I recently purchased a 93 900rr. Before i picked the bike up from the previous owner, he had it at a shop getting the carburetors cleaned and adjusted, it got new plugs, air filter, new coils. The problem i am having is that it bogs down after 5000 with a load on it; meaning it will rev past 5k in nuetral but when it is being ridden it breaks up after 5k. I have a shop manual and i have checked the readings of my coils and my ignition pulse generator and they are within range. Anyone out ther have any ideas i should try or have they heard of this before? Any help would be appreciated.

James

 

i just ran into this same problem

 

just pulled the intake off and i notice that when i twist the throttle everything looks good until like 6k then the # 3 carb all the sudden has no fuel

 

for both of you, it sounds like your carb has got a clogged or restricted main jet. This will effect you pilot, and main jet cicuits and you will notice nothing at idel, or low RPM operation. Its when the carb tries to sifon gas through the main jet that the issue will show itself. If you pull the spark plugs you will notice that one looks a lot more wet than the others. That norrows down the carb, but its not necassary because you need to go through the carbs as a whole, not just one. So time to pull the carb bank, pull the bowls off, and make an initial observation of any debris in the bowls. YOu will also want to pull the top covers, needles, and diaphrams. Look for tears in the diaphrams, or piched gaskets. Make sure that all of the needles have the same clip setting. Now, unscrew the main jets and make sure you can see right through them, its a tiny hole. Also check the pilot jets,which are located next to the mains. If those check out then you may have something in the ports that these two jets thread into. For the main jet this is the hole that the needle will go into when the throttle is closed. A huge mistake that most shops make is they use RVT sealant around the bowls to make sure there will not be leaks. RVT is gas soluble so it will be ok for a short period but then the gas will turn it into a very sticky gummy mess that sits in the bowls and eventual it gets pulled into the jet, especially if you run the bike low on fuel. If you see any orange sealant, or sealant of any kind, then I can garantee you that you have found your problem. Regardless of whats clogged up your carb you need to use the proper cleaner and compressed air to thoroughly clean all ports and jets. An alternative is ultrasonic cleaning, but most folks do not have access to that. Don't use wire or anything like that, just soak the thing with cleaner and blow it out. Simple Green is also something that you can soak the carbs in for an hour or so prior to this cleaning to loosen stuff up. If RVT wasn't used then there can be sand, or other debris that make their way into our fuel delivery systems, so don't rule anything out. Be thorough and don't rush and you will find the issue and fix it the first time. And REMEMBER to place each carbs internals in its own labeled contained so you do not mix stuff up when you re-assemble. There is an off chance that this is ignition related, but the carbs are easier to clean and check than the ignition, and they deserve your attention from time to time. Good luck and be sure to update the post when you find the issue to assist others down the road. I bet you the repair shop used sealant. Let me know, and never ever use RVT on any part of a fuel system!

 

Good info Fighter!

 

i compleatly went through the carbs and cleaned every thing (no sealent found).. i cleaned all the jets,bowls,needles and put them back on, and then it still wouldnt start at all so i cleaned the plugs still nothing. so i unscrewed the bowl valves and nothing.the bowls wernt filling with gas. so i took them back off and lubed the float jets and now it starts for a second then dies. the funny thin is that when i spray carb fluid into the carbs and start it it runs as long as i spray fuid into it, so i dont think i have a spark problem. def a fuel issue

thanks for all the help

 

I believe the 93's have a fuel pump and it sounds like that may be your problem.can you here your pump run when you turn the key on?if you can here it, your filter may be clogged.usually when the filter is clogged the pump will be louder than normal.

 

i dont hear it but it does work it spits fuel ever other second

 

ok i cleaned them again with compressed air and cleaned the plugs again and bam started right up and i could rev through the entire band but once it warm up its now flooding the engine at all rpms i have to hold the throttlle full twist just to get it to start and then it just floods out after a second

 

you have got a float issue here maybe. If your not really familiar with carb work and don't have the tools like a sync, and float guage this might be a project for a shop. The manual will only get you so far with the carbs and the rest is up to you. When you blew out the carbs did you really go through the, fully or just hit the jet ports? The more attention you give something like this the faster the repair usually goes. I know its frustrating to have the bike down but you gotta take a deep breath and just look at it systematically. Obviously you need to pull the carbs again and this time really go through each system on them, and check the specs to the manual. Float height is of paramount importance, and if one of your floats is sticking then you will see flooding like your experiencing. There is no adjustment for float height, if they are off then you must replace the float. I can't walk you through each step, it will take an entire page, you need to look at the manual and fallow it paragraph for paragraph. It would seem that you fixed one issue with the cleaning you performaed, and maybe caused another by being rough with a float. There is a sealant that is used by Honda on the drains to each bowl and when you drain the carbs and reassemble them it is possible to have a float stick to the residue on the bottom of the bowl. Good luck, your getting there you just need to really take each step one by one. And I would really recommend soaking the carbs overnight or at least for a few hours because you do not want to pull them again, do it once and do it right. Whatever you do, don't try starting the bike anymore as it is, your washing down the cylinder walls with gas and contaminating your oil, as well as robbing the rings of lube. Pull your plugs again and re-clean very thoroughly with a high grit sandpaper and acetone. You shoudl really replace them to be sure but you can get by if you get them clean enough. Keep us updated. And have a happy Thanksgiving everyone.