97' YZF600R Issue

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  #1  
Old 05-06-10, 12:29 PM
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97' YZF600R Issue

Hi all, I owned the above bike for the last year+, and I'm in need of some advice on a problem. Here's the situation:

The bike was stored for several months over the winter season here in Wisconsin. I pulled the battery, left just a little fuel in the system and put a little stabil in there. I was told in hindsight that I should have left a full tank and I might have used too much stabil, but that's what I did and now I'm moving forward. Taking her out of storage just recently, I filled up the tank with premium she she starts really hard. The throttle and choke have to be played with the entire time or she will die, and after about 30 seconds of running, unspent fuel will begin to leak out the seam where the exhaust pipe fits into the long exhaust piping that comes out of the manifold (aka way back by the footpegs not anywhere near the engine).

So first thought is that combustion is not happening in 1+ of the cylinders, causing the engine to run like crap. The unspend fuel is just going completely through the unfiring cylinder(s) and gets shot out with the exhaust fumes, builds up in the vertically angled exhaust pipe, pools up inside and leaks out at the seam into a puddle on the ground.

We checked the spark plugs, dirty but not seemingly fouled so we put them back in and moved out. Yanked the fuel tank and air box, took a basic look at the carbs. All of the butterfly valves seem to open close fine when we play with the throttle, couldn't see anything else weird but we have not done any disassembly of the carbs (yet). Never done anything like that before (but we have some basic experience and a haynes manual to help) so maybe we will.

Here is the twist that I'm hoping might make the light bulb turn on for someone reading this: When we drained the carbs, we got about 3/4 dixie cup full of fuel from all of the carbs, except the far right one, which was COMPLETELY dry, not a drop to her. Someone suggested the float might be stuck, do you agree? What else could it be? I don't know engines through and through, but it baffles me that fuel could go through the carb, through the engine, not detonate, build up in the exhaust pipe and pool on the ground and that absolutely none of that uncombusted fuel residually ends up sitting in the carb to be drained when I loosen that drain screw.

Any advice would be great, trying to avoid taking it to a shop, finances are tight.

Thanks
 
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  #2  
Old 05-06-10, 08:33 PM
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Motorcycle carburetors are very tempermental. They have very small jets and the least amount of sediment or bad fuel residue will cause a running issue.
Today's gasoline is different then it was just a year ago. Storage , with stabilizer, can be only a few weeks
I have run into this a few times this year.
If this was my bike, I would do a complete tuneup with new plugs and freshly cleaned carburetors. I realize this may be a problem for you but you can do the repair if you take your time and even take a few pictures while working on the carbs.
Many times I have troubleshot a bad running engine and did a lot of unnecessary work but that just goes with the DIU group
 
  #3  
Old 05-07-10, 04:08 AM
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You likely have float problems in at least two if not three of the carbs. The one with no fuel has either a stuck float or a restriction in the fuel delivery to the carburetor - probably the stuck float. The other one or two has a sealing problem with the float valves (likely anyway). It could be in both or one.

The dry one is a dead cylinder while the other one/or two are flooding = crappy running engine.

First turn on your fuel to the carbs and use a screwdriver (plastic handle). Tap on the outside carb with the dry bowl. Leave out the drain on it and see if you can get fuel flowing through it.

Then get Sea Foam from an auto parts store and solution it with 4 oz to a half gallon of fresh fuel. Drain all the bowls and let them fill with that mix from the tank.

Start it, let it run for about five minutes, choke it a couple of times and shut it off. Let it set for about an hour, then repeat. Then fill the gas tank completely with gas and see how it's running.

This will take car of problems about 3/4 of the time without dismantling the carbs.
 
  #4  
Old 05-11-10, 09:48 AM
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You surely have carb problems. "marbobj" is correct in his advice, but getting that one "dry" carb to flow will be a minor miracle and whether or not the seafoam will cure all the ills is a 50/50 shot at best.
I know pulling the carb rack seems like alot of work, but you probably have to. Get the carbs off and remove the bowls and clean it all up. Get the floats off and the needle and seats cleaned out and flowing freely. The same with the main and primary jets. Do ONE CARB at a time! Don't mess with any settings.... when you put it all back together, it is usually fine.
Next time you store this unit, full tank of gas to keep the tank from rusting, and pull the vacuum line to the fuel petcock and let the engine run the carbs dry. If you can get the drain screws in the bottom of the bowls to work, that would be OK to drain them too. This will be OK for storage of a motorcycle for the winter. This is NOT for extended periods of storage.
When you're ready to fire it up, turn the petcock to the "prime" position to fill the carbs and then fire it up. Hopefully you put that vacuum line back on after running the carbs dry and closed any drain screws you may have opened.
Everybody has a storage system that they thoroughly believe in, but I've had motorcycles in New England since.... geez... a long goddam time! And this procedure is all that is needed to keep the carbs from getting all messed up during a winter storage. I have used the gas additives and all the voodoo techniques and this is what I've boiled it down to.
Again, this is for a winter storage.... you go any longer and you are on your own with the results.
 
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