Engine noise - loose valves or loose rods? - analysis needed

[JP50515]

Hey guys so i've had an engine noise going on for a while now that i'm curious about. So the story goes, I rebuilt my 77's, 447 engine last summer, replacing piston rings, pin cir-clips (with original wrist pins), valve seals, cam guard and chain, and all gaskets and seals. Since then my bikes engine has been broken in but not much beyond that. Only got about 1 month of riding it in before it got cold last year.

My issue now is this, I adjusted the valves, the cam chain, and timing to spec at the end of last season....however after riding a bit i could hear what sounded like valve noise again. So... I opened it up and found the valves had come loose after only a day or so of riding, i chalked it up to a poor adjustment and readjusted them back into spec.

At this point I thought the noise was gone, however it was not. The noise only appeared after the bike had been properly warmed up and driven for some time which heads me in the direction of the rods. I made a note to adjust the valves when summarizing and stored it.

I started it for the first time this year last week and went for a 30 minute ride. Ride went smoothly, bike started first kick with the choke and had no other issues, however at about 20 minutes into it, the noise reappeared.

I have not yet checked the valve clearances this year, but am hoping they are loose again. If this is the case I will be replacing the tappets, under the assumption that they are probably worn out after 30 years.

However....if they are not loose.....is there a way I can check the rods without another overhaul? maybe through the sump hole?

The fact that it only makes this noise once the engine warms up is what concerns me....if the threads were going bad on the tappets I would assume heat would only cause them to snug up a bit...not get loose....yet they did just that last time.

I should also mention a rhythmic droning that also exists, upon fully warming up the engine. It can be heard through both the engine noise and the exhaust when standing farther then 5 feet away, but when i hold my hand to the end of the mufflers they are firing in synchronicity. If i come closer than five feet to the bike, its presence exists more through engine noise than the exhaust. It's like a deep waaahhhhh..............waaaaahhhhhhh.............waaaahhhhhhh........that cycles about ever two seconds. However it is not a prominently loud noise...it sounds deep within the engine if that makes sense.

What I know:

Cam chain is adjusted properly (i can hear that its not too loose) and adjuster pin moves within spec.

Ignition is timed properly. Verified with timing gun.

Starts first kick and runs fine with no popping or backfire so I assume the carbs must be in a good place but did have previous float height issues.


What I want to know:

Cause of "valve" like noise.

Source and cause of drone.



Any ideas or experience with this issue would be greatly appreciated.


I have a video that I will try to post a youtube link to once I get it uploaded.

Thank You.

 

[JP50515]

Alright here are the links to a couple videos:


This is prior to the very first valve adjustment mentioned. It sounds quite obviously like loose valves in this video and it was.

Now here is the bike....and i'm kicking myself for not being able to remember, but it was either after the first ride out....or before the second one the next day.... (last weekend). It could very well be a video of the bike before it was warmed up and driven.....my gut tells me it is...but this regardless this is what it sounds like before riding it....its not as severe as the first video but a similar noise after its been ridden for a while.

(I just uploaded these to youtube so they may not be available to the public yet! If thats the case and you are inclined to help, please check back between 30-60 minutes from now)


You cannot hear the droning in either video. It is hard to capture its audio.

Thank You!

 

[JP50515]

I hate to bug anyone, however if someone has an idea it would be greatly appreciated. Tomorrow is the only day this week i'll be able to work on the bike and I am wondering if I should be starting to tear it all down again to get the engine out or not. Wanna get this thing done before mid april if that's the case.

Thanks Guys

 

[jay760]

Difficult to say from the video's, worth checking the valve gaps , could be the front cam chain guide gone, or I have known the cam chain adjuster to be tapping against the outer dome nut.

 

[hotdog]

Check your valve clearances & make sure the dampner washer is installed on you cam chain tensioner assembly.

 

[JP50515]

Does anyone know if you can check the rods through the sump filterhole?

 

[hotdog]

If your hellbent on checking your rods, then drop the sump trapdoor & have a look. Personally I would be checking that everything is tuned & in spec first.

 

[EvenmoreXS]

Check your valve clearances & make sure the dampner washer is installed on you cam chain tensioner assembly.

That Dampner from Mikesxs does help. I had a similar problem. Got better once I put in the rubberized damper. Still a touch of engine noise, but consider all the activity going on inside an engine. Gonna have some noise just because. Id replace that dampner first and see how that helps. Cheap and quick and it removes one possibility.

Good Luck. You'll get it.

 

[ClOckwOrk]

Mine sounds like your first vid.....but after proper valve adjustment. Turned 20k and I assume my cam chain tensioner and guide are botched up

Posted via Mobile

 

[5twins]

Keep in mind that these aren't going to be as mechanically quiet as a newer, more modern motor. The trick is knowing what noises are supposed to be there and which ones are not. Have you tried the old screwdriver trick to try and isolate where the sound is coming from (screwdriver handle against your ear, blade pressed against various locations on the motor)? HF also sells an engine stethoscope for a few dollars that works quite well.

 

[JP50515]

Thanks guys, I'll check out that dampener. And yes I did "scope" with a driver before I stored it, so I'll have to get it out next week and ride it for a while and then try to isolate the sound again. I am going to do the holy trifecta of valves, chain, timing once more here and try a little locktite on the tappets...not sure if it will actually do anything in that kind of extreme heat but we'll see. I know its not the chain because i can hear the chain and it sounds like it should but it very well could be the dampener....would that only make noise when heated up though? Someone told me it may be bottom end main bearing noise........i hope not....lol

 

[EvenmoreXS]

Thanks guys, I'll check out that dampener. And yes I did "scope" with a driver before I stored it, so I'll have to get it out next week and ride it for a while and then try to isolate the sound again. I am going to do the holy trifecta of valves, chain, timing once more here and try a little locktite on the tappets...not sure if it will actually do anything in that kind of extreme heat but we'll see. I know its not the chain because i can hear the chain and it sounds like it should but it very well could be the dampener....would that only make noise when heated up though? Someone told me it may be bottom end main bearing noise........i hope not....lol

+ 1 on the HF stethoscope. Better sound than a screwdriver and only 4 bucks.

+1 on the engine sounds. Could be something, could be just operating noise. Be both vigilant and patient. You will get it.

-1 on the Main bearing. I hope its not that too. Its a real possibility,

Keep it simple, start at the beginning, and don't just throw money at it.

Id replace that damper first.

 

[XSLeo]

On the cam chain tensioner I like to get the engine warmed up, not hot but warmed up well. Now with it idling I adjust the tension so the plunger comes out flush with the end of the adjuster. It should also move in and out about 1-2 mm. If it moves more than 1-2 mm it is too loose, if less than 1-2 mm it's to tight.
You can adjust it in and out a bit and listen, you will hear when it's right.
You say you rebuilt the engine. You say you put in a new cam gaurd and chain. I assume you mean front cam chain guide, since there is no cam guard.
If so then you should be able to get a good adjustment on the tensioner.
You shouldn't need any lock tight on the valve adjusters, just torque the lock nut to 10-18 ft/lbs.
The only way to check for wear on the rods to pull the top end of and check clearances as described in the repair manual.
On the damper, there are different styles used depending on the year. On this chart you see your should be a type D. Looking in the parts fiches at boats.net for the part number. The one Mike's sells references the same part numberand should be the one you want. Some years used a copper washer.
Leo

 

[JP50515]

Hey thanks for the info. And yes I did mean the front cam chain guide. guard...guide.....brain fart lol. I will check and make sure that washer is even in there. It very well may have been misplaced and never made it back in during the rebuild...however if that is the case I know right where it would be. So that's a plus I guess.

 

[EvenmoreXS]

Hey thanks for the info. And yes I did mean the front cam chain guide. guard...guide.....brain fart lol. I will check and make sure that washer is even in there. It very well may have been misplaced and never made it back in during the rebuild...however if that is the case I know right where it would be. So that's a plus I guess.

Mine didn't have one at all.

 

[5twins]

A few things to consider here when talking cam chain adjusters. First, your '77 probably has the type D adjuster set-up that used the acorn cover nut as the lock nut for the adjustment. There is no separate lock nut for the adjuster screw as on earlier and later versions. I feel this set-up is flawed. There's no way to tell if the final tightening of the acorn nut is changing your adjustment setting. You could very well be tightening the adjuster screw more along with the acorn nut. I think Yamaha realized the "error in their ways" with this type D adjuster and returned to using a lock nut on the next type E set-up.

Your D type would use a copper washer. You can remove the screw/plunger/spring assembly as a unit to check .....

The newer style rubber/metal damper washer is thicker than the copper one so can present some minor problems when installing it on an older tensioner assembly. The plunger end will no longer come out flush with the adjuster screw end when properly set, it will be inset some. You can make it flush if you crank the adjuster screw way in but then you have no plunger movement and your cam chain is way too tight. You can plainly see the obvious differences in the various tensioner assemblies in the pic above. What you can't see are the minor changes, slight differences in plunger and maybe adjuster screw length, that Yamaha made to accommodate the different damper washer thicknesses.

So, what should you do? Well, the solution may be as close as your '81 project bike. That should have the later E type adjuster with a separate lock nut. It should also have the later screw/plunger/spring designed to use the thicker rubber/metal damper washer. You can swap that entire assembly along with the separate lock nut onto the '77. No need to swap housings, it will screw right into the '77 one.

 

[JP50515]

5twins, That is exactly the scenario in terms of what dampeners are on the bikes. And I have often wondered if I am overtightening when I lock down the acorn...in fact I learned that I was. I will first pull out the D type and check to make sure that washer is present, and if not try it with a new washer. If that doesn't solve the problem (after a valve adjustment) I will try swapping units completely.

Now 5twins, here's a question you may be able to answer. If this were the issue...a missing washer on the dampener.....why would it only become noticeable after the bike has been thoroughly warmed up?

 

[JP50515]

*edit* Re wrote above post.

 

[5twins]

Your oil when cold may be thick enough to deaden the sound. When it gets hot and thin, the noise level goes up. That would be my best guess. That's why I stopped using that 15w-40 diesel oil and went back to 20w-50. The top end made lots more noise with that 40wt.

 

[EvenmoreXS]

I think locating the source is the first thing. "Why" would be next. The dampner just seems super easy, cheap, and fast to rule out first. Process of elimination type thing.

As for a leap off a cliff.......maybe......and Im like Forrest Gump smart here, ......cold oil seems thicker that warm oil. Maybe when it warms up there is a little less coverage.

Im reaching for straws here.