VTEC - Page 3 - SV650.org

Sid Squid · 12-09-05, 05:54 PM

True of course, but I wasn't much concerned by what Honda describe it as or call it.

VVT = Variable Valve Timing

VTEC doesn't vary the valve timing, duration or lift, it makes two of the four valves in each cylinder work at low revs and all four at higher revs. (But I'm sure you realise this).

northwind · 12-09-05, 05:59 PM

I do

But like I say, that's all definitions. You could still call that variable valve timing, just with 0 as one of the settings for one set of valves.

Biker Biggles · 12-09-05, 06:05 PM

Whatever the correct names,the current systems are pretty crude.They are all two stage systems with one map for the lower end of the rev range and another for the top.Whether that is two valves going to four or a genuine second cam profile coming on stream matters not,you still have low\high rev tuning,one or the other.
If you could have a different map for every RPM\gear\throttle scenario there is scope for massive progress.
You could build an engine of about 600 cc with the top end of a superbike,the bottom end of a Harley and anything you wanted in between-------In theory,and no doubt at a price.

Sir Trev · 12-09-05, 07:31 PM

I know several people who, after getting a quote for their up-coming major VFR VTEC service, where the timing is checked, have put their bike straight up for sale. The additional hours of labour are apparently quite severe.

The other problem of course is that if you put something so different on a bike the independant trade are not so sure on how to service them, so you are more likely to be forced* to stick to the (much more expensive) franchise dealer with their "factory trained" technicians.

It is good that Honda and others are experimenting. Progress needs it and you have to try things in the real world sometimes. Can't blame them for it and hopefully knowledge will increase as a result of it. Personally though I'll keep clear for now!

*this may be just in your mind of course

12-09-05, 05:54 PM	#21
Sid Squid No, I don't lend tools. Mega Poster Join Date: Jul 2003 Location: Skunk Works, Nth London Posts: 8,680	True of course, but I wasn't much concerned by what Honda describe it as or call it. VVT = Variable Valve Timing VTEC doesn't vary the valve timing, duration or lift, it makes two of the four valves in each cylinder work at low revs and all four at higher revs. (But I'm sure you realise this). __________________ If an SV650 has a flat tyre in the forest and no-one is there to blow it up, how long will it be 'til someone posts that the reg/rec is duff and the world will end unless a CBR unit is fitted? A little bit of knowledge = a dangerous thing. "a deathless anthem of nuclear-strength romantic angst"

12-09-05, 05:59 PM	#22
northwind Moderator Mega Poster Join Date: Jan 2004 Location: In the garage where I belong Posts: 17,083	I do But like I say, that's all definitions. You could still call that variable valve timing, just with 0 as one of the settings for one set of valves. __________________ "We are the angry mob, we read the papers every day We like what we like, we hate what we hate But we're oh so easily swayed"

12-09-05, 06:05 PM	#23
Biker Biggles Member Mega Poster Join Date: Jan 2005 Location: Barnet Herts Posts: 5,071	Whatever the correct names,the current systems are pretty crude.They are all two stage systems with one map for the lower end of the rev range and another for the top.Whether that is two valves going to four or a genuine second cam profile coming on stream matters not,you still have low\high rev tuning,one or the other. If you could have a different map for every RPM\gear\throttle scenario there is scope for massive progress. You could build an engine of about 600 cc with the top end of a superbike,the bottom end of a Harley and anything you wanted in between-------In theory,and no doubt at a price. __________________ On a clear day we stand there and look further than the ordinary eye can see.

12-09-05, 07:31 PM	#24
Sir Trev Member Mega Poster Join Date: Jun 2005 Location: High Wycombe, where the chair factories used to be Posts: 1,479	I know several people who, after getting a quote for their up-coming major VFR VTEC service, where the timing is checked, have put their bike straight up for sale. The additional hours of labour are apparently quite severe. The other problem of course is that if you put something so different on a bike the independant trade are not so sure on how to service them, so you are more likely to be forced* to stick to the (much more expensive) franchise dealer with their "factory trained" technicians. It is good that Honda and others are experimenting. Progress needs it and you have to try things in the real world sometimes. Can't blame them for it and hopefully knowledge will increase as a result of it. Personally though I'll keep clear for now! *this may be just in your mind of course __________________ We are the Goon Squad and we're coming to town, BEEP BEEP!

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