[Discussion] CB400 SUPER FOUR HYPER VTEC Revo

[ramsnake]

[video=youtube_share;bu-6eLTvEqY]

 

This is a Dec 2008 model and has about 85,000km on the clocks at the time of this video.

 

There are 2 sounds evident from the clip:

The first is a tick-tick-tick metallic sound. This is the sound of the cam lobes contacting the valve stems to open and shut the valves. This is perfectly normal.

 

The second sound is sort of a humming sound. Watch the clutch cable as I depress and release the clutch lever. When the clutch is engaged, the sound goes away. The humming returns when the clutch is dis-engaged. I started noticing this sound at about 70,000km mileage. A visit to my mechanic reveals that this is a normal Honda trait. It is the sound of the clutch basket humming due to normal wear and tear. My mechanic also recommends not to change the clutch basket or clutch plates so long as the clutch isn't slipping and there is no problem shifting through the gears.

 

Since detecting the humming sound, I have covered quite a few long distance rides, the longest of which was about 900km one way. During these rides, I have also pushed the bike to the max, speed wise. Absolutely no problems.

Edited November 29, 2012 by ramsnake

[ramsnake]

@StrongBow & @mrkookz

 

Firstly, John, kudos to you for using the mechanic's stethoscope! This old school gadget can't be seen in many shops nowadays...

 

I can't really distinguish the sound from your engines as you describe because when you rev the engine, all I can hear is the induction roar. Is it similar to that tick-tick-tick sound you hear on my video clip?

 

My initial response to StrongBow's clip is that it is the sound of the cam lobes contacting the valve stems and it sounds very much like that from my bike. I wouldn't call it a "rattle". For the benefit of everyone here, StrongBow's bike is a new bike and he has gotten his bike hard run in on the dyno by an experienced mech in Singapore. That mechanic's feedback was that StrongBow's bike "is as healthy as any other new Revos". I take that to mean that power output is healthy and at the normal expected range. That being the case, I wouldn't be too concerned by the "sound". Sounds quite normal to me.

 

Can you give us some info on your bike, @mrkookz?

[StrongBow]

I am really not a very mechanic person so i have no idea what a cam lobe is... Is it the same thing that causes ur rattling sound ramsnake? But if so why doesnt the sound go away when me and john depress our clutch? And why does the sound disappear after the engine is warmer?

 

I have contacted boonsiew about this and service center is trying to get back to me. I guess i will get to talk to them in the morning. Hopefully everything is well. To me my bike is still damn fine. Fetch me and my another bigger size friend still perform extraordinarily well. But i just cant overlook this sound if it wasnt there when i first got my bike. i have already been in contact with john here and will update him and you guys upon any discovery. Stay tuned!

[ramsnake]

http://en.wikipedia.org/wiki/Camshaft

 

See pic on top right of the wiki page. Cam lobes are that part of the camshaft that is egg shaped. This is the part that open and shuts the valves.

 

What do you mean by "I have contacted boonsiew and ... get back to me"? I surely hope that you are not asking them to diagnose a noise issue via YouTube! Send in your bike, bro. It's under warranty!

[mrkookz]

@ramsnake - thanks for the feedback and for posting a clip of the clutch noise. I can hear the difference on yours with the clutch in/out and have a similar sound on mine when I do the same. However, it's not that sound that troubles me.

 

The rattling is a definite rattle as opposed to the ticking of valves or the hum of the clutch. I'll try and record it again this morning, when it's completely cold and most noticeable. I had a friend of mine who I tried to demonstrate the sound to a few times and he could never hear it - but he did recently.

 

@StrongBow is getting in touch with Honda today and I've suggested he send them links to both his and my video clips so they can hear the issue. The noise is much "harder" and substantial than a tick or hum and can't be heard at idle - only when between about 3-5,000rpm. Its more like a knocking sound. To me, it sounds more like it could be something like the chain slapping against the engine walls (although unlikely given the replacement of the cct on mine) or a failed bearing. It's annoying, but I'm hopeful it's something trivial - Especially since its noticeable on bikes with very low km.

 

Mine is an 08 CB400 ABS. I bought it used in March when it had 4,800km on the clock. It now has over 10,700km. It's stock, although I'm keen to get a slip on can to make it sound good. I've bought it just while I'm on my learners and provisional licences here in Aus. I'll graduate to a new bike next year - hopefully a Street Triple

[StrongBow]

@ramsnake - thanks for the feedback and for posting a clip of the clutch noise. I can hear the difference on yours with the clutch in/out and have a similar sound on mine when I do the same. However, it's not that sound that troubles me.

 

The rattling is a definite rattle as opposed to the ticking of valves or the hum of the clutch. I'll try and record it again this morning, when it's completely cold and most noticeable. I had a friend of mine who I tried to demonstrate the sound to a few times and he could never hear it - but he did recently.

 

@StrongBow is getting in touch with Honda today and I've suggested he send them links to both his and my video clips so they can hear the issue. The noise is much "harder" and substantial than a tick or hum and can't be heard at idle - only when between about 3-5,000rpm. Its more like a knocking sound. To me, it sounds more like it could be something like the chain slapping against the engine walls (although unlikely given the replacement of the cct on mine) or a failed bearing. It's annoying, but I'm hopeful it's something trivial - Especially since its noticeable on bikes with very low km.

 

Mine is an 08 CB400 ABS. I bought it used in March when it had 4,800km on the clock. It now has over 10,700km. It's stock, although I'm keen to get a slip on can to make it sound good. I've bought it just while I'm on my learners and provisional licences here in Aus. I'll graduate to a new bike next year - hopefully a Street Triple

 

Made an appointment with honda! Will be going down next thursday! Stay tuned

[joeboxer82is]

Any idea what's e machine price of a brand new Revo?

[static369]

@azman ibrahim

 

If he hasn't changed his pricing, the rear shocks should be $240/pair. Forks are about $320, I think.

 

David Ong (Teck Thye)

12 Braddell Road Singapore 359900

Tel: 62803138

 

Evening guys, isn't $320 a little pricey? I need to service my forks badly. Rear Showa's seems fine. Will go down and check it out first.

[ramsnake]

@mrkookz

No worries, John. Let's wait for @StrongBow to send his bike in to Honda for better feedback as it's difficult to diagnose sound issues without listening to the bike in person.

[ramsnake]

Any idea what's e machine price of a brand new Revo?

 

$15,207 - Machine price + GST + LTA transfer + IU

Price excludes COE and insurance.

Comes with lots of free gifts.

 

I've just helped another forum member shop around for a new Revo which he is collecting tomorrow. After visiting quite a few shops and being given the usual sales crap, he found my recommended shop to offer the best deal.

 

PM me your HP no and real name if you're interested.

 

 

Evening guys, isn't $320 a little pricey? I need to service my forks badly. Rear Showa's seems fine. Will go down and check it out first.

 

I suggest you visit David to see what needs to be done for your forks. That $320 price is the full price for full forks rebuild. If your's don't need a full re-build, it may be cheaper.

[urbanfighter]

Ramsnake- pm me the shop name..thx..

[ramsnake]

Ramsnake- pm me the shop name..thx..

 

Err... this is what I stated in my earlier post: "PM me your HP no and real name if you're interested."

[joeboxer82is]

Err... this is what I stated in my earlier post: "PM me your HP no and real name if you're interested."

 

Done.PMed liao...

[chiaph]

anyone knows how to install a Bagster Tank Bra? I just purchased mine today. also are all the oil filter of CB400 the same throughout the years? I am referring to the housing measurement.

[chainteef]

Hey Bros,

 

jus wanna ask a stupid question... does cb 400 spec 3 have a throttle body? i really have no idea if this pertains to EFI bikes only or carb bikes also hv?

[mrkookz]

The rattling is a definite rattle as opposed to the ticking of valves or the hum of the clutch. I'll try and record it again this morning, when it's completely cold and most noticeable. I had a friend of mine who I tried to demonstrate the sound to a few times and he could never hear it - but he did recently.

 

Here's another video of the rattle taken last night.

 

[StrongBow]

John. Could u do a video without any sudden revs? Let the rpm gradually ascend to 4krpm. The sudden rev makes it hard to hear the rattle.

 

 

PS. Nvm its okay i hear it now. But when u hold ur video recorder near to the right side of the engine. The sound is really loud!

[kelena]

looking for a stock header and midpipe for revo. please sms me at 96880675 if there's one you're letting go!

[ramsnake]

Here's another video of the rattle taken last night.

 

 

John. Could u do a video without any sudden revs? Let the rpm gradually ascend to 4krpm. The sudden rev makes it hard to hear the rattle.

 

 

PS. Nvm its okay i hear it now. But when u hold ur video recorder near to the right side of the engine. The sound is really loud!

 

There's nothing wrong with your engines.

 

Here's the

for my bike.

The bike was started with a cold engine and then rev'd to 3,500-4000RPM. There is a sort of rattling sound from within the engine.

 

 

This is a normal rattling sound produced by most engines. It is caused by resonance within the engine whereby the parts vibrate at a particular engine speed. In the case of this CB400 Revo, the engine resonance occurs at revs between 3000 - 4000 RPM.

[ramsnake]

Hey Bros,

 

jus wanna ask a stupid question... does cb 400 spec 3 have a throttle body? i really have no idea if this pertains to EFI bikes only or carb bikes also hv?

 

On Spec 3, the throttle body is part of the carburetor. It is that part of the carb (usually round or oval) that is connected to the top block.

 

http://www.dansmc.com/cb400f.pdf

 

See page 5

[mrkookz]

Hmm..I appreciate your suggestion, but unfortunately, I'm still not convinced. I understand about resonant frequencies and know what you mean, but it really doesn't sound like a sound that should occur normally...especially from a Honda.

 

I could well believe there is a faulty part which is resonating at a specific frequency which causes the rattle at those rev ranges, but I struggle to believe this is normal for a bike like this. Especially for say @StrongBow's bike, with such low kms. Engines are well tested for resonance and components are balanced to avoid/eliminate untoward shakes and rattles under normal operating loads. I could understand it if it was say the instrument panel, or the fuel tank that vibrated, but for something internal within the engine to make a sound like that, I can't see it as being normal.

 

I've spent a lot of time looking at and listening to YouTube clips of CBs with different exhaust slipons (to find one I like! - suggestions very welcome btw... ) and at the same time I've also listened for engine sounds since most of the clips are done at idle or low rev ranges and its clear that the sounds we're discussing are not present on all CBs.

 

I'm still keen for other suggestions and appreciate the dialogue/discussion, @ramsnake.

 

 

There's nothing wrong with your engines.

 

This is a normal rattling sound produced by most engines. It is caused by resonance within the engine whereby the parts vibrate at a particular engine speed. In the case of this CB400 Revo, the engine resonance occurs at revs between 3000 - 4000 RPM.

[ramsnake]

Hmm..I appreciate your suggestion, but unfortunately, I'm still not convinced. I understand about resonant frequencies and know what you mean, but it really doesn't sound like a sound that should occur normally...especially from a Honda.

 

I could well believe there is a faulty part which is resonating at a specific frequency which causes the rattle at those rev ranges, but I struggle to believe this is normal for a bike like this. Especially for say @StrongBow's bike, with such low kms. Engines are well tested for resonance and components are balanced to avoid/eliminate untoward shakes and rattles under normal operating loads. I could understand it if it was say the instrument panel, or the fuel tank that vibrated, but for something internal within the engine to make a sound like that, I can't see it as being normal.

 

I've spent a lot of time looking at and listening to YouTube clips of CBs with different exhaust slipons (to find one I like! - suggestions very welcome btw... ) and at the same time I've also listened for engine sounds since most of the clips are done at idle or low rev ranges and its clear that the sounds we're discussing are not present on all CBs.

 

I'm still keen for other suggestions and appreciate the dialogue/discussion, @ramsnake.

 

@mrkookz, I likewise welcome the good discussion we're having here.

 

I am convinced that the sound heard from my bike engine is a resonance frequency sound. I emphasise that my conclusion is based on my bike only because I honestly can't be sure it is the case for your engine based on hearing the sound on youtube alone.

 

Let's assume that you are correct in that the sound comes from a faulty part. If that is the case, then my bike would have broken down a long time ago as I do really push the bike to the max when chasing litre sportsbikes on the highway!

 

As for @StrongBow's bike, his bike would also have the same sound because our bikes came from the same factory with the same parts. Thus resonance frequency sounds generally affect all engines of the same make and model at the particular engine speeds.

 

With regards to your listening to other CB sounds on youtube, were those bikes also CB400s or other CBs and were they rev'd to higher revs? The sound on my bike is not obvious until it is rev'd to 3.5-4k RPMs.

 

StrongBow also asked me a question offline, that is why does the sound disappear after the engine is warmed up? My theory is that the rattling doesn't disappear as such i.e. the resonance frequency vibration is still there. However by the time the engine is more or less warmed up, there is sufficient engine oil being pumped from the oil sump so that the oil dampens the vibrations. Thus less or no sound.

 

As for exhausts, the ones available in Singapore for Revo which are road legal are Yoshimura and Leo Vince. These are endcans only, not full systems. They are retailed at about S$900 and S$650 respectively. I've listened to both sound and they more or less sound equally bassy and rich. So, if I were to fit one, I'd go for the Leo Vince.

 

I'm not sure about your legislations in Australia. If Blue Flame exhausts are available there and they are road legal, go for it. They sound a bit louder than Yoshis and Leo Vince.

[ramsnake]

@StrongBow

Since your bike is under warranty and you already have an appointment with Honda, I suggest you send it in anyway. Don't just take my word for it, ok?

Do update us on what Honda says.

[StrongBow]

@mrkookz

 

i think i understand where ramsnake is coming from and might skip this trip down to boonsiew(honda distributor in singapore).

i will experiment again with a fully synthetic engine oil on my next change and see if this problem resurface.

May i know the viscosity of the engine oil u are using?

if i use a less viscous engine oil and still is experiencing this problem then only will i head down to boonsiew.

i will update again after my next engine oil change of course!

[ramsnake]

@mrkookz

 

i think i understand where ramsnake is coming from and might skip this trip down to boonsiew(honda distributor in singapore).

i will experiment again with a fully synthetic engine oil on my next change and see if this problem resurface.

May i know the viscosity of the engine oil u are using?

if i use a less viscous engine oil and still is experiencing this problem then only will i head down to boonsiew.

i will update again after my next engine oil change of course!

 

Eh, just go and see what the say, bro.

 

BTW, stick to 10W40 oil (as recommended by Honda) as your engine is new. My 85k km bike is still running on 10W40 too.