clanging engine noise after warmup

[trbig]

I'd do a compression check. Backfiring isn't a good sign. These bikes running on 3 cylinders is still pretty smooth, so you might not notice if one isn't working. If the bike sat, it could have rusted the rings to the walls.. then when cranked, broke a ring, messed up a rod or pin, smashed the top of the piston down onto the compression ring.. Lots of stuff.

The good news is.. .with that few of miles on it, it's going to be pretty salvageable even in a worst case scenario.


Tod

[dbeardslee]

With the stock cam chain tensioner, you can set the adjustment right on the money, and then do a hard decel and a lot of times that will push the tensioner back out. They do tend to be kind of noisy on top, and particularly when the tensioner wants some attention. Tech tips tells you how to do the adjustment.

The other thing that can cause them to make all kinds of strange noises, including backfiring, is badly out-of-sync carbs.

On the pictures, you need to setup an account on photobucket (or similar service), and then link to the picture using the picture icon (funny two-mountain looking thing). I think there's a tech tip on that too, but I can't remember where it is.

[CatatonicBug]

One thing that I seem to remember having heard is that 10w40 is not thick enough. I use 20w50 Castrol MC oil that I get from Kragen/O'Rielly auto parts (get my filters there too). Using the thinner oil can cause a lot of extra noise, especially once it warms up and thins out.

One problem with that though is in cooler climates, 20W50 can get a bit TOO thick, especially overnight, when the temps are below 40F. Makes it tough to start in the morning. I plan to swap out my 20W50 for 10W30 or something close to it in the next couple of months, as the temps drop. I ride though the winter, so being able to start in the morning is important.

[Larrym]

Stubborn Mule

When I first got my "low mileage" bike it had a "clang" also. Present at warm-up and still going on afterwards. The motor would "kick" like mule intermittently and backfire out the left side of the pipes. I mean a real kick where the whole engine would shudder as if it were trying to run backwards or something. The sound was sort of like a "diesel" piston noise. This didn't happen every time like it was a mechanical failure happening every time the cylinder rotated. It was unpredictable and even random. This was accompanied by the fact that the #1 cylinder exhaust pipe didn't get as warm as the other three. (Misting the pipes with a water spray bottle revealed this...)

I swapped the carbs out with a test bank and the problem remained. It was then that I pulled off the #1 spark plug cap from the end of the high tension lead and found that it was all corroded and green at the end going into the high tension wire. It also appeared that the cap had never been truly screwed into the wire but rather had just been pushed on just enough to make it not fall out. I cleaned up the corrosion, cut 1/4 inch off the end of the wire and reinstalled the plug cap. Problem was solved and the motor ran like it was supposed to with out any "clanging". I swapped the original carbs back and synched them up with out even having to adjust the float levels. (they were all Right where they should have been...)

Oddly enough this simple problem had been the reason the former PO's had bailed on the bike and why the mileage was so low. They kept taking it to a repair shop where the techs kept going in and out of the fuel system/carbs/valve train. Each owner forked over his share of $$$ but gave up after the repair bills met or exceeded the price they paid for the bike in the first place.

Just look at #3 and #4 spark plug caps if this sounds familiar....

[jeffnew29]

low oil level

Just so you know....on the XJ the oil light is not a oil pressure light but rather a low oil level light.
Does the noise change if under load or coasting or only noisy at certain RPM?

No the sound is always there. Diesel like clanging sound. Only put in 3 quarts, oil light off, and level between marks on window,,center stand. Used 10-40w Yamalube but worried now that may not be reaching the valve train

With the valve cover off, could you see oil pumping up to the valve train when engine cranked?

[jeffnew29]

When I first got my "low mileage" bike it had a "clang" also. Present at warm-up and still going on afterwards. The motor would "kick" like mule intermittently and backfire out the left side of the pipes. I mean a real kick where the whole engine would shudder as if it were trying to run backwards or something. The sound was sort of like a "diesel" piston noise. This didn't happen every time like it was a mechanical failure happening every time the cylinder rotated. It was unpredictable and even random. This was accompanied by the fact that the #1 cylinder exhaust pipe didn't get as warm as the other three. (Misting the pipes with a water spray bottle revealed this...)

I swapped the carbs out with a test bank and the problem remained. It was then that I pulled off the #1 spark plug cap from the end of the high tension lead and found that it was all corroded and green at the end going into the high tension wire. It also appeared that the cap had never been truly screwed into the wire but rather had just been pushed on just enough to make it not fall out. I cleaned up the corrosion, cut 1/4 inch off the end of the wire and reinstalled the plug cap. Problem was solved and the motor ran like it was supposed to with out any "clanging". I swapped the original carbs back and synched them up with out even having to adjust the float levels. (they were all Right where they should have been...)

Oddly enough this simple problem had been the reason the former PO's had bailed on the bike and why the mileage was so low. They kept taking it to a repair shop where the techs kept going in and out of the fuel system/carbs/valve train. Each owner forked over his share of $$$ but gave up after the repair bills met or exceeded the price they paid for the bike in the first place.

Just look at #3 and #4 spark plug caps if this sounds familiar....

Never thought it could be ignition,,what an interesting idea. The bike does run poorly, Do I need to pull the tank to check?

[Larrym]

You don't have to pull the tank to check the spark plug caps. Just pull the caps off the spark plugs and then unscrew the caps CCW from the black wires. There are resistance checks you can do but Mine checked out OK within the readings I was supposed to get. It was only after I physically unscrewed the spark plug cap that I saw the corrosion which was causing my ignition system to misbehave.

Remember that my symptoms were that the engine kicked/clanged HARD but only randomly...not at every rotation of the piston. The cylinder fired correctly sometimes and sometimes not. From what I gather your clanging "sound" is always present and just gets louder.

Still...looking at the spark plug cap-to-spark plug wire is an easy visual check and reattaching the ends isn't a big deal.

[cruiser]

Oil level between marks is ok but I prefer to fill on center stand to top mark which is about 3.7. The more oil within the marks the cooler the oil will run.
I run 20-50.
Never tried cranking with valve cover off to check for oil flow but certainly should work. Would caution if you try that to limit cranking time to avoid starter problems. Maybe 15-20sec at most. Allow cool down time between.

[cywelchjr]

Oil level between marks is ok but I prefer to fill on center stand to top mark which is about 3.7. The more oil within the marks the cooler the oil will run.
I run 20-50.
Never tried cranking with valve cover off to check for oil flow but certainly should work. Would caution if you try that to limit cranking time to avoid starter problems. Maybe 15-20sec at most. Allow cool down time between.

While that point is indeed correct, I have seen in many Yamaha related forums that filling to the full mark can tend to have the oil hit the bottom of the crank causing additional resistance to rotation which lowers mileage. I don't know if it's true on these motors, but on my 400 if I keep it at the middle or below I get better gas mileage, and this has been reported by some other riders as well. I try to run my 1100 in the middle between the lines, so I can't say if running it to the top makes any difference on these bikes or not.

[jeffnew29]

Engine Knock?

Wonder if the noise is engine knock from carbon buildup. Sort of sounds like a diesel. Spark plugs are totallyy carbon fouled.

[jeffnew29]

Thanks Larry

Wires were ok and also checked the timing. Looked ok.Guess there is no adjustment fior this,,timing?