Honda VFR Club  

Go Back   Honda VFR Club > Technical Questions
Forgot Password? Join Us!
Sponsor the Club   Shop        Oracle Central        BikersOracleTours.com  

Reply
 
Thread Tools Display Modes
  #46  
Old 11-04-2005, 20:25
Rexb's Avatar
Rexb Rexb is offline
Registered User
 
Join Date: 06-12-03
Location: Newtownabbey , N.I.
Posts: 6,529
Thanks: 72
Thanked 37 Times in 33 Posts
Very Interesting, But Stupid !!!


I haven't read all of the discussion on this matter of Vfr low speed running but I can see what you're all getting at .

I can only say that when I got my 53 Reg Vtec(new) it had a low speed running problem too . After my Hornet this was a dissapointment ! At the 600 mile service/oil change I asked them to balance the starter valves and it was better after that . My friend Greg says that my bike runs rich , so maybe they "cheated" by just richening the mixture at low revs ?

Anyway , I for one would like my Vtec to run as designed , and not have to put Optimax or BP Super in to get it to run cleanly at low revs !!!

Thanks guys ! Keep up the good work !!
Reply With Quote
  #47  
Old 11-04-2005, 20:49
GreenVFR GreenVFR is offline
Registered Users
 
Join Date: 04-09-12
Posts: 3,325
Thanks: 0
Thanked 11 Times in 8 Posts
Hmmm. I've been staying out of this one because I was getting flamed early doors but I've improved my asbestos suit so here goes…

Without spending ages typing here is what I know to be fact:

If the O2 sensors were the "wrong" way around then the ECU would know. When it adjusted the mixture in, for example, cylinders 1&2 it would not see a corresponding change at the O2 sensor. As a result it would class the sensor as faulty and ignore it. This is why some of the people who swapped them over had the Fi light coming on. The O2 swap is therefore almost certainly a complete red herring. Ironically, the bike might well run "better" once the ECU decides the sensor(s) are faulty because it would be running on its much richer base map. However, it can't be left like that permanently.


Starter valve balance:
All the VFR800s run better with the valves properly balanced, particularly the FiYs/Fi1s and VTECs. I always balance the Fi bikes with 1&2 the same, 3 down 20 and 4 down 10, as specified.

For the VTECs I have been balancing them flat as per the manual. This, as a general rule, improves the bike. However some of them are very far out to begin with, so of course making them flat is going to help. Whether setting them differently would make it better still I can't say 'cos I 'aint tried it. What I can say is that it varies quite a lot from bike to bike. Some bikes seem OK with the valves way out, some need them to be spot on. However, this is probably as much due to "other factors" as the engine itself. For example a slack chain (most of 'em!) will make even the smoothest bike seem snatchy.

The reason I'm posting this now though....

I have an Fi myself, as you all know, but I also have a VTEC currently in bits in the workshop for its 16k service. So (with the owners permission) I'll do some experimenting. I'll try both my FiY and the VTEC with the SVs setup both ways. Because I can test them back-to-back we should get a much clearer idea how much of a difference it makes.

I should be able to do this on wed/thurs this week as those are my workshop days. I'll get someone with smooth throttle hand, probably Schtum (are you listening, clothlugs?), to run 'em as well and give a second opinion.

FWIW - (And this bit is my OPINION, ok?) I think it may be another red herring. While the SV balance certainly affects the bike I haven't yet found it to transform a good 'un to a bad 'un or vice-versa. Furthermore, the chances of the "missing" valve balance procedure being a simple typo seem slim. The induction system on the VTEC is quite different to the FiY/1. The throttle bodies are different, the SVs are drilled and plumbed differently and the intake trumpet lengths are different. Therefore it would seem unlikely that the balance should be the same as the Fi. However that is based on my own cynicism and no real evidence whatsoever. I look forward to being wrong....


Dave
Reply With Quote
  #48  
Old 11-04-2005, 20:54
Schtum's Avatar
Schtum Schtum is offline
Club Bard
 
Join Date: 13-03-02
Location: In the Howe of Fife
Posts: 17,769
Thanks: 12
Thanked 250 Times in 182 Posts
Quote:
Originally Posted by greenVFR
I should be able to do this on wed/thurs this week as those are my workshop days. I'll get someone with smooth throttle hand, probably Schtum (are you listening, clothlugs?), to run 'em as well and give a second opinion.
Finally.... Recognition.....

Ooh....does that mean I get to thrash the mammalian protruberances off somebody's VTec then?
__________________
"If it were done when 'tis done, then 'twere well it were done quickly" Macbeth
Reply With Quote
  #49  
Old 11-04-2005, 20:57
greeners's Avatar
greeners greeners is offline
Registered User
 
Join Date: 26-08-02
Location: Welwyn Garden City
Posts: 3,206
Thanks: 0
Thanked 1 Time in 1 Post
Quote:
Originally Posted by Schtum
Ooh....does that mean I get to thrash the mammalian protruberances off somebody's VTec then?


Glad mine's tucked up down south......away from you right pair of scally wags......
Reply With Quote
  #50  
Old 11-04-2005, 22:36
Wiz's Avatar
Wiz Wiz is offline
Tea Boy
 
Join Date: 12-03-02
Location: Essex
Posts: 8,126
Thanks: 67
Thanked 279 Times in 156 Posts
Quote:
Originally Posted by greenVFR
The induction system on the VTEC is quite different to the FiY/1. The throttle bodies are different, the SVs are drilled and plumbed differently and the intake trumpet lengths are different.

An interesting and useful contribution Dave, thanks.

A couple of points:

1) On the above, similarity must be a matter of opinion 'cos the training manual says:



2) I know that my problem isn't down to chain slack because a) I know what chain slack feels like and this isn't it and b) My bike has done under 2000 miles and this problem has been evident since I first rode it at 800 - there is no excess chain slack.

Your experiences adjusting the SVs are very interesting. I must admit I was hoping for a greater effect to be felt, although some people seem more sensitive to this problem than others. Dan didn't see a problem with my bike, but having last owned a silky smooth carbed bike, it seems intolerable to me. There is also a possible reason that balancing the vtec flat might improve things, all be it not be as good as it should be if my theory is correct (i.e. as not good as a 2001 model): The vtec registration SV is number 4, which on the previous model is slap bang in the middle of the recommended range. If the settings should be the same as the previous model, setting them all flat would put all the valves within 10 mmHg of the proper settings. Whilst this may not be optimal, it could well be much better that where they were before hand.

Thanks for your kind offer of experimentation. If I get success with mine and Honda do not want to comment, it will be very useful to have as many people trying this as possible.

Looks like I'll be seeing you the weekend after next and you can ride my bike and tell me what you think .
__________________
"There is no cure for birth and death - save to enjoy the interval."

Last edited by Schtum; 07-08-2011 at 19:14.
Reply With Quote
  #51  
Old 11-04-2005, 23:21
Rhencullen Rhencullen is offline
Banned Users
 
Join Date: 14-05-02
Location: Scunthorpe - Lincs
Posts: 2,603
Thanks: 0
Thanked 0 Times in 0 Posts
Quote:
Originally Posted by greenVFR
I'll get someone with smooth throttle hand, probably Schtum (are you listening, clothlugs?), to run 'em as well and give a second opinion.
Hmmm... you give someone an ounce of responsibility.......

Quote:
Ooh....does that mean I get to thrash the mammalian protruberances off somebody's VTec then? Schtum
and what do you get.....
Reply With Quote
  #52  
Old 12-04-2005, 00:32
GreenVFR GreenVFR is offline
Registered Users
 
Join Date: 04-09-12
Posts: 3,325
Thanks: 0
Thanked 11 Times in 8 Posts
Wiz,

The throttle bodies look similar and, from a mechanics point of view, they are similar. They write that training manual for mechanics, hence the wording of the manual. However the design of them is quite different. Some examples: the injectors are different. The pressure they run at is different. The pressure regulator is therefore different. The bodies themselves are different. The starter valves are different. The new valves are linked, just like it says in that page of yours, the old ones aren't. The valves draw their air from a different place, route it differently and then dump it into the intake in a differnt place, therefore the flow charteristics will be quite different. Etc Etc Etc Etc.

A tractor tyre and a bike tyre are both black, rubber and round. That does not make them the same. I have a set of VTEC throttle bodies and an set of Fi throttle bodies sitting on my bench side-by-side. In fact I have one of each engine open for fiddling, poking, prodding and your general delictation.

I don't do "opinion" when it comes to matters of engineering. I only deal in fact.

I wasn't suggesting for one minute that the problem with your bike, or any other bike, was caused by chain slack. I was simply pointing out that one bike being slightly better than another has many factors, not just the engine and throttle response. Furthermore those factors overlap, interact and generally affect one another, making sorting the wheat from the chaff very difficult.


See you in a fortnight, bring your drinking trousers and prepare for me to give you a world tour of V4 engines. Glazed expression optional, but if you fall asleep I reserve the right to have KDNY shave your eyebrows (He likes that sort of thing :k )


Dave
Reply With Quote
  #53  
Old 12-04-2005, 00:37
GreenVFR GreenVFR is offline
Registered Users
 
Join Date: 04-09-12
Posts: 3,325
Thanks: 0
Thanked 11 Times in 8 Posts
Fuck me. I just realised I'm close to 2000 posts. Far, far, far too much time on my hands.....



Dave
Reply With Quote
  #54  
Old 12-04-2005, 02:06
mark mark is offline
Registered User
 
Join Date: 13-03-02
Location: Stockton on Tees
Posts: 720
Thanks: 2
Thanked 1 Time in 1 Post
Quote:
Originally Posted by Wiz
As I understand it, from 0 to 4% throttle, the butterflies are closed and all throttle control is via the SVs which act as kind of "mini" butterflies.
I am unsure how this can be. Isn’t the throttle cable connected directly to the butterflies in the throttle bodies so as soon as the slack is taken up they will begin to open from 0-100%

I thought the SV (Starter Valve) were so known because they are modulated by the temperature of the cooling water, as is an automatic choke so they control startup RPM when the engine is cold. Once the engine is up to working temp they static.

but there again
Reply With Quote
  #55  
Old 12-04-2005, 07:49
Muppet's Avatar
Muppet Muppet is offline
Herr OberGruppenFuhrerReiseWan cer
 
Join Date: 13-03-02
Location: Bath (ish!)
Posts: 7,452
Thanks: 8
Thanked 50 Times in 39 Posts
Quote:
Originally Posted by Wiz
That was what I intended trying first on my bike, unless I can get an answer from HUK. If I can't, I will try emailing Japan as well.
Keith,

If you do need to e-mail Japan, you'll probably get a far better response if it's done in Japanese. The full character script, not just using the English alphabet. Even big corporations like technical requests done in their native language. If so, I obviously can get Keiko to do that for you. Thinking further about that, I wonder if anyone has the original, Japanese workshop manual she could have sight of to try and see if there's a difference/mistake due simply to translational errors. You may think it impossible with such a big company, but it's a complex language (I know, I'm trying to learn it ) and it's easy to alter the context of things. There are about 4 different ways of saying "and" for example.

Let me know if you need help on this.
__________________
Cheers
Clive

Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaim:

"Wow, what a ride".



Reply With Quote
  #56  
Old 12-04-2005, 10:10
Kieran's Avatar
Kieran Kieran is offline
Banned Users
 
Join Date: 13-06-02
Location: South Lincs
Posts: 1,200
Thanks: 0
Thanked 0 Times in 0 Posts
Poor throttle control & FI light

I can't add much to the ongoing technical debate, but for your general info.

My bike had it's first service yesterday (600 miles) and once the engine had warmed up after riding away from the dealer, I did Wiz' simple throttle test (3500prm +/- 500 prm).

What I found was that as I increased the revs, I could control the revs perfectly below 2500rpm. When the revs got to about 2700rpm, the revs automatically increased to about 4000rpm. I re-did the test about 10 times to make sure that it wasn't small movements of my hand causing it.

What I also found was that if I held the revs at about 4000rpm and tried to reduce the revs, as soon as the revs got to about 3800rpm, the revs just dropped off to about 2000 rpm.

Summary: I was not able to control the revs in the rev range 2500 to 4000 rpm.


Maybe not related but, on the 2nd/3rd day that I had the bike, the FI light came on as I was on the A34 passing Oxford. Had been riding for about 1.5 hours and was happily cruising along in 6th between 5000 - 6000 revs. Once I pulled off the road, I switched the engine off and back on again, and the FI light stayed off.

I did call the dealer right away (from the roadside) to get advice, in short he said that I could ride the bike home. When I took it into the dealer the next morning he said that the onboard computer hadn't registered any fault, and that as the bike has a Honda standard immobiliser & Averto alarm (which aparantly are wired into the FI light circuit?), it could have been the alarm system which caused the light to come on. I remain a little sceptical!!

Kieran.
Reply With Quote
  #57  
Old 12-04-2005, 12:35
GreenVFR GreenVFR is offline
Registered Users
 
Join Date: 04-09-12
Posts: 3,325
Thanks: 0
Thanked 11 Times in 8 Posts
I assume these "hold steady revs" tests are being done in first/second gear while the bike is moving? If so, OK. If however they are being done with the bike in neutral they are meaningless.



Purpose of starter Valves:
The purpose of the starter valves is to bleed air past the main throttle valves when the throttles are closed. Otherwise the engine would get no air at all and would stop. Hence their alternative name of "idle control valves". The same problem on a carb'ed bike is solved with a pilot jet(s) and pilot passage(s).

At very small throttle openings (approx 4%) the amount of air going through the starter passages is a significant proportion of the total airflow. (Air in starter circuit + air passing throttles ) Over approx 4% throttle opening the amount of air going past the throttles becomes so large that the air going through the starter passages becomes insignificant and can be ignored for the purposes of calculation.

All af that refers to THROTTLE POSITION it has NOTHING WHATSOEVER to do with engine RPM.



Dave


-Edit- P.S. 10mmHg is a ba' hair. In fact it would be unmeasurable on some cheap gauges. I'm struggling to see therefore how it could be responsible for such vicious symtoms. The next couple of days should tell...

Last edited by greenVFR; 12-04-2005 at 12:40.
Reply With Quote
  #58  
Old 12-04-2005, 17:38
nealeb nealeb is offline
Out of the flying Pan...
 
Join Date: 01-11-02
Location: Winchester
Posts: 3,807
Thanks: 0
Thanked 1 Time in 1 Post
My '03 VTEC ain't bad in the context of this discussion; a K&N a long while back improved it to the point that I never really think of there being a problem and what there is, I ride round. However, some of the earlier comments have made me realise that there is one occasion when I really do have problems, and that is "slow control". I realised just how bad this was doing practice manoeuvres during IAM riding. I just cannot hold the revs steady in the right kind of range to allow proper clutch control. I know that I am trying to control a big engine right down at a fairly sensitive level, but after a couple of years and the thick end of 30K miles, I should have reasonable throttle control. But I don't! But when I think of it, this is exactly the rev range in which the "test" mentioned above demonstrates problems! Now that it is out of warranty anyway, I feel that a Carbtune is on the cards and I shall have a go myself. Always wanted to have a play, anyway, and any excuse to buy new tools works for me
Reply With Quote
  #59  
Old 12-04-2005, 18:13
Wiz's Avatar
Wiz Wiz is offline
Tea Boy
 
Join Date: 12-03-02
Location: Essex
Posts: 8,126
Thanks: 67
Thanked 279 Times in 156 Posts
Quote:
Originally Posted by greenVFR
I assume these "hold steady revs" tests are being done in first/second gear while the bike is moving? If so, OK. If however they are being done with the bike in neutral they are meaningless.
Can't agree with you on that one Dave. I accept that the test if very far from being a good one, but by doing the test in 1st or 2nd gear, you are adding load to the engine which will serve to reduce the effect of any surging. By have no load on the engine, you are showing up any surges in the very worse case situation (other than maybe in a negative load situation such as when coming down a steep incline.)

There is also the fact that three other bikes I have tried (a 2001 model, a Blackbird and a CBR600) can all pass this simplistic test, so why not the VFR? All it is demonstrating is the ability to control a throttle with no load on the engine and if you can do that, controlling it with load should be easy. Most importantly, it is an actual test that I can carry out, rather than the more subjective "it seems much better to me" type thing.

With regard to your edit, the specification for the previous model was only to allow a margin of error of +- 5 mmHg. If that is unachievable or makes no real difference, it would seem strange that Honda should specify it in the manual . That, coupled with testimony from Geoff and other members who have had their SVs balanced and have noticed very big differences, would suggest that values of more than 5 mmHg could have a significant effect on performance.

Still, Geoff will be here in about 1/2 an hour and the speculation can end
__________________
"There is no cure for birth and death - save to enjoy the interval."
Reply With Quote
  #60  
Old 12-04-2005, 21:36
TUBMAN's Avatar
TUBMAN TUBMAN is offline
Registered User
 
Join Date: 16-01-05
Location: South Shields
Posts: 69
Thanks: 0
Thanked 0 Times in 0 Posts
Offload Testing

I have swapped my 02 sensor plugs around & balanced my SV,s within +/- 1.5mmHg - about half of one graduation which is 5mmHg per graduation (in parallel - used carbtunes) and my control of revs under no load is absolutely crap compared to other bikes i have owned (tried the 3500 - 4000 rpm test etc & totally failed). The fluctuation is just not right. Under load conditions problem is not as apparent but you can feel/sense that it could be a lot better but you tend to live with it. Once you get above 4000 revs the bike performs turbine like with strong smooth power delivery but feels lumpy below that unless you are accelerating thru and above 4000 revs. For anyone using carbtunes would advise to keep as vertical as possible as the indicating rods do not respond as well if slightly leaned backover.

Paul

Last edited by TUBMAN; 13-04-2005 at 18:58.
Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump


All times are GMT +1. The time now is 10:25.


Powered by vBulletin® Version 3.7.3
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Copyright Bikers Oracle Ltd 2004 - 2009