Ok, so there is a big difference between disassembly/reassembly and rebuilding.
Yes and no. Carbs seem very scary at first, but if you take it slow and are very methodical, you will be just fine. I will have to admit, I've only taken mine off , removed the bowls, and replaced the float needle and seat. From what I have read, unless your carbs are very worn, or are corroded, a simple cleaning should be fine.
While you have them off, I suggest changing out the fuel lines as well, unless yours are pretty new. Also, if you want, put some inline filters in. At this point, I should admit that my bike is a 73 cb500, but my understanding is the bikes are basically the same. Is your bike the F or the K1 model? I don't think it will make a difference, I looked at the exploded diagrams of the two carbs and they look basically the same. Kinda a basic step by step from what I remember. Also, a digital camera is awesome to take pics with as you go along, so when it comes time to put it back together, you can see how it was if you can't quite remember. This isn't so much fun you want to do it more often than necissary
1) Remove fuel tank from bike. Sounds obvious, but be sure the petcock is in the off position. Set it on top of like a 5 gallon bucket so the petcock won't be damaged. Make sure no one bumps it off. If a little gas leaks out that is kinda normal, remember, the petcock bowl is gonna have some gas in it. But if you get more gas leaking out that a tablespoon or so, check to see if the petcock is leaking by emptying the petcock bowl and letting it sit overnight. I know on mine, the stupid little washers that held it to the tank were leaking and once I replaced them, no more leaking petcock.
2. Remove the carbs from the bike. I am hoping someone else will chime in with a better way to do this, cause I hate this part. The way I do it is, loosen all the clamps around the airbox side, and the ones on the carb side of the intake boots. It isn't necissary to remove the intake boots from the engine. At this point, I can't completely remember, but if the boots at the airbox aren't too stiff, take them off that end first by pushing each one off one at a time. the pull it out of the intake boots. This part always involves a lot of brute strength and cursing for me, so I can't help but thinking there has to be an easier way to do it. Anyone else have one??
3. Once you have them off, its fairly simple from here. If you haven't already done so, drain each float bowl. If you want, you can do it in a glass jar, one by one, to see if any crud comes out. This could help you figure out which one of the carbs is giving you problems. Once you have drained them, remove the 4 screws holding the float bowl on, and gently pull it off. Be careful not to twist it, as the clearance between it and the floats isn't very much, but it should come off very easily.
4. There is a little clip thingy that you kinda spin to take it off.
5. Next, remove the little retaining pin that holds the float to the carb. If it is difficult to get it to slip out trying one direction, try the other direction. Remember which way it came out and put it back the reverse way. Also, be sure to pay attention to which direction your float is in, as my understanding is these can be put in upside down. Depending on what your float is made of, you may need to replace it. Mine were made of a black foam, so they were ok, but I think some are just like toilet floats and are plastic boxes. If fuel can get into the plastic box, it will cause it to stay down even though the the bowl is full. If that is the case, you may need to replace it. Not sure if you can repair those, as I have no real experience with them.
6. Once the float is off, you can remove the float needle. Again, be sure to note how the needle is in the seat, as it is very easy to put in upside down. The little springy part is on the bottom so the float tab can push against it. Once the needle is out, remove the Phillips (at least on mine they were) screw holding the seat collar and remove it. Be sure to note its orientation, as this is also easy to put in upside down, and that will allow the seat to move which would cause leaking.
7. Once the retaining collar has been removed you can remove the seat. On mine I used a clean pair of pliars and firmly grabbed the seat and pulled it out. Mine wasn't really stuck in, and it didn't deform the old seat any. If you are having difficulty getting it out with firm pressure, something may be wrong, don't go yanking on it as you could damage the part where the seat sits.
8. Once you have the seat out, spray carb cleaner in there to clean the area out. Go ahead and spray cleaner through the other orfices in there until it comes out clean. Once you are satisfied it is clean (which it probably isn't but unless you have had problems with the bike not running right, you are probably ok) go ahead and put the new seat in and just reverse these instructions.
9. Now do the next carb. I suggest doing one at a time, as you don't want to mix parts from the different carbs up. When you go to put the float bowls back on, if your gasket is a little round rubber thing, to get it to stay in, put a fine bead of gasket sealer in the little groove in the bowl. Wipe it so it is flush with the edge of the groove and make sure none of it ends up in the bowl or else you may be doing this all over again when it clogs up a jet. Let it dry till its tacky and push the ring in that. This will keep the ring from popping out and getting pinched. Once you have the bowl back on, just look all the way around it to ensure this silly little ring didn't some how come out a bit and get pinched. It has happened to me a couple times and its annoying.
I don't have any mechanical training (unless you count my Jr High small engines class way back in the day, which I don't), but I am good with a wrench, so if I can do it, most people should be. With this forum, you will be fine. Don't let these instructions scare you, if you take a bit of time and record how parts relate to eachother, this is really pretty easy. Just be aware its gonna take several hours your first time. The upside is, the next time you have to get into your carbs, it will be a cinch and you will be a lot more confident.
Also, if you do decide to replace the fuel lines, let me know and I'll try and give you some detailed instructions there, as theres a couple things you will want to pay attention to, but again, just takes time.
I can actually take them apart, clean, and put them back together without the need for re syncing.
I did what I have given you instructions on after I had a mechanic sync my carbs (
I don't have the carb sync gauges, so it seemed like a good idea). After I was done, I put them back on and my bike runs pretty good without doing anything additional. I also changed my exhaust pipes from the 4-4 to a mac 4-2 at that time, so I blame that for the slight idling problems it has now. That being said, I plan to completely tear my carbs apart and do a thorough cleaning next spring where I will be removing everything and soaking it in carb cleaner and replacing all the rubber orings and such and buying the gauges to sync it myself. I want to try and do one of those awesome how-to's with lots of pictures and stuff that I have seen on here as I know when I first thought of working on my carbs it scared me to death.
Well, hope I haven't put anyone to sleep yet, and hope this helps.
Brandon
