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Introduction and Newbie Question re VTEC Transition


BlackheathMatt

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Hi All - First Post.

 

I've had my 2005 6th Gen since the beginning of the year. I haven't had a bike for 10 years or so prior to that, but always liked VFRs and was pleasantly surprised how affordable they've become. I'm loving my bike so far.

 

I bought my bike from a private seller with 32,000 miles on the clock - bike is nice and clean and seems to be completely unmodified apart from R&G fairing protectors. I haven't ridden much until recently due to lock down, but have enjoyed working on the bike and getting it the way I want it.

 

I inherited the previous owner's charging problem, "The Drill" and the vast amount of knowledge here were very helpful. My problem was a burnt stator but I also changed the R/R for a MOSFET one and added a VFRNESS and a voltmeter. Now gives a consistent 14.4v throughout the rev range. Fingers crossed.

 

My question is about VTEC transition - or in my case the apparent complete absence of any noticeable transition. Having had a 10 year break from bikes, I'm taking it easy and progressively building more confidence, but am now getting more confident using more throttle and revs - from everything I read and particularly with my bike being a pre-2006 VTEC I was expecting a noticeable, disconcerting "jolt" at 6.7k rpm when the additional valves start operating, but I haven't noticed anything. The bike obviously starts pulling much harder at 7k+ and there's a noticeable change in the exhaust sound, but no "jolt" that I can notice - just a nice smooth linear increase in power. 

 

I conclude that either the VTEC transition "problem" has been massively overstated - or my bike has been modified by a previous owner (of which there have been several) to smooth it out. I read that a Power Commander is the favoured way to smooth out the transition - I've had both front fairings off and I see no evidence of one there nor under the seat - but I haven't had a need to remove the rear fairings - not sure where to look for a PC if there was one. I have noticed though that both 02 sensors have been disconnected and replaced with blank electrical connectors ( I think with resistors in them but haven't put a meter on them to check). No complaints at all about how the bike runs.

 

Would be very grateful for your thoughts - is VTEC Transition simply not a big deal ? Or have I been lucky and a previous owner has sorted my bike - and if so what might they have done ?

 

Cheers

 

Matt

 

   

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  • Member Contributer

Hi Matt

 

Welcome back to riding and congratulations on owning a VFR. The normal place for installing a PC is under the seat. You then have an earthwire that bolts directly to the negative terminal of the battery and then two large multi plugs that break into the loom under neath the right hand side of the fuel tank and below the air filter by the throttle bodies. If you can’t see it under the seat I would be surprised if it was fitted anywhere else due to space. Mine is fitted on the opposite side to where the tool kit is housed under the big rubber band, almost under the passenger grab handle.

 

Have a look at this video as it will show you where it fits a connects. This is for a PC 3 USB version which is the same as mine

 

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2 hours ago, Marooncobra said:

Welcome back to riding and congratulations on owning a VFR. The normal place for installing a PC is under the seat. You then have an earthwire that bolts directly to the negative terminal of the battery and then two large multi plugs that break into the loom under neath the right hand side of the fuel tank and below the air filter by the throttle bodies. If you can’t see it under the seat I would be surprised if it was fitted anywhere else due to space. Mine is fitted on the opposite side to where the tool kit is housed under the big rubber band, almost under the passenger grab handle.

Welcome to VFRD, Matt!  As you're already found, this site has a wealth of great information on VFRs.

 

I agree with everything Marooncobra said.  I have the same setup on my 6th gen.  I don't know why anyone would mount a PCIII anywhere else.  But since it sounds like oxygen eliminators are installed, I would figure there has to be a Power Commander installed somewhere.  If I remember correctly if a bike only had the O2 eliminators installed and not a PCIII, it would run very badly.  But it's been so long since I researched this I really can't remember for sure.

 

I will tell you that even without a PCIII, the bike's VTEC transition should have smoothed out over time, especially as the mileage increased.  Again, if I remember correctly, around 10,000 miles things just smooth out in general.  The only times I've felt a jumpy transition over the last 10+ years has been after I've ridden the bike through rain.  For some reason it makes the next VTEC transition kind of rough, but I learned to anticipate this and live with it for many years, so it doesn't bother me.

 

Have fun riding your VFR and stay safe!  🙂 

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Thanks Chaps. I got quite familiar with my bike's electrics as a consequence of sorting out the charging problems and there's nothing that looks like a PC under the front fairings or seat - so unless it's tucked under the rear fairing somewhere, there isn't one. But the fact that it's got O2 eliminators and it rides so smoothly made me wonder.

 

The install video is useful, thanks - I'll check if the additional plugs are present next time I have the fairings off and follow back any wires if I find. But hiding the PC somewhere you can't easy access it when there's a convenient place for it under the seat doesn't make much sense.

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Hi Matt and welcome to VFR ownership.

 

I don't believe you need a PC if you have O2 elims fitted. I fitted them to my 08 VFR and never fitted a PC and she ran beautifully. I also removed the PAIR system completely, blocking off the PAIR valves with a set of Mello Dudes blocking plates and again, she ran beautifully. 

 

As for the VTEC transition, some VTECs have a rough and noticeable transition, some have a fairly smooth one. Sounds like yours is the latter. If yr not sure, bring yr bike up to me and I'll see how it is. I'm near J10 of the A1.

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Thanks Skids - that's reassuring. I'm pretty sure that if there was a PC I'd have found it but nice to know that the bike apparently running O2 eliminators without any other obvious changes isn't cause for concern. Sounds like I've just got lucky and got one of the smoother ones.

 

I live in London but often spend weekends in Dorset where my bike lives (don't ask, its' complicated!) - but if and when I bring it to London I'll take a run up the A1 and see when you think.

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  • 2 weeks later...
  • Member Contributer

My bike is a 2002 and I never thought the transition was particularly annoying or even noticeable unless I was looking for it.  Now at 42K miles and with the flapper valve delete, etc...I don’t even notice a change in sound, it just gets louder as the RPM’s go up.  I do not have a PC or O2 eliminators installed, but I did take out all the things that would make a difference in sound, the PAIR and flapper valves.

 

One thing to try though since I just discovered it (recently re-acquired my VFR), is it looks like we can defeat the closed-loop O2 mode entirely with a start sequence trick.  Turn the key on, igntition switch on.  Let the FI system charge completely (whine from the pump and start up on the console).  Key off for a second, then back on and hit start before the start up sequence can complete again.

 

It definitely works on my bike and shuts off some annoying aspects of the closed loop mode.  It doesn’t bother everyone as much but it’s super annoying to me to have to fight the throttle when I am in and out of steady speed.

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