Hey guys, I've read some threads indicating some noise is fine... and honestly anything is better than the rattle can sounds I heard with the auto tensioner. But I'm wondering if this is normal.

Basically, once my bike is warmed up there is an audible swishing / whirring sound (metal sliding on plastic) that's matched to the RPM of the motor. It's constant and audible through my helmet, even at speed. Seems to get louder as the bike gets hotter.

It's not very evident (or at all) while the bike is cold.

The cam chain tensioner was installed by tightening it as tight as I could get it with my fingers, then tightening the lock nut. The engine was cold when this was done.

Anyone experience something similar?

 

Mark will answer better than me...but in my experience, I installed it and set it per instructions cold like you did. I have a pretty good rock climber/guitarist grip so I used two fingers to tighten and it seemed perfect. The second time was after a shim change, I did the same thing and it was perfect.
I'm getting there...
The third time was another shim change, but that time I experimented with it while running (after setting it like normal). First I loosened it and immediately felt the pulse of the engine pulling on the slider, then I tightened slowly. As I got to what I thought was too tight there was a whirring chain noise. You don't want to hear any whirring, ticking yes. Whirring indicates a lack of lubrication or too much tension (in this case).
So I think it's a tad tight, but try what I did.
How'd I do?

 

You are running a bit too tight.

In the directions:

• 7 Turn the adjuster bolt in as far as possible by hand while cold or with 6mm ball end of allen wrench, but do not overtighten with allen wrench, keep in mind you are just removing play and not applying tension to the cam chain.
• 8 Using the appropriate socket and ratchet on the bolt in the end of the crank shaft,
  1. From the left side, rotate the crank shaft slowly counterclockwise, (from the right side rotate the crank shaft slowly clockwise) which will pull the cam chain taut on the drive side making the tensioner side slack, while turning the tensioner adjustment screw by hand. DO NOT spin the motor over with the starter, you risk jumping cam timing or possible valve damage due to excess chain slack. Do not force the crank if it should hit something solid, you do NOT want to damage a valve. Do not turn the engine over with the starter, that could also result in valve damage.
  2. Turn the motor over for a few revolutions with the ratchet while tuning the adjuster bolt by hand, the tensioner bolt will turn in easily when taking up slack in the chain, but will resist turning when either the chain is under tension (turning the crank the wrong way) or when the slack has been taken up. Again do not use much leverage on the L bend of the allen wrench.
  3. You should be able to tell when the slack is gone, the bolt will no longer turn easily.
  4. Back off 1/6 turn (one flat of the jam nut).
  5. Using one wrench tighten the tensioner locking nut down tight holding the allen nut with the allen wrench to keep the adjuster bolt from turning..

Missing step 8d you end up too tight. Likely no damage, but adds to wear. That swishing is the excess pressure forcing the slider tight against the cam chain. Back the adjustment off about 1/8 to 1/4 turn, the swishing should either become way quieter or go away. When cold the drive may tick slightly due to having that slight bit of play, that noise is no problem. It will go away as the cylinder and head expand as they heat up, it is only a few thousandths change, but it happens and the extra play in the cam drive to allow for it needs to be there.

It is always better to run a bit loose than too tight, just not sloppy loose.

Key point here for the non-mechanical. The noise is only a symptom, not a problem. It's like a runny nose when you have a cold. You can do stuff to stop the symptom, but not solve the problem. The problem is keeping proper cam drive slack adjustment. The OEM fastener fails to keep control of the slack, allowing it to slap back and forth and having cam timing variation. In worst case wear, the chain can get so much slop it may jump or break. With the manual adjuster you can over tighten, which can pull the cams possibly causing metal to metal contact and seizure in the head. Proper adjustment that may leave a few thousandths of play - remember that 1/8 to 1/4 turns back? - keeps the play at a reasonable (quiet) level without pulling on the cams.

By the way, do not be afraid to call or email and ask. My phone number is on my card and I think in the instructions. (I'm going to add the email to the card for the future.) I'd have told you in my long winded way exactly what I just wrote.

 

Maybe I'm just being paranoid.

I was tinkering with it a bit today. Backing it off didn't seem to help much. I took a video and you guys are welcome to tell me what you think.

In the end I settled with going as finger tight as possible while the engine is warmed up. I adjusted it while running, not sure if that's bad or not but I think I backed it out about 1/2 turn or so in the end. With the engine running i backed it out 1 full turn, then noticed some movement from the inconsistent chain pressure between strokes, I tightened it up by hand untill there was enough pressure on the bolt to want unwind itself, backed it off a bit and locked it in place.

It's quieter now but still making a whirring noise - as shown in the video:

Video

 

Call me crazy but maybe thats just normal noise from the chain and slider components. Maybe you've never noticed it because it was so ticky and clacky with the factory auto tensioner before you installed the manual unit.

 

That's certainly possible. I swear it's gotten louder in the last 500 Kilometers since I've done the mod though. Bleh.. what's the worst that could happen? Worn out chain guides?

I'd like to know what a bad chain guide / chain sounds like actually.

 

When you tightened the bolt down until it wouldn't move you were putting tension on the cam drive, chains are not meant to run under tension, they are meant to run at either zero tension or slightly loose.

I need to rewrite the fine tuning steps in my instructions. I just read it and it isn't clear. In the fine tuning stage all you are doing is taking all the play out. No extra tightening.

Here are the new steps:

1. Break lock nut loose
2. Very slowly back out the adjuster bolt until you hear ticking or feel tapping.
3. Slowly turn the adjuster bolt in until the ticking/tapping disappears.
4. Tighten the lock nut dow securely tight.

That is perfect adjustment, any noise you may hear from there is either not a problem or coming from somewhere else.


It is possible to turn the adjuster tighter, but that is not to be done. The tapping or ticking comes from the slight bit of play in the chain, when it goes away there is no slack in the chain. Any tighter is simply putting unwanted tension on the chain. As I've said, better loose than tight.

 

I apologize if this sounds blunt, but I believe you are imagining things. When i had my first street bike it was a Kawasaki S3 400cc triple. At 300 miles on the way to Indy in 1975 I could have sworn I could hear the center cylinder starting to seize. It wasn't. I ran into this again with my truck when I lowered it with a 3/4 drop kit. I felt it was riding really rougher... but after some thought, I realized nothing changed with the springs. The front had a 3" drop beam using the stock springs, the rear placed the differential on top of the stock spring instead of under it for a 4" drop - the springs were exactly the same as it was before it was lowered, nothing changed there. I was imagining the roughness because I became hyper-aware of the feel. The only real issue, which was very clear, was when the back bottomed against the frame - very clear! BANG! But otherwise the truck rode as it should.

What I'm saying is you are hyper-aware of noises. You are likely hearing what are normal noises that you never really noticed before when it comes to the cam drive or other noise, like the meshing of the primary drive gears while the engine is in neutral. Provided the manual tensioner is adjusted to take out the slack without tension.

If you had bad guides you'd hear a lot of noise, the only way they are bad is if they break. They're just reinforced plastic runners on which the back side of the chain will slide. There will be swishing, but not excessively loud. It takes forever to wear through, but a slapping chain due to extreme slop in the cam drive can damage and break them. It will get crunchy in there if they break. You will know it, it won't be swishing.

I had a 15,000 mile rattly engine in my KLX250 when I put in the adjuster. I did the simple cold set, noise gone, but my concern - variable tiiming and slapping chain gone! On my 650, where I've run a manual tensioner now for 33,000+ miles and done 4 adjustments, when I heard light ticking when it was at full operating temperatures, I did the hot set as described, because it was easy to do with the tensioner wide open on the left.

I know enough about the cam drive to tell you it is a simple system, no complexity. A chain that runs over three fixed position sprockets with a lot of slack so the chain can be placed over the sprockets. There is a bowed fiber/steel reinforced plastic leaf spring like slider that pushes in gently against the cam chain to take up that extra slack. All that adjuster does is push in on the top of the slider to push it in to take out the slack. Pretty simple.

Now why I emphasize loose over tight - First, too tight can cause excessive premature wear on the sliders and chain, but it is the worst case scenario I emphasize.

The cams ride in a machined plain bearing surface in the head on a film of as little as .0004" to .0012" of oil between the cam and head bearing surfaces. Camshaft/Cap Clearance from the manual

• Standard 0.00079-0.0024 in. (0.020-0.062 mm)
• Service Limit 0.0059 in. (0.15 mm)

Talk about little room for error! Now you know why I say a few thou loose versus having any tension on the cam drive.

The oil is under pressure from both the oil pump pressure and fluid dynamics created by the spinning of the cams in the oil in the bearing surface. You do not want to pull the cams down in that bearing area, if you pull too far it will have metal to metal contact. In worst case circumstances a ruined head is possible if the tension is extreme enough to break that film when running. There is the very real wear when the bike sits for some time, the tension on the cam drive pulls down on the cams, some contact as the engine sits. When cold the first second may be metal to metal since the oil has been squeezed out to an extent. That initial wear at warm up... No tension means a higher likelihood of a thin film of oil not being squeezed out.

You are over thinking things here. Get the whole "noise is the problem" out of your mind. Focus on root causes of noises. You had clicking that had a root cause of having too much cam chain slack due to a bad tensioner, which can vary cam timing and if allowed to go too long can result in damage. You fixed that. Now realize it is a mechanical item, not an electric motor, which also will have noises, they hum and can have swishing noised from bearings.

You have done the right thing asking questions though. Better to find out that a noise can be verified as a normal running characteristic or if it is a symtom or characteristic of a problem. With the over thinking of the tensioner adjustment, you need to verify either through thought about how your adjustment was done or through repeating adjustment, that your cam drive is set up correctly. If it is correct, your swishing is normal.

I hope the technical nature of this is not confusing, but if it is suffice it to say again:

 

Mark, I think all those 400 triples had noisy cam chains. Do you have a tensioner for one of those? I had two of those 750 triples, and they had a horrendously loud cam chain.

 

I'm not sure, but I think you got me with that stuff before...

Gotta say they did have their noises. My brother was riding it one day and I was standing behind him as he pulled away. Boy, I can still hear the burble from the chambers. Sounded great.

I want another two stroke!

I can drill an end fin and fit a tensioner on it.