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Jerky At Low Speeds


Pymzola

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Hi all,

I'm Martyn from the UK. New to the forum :) Love all the great info.

I've not long owned a 2003 VFR800 with 11,000miles. It seems that it is very lumpy/jerky in traffic or up to about 5k RPM? I tried the PAIR and flapper mod and this improved it however feels a bit rough. Is this normal?

I also carried out a few voltage checks on the bike as it feels like its misfiring and what I noticed is that at idle I'm at 14.0v but when I rev it to 5k RPM the voltage drops to 13.8v? should the volts not go up?

Thanks.

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One really easy fix is throttle free-play. I've had issues with both my 02 and 03. Beyond that, look into a power commander to correct the fueling. Loads of stuff on here about that. Welcome to the club.

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Also check the spark plugs for wear and spark. while you have the tank up for the plugs balance the throttle bodies.

For the voltage concern check the stator to R/R connection for corrosion/melting and test the stator.

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Starter valves, as Switchblade says. Start there and work down the list if that doesn't sort it.

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Hi thanks for the replies.

The Honda garage that I bought it from carried out a service so new plugs etc, they also balanced the starter values. I'll check the stator to R/R connection for corrosion/melting and test the stator as mentioned.

Oh does a Power commander make a noticeable difference?

Thanks again.

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Are you sure they balanced the SVs? It's not part of a Honda service and many garages have never even heard of it. But if yr sure, then check the throttle cables, spark plugs, fuel filter and refill the tank (I presume you've done this anyway), check the air filter. I'd recommend you also remove the O2 sensors and replace with O2 eliminators.

My 08 Vtec is very, very smooth, easily rideable on the throttle at lows revs and I don't have a PC.

YMMV.

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Honda made some changes to the fueling in 06, I think, and it seems the later bikes don't have as much problem. As for the Power Commander, it makes a completely new bike on my 03. Low speed throttle response is less of an on-off situation and the dreaded dead spot at around 5K is no more. I had trouble riding the bike at steady throttle between 70 and 75 before the PC. The bike would either be losing speed or gaining.

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Try numbers 1 and 2 first due to them being basically free and they are super easy to do.

1. Taking up throttle slack is free and easy and will definitely make a difference. I've had my hands on about a dozen 5th and 6th gen VFR's over the years and they all had a lot of free play before adjustment.

2. o2 eliminators will allow the bike to run a bit richer and smooth out surging issues on some bikes around the 4-5k rpm range and make the throttle a little nicer off idle too. It made a huge difference on my 2008 which was terrible without it, but my 2007 doesn't need it at all. I wish I had known about it for my 2004, as I think it would have helped it a little. It costs just a few cents if you make your own out of a couple of common 330 ohm resistors. Obviously, YMMV on the effectiveness of the mod, but it's so cheap it can't hurt to try. If you don't see any change, remove them and move on to number 3. Trace has a tutorial on this mod.

3. Sync the starter valves. If you can borrow the sync tool/gauge, and can DYI, it won't cost a thing. Otherwise, it will cost you the price of the tool or the visit to the shop. The job is fairly easy to do and there are tutorials here.

4. Power Commander or other tuner. Costs quite a bit but is easy do install and can help make your engine better at any rpm.

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I have a 2005 and experienced similar issues. I found this in the archives:

http://www.vfrdiscussion.com/forum/index.php/topic/77021-nasty-snatch

The suggestions I took from that thread are largely already captured in the replies above, but I'll summarize them here for simplicity:

1. Remove slack in throttle cable
2, Adjust idle to 1300/1400
3. Disable PAIR
4. o2 eliminators
5. Sync starter valves
7. Clean fuel injectors?
So far I've only worked my way through the first four. The problem seems at least somewhat improved.
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For removing O2 sensors, 1/2 watt or more resistors will do. I just taped mine in place.

The PAIR system and flapper/ snorkel often get blamed, but many of us run those as stock and all is good. On my '08, the PC with O2 elims cleared up about 90% of those symptoms - sending the injectors out to have them professionally cleaned gave it the last 10% - runs beautifully.

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I wish emphasize the effects off too much chain slack from the
prospective of an RC45 owner... You see some magazine testers
complained about the RC45 slight off idle jerkiness while others
praised the fuel injection as flawless... what was the chief
difference??? simply the amount of slack in the chain... the chain
slack must be set at the absolute minimum prescribe by Honda or an
abrupt off idle jerkiness a key element of instantaneous fuel
injection may be magnified by the seat of their pants... it also helps
to be smooth at the critical on off throttle transitions... fuel injected V4s

are not only sensitive what you do but how well you do it...

Chain Rollers and Pads...

The purpose of the chain roller is to take up the slack generated
after the swingarm is lower during ride height adjustments... The
lower the swingarm is adjusted the more slack appears in the chain...
instead of suffering excessive chain slack HRC added a roller... with
the chain resting on the roller less slack is felt through the
throttle during on off transitions... it works a lot like a chain
roller on a dirt bike if you will... in fact I employed a ball bearing
dirt bike roller purchased at a cycle accessory store...

Thanks to KTM for their trick chain pad... I up graded Mr.RC45's noisy chain roller to a silent KTM chain pad...

subcat-KTM-FP2.jpg
ChainGlider%202_zps3cuwc3um.jpg

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Did you ride the bike before they did the service work .

Morning,

The bike was like it before the service. They carried out the service, rewound the stator as they mentioned that it has a few burnt areas, new plugs etc and sync'ed the valves. for the 1st 100miles the bike was great but it then went back to being rough under 5k. The pair and flapper mod made it better but it still feels as if its misfiring at low speeds. Checked the FPR and that is ok but noticed a drop in voltage when revving.

Try numbers 1 and 2 first due to them being basically free and they are super easy to do.

1. Taking up throttle slack is free and easy and will definitely make a difference. I've had my hands on about a dozen 5th and 6th gen VFR's over the years and they all had a lot of free play before adjustment.

2. o2 eliminators will allow the bike to run a bit richer and smooth out surging issues on some bikes around the 4-5k rpm range and make the throttle a little nicer off idle too. It made a huge difference on my 2008 which was terrible without it, but my 2007 doesn't need it at all. I wish I had known about it for my 2004, as I think it would have helped it a little. It costs just a few cents if you make your own out of a couple of common 330 ohm resistors. Obviously, YMMV on the effectiveness of the mod, but it's so cheap it can't hurt to try. If you don't see any change, remove them and move on to number 3. Trace has a tutorial on this mod.

3. Sync the starter valves. If you can borrow the sync tool/gauge, and can DYI, it won't cost a thing. Otherwise, it will cost you the price of the tool or the visit to the shop. The job is fairly easy to do and there are tutorials here.

4. Power Commander or other tuner. Costs quite a bit but is easy do install and can help make your engine better at any rpm.

Thanks I'll think I'll look into the O2 eliminators :) I don't really have an issue when going on/off the throttle its more when I hold or slowly accelerate / in slow moving traffic.

I wish emphasize the effects off too much chain slack from the

prospective of an RC45 owner... You see some magazine testers

complained about the RC45 slight off idle jerkiness while others

praised the fuel injection as flawless... what was the chief

difference??? simply the amount of slack in the chain... the chain

slack must be set at the absolute minimum prescribe by Honda or an

abrupt off idle jerkiness a key element of instantaneous fuel

injection may be magnified by the seat of their pants... it also helps

to be smooth at the critical on off throttle transitions... fuel injected V4s

are not only sensitive what you do but how well you do it...

Chain Rollers and Pads...

The purpose of the chain roller is to take up the slack generated

after the swingarm is lower during ride height adjustments... The

lower the swingarm is adjusted the more slack appears in the chain...

instead of suffering excessive chain slack HRC added a roller... with

the chain resting on the roller less slack is felt through the

throttle during on off transitions... it works a lot like a chain

roller on a dirt bike if you will... in fact I employed a ball bearing

dirt bike roller purchased at a cycle accessory store...

Thanks to KTM for their trick chain pad... I up graded Mr.RC45's noisy chain roller to a silent KTM chain pad...

subcat-KTM-FP2.jpg

ChainGlider%202_zps3cuwc3um.jpg

Like the idea of these. I suspect it not chain slack as mentioned its more when slowly accelerating / slow moving traffic. Slack looks ok. Thanks.

I have a 2005 and experienced similar issues. I found this in the archives:

http://www.vfrdiscussion.com/forum/index.php/topic/77021-nasty-snatch

The suggestions I took from that thread are largely already captured in the replies above, but I'll summarize them here for simplicity:

1. Remove slack in throttle cable
2, Adjust idle to 1300/1400
3. Disable PAIR
4. o2 eliminators
5. Sync starter valves
7. Clean fuel injectors?
So far I've only worked my way through the first four. The problem seems at least somewhat improved.

Wasn't too sure if people carried out the O2 and PAIR & Flapper at the same time? think I'll give it a try :) thanks.

For removing O2 sensors, 1/2 watt or more resistors will do. I just taped mine in place.

The PAIR system and flapper/ snorkel often get blamed, but many of us run those as stock and all is good. On my '08, the PC with O2 elims cleared up about 90% of those symptoms - sending the injectors out to have them professionally cleaned gave it the last 10% - runs beautifully.

My 2003 VFR has only done 11k miles, well is did when I bought it a few months ago. I'm now at 14k do you think cleaning the injectors is required? Or can they clog irrespective of mileage? Thanks

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More likely that the injectors would be affected by age than miles and yours is 13 yo.

My 08 has both the flapper/PAIR mod & O2 eliminators, in fact I fitted the eliminators before the flapper/PAIR mod and it was smooth then. Didn't notice much difference following the flapper/PAIR mod, except the fuel consumption got marginally worse.

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I fitted a PC and 02 eliminators at perhaps the 7k mile mark on my '04 because of the abrupt on/off throttle and the 4,500-5000 rpm hesitation and never looked back, I now have 70k smooth as butter miles on it. Personally, I feel it was probably the best money I spent on the bike. Perhaps the other mentioned ideas will work, I'll never know, I just went right to the PC... problem solved.

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Been reading up in seafoam but not to sure about it. It's quite an old bike so do not want to kill any seals etc. May just take the injectors out and get them cleaned and flow tested. Before I do I'll get the o2 eliminators first :) thanks for your help and advice.

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For removing O2 sensors, 1/2 watt or more resistors will do. I just taped mine in place.

The PAIR system and flapper/ snorkel often get blamed, but many of us run those as stock and all is good. On my '08, the PC with O2 elims cleared up about 90% of those symptoms - sending the injectors out to have them professionally cleaned gave it the last 10% - runs beautifully.

My 2003 VFR has only done 11k miles, well is did when I bought it a few months ago. I'm now at 14k do you think cleaning the injectors is required? Or can they clog irrespective of mileage? Thanks

Mine were done with about 5,000 miles on the bike. The report showed 3 having flow / spray patterns as "Good" and 1 as "Average" prior to cleaning. Of course all 4 rated "Excellent" afterward. Maybe they were blowing smoke at me - no way to know. However there was a notable difference in smoothness / responsiveness afterward, so for me $100 well spent. YMMV

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More likely that the injectors would be affected by age than miles and yours is 13 yo.

I'm not an engineer and I have very limited wrenching experience, but this sentiment aligns with my personal prejudices. Most motorcyclists (like me) have bikes that are very low mileage for their age because (outside VFRD circles) motorcycles are a class of toy that is over-coveted and under-utilized. For every bike that is a daily commuter, there are three sitting in someone's garage cold and dusty with disuse. This suggests the maintenance priorities for this class of bike will likely be age-related (desiccated rubber, degraded fluids, etc) rather than wear-related. It would not be uncommon for a bike to have sat still in garage for years while the fuel turns sour. With this in mind, I hope to do some fuel system maintenance, including the injectors.

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For me the biggest results were a Power Commander and the O2 eliminators it came with. I use a downloaded map that fit my mods and the results were more than satisfactory. A PC with a custom Dyno map should be even better, but I have no complaints about the low end performance.

@ BusyLittle Shop. Would the KTM chain pad fit a 6th gen and if so it is a straight bolt on replacement? Seems like a nice upgrade.

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Posted Today, 03:45 AM

Switchblade, on 06 Feb 2016 - 6:22 PM, said:snapback.png

Did you ride the bike before they did the service work .

Morning,

The bike was like it before the service. They carried out the service, rewound the stator as they mentioned that it has a few burnt areas, new plugs etc and sync'ed the valves. for the 1st 100miles the bike was great but it then went back to being rough under 5k. The pair and flapper mod made it better but it still feels as if its misfiring at low speeds. Checked the FPR and that is ok but noticed a drop in voltage when revving.

Try disconnecting the battery and see if it resets the ECU.

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@ BusyLittle Shop. Would the KTM chain pad fit a 6th gen and if so it is a straight bolt on replacement? Seems like a nice upgrade.

I can't say for sure because I don't have a 6th Gen in the shop to make sure of a straight replacement...

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