5th Gen Surging

[stevens9757@bellsouth.net]

OK after 9000 trouble free miles my Y2K with 30K miles started to surge, most notibly around 6K RPM but will at lower RPM's. Bike has an aftermarket slipon with no Power Commander mods. Will replace plugs next but would like input as to likelyhood of this being an electric or fuel related issue. Actually runs smoother while in surge mode. Any input would be appreciated.

[drewl]

Surging is not that uncommon in the 5th gen. Mine kind of "stumbles" from time to time. I am not sure how to get rid of it though.

[karllheinz]

I have an '01 w/D&D pipe, pcIII w/02 eleminators, 98 catless header
I was having the same problem. I first had the pcIII remapped which helped a lot so I recommend adding a pcIII. It didn't cure the surging altogether so I tried some common mods and have rectified the issue. Check out these links:
'98 VFR800FiW to '01 VFR800Fi1 Increase in Fuel Consumption and Loss of Power - Honda VFR Club
PAIR and Flapper mod, with bonus snorkel mod for VFR « Johnny Chadda .se
Important to note that the electrical connector for the PAIR solenoid valve is located under the left hand side panel. It is tricky to get to. Follow the wires from the solenoid valve itself behind the oil cooler(you'll see the air hoses plugged up to it) and you can figure out how to best unplug it. I recommend removing the PAIR system completely and installing blockoff plates which I did. If one of the reed valves is stuck open you will continue to experience problems even if you unplug the system. With the blockoff plates installed and the PAIR system removed you will resolve that issue. Here's a link to where I bought my plates. They came with a set of vacuum caps which you will need one to plug the spot where the PAIR plugs into the airbox.
TPO Parts
I live in the Columbia SC area and I will perform these mods for you for $65 you supply parts and bring your bike to me. It is easy enough to do on your own but if you do not want to attempt it I have successfully accomplished it and would do it again for that rate. Hope this helps!

[steven113]

Originally Posted by karllheinz

I have an '01 w/D&D pipe, pcIII w/02 eleminators, 98 catless header
I was having the same problem. I first had the pcIII remapped which helped a lot so I recommend adding a pcIII. It didn't cure the surging altogether so I tried some common mods and have rectified the issue. Check out these links:
'98 VFR800FiW to '01 VFR800Fi1 Increase in Fuel Consumption and Loss of Power - Honda VFR Club
PAIR and Flapper mod, with bonus snorkel mod for VFR « Johnny Chadda .se
Important to note that the electrical connector for the PAIR solenoid valve is located under the left hand side panel. It is tricky to get to. Follow the wires from the solenoid valve itself behind the oil cooler(you'll see the air hoses plugged up to it) and you can figure out how to best unplug it. I recommend removing the PAIR system completely and installing blockoff plates which I did. If one of the reed valves is stuck open you will continue to experience problems even if you unplug the system. With the blockoff plates installed and the PAIR system removed you will resolve that issue. Here's a link to where I bought my plates. They came with a set of vacuum caps which you will need one to plug the spot where the PAIR plugs into the airbox.
TPO Parts
I live in the Columbia SC area and I will perform these mods for you for $65 you supply parts and bring your bike to me. It is easy enough to do on your own but if you do not want to attempt it I have successfully accomplished it and would do it again for that rate. Hope this helps!

What is the downside to removing the pair valves and replacing them with the block off plates. I recently got a custom tune and my tuner accidently left the clamps on the bike to block off the hoses so I searched the forum to find out why they were blocked off to begin with. From what I understand you can knock off 3lbs and free up alot of plumbing from this mod and it is only emissions crap that hinders the performance of your bike anyways. I live in Florida and emissions is not a big deal here as it is in California so I am considering this mod.

[Deadsmiley]

...

Sorry too many windows open.

[karllheinz]

Originally Posted by steven113

What is the downside to removing the pair valves and replacing them with the block off plates. I recently got a custom tune and my tuner accidently left the clamps on the bike to block off the hoses so I searched the forum to find out why they were blocked off to begin with. From what I understand you can knock off 3lbs and free up alot of plumbing from this mod and it is only emissions crap that hinders the performance of your bike anyways. I live in Florida and emissions is not a big deal here as it is in California so I am considering this mod.

There is really no downside to this mod. If one of the reed valves for the PAIR system were to get stuck in the open position then dirty crankcase gas would escape through the PAIR system into your airbox. That would degrade performance and become very aggravating to diagnose, trust me. I removed it all and it was fairly easy. You can save some weight but more than that is the peace of mind that comes with not having to maintain that system anymore.

[CandyRedRC46]

Originally Posted by karllheinz

There is really no downside to this mod. If one of the reed valves for the PAIR system were to get stuck in the open position then dirty crankcase gas would escape through the PAIR system into your airbox. That would degrade performance and become very aggravating to diagnose, trust me. I removed it all and it was fairly easy. You can save some weight but more than that is the peace of mind that comes with not having to maintain that system anymore.

+1 get rid of the pair valves, youll basically be taking out a 3 pound rats nest out of your bike.
the stubling though is from the o2 sensors. it is your bike going in and out of open/closed loop fuel injection.
putting 330 ohm resistors in their place will do the trick.
add a pc3 with a proper map and your bike will be smooth as glass!

[Capt. John]

Surging can also result from a clogged air filter - unlikely though as the air filter would have to be very dirty to bring on the condition.

[jobvfr]

The "pair" valves as you call them seem to be part of the pcv (positive crankcase vent) system. If you block them off wouldn't that cause oil leaks? It certainly would on a car engine. I checked some of the instructions above and they don't make sense to me. There isn't any exhaust gas in the valve cover area, nor do these valves let extra air into the exhaust system. (maybe on california emissions models) My '01 is stock except for the flapper being bypassed and she seems run well, no surging. The air suction valves balance blow-by gasses between the cylinder heads and vent into the airbox. I'm not sure what would be gained by removing them, aside from the weight savings.
Sorry if it seems like I'm ranting, but I'm curious!?!

[John451]

Originally Posted by jobvfr

The "pair" valves as you call them seem to be part of the pcv (positive crankcase vent) system.

No, the Pair reed valves just sends air FROM the air box INTO the exhaust port of the cylinder heads, its main purpose is to clean exhaust emissions on underrun.

Problem happens when the reed valve gums open allowing exhaust gasses back up into the airbox affecting both power and economy like happened to my '99 in Feb '07.

On surging, wondered if it's related to the Open / Closed Loop running, my previous '03 Gen 6 used to surge on the odd occasion especially when cruising on light throttle for a while then rolling off then on again eg coming into a lower speed zone, my '99 Gen 5 Mk 1 without O2 & Cat never has.


See below older thread on Throttle response:
2003 VFR 800 Throttle response

[CandyRedRC46]

Originally Posted by John451

On surging, wondered if it's related to the Open / Closed Loop running, my previous '03 Gen 6 used to surge on the odd occasion especially when cruising on light throttle for a while then rolling off then on again eg coming into a lower speed zone, my '99 Gen 5 Mk 1 without O2 & Cat never has.

ding ding ding
we have a winner

[jobvfr]

See thats what I don't get -- I did a valve adjustment to my bike and I'm not clear on the exhast port idea. There didn't seem to be a port for the exhaust. Is this a Cali thing, or should I put down my beer and check for more than just valve clearance. Also if the computer controls the valve, then why would it cause surging or a conflict with the O2 sensor?
I guess my theory is "if the bike runs, don't mess with it". But I'm getting old...

[Jollyhart]

I had the same problem with my 5th gen.And I by-passed the pair stuff as well as balanced the throttle bodies.(sync)
And I tell you what- it fixed it!
The old girl goes great all the way through the rev range,as well as no "surging" and no difficult slow speed manouvering problems.
Give it a go.You will like the results.