Is this a reasonable guide to carb syncing? http://www.motorcyclistonline.com/ho...cle_carb_sync/
That's not to say that I'll do it, cuz I'm pretty inexperienced and a bit afraid of taking my bike apart and never getting it running again, but I'm willing to read up on the process and think about doing it myself.

[hampshirehog]

If pulling the clutch lever in doesn't alter the noise it's not the clutch. If you can feel it through your bars it sounds serious. Can you put a video on Youtube? That might give us a better clue of what noise you are talking about.

[Nessism]

http://members.dslextreme.com/users/bikecliff/

Tons of good info here, including a carb sync tutorial.

Rotella diesel oil is a forum favorite. Auto oil doesn't have as much zinc and phosphorus.

[Steel Toed Tank]

A carb sync with a carbtune will only do good things for your bike. I would recommend it.
But I am unsure if that is the problem you are experiencing.
One thing to check may be valve clearance, but I have only done mine once and have not had any knocking issues to deal with so I can't help much more than that.


Tank

[Roger P.]

Overfilled? Cam chain jumped a tooth due to stuck adjuster? Dead cylinder?

[volvo64]

OK, first things first. I'm going to buy a new filter on Monday and a gallon of Rotella T6 and replace the 20W-50 I put in there.

To be clear, this is the stuff that's widely recommended, right? http://shop.advanceautoparts.com/web...T%7CGRP2046___

[earlfor]

But would the oil change bring that on? There's no doubt in my mind that the oil change did something to trigger this knock.

I can feel the knock in my handlebars and on my gearshift. I just took it out for a spin to check how the clutch played in: it knocks in gear and in neutral, and with the clutch engaged and disengaged.

Is this a reasonable guide to carb syncing? http://www.motorcyclistonline.com/ho...cle_carb_sync/
That's not to say that I'll do it, cuz I'm pretty inexperienced and a bit afraid of taking my bike apart and never getting it running again, but I'm willing to read up on the process and think about doing it myself.

I ran Castrol 20w50 for twenty years in all kinds of bikes. It never caused a knock or any other problem. All you did was change the oil, so I only see two possibilities. You installed the oil filter backwards or you put too much oil in it. Oil to the top of the window is overfilled. the full line is the center of the window to slightly above. I think your problem has to be one of those two things.

[volvo64]

You installed the oil filter backwards

I think that's it. I looked up the fiche (http://images.powersportsnetwork.com...les/2114_6.gif) and I'm pretty sure I installed the filter with the open end backwards. It simply never occurred to me that it cold go the other way around...

I feel kinda silly now. I'm going to pick up a spare filter tomorrow then open it up and turn it around. Hopefully that'll take care of it.

[earlfor]

I think that's it. I looked up the fiche (http://images.powersportsnetwork.com...les/2114_6.gif) and I'm pretty sure I installed the filter with the open end backwards. It simply never occurred to me that it cold go the other way around...

I feel kinda silly now. I'm going to pick up a spare filter tomorrow then open it up and turn it around. Hopefully that'll take care of it.

If you did install the oil filter backwards, then the only oil flow you have through the engine is through the bypass port, so you are getting minimal oil flow (which is not good) and the knocking you're hearing is likely because the top end is not getting enough oil.

[volvo64]

OK. So I picked up a new filter and a gallon of 10w40 motorcycle oil today, which is recommended for my bike and did a complete oil change. Turns out I had the filter installed correctly all along, it's just that the fiche is a bit confusing. Changed the oil, took it for a spin, still knocks. Now it dies when I slow down too, which I'm willing to chalk up to my idle still needing adjusted, which is an ongoing thing. I guess I'll have to check out the valves/carb/chains etc after all...

[earlfor]

OK. So I picked up a new filter and a gallon of 10w40 motorcycle oil today, which is recommended for my bike and did a complete oil change. Turns out I had the filter installed correctly all along, it's just that the fiche is a bit confusing. Changed the oil, took it for a spin, still knocks. Now it dies when I slow down too, which I'm willing to chalk up to my idle still needing adjusted, which is an ongoing thing. I guess I'll have to check out the valves/carb/chains etc after all...

Where on the engine is the knock the loudest? Where are you?