[01 B12] Carbs and general troubleshooting. FIXED

[LowRes]

I'm having an issue with the B12. Last week I was spending the night away from my place and bike was forced to live outside and had to endure a heavy downpour. The next morning, the the clouds had cleared, I fired it up and went on my way. One mile down the road I was preparing to leave a stop light when I heard the dreaded "thhhhhhbbbbbbb" (imagine putting your tongue between your lips and blowing- that sound). The power started to dwindle and I pulled off in a church parking lot about 100 yards away and let the bike die as I came off the throttle.

I started it again, low idle and eventual death. Any throttle would kill it. With each attempt to get it running again it would run for less time and idle lower. I rented a trailer and took it back to the house.

I have had this issue before, well the symptoms where similar, a few months ago after washing the bike. At the time I was traveling and without adequate tools so I took it down to a shop who "cleaned the carbs". 450 dollars later it was running right again and that was 3.5k miles ago. I would prefer to fix this myself, save some money, and hopefully gain an education in the process.

Sunday I stripped the carbs off the bike and proceeded to "clean" them as best I could. For a novice who has never worked on a carb I approached it with some trepidation.

On Sunday I did:
- Removed the float bowls, jets (main, starter, and there was a third cap I took off that was brass but did not look like the other jets).
- Checked for spark on all four plugs with each plug on the wire that it would use- these checked out, small blue spark from each.
- Air filter was clean.
- Petcock was operating as expected. In the on position (by sucking on the vac hose) would flow gas. Prime would flow gas regardless.

I did not:
- Remove and clean the mixture screws or the main jet needles (didn't even pop the cap on top of the carb). This was mainly due to my trepidation about that spring on the main needle.
- Drain the tank. Yea, got lazy I suppose.
- I did not use compressed air to clean the fuel passageways when the carb was apart, I just blew carb cleaners in to each jet or passageway.
I reassembled and it sprung to life after a few starts. The bike would run (not amazingly well) with the choke on. Taking the choke off the bike would idle very low and eventually die. Rolling on the throttle with the choke on the RPM's will climb to about 3.5k and then the bike would lose power and the RPMs would fall off, often times the bike would die after reving up to 3.5k.
- The bike has an inline filter which looked like it has some sediment inside. I did not replace this as the part is hard to source (perhaps someone knows of a part from Autozone or Napa or something similar I can use, they never seem to have one in a similar form factor with the proper in/out diameters).


So I've taken the carbs back out of the bike now. I have removed the caps on each carb and the mixture screws with the intention on cleaning them again and using compressed air. I will drain the tank and refill it with fresh gas.

Questions:
- How would you go about diagnosing this, what steps have I missed here based on what I have described?
- It would seem that I have made some progress on my initial cleaning attempt (will run with choke on), what might I have done during that process which is causing the new symptoms (low idle, dies if you give it gas, runs on choke)?
- For cleaning the plastic diaphragms on the needle I was told using carb cleaners would swell these and possible ruin them- is this correct?
- Should I, or is it even possible to, separate the needle from the slide and rubber diaphragms to clean them?

[r_outsider]

I've seen seriously deep sixed dirt bikes and ATVs run fine after a lot less effort than you've put in. Change the fuel filter and run a can of Seafoam through the bike. If that doesn't fix it, it's probably an electrical issue. You might try pulling the plugs and blowing out the caps and every other connection up to the CDI, and putting it all back together with some di-electric grease.

[pmackie]

I'd start with the simple things first:

1. Drain the tank completely, and check for water. The best way to to this is to drain it into a large GLASS jar, let it stand for a minute, and see if you find any water. You can do this by putting the petcock onto PRIME until you get the tank almost empty, and then you will need to remove the petcock off the bike so you can drain the last of the fuel out, as even turning it over and draining through the fill won't usually get it all out, and since water is heavier than fuel, the last of the stuff you drain out will likely be water.

2. Change the in-line fuel filter. If you have to, order a new Suzuki one, but you should be able to find a cheaper one at an Auto Parts store.

3. Drain the float bowls on the carbs...you don't need to take the carbs off to do this, as there are drain screws on the bottom of the float bowls. If you have the carbs off already, just drain them.

As you can tell, I suspect from your description, that you likely have water in the fuel system. The GLASS jar check will tell you for sure. If you actually DON'T find any water, then the next most likely cause is electrical, but I doubt it.

[LowRes]

The Bandit is back up and running again. So, I tore down the carbs again and did a more complete cleaning. I did notice that I was missing that very small o-ring under the spring on the number four carbs A/F screw. It was running before with that missing, and since I can't easily source that part I just reassembled the carbs without that part.

I am pretty certain it was water in the gas. While draining the tank I noticed that the last bit I got out was very cloudy. If you look in the filler cap there is a hole there that allows overflow gas to run back in to the tank. I bet water drained through the filler cap and in to the tank that night it lived outside.

Anyway those carbs are spotless now and I have leqarned my lesson that I should have done the easy thing first which is drain the tank and the float bowls. Live and learn.

Next on the list is the chain. Never replaced one of those before but I'm sure I can find a thread on here to read.

Thanks for the replies guys. 

[strubby]

I hope you don't mind me adding to this thread rather than starting a new one. I have the exact symptoms to a T with my '02 600s right now. When I bought it, it would start or run at all. I pulled the carbs, cleaned them with aerosol carb cleaner, got the residue off the needles (didn't remove any jets, just sprayed them). Drained the gas tank (not by removing the petcock, just drained it on PRIME. Put it back together and it fired up. HOWEVER, now it is doing exactly as the OP said. It starts every time. Idles a little low, any roll on the throttle and it dies. It idles better with choke on slightly, and more often then not I can slowly rev it to 3k-4k on choke. No the OP thinks it was water in his gas since he didn't drain it first time around, do you guys think I just need to do a more thourough clean on the carbs? Any tips? I bought another can of carb cleaner, just spray it into a container and let the jets and needles soak? I wanted to do this today before I left town so I could put it back together when I return in 3 days. Also checked spark, seemed weak to me, but I'm used to single cylinder bikes, and all cylinders fired consistently, so I'm assuming it's fine. Any help is appreciated!

[LowRes]

strubby,

I also found a vac leak on mine which more than likely contributed to the throttle -> dies problem. Mine has developed other problems in the mean time =).

[strubby]

Where did you find your vaccuum leaks? I believe I found my problem. The main jet passage ways on carb 1 and 2 were completely blocked. Took me a little time, some carb cleaner in the face and lots of patience to clear them out. In the meantime all jets and needles are soaking. All pilot and main passage ways are clear now, so I hope it runs better! I'll give an update when I get back, probably Weds.

LowRes - goodluck with the bike!