I hear some rattling on engine brake

bob808

Junior Member
Hello everyone,
I noticed something odd last two weeks. Whenever I do an engine brake I can hear a metallic rattling from the engine. At first I thought that the the chain is acting up but it's slack is proper, and greased. So the sound must come from the engine. It has a short duration, but it's there and I'd like to know what that could be. Any ideas?
FZ6N with 25.000km on clock.
I do ride the bike proper :) but I'm not a speed freak. Did a 500km day on twisty roads few weeks back and I did have the bike spewing it's guts out in every corner exit. And did a lot of engine braking as there were lots of valleys and did not want to risk my brakes.
 

TownsendsFJR1300

2007 FZ6
Site Supporter
Rattling from the engine is generally from the cam chain / or failing tensioner (CCT) allowing the chain to rattle. With only 15,500 miles or so, its not alot of miles but the tensioner, if original, is 9 years old now...

The cam chain is on the right side of the engine, under the ovalish cover.

If you can duplicate the noise while stopped, you can listen to that cover using a screwdriver, handle to your ear, end to the engine.

Also, if you can upload an audio, it would help.

Not to throw parts at it, but it might be worth the investment to replace the tensioner just as insurance. You can pull it out and check for smoothness, tension etc, but again, its 9 years old and its not unusual for it to fail..


Yamaha Motorcycle Parts 2005 FZ6 - FZ6ST CAMSHAFT CHAIN Diagram
 
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bob808

Junior Member
Thank you for the info.
I just took out the rear wheel as I begun to feel some scratching at very low speeds, but only when I am accelerating. I suspected the rear bearings but they seem fine and feel real smooth. Also checked the rear hub bearing and no problems. Checked the whole chain as well and seems to be ok.
The scratchiness seemed to come from the rear wheel but I guess it could be distributed by chain from the engine?
I will put the wheel back and check the tensioner.
The brake pads have plenty of material left on them so I'm at a loss with that scratchy feeling I get from the bike, especially when I'm slowly accelerating at low speeds. Could be related to the rattling I hear when decelerating. I will reply with what I find in the tensioner.
 

TownsendsFJR1300

2007 FZ6
Site Supporter
Thank you for the info.
I just took out the rear wheel as I begun to feel some scratching at very low speeds, but only when I am accelerating. I suspected the rear bearings but they seem fine and feel real smooth. Also checked the rear hub bearing and no problems. Checked the whole chain as well and seems to be ok.
The scratchiness seemed to come from the rear wheel but I guess it could be distributed by chain from the engine?
I will put the wheel back and check the tensioner.
The brake pads have plenty of material left on them so I'm at a loss with that scratchy feeling I get from the bike, especially when I'm slowly accelerating at low speeds. Could be related to the rattling I hear when decelerating. I will reply with what I find in the tensioner.
How old is the chain (mileage)? Do you keep it well lubed?

A worn chain, not lubed often enough will make all kinds of noises and sensations coming thru the bike. Remove the front sprocket cover, 3 allan head bolts. Most likely goo'ed up in there.

Rotate, by HAND, the rear wheel and watch for ANY LINKS NOT straightening out immediatly coming off the front sprocket..

If there's any sticking/kinking, the chain needs attention or at LEAST, a good cleaning and lube, possibly replacement.

Please follow the owners manual adjusting, the FZ like to be about 2" total up and down measured while on the centerstand. It'll look loose but as the swing arm comes up (with your weight), it tightens up..
 
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bob808

Junior Member
Bike has about 25.000 km and I was very diligent with the chain since I had it (3000km on the clock back then).
I only cleaned the chain once with diesel, but I do lube it every 4-500 km or so.
I will take off the front sprocket cover and do your check as well. But anyway, I tried to spin the wheel by hand and it felt smooth.
 

greg

UK Luchador
Moderator
My mechanic mentioned that engine breaking on i4 600's is one of the reasons the CCT fails so often. I'm not sure of the exact mechanics of it though.
 

aclayonb

Junior Member
I've heard some very experience mechanics say the same thing but I've never heard anyone explain why. They said you can engine brake on v-twins but it's hard on the engine of an I4.

Brake pads are cheap, so I've always just used the brakes.
 

bob808

Junior Member
I checked the tensioner and it seems to be working fine. I only took out the screw and it seemed to be working smooth. I event twisted it to the max and let it go a couple of times and seemed to be working ok.
I will clean the chain once more and give it a good lube and report back.
So far I've found nothing wrong.
 

TownsendsFJR1300

2007 FZ6
Site Supporter
Not likely, but with the hard engine braking, the lower part of your DRIVE CHAIN tightens up and the top run NOW has all the slack.

Look around the top run of the frame and see how worn the guide(on the swingarm is) and more importantly, is the chain rubbing up against the frame?
 

TownsendsFJR1300

2007 FZ6
Site Supporter
So I should open the upper part of the engine to check this?
If the cam chain is stretched, the rear tensioner guide worn, the tensioner may be extended fully or close to it.

To safely check it, IME, pull the cam chain cover.
Spin the crank, clockwise by hand to TDC (you'll see the mark on the star trigger and left side of the case).
Put a plastic zip tie around both sides of the chain just snug (to keep the chain from skipping a tooth).

Remove the CCT. With the CCT fully extended, how far away from the block, while up against the cam chain does it go?

Ie, if its really close to the block, the tensioner is extended out a bunch or fully and may not keep the cam chain tight. (While the tensioner is out, a little bit of oil down those threads usually helps with its movement).

I posted earlier, that cam chain tensioner, and the critical spring inside is 9 years old. The springs have been known to loose tension, especially over time.

If the CCT is about fully extended, the chain is likely stretched, the rear guide worn (takes all the pushing force/wear).



As an example. My cam chain at 28,000 miles on my old KLR250 (2005) was starting to rattle. (the chain is easily twice as long as the FZ). When I checked the original chain (same methind as above), the tensioner was maybe 1/8, FULLY EXTENDED from the block(measured the same way as pictured below). With the new chain and rear chain guide, about 7/8". Nice and quiet once re-assembled...

Double click to enlarge
 
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bob808

Junior Member
I gave the chain a good clean and then lubed it proper and now that scratchiness is gone. I still have the rattle inside the engine on engine braking. I will test with the tensioner out and see if the chain is loose or not.
 

FinalImpact

2 Da Street, Knobs R Gone
Site Supporter
I'm guessing i should have many dead engines in my wake but i have none. IMO any quick change in the cranks rotational speed is going to load the cam chain. Its the instant action of trying to change direction that induces the greatest load.
Example would be to chop the throttle and then just bang it down a gear(s) without REV matching. So there is thatside of it. Beyond that any steady state up or down RPM wise is really no different.

Going back to carbs, here we add in a factor not present today. An engine not making power with the throttle plates open (meaning Throttle Plate is closed) is a big vacuum pump. It wants air volume going through it even if the TP is closed. In this case there is very high engine vacuum and in the case of carburetors, high vacuum means they will pull fuel through them which CAN rinse the oil from the rings, piston, and cylinder wall. Over time this could wear the engine. And yes, depending on the FI fuel map, one could induce this on a FI engine too.

REV match FTW and don't worry about it. Obviously if your drive chain has only been cleaned twice in its life time the abrassive road grit will take its life MUCH sooner than one which is properly maintained. And if too loose or too tight, it will increase the wear at the contact points.

I engine brake always and may do so through every gear and/or from 12k. So, if its going to fail you may be reading about it in a new thread! :eek:
 

FinalImpact

2 Da Street, Knobs R Gone
Site Supporter
Adding to the post above on engine braking (breaking???), without a doubt there are two more common issues that will kill this and other engines like it: failure to change the oil at the manufactures suggested interval and treating like a tractor engine lugging throughout the gears. Engines subject to these conditions will fail much sooner than those which are rev'd and/or subject to engine braking to reduce speed.

Lugging/chugging produces huge stress on the crank, rods, wristpins, piston and cylinder walls. Not to mention the loss of cooling from reduced coolant and oil flow/oil splash. The cylinder pressure goes so high it induces preignition hence the bucking sometimes associated with lugging. Its just bad. This engine is much happier when it sings, so let sing!

/all done.... Unless someone has proof how engine braking induces wear, stress, damage. Share your thoughts....
 

bob808

Junior Member
I never went beyond 5000km on oil change :) I feel as the bike is preparing to disintegrate whenever I see the 4500km mark for oil change :D
And I sure do rev the bike, don't think she ever saw lugging in her lifetime. I like to have power ready for delivery whenever I ride so that's not an issue for sure. But I guess I will be sure when I take out the tensioner.
 

Motogiro

Vrrroooooom!
Staff member
Moderator
Elite Member
Site Supporter
A cam chain is not like a drive chain in it's operation. There is always forward force on the cam chain whether it's acceleration or deceleration.

Although engine braking may not be as needed tooling around in town, I use it often when I'm out riding and coming into a turn, as it helps set my speed into the turn and put's me in the right gear to push out of the turn. If I'm doing this more aggressively I'm rev matching accordingly.
My V-twin uses a shorter chain on each cylinder. This short chain drives an intermediate gear that drives the 2 intake & exhaust cam gears.
 

bob808

Junior Member
I don't get it, isn't engine braking one thing and rev matching another? I use engine braking so I don't use the braking system on the bike. Isn't rev matching something you do so you DON'T engine brake when down shifting? :confused:
 

TownsendsFJR1300

2007 FZ6
Site Supporter
I don't get it, isn't engine braking one thing and rev matching another? I use engine braking so I don't use the braking system on the bike. Isn't rev matching something you do so you DON'T engine brake when down shifting? :confused:
Your basically giving the throttle a blip when getting ready to downshift (and release the clutch) so the RPM's match (or at least are close) once in a lower gear (their pretty much matching). Then let the engine braking begin.

To just down shift once or twice (especially at higher RPM's) and drop the clutch, is putting un-due / un-needed stress on the clutch (the frictions specifically).
 

Motogiro

Vrrroooooom!
Staff member
Moderator
Elite Member
Site Supporter
I don't get it, isn't engine braking one thing and rev matching another? I use engine braking so I don't use the braking system on the bike. Isn't rev matching something you do so you DON'T engine brake when down shifting? :confused:

Rev matching takes pressure off the clutch and reduces shock at the rear wheel as the clutch engages because there is less difference in engine RPM when picking the lower gear ratio. It's still equates to engine braking if you're off throttle. It also lends you to a lower gear when you want to stay closer to your power band when coming into a turn and then exiting in a better matched gear to push quickly out of the turn.

Some of these techniques are really for more aggressive types of riding and may not be applicable for average riding although when you need these types of techniques they are good to know. :)
Other considerations would be less chance locking the rear wheel at any critical moment.
 
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lrojasma

Junior Member
I never went beyond 5000km on oil change :) I feel as the bike is preparing to disintegrate whenever I see the 4500km mark for oil change :D
And I sure do rev the bike, don't think she ever saw lugging in her lifetime. I like to have power ready for delivery whenever I ride so that's not an issue for sure. But I guess I will be sure when I take out the tensioner.

jajajaja you have issues men.

I change oil every 10.000km (including oil filter) and this is what is indicated on my manual.

The manual varies from country to country, but on mine, it says 10.000km, and i have change it like that with no issues whatsoever, and i think i could even go longer, the syntetic oil is just amazing.

That feeling that you have a 4500km... is a psicological think, because i feel that at ... 9.900km! jajajaja
 
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