Engine vibration on my new (to me) 8th Gen.

[RedNineOne]

Convinced I was ready to move on from my 1993 3rd gen 750, I found a 2018 eighth gen 8 local to me - 11000miles, full service history, excellent condition. Now having put a few miles on it, I'm noticing it's a lot more vibey than my 750, often too much to be comfortable. Grips and foot pegs buzz a lot, in varying degrees across the rpm range from ~3500rpm upwards. I'm having a hard time really quantifying specific rpms that are a problem; it just seems to be a buzzy bike, to the point where I can get tingly hands / feet now and then. 

 

Oddly, I didn't notice it on the test ride before buying. But on the ride home it was quite buzzy and left me feeling concerned I'd bought a duffer. Thinking 'old fuel' could be to blame, I ran the fuel low then refilled with fresh... and it seemed a lot better and I was happy again. But since then the vibrations seem to have generally returned. I've tried 95RON, 99RON and two tanks of injector cleaner in the hope it was a old fuel / gummed up injector problem. Whilst there's possibly some variability to the vibration severity, it's fundamentally still there.

 

I'm convinced it's engine related - the frequency is way too high and the amplitude too small to be wheel balance or anything like that. Pulling the clutch in when moving makes the vibes stop. 

 

I had the LHS fairings off (to fit a Q/S) and took the opportunity to check every bolt I could find was torqued up, inc engine mounts. I've not done the RHS of the bike yet, maybe I should. What's stumped me though is that sense above that a fresh tank of fuel initially improved things noticeably, only for it to revert to vibey again. It's making me question myself as to whether it really did clear up temporarily or not.

 

So any thoughts?

 

Searching around there do seem to be a fair few threads about vibes on all the 800 FI bikes, but I've not found any real conclusions. I'd welcome any ideas, plus any view on whether the 800s are just more vibey than the 750s they replaced. As a 2018 / Euro4 bike, it's crossed my mind that they are fuelled too lean and maybe that's the issue. But not everyone seems to complain about their eighth gens.

 

I will contact the dealership I got it from, but given it's just out of Honda warranty and now swiftly heading towards the end of the dealerships own 3 month warranty, I can't imagine they are going to throw much effort in to chasing something as subjective and elusive as vibration. Beyond that, I like the bike and will probably sell the 750 eventually... if I can solve the vibes.

[Presson]

My 8Gen seems to be vibey through the grips particularly in the 3500-6000 rpm range. I notice it wearing thin race style gloves after an hour or so with numb fingers but not with thicker RST heated gloves. (I suppose I could just ride more aggressively).  I've not noticed it through the pegs or that different fuel makes a difference and assumed this is just normal. However I was a bit surprised as my old vfour (VF500F2) was buttery smooth through the rev range and I assumed all 90 degree vfours we're the same. Perhaps it's related to bore and stroke dimensions??

[tsmitty]

Are the stock bar ends in place. My 86 was very uncomfortable to ride without those weights on the ends of the bars. 

Some of the VF/VFR masters will be here in a few hours, hang in there...

[Grum]

Having never ridden a 750 I can't make any comparisons. But I can only say that my 8gen is easily as smooth if not smoother than my three previous 6gens.

I do recall once over tightening the drive chain and this certainly induced some strange speed related vibrations under load that I wasn't used to, immediately setting the chain correctly sorted the issue.

So have a good look at your chain, check its condition, age and tension, never overtighten a chain and err on the looser side of the tension tolerance.

The only other thing I've heard is changing the plugs cured some rough engine running with an 8gen, the OEM's were Denso plugs and not very old, fitting the NGK IMR9D-9H's solved the issue.

[VFR80025th]

I would have to agree with GRUM. MY 2014 VFR is so smooth its uncanny. Good luck and I hope you solve your issue.

[Thumbs]

At 11k it hasn’t had its first valve clearance check yet, not that it’ll make that much difference but one thing I noticed when I put a RapidBike fuelling unit on my 8th gen it made it run much smoother, evened out the VTEC transition and generally cleaned up the throttle response, which was pretty good before 

 

@16k you’re due the valve check, new plugs, air filter and the bike plugged into a Honda diagnostic unit, which should put the bike back in the condition it was originally sold in 

 

Using Esso Synergy 99 (which is 100% petrol) will also make a difference, it’s more expensive because there’s duty on 100% of it

[VFR80025th]

I believe Honda has moved the first valve adjustment to 24,000 from 16,000.

New plugs are required to be replace at 48,000km and I just checked the manual.

[Presson]

Correct, valve clearance on 8 Gen at 24k miles/36k km. See extract from the shop manual 

 

 

 

 

 

 

[VFR78]

The workshop manual says 16,000 mile check for 2014 and 2015 bikes, but 24,000 miles for 2016 plus bikes. Go figure! I thought the motors were unchanged, but maybe valve seat material etc. was changed.

[VFR78]

[Grum]

22 minutes ago, VFR78 said:

The workshop manual says 16,000 mile check for 2014 and 2015 bikes, but 24,000 miles for 2016 plus bikes. Go figure! I thought the motors were unchanged, but maybe valve seat material etc. was changed.

I wonder if it's more likley that Honda service statistics were showing that a 16,000 mile expensive valve check was simply unnecessary, and extending the interval was of benefit to both service agent and customer? 

[VFR78]

Maybe, and it was too much faffing about to  change the shop manual. Just add another page!

[RedNineOne]

Thanks for the replies folks. In roughly the order I read them:

 

- Bar ends - looks like the stock ones are in place - overall the bike looks like an original, well cared for machine, free of mods and meddling. Swapping for heavier bars ends has crossed my mind, but I'd rather aim at the root cause to begin with if I can.

 

- Chain - I've not properly checked it out, as the dealer did a PDI prior to selling it to me. But, good shout I'll give it a proper clean, get rid of the cacky chain wax they've covered it in, re oil it and check the tension. There are a couple of sticky links (mildly sticky, not stiff / seized) so I'll see what a clean / lube does for them. Rear sprocket looks in good order. One thing I did notice when fitting the Q/S - you have to remove one of the front sprocket cover bolts to refit with a cable clip; that bolt was wet with oil on the threads. I assume there might be a mild weep from the front sprocket seal.

 

- Plugs - yep, I considered pulling them, checking the condition and possibly investing in a new set. Though the schedule has them as Inspect@16,000mi, Replace at 32,000mi, so with only 11,000mi on the bike I've assumed... so far!... it's probably not worth the tear down to get to them.

 

- Valve clearance - likewise, as you guys note it's now 24,000mi, so again I assumed it wouldn't be worth the work.

 

- CCTs have me curious. I wondered whether a loose one might be knocking timing out just enough to be causing the vibes. It seems they can be removed and tweaked to give a bit more tension to the cam chain before eventually needing replacement.

 

I spoke to the dealer yesterday who will take it in next week for a test ride and go from there. Be nice if they agree and start digging. Fingers crossed!

 

[paulmeisterpk]

Whenever I've noticed vibrations on any of my 5th or 6th gen bikes, It's always been a chain issue of some sort. I'd lean towards the chain as Grum mentioned.

[Presson]

I took Grum's advice and loosened the chain a bit. It did seem to improve the numb hand problem over an hour of riding. Not completely but definitely better than before.

 

I had always adjusted the chain on the centrestand before, but reading here the words of wiser and more experienced heads ( Captain80s and Mohawk if I recall correctly), I did it on the sidestand and then checked slack when sitting on the bike.It's obvious really that loaded up the slack gets taken up. Anyhow, some 30mm of slack loaded up with me seems to make a positive difference. The fact that I also had insufficient preload on the rear probably didn't help. I was running 5-6 clicks from minimum and am now at 9-10 clicks (it's a 'deluxe' type for those in the US and I weigh 90 kg fully kitted).

 

The locus of chain tension on the VFR seems completely different from my GSXR which seemed more happy with a chain at the tighten end of the range whereas the VFR seems to prefer the looser end as Grum pointed out. 

[Grum]

7 hours ago, Presson said:

I took Grum's advice and loosened the chain a bit. It did seem to improve the numb hand problem over an hour of riding. Not completely but definitely better than before.

 

I had always adjusted the chain on the centrestand before, but reading here the words of wiser and more experienced heads ( Captain80s and Mohawk if I recall correctly), I did it on the sidestand and then checked slack when sitting on the bike.It's obvious really that loaded up the slack gets taken up. Anyhow, some 30mm of slack loaded up with me seems to make a positive difference. The fact that I also had insufficient preload on the rear probably didn't help. I was running 5-6 clicks from minimum and am now at 9-10 clicks (it's a 'deluxe' type for those in the US and I weigh 90 kg fully kitted).

 

The locus of chain tension on the VFR seems completely different from my GSXR which seemed more happy with a chain at the tighten end of the range whereas the VFR seems to prefer the looser end as Grum pointed out. 

 

Good news Presson. I guess its also fair to say that a V4, by nature, won't be as smooth as an inline 4 like your GSXR

[Presson]

Apologies to RedNineOne for hijacking his post. Hope a bit of chain loosening might help him or her too 

 

Hey Grum, I was intrigued by your suggestion that a V4 might not be as smooth as an IL4. I had assumed that a 90 degree V4 was always better balanced than an IL4 and not needing a balancer shaft.

[Grum]

56 minutes ago, Presson said:

Apologies to RedNineOne for hijacking his post. Hope a bit of chain loosening might help him or her too 

 

Hey Grum, I was intrigued by your suggestion that a V4 might not be as smooth as an IL4. I had assumed that a 90 degree V4 was always better balanced than an IL4 and not needing a balancer shaft.

Not qualified enough to comment on the primary and secondary balance pros and cons between an IL4 and V4, but it may be as simple as the firing angle pulses that are different between the two engines.

IL4 = Every 180deg of Crank Angle.

V4 180deg Crank = 180, 270, 180, and 90deg of Crank Angle.

[Terry]

I'm not qualified either!

 

Inline fours tend to have fine high frequency vibes due to the secondary crank imbalances, which can be countered using one or more balance shafts and/or rubber mounts. The 90 degree VFRs don't have any balance shafts as they have perfect primary balance but as my learned Australian friend suggests, they do have a more uneven power pulse which may feel like vibration to some or character to others. My argument completely falls apart with my ST1300 which is a 90 degree V4 and with balance shafts; the previous generation ST1100 never had the balance shafts, but that also used a steel tube frame not alloy beams like the ST.

 

My MT-10 is an in-line four with balance shafts, and a V4 firing order. It is nice and smooth at a cruise, and a bit "characterful" (shuddery) at low revs (<4k) under power. It sounds just like a V4 and I love it!

[VFR78]

1 hour ago, Terry said:

I'm not qualified either!

 

Inline fours tend to have fine high frequency vibes due to the secondary crank imbalances, which can be countered using one or more balance shafts and/or rubber mounts. The 90 degree VFRs don't have any balance shafts as they have perfect primary balance but as my learned Australian friend suggests, they do have a more uneven power pulse which may feel like vibration to some or character to others. My argument completely falls apart with my ST1300 which is a 90 degree V4 and with balance shafts; the previous generation ST1100 never had the balance shafts, but that also used a steel tube frame not alloy beams like the ST.

 

My MT-10 is an in-line four with balance shafts, and a V4 firing order. It is nice and smooth at a cruise, and a bit "characterful" (shuddery) at low revs (<4k) under power. It sounds just like a V4 and I love it!

Those cross plane Yamahas do sound great!