I found an older post regarding removal of the pair valve system on 3rd and 4th generation. I ended up doing this as I noticed that my bike had a slight hesitation at low rpm and some of the hoses on the pair valve system looked a little weathered. I thought possibly I had a leak in the system somewhere.
After I removed the system, the bike is running significantly worst. I triple checked every connection that needed to be blocked off to make sure that I did not miss anything. Now the bike hesitates throughout 1st gear (low-high rpms), and hesitates up to 5,000 rpm in 2nd and 3rd. Past 5,000rpm in 2nd and 3rd gear it runs great. Did not get past 3rd gear.
Is re-jetting needed once the pair valve system is removed? Or is there something else I should be looking at. Anyone had this issue come up before?
Ok, I did find one bolt for the block off plate at the rear right cylinder head that was not screwed in as far as it should have. It was kind of hard to get to since it was behind the headers. I'll try riding it tomorrow as I don't want to wake up the whole neighborehood... All the intake screwes look fine.
One thing I realized in the process is the bike did not have an evaporation canister. I think the bike was laid down by the previous owner on the right side. Is the evaporation canister on the right side of the bike? if so it probably never got replaced. Can the Evap. control valve be removed as well since the canister and the pair valve system is no longer connected?
On gen 3, the evap canister is on the right side. I don't know if the valve can be deleted, but as far as I know the canister serves to filter the air that vents to atmosphere. Therefore, it's absense shouldn't affect performance (again, to my knowledge). The canister may be required for smog, should you get checked by our friends in blue. To my understanding, the PAIR system is seperate from the evap.
Another vote here for not requiring jetting with the PAIR removal.
I don't know what part you mean that you have left on....but when I did my PAIR removal I removed everything that was part of the PAIR system. Even the little pump with the tiny filter in it.
Make sure the Block off plates under the exhaust headers (4 in total) are sealed well. <--- the 2 rears were a HUGE pain.
Also, be sure the 2 little ports in the Airbox are propperly capped.
Also the little "nipples" directly under each carb boot need to be capped as well.
I'm so pleased canadian bikes don't have to deal with this garbage...
My US market pair system hasnt bothered me for a split second. I ignore it. Messing with it isnt going to add any power and shaving a few ounces off a 600 pound bike is kinda like pissing up a gum tree.
I'm so pleased canadian bikes don't have to deal with this garbage...
My US market pair system hasnt bothered me for a split second. I ignore it. Messing with it isnt going to add any power and shaving a few ounces off a 600 pound bike is kinda like pissing up a gum tree.
True enough sir. In my case I'm happy it's not there as it keeps things simpler and cleaner for my naked bike project :)
I'm so pleased canadian bikes don't have to deal with this garbage...
My US market pair system hasnt bothered me for a split second. I ignore it. Messing with it isnt going to add any power and shaving a few ounces off a 600 pound bike is kinda like pissing up a gum tree.
True enough sir. In my case I'm happy it's not there as it keeps things simpler and cleaner for my naked bike project :)
And slowbird, both my 02 and 95 haven't had the pair valves, maybe its a per province sort of thing?
I guess what I should have stated is that if it required jetting my bike would probably have been jetted differently from the factory as it doesn't have the pair valves stock, but it is the same as other VFR's.
And slowbird, both my 02 and 95 haven't had the pair valves, maybe its a per province sort of thing?
I guess what I should have stated is that if it required jetting my bike would probably have been jetted differently from the factory as it doesn't have the pair valves stock, but it is the same as other VFR's.
Peace :)
No stir...You have a very good reason as opposed to most, who do it in search of some phantom performance enhancement. I should be the last guy to talk about what one should or shouldn't do with a bike. I was just curious.
Hope you get her sorted out. In line with the problems you are experiencing, is there a set of gaskets to use with the plates or are folks using some kind of Permatex gasket sealer, etc? Or are folks just slapping them on and tightening them up? Your problems are making me second guess doing this as my '95 runs like a top right now. I have a set of plates, just haven't used them yet. Besides trying to get to the rear cylinders is going to be a pain. I read where it's recommended loosening the rear subframe 4 bolts and moving it out just enough to get to the rear ones? A two man job sounds like.
Thanks for the tips guys. I figured I'll go one step at a time to trubleshoot it. I ordered the new gaskets for the block off plates which should be in today or tomorrow. I'll replace them this week and see what happens. I was planning to clean out the carbs anyways, so I'll take a look at the conditions of the boots, passages, and jetting to make sure that was never messed with before. But at this point I am feeling like there might be something else that might have gone wrong in the process of removing the pair system that went unoticed.... I'll keep you updated.
Ok got busy with work but i finally got back to working on the bike. I ended up changing all the washers on the intake screws and gaskets on the block off plates and still lots of hesitation when i run the bike. I also checked everything again for the fourth time. I finally decided to take off the carbs to see whats going on ( wanted to inspect anyway to see if a cleaning is needed). Turns out two of the main jets (rear) are 128 and the other two are 125s???? The slow jets are all 40s. So weird because i thought it ran so so at low rpm before removing the pair valve system, but not that bad.... I actually did a ride from LA to seattle and back this past october with no problem.... Anyway i'll get two 128 jets and see what happens.
What is the stock jetting on the vfr?
Chuckster regarding your question, i cut the mounts off the chrome tubing and had a welder weld the holes for me. I then ordered new gaskets from honda ( i think $2 each). Getting to the rear plates was not that bad from the side of the chain, but the side of the exhaust is a pain. I ended up taking off the heat shield mounted behind the foot peg and using socket extentions with a pivot joint to get to the bolts.
TYPICAL JET SIZE:
Main Jet - 102 to 110*
Slow Jet - 40*
*Typical size only- verify jet size and Compare dimensions to those listed before ordering. See Jet Finder for other jets available.
In the old days it use to be if added a K&N filter or modified exhaust you went up 2.5 on the main jet and if did both you had to increase main jet by 5 and the pilot jet by 2.5 and raised the needle vavle by one shims.
I am suprised this link would reccomend jet sizes of 102 -110, when the vfr parts list has much larger sizes. I checked the honda parts list and it has 125s for two carbs (reference #30) and both 125s and 128s for the other two (reference #31). Why would two different jet sizes be reccomended for two of the carbs and only one size for the other two?
Attached Files
[image: Attached File]
Pages from vfr750partslist.pdf139.06KB
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because of inherent lean conditions caused by carb position and or lack of cooling air. I still have yet to be answered the question of how the pair system affects jetting. It injects air into the exhaust POST mixing of the fuel/air. Maybe if there were O2 sensors, I could see it, but in my mind's eye, jetting and the pair system are 2 separate entities.
And PS...another example of why one should just ignore the pair system.
because of inherent lean conditions caused by carb position and or lack of cooling air. I still have yet to be answered the question of how the pair system affects jetting. It injects air into the exhaust POST mixing of the fuel/air. Maybe if there were O2 sensors, I could see it, but in my mind's eye, jetting and the pair system are 2 separate entities.
And PS...another example of why one should just ignore the pair system.
the problem timmy. the pairs systems FAIL. the tubes rust through . the rubber lines rot and get holes.. when that happens, you get a vac leak at the the intake. which is why i recommend removing the port at the intake completely and using a screw in place of it.
once that happens.. nothing should be effected by the pair,, so take it off and toss it..no more popping sounds.. no more 4 lbs of junk. :beer:
but you ARE right.. it has nothing to do with the jetting.
I've synced my carbs both pre and post de-PAIR. MUCH easier post de-PAIR. Plus it runs a bit cooler in the high altitude/high heat summers we have here. I'm running OEM air filter (because of the super fine dust we have here) and a high-mount Staintune with the big baffle. Jetting is stock and my plugs look perfect. AND it's much easier to work on with all that crap gone.
Timmy, I found the attached diagram for a CBR1000RR that shows pretty well how the pair system works on that bike. I figured it would be a symilar concept on the vfr.
I am still having a hard time finding where the problem is coming from. Again, symptoms are:
starts and idles fine
1-3k rpm runs fine
3-6k rpm hesitation
6k and up pulls fine
None of these symptoms were there prior to the pair valve removal.
I plugged all the exhaust ports by cutting the mount ends of the chrome tubing, welded the holes, and used new gaskets. I removed all 4 brass fittings on the intakes, replaced them with 4 screws off the pair valves, and used new washers from honda. Airbox tubing mounts have been plugged.
There is a small valve on the side of the carburator which had a small 1/4" tubing connected to the pair valves (it had a "T" that went to each pair valve. On the macrofiche it is item #43 ("VALVE ASSY.")
What does that valve do and how is it related to the pair system? Should that tubing be plugged as well? I plugged it and it did not make any difference.
I have no canister on my bike, so the tubing to the canister is open to air. This system appears to be completely independed, but would not having a canister affect performance after removing the pair valve system... I don't know... just thinking out laud at this point.
Hmmmm....maybe you can take some clear pictures of either side of the bike (without fairings of course) so we can see if you are missing or still have certain things attached?
Here are some pics of the items I was talking about
[image: Purge Control Valve1.jpg]
[image: Purge Control Valve2.jpg]
[image: Purge and EVAP control valve.jpg]
[image: EVAP control valve.jpg]
Like I mentioned in the previous post, the 1/4 tubing attached to the Evap Control Valve was connected by a "T" to both pair valves. Does anything need to happen to this valve and related tubing? What about the Purge Control valve? Could any part of this system be the source of my problem now that the pair valves have been removed and can any of it be removed/adjusted to make it run properly?
She's back on the road.
Thank you for helping me sort this out glL429. Turns out that after removing the purve valve and the Evap control valve, all i needed to do is plug the 1/4 inch tubing from the purge valve to the intake. All the other larger purge tubing got rerouted towards back of motor.