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2015vfr

Loss of Power during VTEC transition

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On 7/12/2019 at 11:09 PM, BusyLittleShop said:

I was so surprised to feel the hit in Honda's famous linear power

To the op, sorry I haven't any suggestion other than to ensure that all is well with the bike. The transition on my '09 varies depending on gear, and on how quickly the revs are climbing. My one, short ride on a '14 didn't offer any insight into its VTec behaviour. And frankly, I was more interested in its off-on throttle response, and how that compared with mine.

 

 The VTec is all sizzle and no steak, and is a primitive system compared to its implementation on Honda's cars. The '98-'01 VFR800 have the same performance without the annoying (at times) hiccup in the middle of the power band. And without the equally annoying twitchy throttle that also plagues 6th gen VFRs

  It is clear from Honda's 2002 VFR press blurb that the goal was lower fuel consumption and lower noise, and VTec was their chosen method. 

 

I like my '09 VFR a lot, but despite VTec and not because of it. Fwiw, I've racked up 80,000 km on it, and another 120,000 km on my 5th gens.

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I gather owners either didn't want VTEC or since the VFR is other wise perfect all a rounder they just put up with it... not enough owners say they love VTEC for Honda to justify lower fuel consumption...  

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I just wish they would have figured out a way to do it with gear drive cams!

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VTEC and gear drive are not mutually exclusive; the cams don't care how they are being spun. My take on the loss of the gear drives is it made the engine cheaper to build and reduced engine noise. 

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Absolutely... They could have, and I would be willing to bet that money made the decision, not engine noise. Still, in the end, they didn't...

 

As long as we're way off the OP's topic, did I hear about someone building a hybrid gear driven VTEC from two VFR engines, or did I imagine that?

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On 7/29/2019 at 6:16 PM, Terry said:

 the cams don't care how they are being spun.

HRC cams cares...

Granted most street 4 strokes use a simple chain to turn the cams whereas Honda's

race bred V4s employ gear-driven cams for the simple fact gears provide the most

accurate and reliable form of cam operation regardless of RPM...

 

Every time I hear that cam gear whine I know good things are about to happen...

RC45TroubleShooting_Page_10.jpg

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On 7/30/2019 at 5:46 AM, Marvelicious said:

Absolutely... They could have, and I would be willing to bet that money made the decision, not engine noise. Still, in the end, they didn't...

 

As long as we're way off the OP's topic, did I hear about someone building a hybrid gear driven VTEC from two VFR engines, or did I imagine that?

Mark Harris on the UK VFR forum put a pre-VTEC 800Fi engine into his 6th gen a few years ago, still has the bike. 

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2 hours ago, fatshoutybloke said:

Mark Harris on the UK VFR forum put a pre-VTEC 800Fi engine into his 6th gen a few years ago, still has the bike. 

Not what I meant... I think there are a few of those that have been done. I'm talking about driving a VTEC head with gears. Much more difficult and I think I probably imagined it.

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On ‎7‎/‎9‎/‎2019 at 8:08 PM, squirrelman said:

good luck finding a shop capable of fixing something complicated.

Exactly. This is the problem with today's high tech motors, the mechanics are low wage.

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Hi - did you ever resolve this ? Mine has done it since new - I get a strong judder/stutter/jerk as the vtec kicks in.  Worse when wet - not clever if it kicks in on a wet bend or wet overtake.  Been back to the Honda shop several times and they can't find a problem.  Thanks.

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On 9/15/2019 at 2:24 PM, DanVFR2014 said:

Hi - did you ever resolve this ? Mine has done it since new - I get a strong judder/stutter/jerk as the vtec kicks in.  Worse when wet - not clever if it kicks in on a wet bend or wet overtake.  Been back to the Honda shop several times and they can't find a problem.  Thanks.

No, just happened again today. In 4th gear, moderately heavy on the gas after a freeway transition, jerked me forward into the bars. Unpleasant and does not inspire confidence in the bike.

 

I have not taken it into the dealer yet.

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2 hours ago, 2015vfr said:

No, just happened again today. In 4th gear, moderately heavy on the gas after a freeway transition, jerked me forward into the bars. Unpleasant and does not inspire confidence in the bike.

 

I have not taken it into the dealer yet.

That just should not happen. I wonder wether you have an issue with the VLC solenoid (Valve Lift Control solenoid), could it be internally sluggish or, the one wire electrical connector for it gone high resistance? As it is only a one wire device it requires good Ground bonding to the battery negative! 

Assume you are running correct viscosity oil? (Just a long shot!)

 

During 4 valve transition the ECM will very quickly adjust timing and fuelling as the VTEC valves slip into operation, would imagine the timing of the valve engagement and synching that to what the ECM is doing with fuelling and ignition to be critical for a smooth transition.

 

Seeing its out of warranty and If it was my bike I'd certainly have a good look at the VLC Solenoid one wire connector and try driving the valve independenty with a 12v source listening to the valve click every time voltage is applied (as per service manual)

 

Other than that, I'd probably head off to a reputable Honda dealership, one that would be prepared to consult with Honda Japan if the dealership doesn't have the answer.

Not sure if this helps but good luck with getting it sorted.

My current 2014 8gen most definelty has the best overall VTEC transition than my three previous 6gens.

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All this talk of the VTEC taking you by surprise WTF ....transition is 6,700, it doesn’t move around

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3 hours ago, Thumbs said:

All this talk of the VTEC taking you by surprise WTF ....transition is 6,700, it doesn’t move around

I often look at things other than my tach. 

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On 19 September 2019 at 3:57 PM, 2015vfr said:

No, just happened again today. In 4th gear, moderately heavy on the gas after a freeway transition, jerked me forward into the bars. Unpleasant and does not inspire confidence in the bike.

 

I have not taken it into the dealer yet.

Is there any chance you could get to compare your bike to another 8gen. Perhaps there might be a VFRD member near you that may be able to help you out, shouldn't matter wether it's a 2014 model onwards. Think this is the only way to conclusively know if you have an issue, although, based on what you say, it doesn't seem right.

 

Also DanVFR2014's comments "I get a strong judder/stutter/jerk as the vtec kicks in.  Worse when wet". Think he also needs to compare his to another bike, especially as he states the "Honda shop" can't find a problem!

 

Another more scientific option may be to have your bike Dyno checked and present any findings to the Honda dealership.

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