Cleaning carbs

How aboot this?

http://vfrworld.com/forums/showthre...ld-Cleaning-Parts-whose-got-and-who-does-what

 

Actually, it's only necessary to remove 2 carbs from the plenum, either left or right, to replace tubes or O-rings

 

If it helps, here's the printed instructions I provide with my o-rings and line kit:


VFR Fuel Joint O-ring Install
V4 Dreams

If you ordered the replacement fuel line kit: The carb fuel lines are two distinct*lengths: the 5" is routed alongside carb #1 and the 7" alongside #3. They are then joined to the "T" fitting so that the remaining open port (from the fuel pump) is facing to the left, as it was originally. The lengths were carefully determined by trial & error to avoid kinking.

———————

O-ring replacement: Like everything mechanical, this process is easier with the carb rack cleaned. I start the replacement process by removing the plenum screws — 8 inside the plenum plus 2 on the sides. These screws often require an impact driver to loosen (carefully). With the carb rack then turned upside down (plenum down) on the bench with carb #2 & 4 facing me, remove the center bracket and its 4 screws. All the linkages can remain in place. I now remove #1 & 4 tiny sync screws (unscrew them about 5 turns out and when reinstalling screw the same amount back in), in addition to the two large throttle shaft springs. For some reason the #3 sync screw needn't be removed. Set all the removed parts aside in the order removed. I wriggle completely free carb #4 and loosen (but leave in place) #3 & #2.*Note that the carb bases are located to the plenum on dowel pins.

Now is the time to note how the lines are routed, you may want to take a photo. I then cut the old fuel lines (assuming they’re being replaced) as short as possible to get them out of the way (don't pull them, you could break the plastic joints) and gently free the #2/4 fuel joint and then the #1/3 joint. NOTE: the joints are identical -- just installed in a mirrored fashion. There are fitting nubs, one per joint — one goes into carb #1 and one into #4 — have a look. The two air vent joint pipes will fall free, just let them be till installation. I then take a moment to clean the holes where the o-rings will seat with a bit of electronic cleaner (not brake solvent) and small brush or whatever, taking care to avoid any debris going into the carbs.

Installation, as they say, is the reverse of disassembly. Only in this case all the pieces have to line up, a bit like herding flies, but it can be done. Coat the new o-rings with a bit of silicon or grease, mount the new fuel lines (if applicable) and work #1/3 joint back into place followed by #2/4, taking care to put the locating nubs back into carbs #1 & 4. The choke shaft will have fallen free of #4, so be sure it and its spring are back in place. When all the fuel and vent joints are lined up, gently work all the carbs back into place and fit onto their respective plenum mounting dowel pins. Note that there's large o-rings between each carb and plenum -- make sure they've stayed in place.

None of this requires force. If you find yourself forcing it, take a breath and figure out why. It's a three dimensional puzzle, but it does fit back together.

When it's all back in place, carefully right the carb rack and loosely reinstall the 8 plenum screws, 2 side screws and then the center bracket on the underside — again, they should all go in and bottom easily if everything is lined up. Once all are in place, tighten them up. Flip the rack upside down and reinstall the missing shaft and sync springs (be careful, these will try to escape across the room). During the reassembly process, you should be continually checking that the throttle and choke mechanisms are free and correct. There should be no binding. Apply a bit of motor oil on the pivot and sliding areas of those shafts. Visually check that all the carbs are seated squarely.

At this point I determine if the choke (actually enricher circuit) is opening fully. If the bike was sluggish starting, would barely run with full choke or just didn't seem to be choking enough, I carefully bend the forked fingers (where the choke shafts meet the carbs) at carbs #2 & 3 in order to provide more leverage, opening the slides farther. This is done delicately, and requires that the little screw-secured bracket on the shaft be moved out of the way during bending. There's a trick to easily moving that bracket out of the way and involves loosening the brackets’ holding screws, sliding the entire shaft free of their little locating pins, and rotating the shaft, which allows the bracket to be slid out of the way. Reverse the dance to put the brackets back into place. Play about with it.

The carbs will need to be sync'd on the running bike.

Copyright Joe Nelson 2016
V4Dreams.com

 

Gents,

Thanks for all the great info! I was a regular poster here way back when it was a different server & provider (late 90's?), and I made a few runs to Daytona before life took over, and met up with a few of you I'm sure! I had to get a new sign on it's been so long.

I've owned my '92 VFR since '93, and it's always been a great machine. I made the mistake of parking it three years ago when it was getting poor mileage, thinking, I'll get right on that.... sure I will! A few tractor clutches, a four wheeler, and multiple other repairs later, I was able to get back into the carbs. I've been there before, but the memory has faded a bit and the help above was fantastic! Since I had some fuel leakage I wanted to do a complete rebuild, including the bowl gaskets at the O-rings at the overflows, fuel fills, and vacuum tubes. The OEM parts were way out there cost wise, but I found a place that has a full Viton rebuild set for $47 USD, absolutely every little part!! The downside is it comes from Asia, and has a 2-3 week delivery, but it was worth every penny and the quality of the material was excellent:

http://litetek.co/Carb_Kit_Honda_VFR750_RC36.html


FYI, you can replace all the O-rings without losing sync in the carbs by pulling just #2 and #4 off. They would be considered the "weak side" carbs, you can tell by the linkage - their linkage is 'driven' by the opposing two carbs. Here's a quick summary of how to do it:

1) remove the underside 4 carb connector plate (8 screws)
2) Pull the larger spring out between the two linkages,
3) mark the location of the choke arm linkage on the shaft, loosen screw, remove the choke shaft by sliding it out. retighten screw to keep spring in place!
4) loosen the two large platen bolts holding the carb in place from the top
5) separate the platen from the carb slightly. It will be sticky!
6) rotate inlet cone 120 degrees and remove. Pull the round gasket and set aside.
7) Flip back over and wiggle, slide, and wiggle some more, pulling the two carbs apart. Watch out for the little spring underneath the connecting linkages!!
8) that little spring should stay in place, but pull it out now because the linkage won't go back together with it in the way.
9) clean, repair & replace everything you can get your hands on - use a paint pen to mark numbers on bowls, and small cups to hold associated pieces!!
10) consider new fuel lines - now's the time to do it...
11) clean everything again, carbs can't be too clean!!

Reassembly is the reverse of the above, except put your small and large linkage springs in dead last, and use needle nose to get the small one back under the linkage. As noted above, use a little lube of your choice on the O-rings and their holes to help it all slide back together. I also find that lubing the rubber intake mounts on the V block helps a good bit. I push the front carbs in first by hand, and then give the rear plate a little tap with a wooden block and rubber mallet (little tap, don't break the plate!!)


None the less, hopefully this helps the next guy who reads this thread, and thanks again to you guys who continue to ride one of the best all around bikes ever built!

 

Can you please tell me where do you get the metal tubes?

 

Well, I used to have a link to a store, but I can't find it. I did find this seller on Ebay, though.
http://www.ebay.com/itm/Honda-1986-...279329?hash=item2cc2c56ca1:g:emQAAOSwHnFV2JLM

You can get just the fuel tubes or both fuel and vent tubes.