New noise from engine...should I panic?

[Newoldbiker 45]

Hi

 

My '63 plate NC700 S has now done about 22K miles and I think the engine is making a new noise.  It's a 'clacking'/'flicking' sound from the engine when I accelerate in 1st and 2nd between about 2 & 3K on the tacho. It's like a regular flick, flick, flick that matches the acceleration but when I get above 3K revs it stops.  Don't notice it at all at higher revs.

 

Bike is running fine, mpg as usual, starts first time always.

 

Thanks in advance for any advice     

[embee 7,288]

What state are the chain and gearbox sprocket in?

[suffolk58 2,286]

Have you checked the obvious Paul?

Check to see if there is a stone stuck in the tread of your tyre.

This has happened to me before, at higher revs you are going faster so don't hear it.

[Newoldbiker 45]

Chain and sprockets fine, original chain but I have a chain oiler and it's nowhere near the limit on the tensioner- will check the tyre this weekend.

[trisaki 2,029]

Hooked front sprocket ?

[djsb 493]

Cam chain tensioner?

[Griff 1,556]

It is very difficult to tell what this is from the description in words. Ideally if you could post a vid clip then some really helpful opinions could be offered. This bike will produce a sort of whistle on full throttle in the higher gears. It is coming from the airbox intake which produces a sort of metallic whistle coincidental with the firing sequence of the motor. That intake is very close to the steering stem.  

 

This could also be chain related if you are still on the original chain. I have found a knock related to one revolution of the chain when the bike is cold, in the lower gears. A replacement of the chain sorted that.

[Newoldbiker 45]

It sounds like something is loose and knocking as you accelerate.  It only happens when the clutch is let out.  When I pull the clutch in to change gear it stops.  It's regular - like every second or a bit quicker.  I wear ear plugs but you still hear it.

 

Will check the front sprocket but have no idea how to check/adjust the cam chain

[Newoldbiker 45]

Just rode to work. It only happens in 1st and 2nd gear - between about 2-3K revs.  In second at exactly 2.5K.  It's a bit like the sound train wheels make when they go over the gaps in the track.  It's quite subtle.   As the revs build it disappears.  Doesn't happen in 3rd gear.

 

Might have to visit Mr Honda Chiswick after I've sold my son to pay for the bill........

[embee 7,288]

I'm still suspecting the chain. Have you checked it carefully for tight links? The OE chain at 22k miles has earned its keep, I'd be expecting it to be near the end of its life.

[Newoldbiker 45]

re chain - why would it only make the noise when the clutch was out?  Wouldn't it just sound whilst moving forward whatever?  Not doubting your expertise Murray.

[Griff 1,556]

Yep, I am also still thinking chain. Tight link running over the front sprocket every full revolution of the chain. I had that until I replaced the chain. Generally it only happened in the lower gears and under acceleration. When the speed was up it was no longer audible.

 

 I agree with embee that 22k Miles is a good innings on that chain. In fact many chains are replaced well before that mileage. Personally I would change it asap. I have heard of one or two chains letting go on this bike and it can do some damage on the engine casings when it does.

Edited March 24, 2016 by Griff

[Tex 36,817]

 

Might have to visit Mr Honda Chiswick after I've sold my son to pay for the bill........

Let me know if you get a good price for him, I've got a couple I could spare..

Sounds like a chain problem to me too, so you might be able to afford to fix it and keep the family intact.

[Guest machinman]

Manifold blow / crack.

[embee 7,288]

re chain - why would it only make the noise when the clutch was out?  Wouldn't it just sound whilst moving forward whatever?  Not doubting your expertise Murray.

Good to question stuff.

 

The chain will behave a bit differently when under some load compared to free running (clutch disengaged). It'll pull down into the roots of the teeth whereas under no load it can tend to ride up a bit if it has stiff links. It may well be something else, but the description fits with what we all know about the original chains used on the NC and the fact that yours has done well to get to that mileage.

 

I fitted a new DID VX2 chain after only about 5k miles because I didn't like the feel of the OE chain, it made a world of difference, completely eliminating the cyclic thrumming I was getting.

[Newoldbiker 45]

Thanks very much guys.  Looks like a new chain is in order.  Riding home today the noise could come from the left foot area by the front sprocket.  Word is DID chains are the way to go?  Anyone know the best place to buy?

[embee 7,288]

I can only comment from personal experience, but the DID VX2 is a much nicer chain than the OE spec version. There is a higher spec DID ZVM chain, at a higher price.

http://www.didchain.com/streetChains.html

 

I got mine from Busters' shop on the auction site purely because I had a voucher. Try Busters online shop, also M&P, Intobikes and Wemoto for some prices. I suspect there may well be some fakes on the auction site, there are fake everything else.

 

Consider an endless version and take the swingarm out to fit it. It means you don't need to rivet the new chain link (needs the riveting tools). It's not a difficult task if you have a centre stand, no special tools required beyond the normal socket set/spanners and gives the opportunity to grease all the bearings. Just an option.

 

At that mileage you'll want to replace at least the gearbox sprocket, the rear may be serviceable if it's been well lubricated, you need to judge that one. Possibly false economy not to renew the whole set.

Edited March 24, 2016 by embee

[Newoldbiker 45]

Thanks Murray and everyone else for your help.  

 

This site is great - I've never had a bike get to this mileage before & having decided to start servicing myself rather than the King's ransom my local dealer wants where else can you go for help and advice 

[Griff 1,556]

Thanks Murray and everyone else for your help.  

 

This site is great - I've never had a bike get to this mileage before & having decided to start servicing myself rather than the King's ransom my local dealer wants where else can you go for help and advice 

I would recommend using the riveting link rather then a spring clip. Perhaps you have already thought of that, but just in case.

[Tonyj 6,907]

Paul I had a very similar noise on mine and it turned out to be one of the three rear bearings , this was done at about 16k under warranty.

I thought it was the chain and adjusted it and the noise stopped for a while , it makes a clacking noise in lower gears , 1st or 2nd but it wasn't steady with the speed of the bike if you know what I mean . While it was in the garage I also told them to fit a new did chain and sprockets as the old one was coming to the end of its life. The reason I didn't think it was the chain at the first because the noise started at about 10k but it did give the impression that it was jumping on the sprocket .

In my case it may have been both as the chains are a bit under spec'd ( is this a word) :0)

[embee 7,288]

Tony's comment above is a good point. I've not had this so don't recognise the symptoms. With the wheel out you can easily check the 3 bearings, 2 in the wheel itself and one in the sprocket carrier, they should feel perfectly smooth, any notchiness is not good news.

[Tonyj 6,907]

Tony's comment above is a good point. I've not had this so don't recognise the symptoms. With the wheel out you can easily check the 3 bearings, 2 in the wheel itself and one in the sprocket carrier, they should feel perfectly smooth, any notchiness is not good news.

It was the one on the sprocket , it would move back and forth not side to side . Like a Cush drive failure

[michael 324]

re chain - why would it only make the noise when the clutch was out?  Wouldn't it just sound whilst moving forward whatever?  Not doubting your expertise Murray.

Potentially because the chain is under tension/load.

My personal "end of chain life experience," was very similar.

 

Now I'm not saying it might not be something-anything-else I'm only remarking on my own experience. 

 

Here's to hoping it's nothing more sinister!

[Newoldbiker 45]

True dat!  Have ordered a new chain - will report back when it's fitted

[kyrioskiros 2]

I had a similar noise at a specific engine speed(3000rpm) on my NC700s. After replacing the Cam chain tensioner the noise was still there. I found the solution some months later:

 

the horn was very close the the engine and with the vibrations at 3000rpm was knocking the engine, creating this noise. Once I moved the horn a bit away, the noise disappeared.