Winter 4G maintenance

Hey VFR crew-

My 4G is all apart right now, as the carbs get their first cleaning in 17,500 miles. The way the bike was running this fall spurred my decision to clean them up. Even though I've done it before (to Mikunis) any Keihin carb clean-up advice will also be greatly appreciated.

I have read many threads about how difficult it is to get the carbs off/on the bike, but I found it pretty easy. 14" pry bar on the rear valve cover bolt flanges makes everything easy... :biggrin: My Yamaha parallel twin was a much bigger PITA.

However, I had to "move" what I suspect was the "PAIR" valve to get at the clamps for the RF carburetor. I know that this is an emissions related gizmo, and that it has been removed on some 5G and 6G bikes with some sucessful results. I live in a state where emissions are not tested annually, and would like to contibute to global warming a little bit... (The 2 or so pounds the bike would lose should offset this, right???)

How would I go about removing it (how much should come off - PAIR unit, hoses/tubes/etc.???)? I know that I will need to block orifices off as well, can someone shed some light on this?

Simplicity=better. PAIR valve=not simple.

 

When I got my 96 last spring, I pulled the carbs. Yeah not too tough, getting them on was more of a pain. I left them assembled together and removed the bowls/caps/jets and sprayed everything down good with cleaner. Amazingly, they were pretty clean. Use a good screwdriver and tap the screws with the driver and a hammer as they will be VERY tight. Spraying them down before hand with some penetrating oil is a great idea too.

TIP: while they are still off, add tubing (6+ inch or so) to all the cylinder vacuum ports which only come with small rubber plugs. Plug the end of hoses or the bike will run like crap! Stash hoses in the valley of the V. This will make the carb synch and future ones MUCH, MUCH easier.

I also removed all the pair crap. I had to plug the airbox inlet and fab up four covers for the exhaust ports.

 

Last night I completed the carb cleanout on the whole set. I was also surprised to see that they were pretty spotless inside, I had expected a little varnish at the very least. Anyways, pulled out the jets and soaked them in carb cleaner, and blew them out with compressed air, as well as all of the passageways. However, they have been off the bike and opened up at some point, some of the bowl screws were slightly stripped out. I also pulled the petcock/shut-off and it was functioning normally and was not gunked up at all. I will replace the fuel filter before the end of this, too. Hopefully it will run spectacularly in the spring!

Also of note - the carbs (at least on the 4G) are best cleaned as per-side pairs, as the inner bowl screws are all but inaccessible with the outer bowl still screwed on.

I looked at the PAIR valve garbage, to remove it, I assume I will have to create 4 exhaust header block-offs, and plug up all of the intake related stuff as well (RF cylinder vacuum line and two 3/4" hoses on the carbs/airbox), right? I still have not found a "how-to" on this for a 4G bike. Although I have read that the benefit is marginal if any benefit.

 

All I know is the carbs on a 4th gen, 3rds too, are a pain in the butt. more or less all fuel systems on a VFR are. I look at all other options before I fiddle around. Hmm sorry not much help with the pair valve, in fact I've never messed with one. Hmm don't think I even have one of those, at least I don't recall seeing anything that resembles that. could be you have a Ca. model?
Back to the question, I make sure tank is full of fuel, run the bike ever two weeks if possible, if not add in some fuel stabilizer or injector cleaner from chevron thats some good stuff. I've been lucky where I've never had fuel problem with a VFR on a 4th gen. Now on a first gen that sat 6 years, thats different, I ended up getting a complete set of carbs to get that one going. other wise making sure the fuel is as clean and as fresh as possible is good preventive medicine to start off with.

 

I think all the more recent bikes have the PAIR valve... If you can see the chrome "tubes" under your radiator, you have a PAIR equipped bike. The PAIR valve is located behind the upper radiator hose on the right hand side of the bike. It snuggles up against the frame. A California emissions bike has this system as well as a EVAP system for containing fuel vapors. My bike thankfully, does not have this extra garbage.

As I understand it, the PAIR system "cleans up" the exhaust emissions by injecting atmospheric air into the exhaust system with the exhaust stroke. It has a vacuum connection at the RF intake port, as well as air intakes off of the airbox. Something like an EGR valve.

If I decide to go through with the de-PAIRing of my VFR, I'll document and write it up for all to see. I will have to fab up some exhaust header port covers, however.

 

Call me crazy,but when I was involved in the sport of drag racing, I really liked working with carburetors. One thing an old timer taught me,was to be very careful when cleaning air and fuel jets and passageways located inside the carbs. He said never to use high pressure air for that purpose. He claimed the high pressure air would distort some of the delicate parts. So just a friendly suggestion,clean carbs run best ,but dont go crazy with the air.
eddie

 

Eddie -

Even though I really don't understand fully how carbs work, I also enjoy working on them.

I was working with 30 psi while cleaning mine (as I have done numerous times before with other carbs), and they were fully disassembled when I was using it. Hopefully this is "low pressure" enough. I certainly wasn't running 140psi through the passages.:biggrin:

The only thing I did not do (because I couldn't figure out how) was to remove the float valve seats/screens. Do you think this is a major oversight(especially considering that the carbs were so clean in the first place)?

 

The float valve is also called a needle and seat valve. I guess its a coin toss as to weather or not you should have claened them. Does Honda give specs
on the float height adjustment? If so that would probably have been a good thing to do, that is when they were apart. Yea, I dont think 30 psi is overboard for cleaning . Anyway if you didnt do the needle and seats and set the float heights, I guess you should do it next time around. eddie

 

This is the first bike I've worked on that has a rubber needle on the floats.

I imagine that it is less prone to wear out (and flood the bowls) than a steel needle with a brass seat, correct?

 

I am not sure about longevitivy with the rubber,I believe they use a material called viton, needle valves. One advantage of the viton is that it seals better than the metal type. Really not sure about the wear out factor. eddie

 

After much consideration, I decided to leave the PAIR system intact. I am just not finding the time to work on fabbing up covers or trying to pull all of this stuff off. This is especially true since I have not been able to uncover any benefit whatsoever to doing so. At the very most, I'll pull the valve off and make sure it's 100% before putting the bike back together.

I'll be pulling the throttle cables at some point today to get them lubed up and ready for that first spring ride. If the bike shops in the area were actually open, I'd try to find a new fuel filter. Is this a part that HAS TO come from Honda, or is a generic M/C fuel filter a perfectly acceptable substitute?

Happy Sunday Morning!:ranger:

 

Did you notice any difference in how the bike runs (good or bad) after removing the PAIR system on your 4th gen?

I am considering shedding that crap as well. If nothing else - just for better access to the right side float drains and vacuum ports.