Hello - sorry this is so long.

As a followup to my post a few days ago - I have a rough running problem where one cylinder cuts out at about 4K RPM and then rest of RPM band is strong up to redline....I decided to just deal with what I have on my bike rather than roll the dice and buy a set of used carbs off eBay, since I would not know if they were for my year, and would not know their condition until I opened them up, etc, etc. I took off my carbs for the first time yesterday, and I inspected everything looking for clogged jets, broken float or any other simple things I could address on my own.

I think I got things looking pretty good, moved the clip on the needles down two spots to try to lean things out a bit... and put the carbs back on. I went for a ride and it ran much better throughout the whole RPM range so I gave myself a pat on the back for saving lots of money;-) This morning I found a very small puddle of gas on my garage floor. It is impossible to tell where it came from since the bike leans to the left on the side stand, and the gas found its way to the left side of the bike and dripped off of the carbs down along the engine and onto the floor. On this model of CBR would it be safe to assume that one of the float bowl gaskets is failing, or are there other areas prone to leaks that I may have worked loose with all the prying and disassembly? I did not break the carbs apart from one another, I just did each one top and bottom leaving the bank of 4 carbs intact the whole time.

I am thinking of ordering the gasket sets for float bowls - I read somewhere that the set includes lots of other O rings and gaskets... do you know where these go, or if I should just try the float bowl gaskets first and see how it goes? If I place a parts order I thought I might as well get new jets as well... does Honda ship these so that it is clear which jets go into which carb, or are all four the same for main jet and slow jet?

THANKS as always, there is a wealth of information here in this forum!

 

first, its hard to say where the fuel is leaking from, if even you dont know.
could be a sticking float, bad bowl o-ring, maybe you disrubted the fuel transfer tube o-rings, or possibly you didn't put the fuel line back on right... you need to clean, and inspect where its coming from.
i've never seen an entire rebuild kit. you have to order the o-rings and seals individualy. the little o-rings are for the fuel transfer tubes that interconnect the carbs.
why do you want to get new jets? are you getting different sizes? pilot jet and main jets are entirely different looking and obvious where they should go.

 

First, thanks for reading through my post and taking the time to answer - this has been frustrating to say the least - I ordered a set of float bowl gaskets. Looking at some pics here in this forum on carb care I am thinking that my gaskets are crushed pretty flat and have not much life left in them. That should help I am sure, but I am not clear on my running problem now..... I just drained the gas from the bowls so that no more drips on my floor. All four carbs were full of gas, so that's a good sign in a way I suppose. The carb on the far left (as you sit on the bike) is the one that I think is the problem. On Saturday, I gave all of the jets a good cleaning and put them back in, checked that the slide and floats are moving freely with no sticky parts, then put the carbs back on the bike. I suppose next time around I will take apart top and bottom and set the jets and needle/slide aside for each carb and try to clean more of the carb completely - maybe I missed a passageway under the idle jet? The thing that I just noticed that is really killing me is that I could hold my hand on the header for that far left cylinder while it idled... it was cold as ice and the other three were getting too hot to touch before I shut it off. So that cylinder is basically dead while at idle with choke applied :-( I know - or at least I think that the bike is running on all four cylinders above about 4K RPM, so I would think that I have a big problem with my slow jet but no problem with my main jet? I could sweat that I cleaned the jets completely and they were not that dirty to begin with....Do I need to clean below the seat for the idle jet? Or could it be a problem with the float? I am pretty new to this whole carb thing... when I owned a 90 600F many years back I was lucky enough that nothing ever went wrong with it!

To answer you question about the jets - the PO of this bike installed some sort of jet kit and I was thinking of just going back to stock to make things simpler... I was afraid that maybe there were different size main jets for the inner two carbs.. I guess that is not the case?

 

all four carbs should have the same jetting.
i've heard of some mechanics where i live, colorado, only changeing the outer two carbs jets when jetting for altitude. this is just a shortcut and not really the way to go.
back to topic, the main jets are pretty easy to change back to stock. but, you mentioned your needles have clips. stock was set in one position. the diameter of your new needles and stock needles are gonna be different also.
could very well be a clogged passage on the one carb. do you have an aircompressor, or access to one? i really like to blow everything out after a good cleaning. if you do decide to seperate the carbs for cleaning, i recomend you get the o-rings for the fuel tubes.
i would also check to make sure that the cold cylinders spark plug is actualy firing.

 

I have been looking at quite a few tutorials that people have created and posted up in various online forums - and I may have missed a few spots with my first "cleaning" last weekend. It really seems to be that one carb that is the culprit. Yes... first thing I did when I felt that cold exhaust pipe was to pull the plug and check for spark. It is getting spark, and at this point I am crossing my fingers that there is no issue inside of the cylinder causing no firing.... my gut tells me fuel is not getting to the right place at the right time since it will pull so much smoother and harder above like 4500-5000 RPM, which I have learned is the spot where the main jet begins to take over the fuel delivery.... so I must be running on just 3 cylinders in lower speed around town riding.

Since I would have to replace the needles as well, I will just stick with the jets I have for this season. I figure that over the winter I can always get a good set of used carbs and make a complete setup made of OEM pieces from the ones on my bike plus the spares.... Plus, I did not take out the floats to clean the seats or even clean that one jet that is fixed in place (pilot jet?) last time around since it looked so clean in there... I am hoping that next cleaning will do the trick and I will seal things up with the new gasket sets. I also read that it is important to back out that screws that controls the idle and clean things up on each of those seats, which I did not do. Thanks again for the input - the factory manual I have does not go into this sort of detail on the carb setup !

 

I skimmed, so forgive me if I missed something.

You an always adjust the pilot screw on the carb that's not functioning since that may be a simple fix (keep a mental note of where it was before you moved it though in case that's not the answer! ). If fuel's getting to the bowl but the jets are clogged then you might be getting a backup from the extra fuel and it makes sense that this might lead to a leak somewhere along the line (if you're still experiencing the leak).

If you are still seeing a leak, you can always put the bike up on the center stand or on a rear stand so that the bike sits up vertically and you can tell exactly where the leak is coming from (left to right) instead of speculating that it came from a certain place & dripped based on the fact that the bike is leaning on the kick stand.

 

thanks again, guys. I took the carbs off again today and I think I got through the pilot jet with a fine piece of wire and some carb cleaner.... I am referring to the one jet that does not thread in... the one that does not come out.... I am getting more and more upset with the PO of this bike. I am inserting/attaching a pic here to ask - I found a spot on the carb that is connected to the non-firing cylinder... right alongside the little piston that moves as you apply the choke, there looks to be some dark brown epoxy or some sort of filler material. I am wondering if I need to dig that off of there and see what's happening under there. The other three carbs have a shiny copper colored cap where this piece of epoxy is placed.. what is under there? See the white arrow in the pic. It is a concern that this is only on the "bad" carb.

And I also noticed that this one little tiny adjustment screw was practically falling off..see the red arrow in the pic. I am not sure what this does either! There are four of these, and the "loose" one will turn in several times, while the other three can rotate just once around and will rest against a sort of lip or stop. Metalord suggested looking at the pilot screw - I have a manual but can not seem to locate this.. is this under a cap that needs removal? I read that some later models have a D shaped fitting that requires a special tool or piece of pipe to turn?

These carbs are killing me.. maybe I should buy a new set and start over ;-)

 

the red arrow points to the pilot screw. the aluminum peice is a limiting cap, and is glued onto the screw to limit its adjustment. you have to remove the cap to adjust the screw. manual states 2 1/4 turns out, then gives a procedure to fine tune.

i'm not an expert on exactly how carbs work. i couldn't get the caps off my carbs when i had them apart, so i left it alone. but it could be part of the problem, if the screw is turned out too far, the o-ring on it might not be seating, and allowing air in.

the blob of stuff at the white arrow is somewhat of a mystery. i'm sure that is supposed to be a cap from the machine work to drill the necesary passeges. hard to say if the PO was sloppy and got it in the carbs passages. might just be covering the cap, or the cap might not be there? might try scraping some off the top so see if the cap is there. normaly they are pressed in, and no reason to remove them.

 

Good call.... thanks. I did go ahead and dig out that filler that was on there.. At some point it appears that someone tried to drill out that area ! I have no idea why, but under that mess of crap there was a partially drilled out cap, and the one next to it looks like it was drilled a little bit too. As you say, no harm done, since there is just a little brass looking cap pressed into place, and nothing of importance is under there. I just pressed it back into place and will cover it again with some JB WELD or something again like the PO did... I wonder if the person who had the bike before me thought that there was something under there that needed cleaning or adjusting.. I know that when I saw the putty on there, I sure thought that was the case ;-)

Thanks for the tip on the pilot screw.. there must still be "caps" on 3 of them, and this one is backed out really far. I will try to seat it in gently and turn back out like 2.5 turns and see if this helps. Can the pilot screw be take all the way out and cleaned?

 

^^Before you go messing with the pilot screws, write down EXACTLY how many quarter turns out they are. The pilot screws are how you sync the carbs and if you mess with 'em, you could un-synch them and give yourself a bigger problem.