2000 VFR Engine Vibration - diagnosis?

I've been enjoying my 2000 VFR800 immensely since I got it this past winter.....put a couple thousand miles on it already due to the warm winter and unusually warm spring. Overall the bike runs great, gets great gas mileage (average 47mpg), and is a blast to ride.

That said, I noticed from day one some vibration that I never had with my old gen2 VFR700.....I know that bike was a completely different beast, but it was smooth as silk and this new bike feels like a log wagon in comparison sometimes. Here are the "symptoms"....

For starters, the bike runs/idles smoothly and pulls strong, however, when accelerating I feel a lumpiness or "chatter" vibration....almost what you would feel if the bike was in too high of a gear while trying to accelerate, but not that extreme. I feel the vibration in the bars and in the footpegs the most.

The other time that it gets noticeable is when cruising (in any gear really) between 4500 and 5000 RPM. The vibration almost feels like an out of balance wheel....but it definitely is not that....I can pull the clutch and coast at speed and the chassis is smooth as silk.....the vibration is definitely the engine/tranny. This is unfortunate, because cruising at about 65-70 mph is right in that range.

The bike has roughly 16k miles on it. It is due for the valve clearances checked right about now. Other than an oil change and filter replacements, i've not touched the drivetrain since getting the bike this winter. The chain and sprockets seem fine and the chain slack seems within spec.

This is my first Fuel Injected bike, so I'm unfamiliar with how these bikes normally run. Is it possible that this is a starter valve synchronization issue? Any other thoughts?

 

Not sure if the same issue but I had a weird ambiant temperature related vibration issue where even if the engine temp was low when riding on open roads a vibration would start around ambiant 18C ( 65F ) then worsen gradually as the ambiant temp rose.

My resolve was plugs were checked ( were good ) , oil / Filter changed, Oil Cooler removed and cleaned, air box air senser cleaned and the engine bolts removed and re-torqued to factory specs.

Not sure which fixed it as they were all done by my regular mechanic at the same time but it worked for me.

 

Well for starters the firing interval of the newer 750 and 800 bikes is different than the early bikes which used a standard 180 degree firing interval. The newer bikes use an uneven firing interval which is done to alter the inertial characteristics of the crankshaft in order to achieve more controllable output at higher rpms. Since the gaps between firing pulses are inconsistent, it is to be expected that the engine vibrate a bit more. This uneven firing interval also gives you the great sound these bikes are known for. (Look up crossplane R1 explanation on youtube for a very nice clip explaining this kind of firing interval in a four cylinder engine.) These early fuel injected VFR's also do not like to be run at low rpms, anything below 3500 rpm is generally off limits and the engine will chug and snort if given anything more than slight throttle at this engine speed. There is also a possibility that the throttle bodies are out of sync and causing a power imbalance between cylinders. The last thing I can think of is have you checked the chain very closely? Worn or out of adjustment chains will cause vibrations on these bikes. I can almost tell when mine needs attention. At 16k if the bike still has the original chain and sprockets, its likely time for a new set. Be careful not to make the chain too tight. I always err on the loose side as overtightening will eat the chain. If you grab on of the pins at the center of the rear sprocket and pull the chain away from the sprocket, it will give you a good indication of chain wear. It you can see more than half of a tooth on the sprocket, the chain is toast. I hope I could help, good luck.

 

Thanks for the explanation of the engine differences between new/old. Interesting and I will go look up the video you suggested.

Good to know that the low RPM "chug" is normal....that takes relieves a bit of my worry. I still feel like this cruising RPM vibration is excessive, though. My gut tells me that it's the throttle bodies are out of synch and that's where I should start. The drive chain really is in good condition and doesn't show any signs of stretch and is slacked properly. I may go ahead and change it and the sprockets out, though, simply because I don't know the history of the chain (how it was maintained)....and to just rule that out as the source. Seeing as the vibration tends to be related to RPM regardless of gear/speed, I'm thinking the chain is not the source of the issue, though.

Appreciate the help!

 

Its normal for a big bang engine, both my 6th gen and my 5th gen does it and my 09' R1 was the same way in the lower rpms under load it rumbles and vibrates until it gets to a higher rpm.

 

My 5th gen 2000 model had this same problem when i got it, all it needed was the chain adjusted correctly & the throttle bodies balanced as per the Honda manual, unlike normal 4 cylinders every cylinder is NOT the same on the vacuum gauges. the 5th Gen should be set as follows;-

Warm engine to normal operating temperature.
Set idle speed to 1200rpm +/- 100rpm, using idle speed adjuster through the right frame rail, long thin screw driver required.
(Note on mine the Tacho reads 150rpm high compared to computer readout from my power commander !)
Attach vacuum gauges or use a single gauge if you are not sure they all read the same !
#1 (rear left when sat on bike) is the base line fixed reference vacuum, so you can't adjust it. Note mmHg reading.
#2 (front left) is set the same as #1 in mmHg.
#3 (rear right) is set -20mmHg from the #1 reference point, plus or minus 5mmHg.
#4 (front right) is set -10mmHg from the #1 reference point, plus or minus 5mmHg.

Recheck idle speed if it has changed reset it & then compare the cylinder reading again & adjust if necessary.

This made a huge difference to the smoothness of my engine. Note that Honda have put vacuum tubes on the side of the airbox to make this simple.

Have fun.

 

Err the 5th & 6th gen are NOT big bang, they are normal with 180degree crank. The orginal VFR, RC30 & RC45 are big bang with a 360degree crank. OK it's not a screamer in the same way as an inline 4 because of the piston firing intervals, but none the less it not a big bang, as only 2 of the power pulses are 90degrees apart. The rest are relatively evenly spaced. So you might get away with a description of semi-big or little bang engine !

I know Yamaha copied its firing order to get more torque from the R1, but its not the same as the 360degree V4's with there 2 -- 2 firing order.

 

Thanks guys. I checked chain slack and wear today. All is good in that regard. Reving the engine in neutral confirms that the vibration I'm feeling is definitely coming from the engine, not the chain/sprockets. I began getting my equipment out to do the synchronization of the starter valves only to find that I don't have a 7 mm wrench to turn the screws.....so it will have to wait til later in the week when I can get one. Will report back once that it's done to let you know results. Thanks again.

 

Hi Indyfour, You don't need a 7mm spanner, they are very lightly spring loaded & have a cross head top, I use a piece of flat 3-4mm wire with a 90degree bend in the end as they are a sod to get at. If you don't have flat wire, like old car wiper reinforcing etc, then a bit ot wire coat hanger can be hammered flat on the end to make your syncro tool !

 

Thanks for the tip. I hadn't thought about that. At one time, I had a couple of 90 degree phillips head drivers lying around and thought about using those, but they may not fit down into the space between the screws and the frame. I will try your trick.

 

Well I finally got around to doing this yesterday. Valve #3 was off (high) by about 15-20 mmHg. Dialed it in the best I could and took it for an extended test ride. Definitely improved greatly. I need to find a single vacuum gauge that is in smaller increments....I have a set of four on a rack (for carb balancing) and it is in 25 mmHg increments....not so good for getting exact measurements. Until then, it is much improved.

Thanks again for the help.

 

:SHRUGS: VFR800 mention as a big bang Big-bang firing order - Wikipedia, the free encyclopedia

 

Don't believe everything you read on Wiki, its written by enthusiastic individuals, that may not have done the research or understood it correctly if they did before submitting data.

The Bing Bang was coined for the NSR500 which fired all four cylinders in <70 crank degrees. The Yam R1 is not Big bang, its cross plane to get the smooth torque delivery of the V4 layout, it doesn't make more or less than older R1's, just in a better way. The RC30/45's are NOT Big Bang, but are closer to it with their 360 crank than a VFR800 with its 180 crank. The VFR800 has one 90 degree firing seperation, so could be called mini or little bang & the RC's could be called Medium Bang. I think the Wiki guys reference to "droner" is better than Bang. It's that single odd firing interval that cause a small amount of vibration on the 800.

See here for a good vid of the Yamaha Cross Plane Crank & what its all about ! 2009 Yamaha YZF-R1 engine technology explanation - YouTube skip to 2:10 to get the full SP from Yamaha.

 

OH & reading this bit "Because of a big bang engine's power delivery imbalance, there exists more vibration and stress in the engine. This imbalance can overwhelm the rear tire, and generally makes a slide harder to catch." kind of proves my point. The Big Bang firing order was designed to make slides easier by giving the tyre a long rest between BIG power pulses ! The old screamer (again coined to refer to the traditional firing order) NSR500 would come on pipe so quickly that a slide would ensue if the bike was still cranked over & then run away before the rider could react. The Big bang motor induced the slide the same, but then having no power output for a 230 degrees allowed thew tyre to grip again & thus broke the slide. Mick Doohan used to ride the screamer covering the rear brake on corner exit, as he wound on the throttle he would press the rear brake if the tyre statered to spin, thus loading the drive train & stopping the wheel getting out of control, i.e the brake reduced the power to the wheel !

 

My idle typically sits at about 1000, and I'd like to turn it up just a bit. Can you give me a little more insight into where this is? I'm not much of a wrench turner, so if you had the layman's explanation, that would be great.

 

If you look on the right side frame rail you should see the VIN plate, just in front of that you should see a black rubber plug, small round & black ! That plugs the frame to keep water out & when prised out allows a long thin screw driver to turn the throttle idle postion adjuster, turn clockwise for more REVS.
You should get the bike to normal opperating temperature before adjusting the idle. If the screw is stiff, just open the throttle a little then turn the screw & release the throttle.
Remember to puty the plug back when finished.

 

Appreciate it, sir. Even I'll be able to handle that!

 

Apologies for reviving an old thread. Tried to sync my starter valves yesterday based on what the manual dictates. The vacuum gauge i purchased doesn't seem to work properly as the needle bounces back and forth so fast I can't get a true reading so I'll have to purchase another. Any suggestions on a particular model/brand? Also, if the #1 is the baseline, what is the actual reading supposed to be? Or will this be different between bikes with varied mileage/engine wear.
Thanks in advance,
Mike

 

Some gauges have an adjustment screw for adjusting that flutter.

The fixed cylinder is preset at the factory. You are right, based on exhaust modifications, wear, valve adjustment, etc. the raw vacuum number may differ. So the point is to equalize the relative vacuum. Now it does behoove us to know an approximate reading to know there is not an egregious leak somewhere. I have not done this but check out youtube videos. I think you'll see 20-25 cm Hg (8-10" Hg)?

I've questioned the brand/model thing and someone who seemed quite experienced stated that for this purpose any should do - the 4-column liquid types, or 4-analog gauges.

Others have posted available gauge models at Amazon. This forum site search is terrible and I cannot find them at the moment. Maybe people will chime in here.

 

Thanks Knight. It was just a cheap ass gauge to begin with. Will source a new one. I'm just trying to sort out some engine vibrations. And I've eliminated most everything else that could be the culprit.

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