Advice/opinions wanted on engine knock on low, cold, idle.

Hi,
After suppressing the exhaust, to introduce some back-pressure, I have run into some other problems and the knocking is a little bit scary.
I'm not sure if this is a correlation but at 90Kmh there is a nasty vibration that dies off at around 100Kmh+ also.
The exhaust collector has no loose baffles as it has been completely stripped and re-welded internally/externally (weighs about twice as much as original now though) and you can hear the noise is a definite knock over and above the engine rattling... like a chain slapping (gulp).
I've just replaced the cam-chain after lapping and re-shimming the valves and it is tight now but before it was extremely stretched.
So if anyone has any ideas that would be great.
Video is Cold Start 2.

One more thing, while I'm here, I was thinking about adjusting this doo-hickey thinking it would adjust the starter chain but after reading the service manual on the XJCD I'm a bit confused as to its purpose also.

 

videos dont work with my browser? would like to hear it

 

Re: Advice/opinions wanted on engine knock on low, cold, idl

Hi,
Sorry about that.
Here is the audio component in mp3 format.
You can hear the knocking about 20[EDIT: 40] seconds in as I get closer to the bike with the camera.
Thanks for looking

 

how many miles are on iyt kinda sounds like the timing chain but dont hold me to it . you dont have an exhaust leak at the head to header pipe do you. i find this very interesting im tracying a noise in 1 of my viragos here is what it sounds like http://s410.photobucket.com/albums/pp18 ... V02521.flv

 

As far as miles is concerned I'm not sure but the ODO shows less that 20 Thousand Kms, although the bike didn't have a speedo cable when I got it and was thoroughly thrashed as the PO told me.
I just replaced the timing chain too but it sounds almost hollow like a tapping on the headers or the motor casing... hmm hmm
As far as your sound though, which sounds more exotic than mine I have to say... is it the electric whistle type noise at the end or the whole soft, almost scuffing type of sound which is the puzzle?

 

if you got a stethescope see if you can pin point it good chance its an exhaust leak adding more back pressure makes it worse. you replacewd your timing chain how was the guides you got them instaloed properly and the ajuster is it working good you might want to pull it out clean it make sure it extends all the way. my 1100 noise is weird the po pulled the motor to paint the jugs and replace leaking gaskets got the heads swapped and the cams were in the wrong head swapped them starts up but i have to drill out the air screw the head is stripped and i cant get it out plus i have to put the stock mufflers on it to quiet it down so i can figure out the noise

 

Re: Advice/opinions wanted on engine knock on low, cold, idl

Thought I'd post this small screen cap for getting useful results from the search engine after doing some more searching about the starter chain.

1. Always use AND for each word you want to see, even the first word.
2. Display results as posts, not topics.
3. Return 'All available' characters, that way all the info is within the search results.

AND I AND believe AND I AND will AND be AND doing AND a AND lot AND better AND with AND the AND search AND results.

 

A quick testing will not require a Stethoscope.

PROBE the Engine to isolate exactly where the noise is originating from.

Buy a Wooden Dowel, cut a length of Fiberglas Driveway Marker, a Broom or Mop Handle.
Hold the Probe like a Ski Pole. Place one end of the Probe on the Engine.
Put your fist around the opposite end. Apply pressure on the Probe with your thumb on the End of the Probe.
"Listen" to the Probe.
Place you ear on your thumbnail and actually listen to the Engine.
Roll tape, rubber stopper anything to put your ear too and hear the vibrations carried by the Probe.
Make notes.
The noise is located at this spot.
Knock, vibration, rotational, scraping sound ... etc,

Isolate where the noise is coming from.
Rule-out exhaust leaks!
"Flag Check' for exhaust leaks.
Tape a tissue "Flag" on the end of a Screwdriver.
Check Flanges and Clamps with the Flag, ...
It will flutter if theres a leak.

Check Mounts.
Lay a wrench or tap on Motor Mounts with a Hammer.
Ring = Loose
Thud = OK -Tight.

 

Just as a followup.
I think I've successfully found the culprit for the low idle knocking and the clutch seems to be at fault.

I just replaced the clutch plates and springs after running a bottle of Nulon engine flush through the motor to clear out some more gunk.

When i was replacing the clutch plates I could spin the clutch boss freely as there was no build up or oil. The noise is a fairly constant rumble, like marbles rolling about under something.

After refitting everything, I can hear the same type of noise is coming from the clutch when the engine is idling roughly and if I pull the clutch lever or increase revs > 1.2k it goes away.

I'm not too happy with the sound of the marbles when it was dry and open but doing the same test on the parts motor, which is full of sludge, felt the same although without spinning freely, because of the buildup.

After reading quite a few other posts with the same type of issue I'm going to get my homemade YICS tool and homemade 2 bottle sync tool(both made from instructions from here) ready for action and hopefully remove the rough idle, which will remove the knock! Hopefully...
Thanks again for the help.

 

When you did all the work on the head new chain and all did you install new guides also did you remove the tensioner?
Quote from your first post,
"One more thing, while I'm here, I was thinking about adjusting this doo-hickey thinking it would adjust the starter chain but after reading the service manual on the XJCD I'm a bit confused as to its purpose also."
If you did not this is probably whats causing all the noises. The video soundtrack sounds like you have a rattle in your inner exhaust pipe tubes they have an inner pipe that sometimes breaks loose.In my experiences I have never heard a clutch knock, they chatter and slip and squeal. Nice looking bike

 

Being based on th 750 seca I would think you camchain tensioner is th automatic type..there was a 'how to' help it manually on here just a coupla days ago..

 

I was about to return to your original post and explain that the "doohickey" you found on the XJCD and initially posted about is a manually adjusted cam chain tensioner.

IF your bike has a cam chain tensioner as pictured, it is the manual type and you would need to adjust it.

If your bike has a cam chain tensioner with no adjuster bolt/nut sticking out of it, then it is the "automatic" type which still involves a technique to adjust.

You could also have a simple exhaust leak at the head.

 

I originally thought the stopper bolt and lock nut pictured were on the horizontal face on top of the gear box area which was the part of my confusion originally since the cam chain tensioner is mounted on the vertical face of the cylinders. Must wear my glasses more often.

It looked like where a tensioner for the starter chain would be to me... if there was one, that is... but I didn't touch it and promptly forgot about the reason I didn't touch it also... The actual bolt and lock nut on the horizontal face of the gearbox that is.

I'm sure someone who has split the cases of the same engine would know exactly what it does, something I'd like to know this is for sure...

I will do a wet float level test and sync soon to get it running evenly and post some more audio to see what you think though as the sounds are a bit different since the original audio/video recording.

Just for the sake of visuals... here is the latest pic I took too.

 

thats a nice looking bike,good onya

 

Re: Advice/opinions wanted on engine knock on low, cold, idl

Swapped in some carbies that I bought of ebay and then rebuilt and after also doing a wet float level set and two bottle sync the bike is now becoming really nice to ride, even in the hot weather were having at the moment. Great low, middle and top end acceleration.

The 90-100Km/h vibration is gone which tells me it was a sync thing causing that I'm pretty sure... being able to see in my rear view mirrors is a real plus now that they aren't nearly vibrating off at that speed.

After recording another video Cold Start 3 and listening to the multitude of noises when the camera is close to the engine, I don't think I removed any noises by doing the sync and still feel there is something floating about but I'm going to re-torque the headers and check the muffler connections to the collector when I redo the cam chain link and check the valve clearances... then I'll check the noises again.

Just an update... if you hear any crazy obvious noise on the video which points to impending doom I'd appreciate your thoughts!
Thanks.

 

Probably the coolest looking ride I've ever seen!

What kind of saddle bags, saddle bag guard rails, and luggage rack are those?

The lines of the bike are really nice.

 

It's a POLICE bike. Sweet, ain't it? You should see the FZ750 version from a couple years later...

I particularly like the rear crash bar/luggage rack frame integration and the factory solo seat.

 

The problem with watching the Videos is that ALL the noise comes from the same spot, ... my speakers.

But, ... after listening to the Bike; I'd say that it might be worth taking the time to check the underside of the Cam Cover for loose Chain scraping.

Also, ... placing a towel on the right-side Clutch Case and see if that High Frequency rattle is muffled.

THAT could be a Oil Pump Splash Shield, ... not home in the slotted holder where it belongs.

The unsteady rhythm of the Engine at Idle is most likely Sync.
One Throttle does not need to be much more opened to cause the Motor to Pulse.

 

Rick
I will definitely do another sync and try to isolate the noises again using your suggestions. The cam chain is annoying the hell out of me because it is tight as anything, since it's new, but when I crimped the link I over-tightened the link and had to pry it apart a little to loosen it up. It seemed good but ever since I've been paranoid about it, which is why I got a few spare links and another chain from chacal and bought a chain link punch/anvil tool to redo it. Which I will definitely do this week.

MidnightMax
I'm trying to restore it to pretty close to original, although the white seat is a colour choice I made when my other half made me a new cover so now I can leave it out in the sun without having to stand up for the first 10mins of riding to let the seat cool down! The chrome rear racks/crash bars are very cool and original on the police special. I didn't have any of the rear stuff but Darkfibre had the racks and Non-quotidiun had the panniers and I ended up with all of it because of their generosity. I have since also made a bracket and fitted a topbox onto the rear rack, where the radio box would have normally have been. (see pic below)
One thing I can say is that a white bike is a lot harder to miss on the road and since I wear a fluoro yellow/green vest too, you can see me coming I'd reckon



Bigfitz
At first I tried to get the double seat (seca seat) that the bike came with to work so my other half could come along but with the chrome racks you'd have to have legs with multiple knee joints to get your feet to the pillion pegs too... in saying that I don't think she was too unhappy about not being able to come for rides, actually she might have been relieved, come to think of it hehe.

 

Police bike? Makes sense now. So steenkin cool!

Were they ever used in this country?

 

That looks familiar....I think they still use those over here in Bahrain!

 

Re: Advice/opinions wanted on engine knock on low, cold, idl

Checked out a FZ750 Police photo.

Realllly Steeenkin Coool!!!

 

With the Cases. Paint and your Hi-Viz Gear, ... the traffic probably thinks you are a Cop.

I'd have a close look at the Plugs.
That's high-heat bluing on the Chrome under the Plant.
You could be way too lean.

 

You've got a good eye Rick!
The bluing was my fault with the oxy/acetylene as I was welding the chrome bits back on after repairing the collector(or should I say rebuilding it... rusty shell as it was) I overheated it a bit when I tacked it back on... probably should have got the bronze out but carried on with mild steel welding instead. But at least its still kinda shiny!

I did have one guy go through an orange light in front of me and then pull up beside me later, lean out the window and let me know I scared the hell out of him, but he seemed happy he was mistaken.

 

When you need to weld a Chrome Part on, ...

Have someone hold a Saturated Rag on the Part as close to where you need the Weld as possible.

Rig some way to keep running "Cooling Water" on to the rag while you strike the arc.
Keep feeding cooling water on the Rag letting the heated water exchange with the cooler water being fed to the Rag near the work.

 

Good advice on the chrome welding, thanks Rick.

On another note... I finally just replaced the cam chain link after imagining clicking and clunking because an overzealous punch I used to splay the end of the softlink pins and basically overtightening the link and prying it open a bit to make it actually work like a link... a couple of months back.

I have to say, not my favourite job. I bought 4 links from chacal and a spare cam chain just in case and the guy I bought a cam chain breaker/rivet tool from also supplied a genuine Yamaha soft link for the XJ chain.

5 Links... I have 2 left!

Can I say I'm not sure why but my inclination to overtighten everything is becoming very apparent to me.

The Yamaha link was so easy to fit and splay the pins compared to the soft links from Chacal I instantly mashed it too far with the chain rivet function and had to punch it back out again.

I'm pretty happy to say that I think I've got the hang of it now and I feel for the other guys who bought at least 2 of my old bikes because I'm pretty sure I didn't pay this much attention to either of them when I did the cam chains.

One tip I have is to drill out the old plate from the old link you removed and utilise this to push the plate onto the new soft link... like a washer/spacer that won't get stuck on the new link pins.

With the Yamaha link, the plate just pushed on with a wiggle but the the EK soft link, from Chacal, the plate is very tight and requires some mechanical finagling and it's easy to over tighten the link or damage the end of the pins but with the spacer, you just made, it gives a good surface to push the plate in after the initial cursing you may experience from trying to get the plate on squarely.

Either way, take it very slowly when splaying the end after you get the plates parallel to each other, as it is SO damn easy to overdo it. Or that could just be me of course.

On a positive note. I wish I had that breaker from day one... an amazing little tool and very clean compared to angle grinding the side of a chain down, this if for sure.

I found 2 Shims need replacing too... although I used 'imperial' feeler gauges as my 'metric' set got caught in the rain and am questioning the accuracy. Either that or my #4 exhaust valve is really working its way into the head after the lapping in and 500+Kms of city riding.

When I get the shims in, after rechecking with some 'metric' feeler gauges, I'll post another video to see what difference the work has done to the knocking and other various sounds... fingers crossed.

 

Re: Advice/opinions wanted on engine knock on low, cold, idl

#4 exhaust is in tolerance according to the new metric feeler gauges. My imperial feeler gauge set only has 10 blades so it's a bit limited and gave me values which showed it was out of tolerance.
#4 Inlet, however, was tight and had to go down a shim size. 270 to 265.

Everything is back together and exhaust bits have been tightened and although the new video sounds horrendous... to the human ear it sounds a lot better.

In advance I apologise for the length of the video, I was trying a bit of a roaming around thing to catch the loudest noise... which made me think most of the noise was coming from around the clutch cover.

I'm not sure if I'm barking up a tree now since everything it's just sounding rattly on the video but any opinions on what you hear are always appreciated!