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Discussion Starter · #1 ·
93 vt1100, cobra pipes, k&n filter, cobra jet kit, custom minimal baffles.

Ok, I'm having some issues here... I read somewhere on a Rebel forum about a guy having issues with his emission system sucking fuel from his tank into his evap can, then it getting sucked in his intake, making it rich and hard to start...well mine is doing that. I disabled the emission system to see if that would fix the problem. I'm ok with keeping the system on (I live in WI), but I need to troubleshoot it. Problem is, with it all off right now, I'm running rich. I pluged the little vacuum ports that run the valves (10 and 11). I also plugged the lines feeding into the intake (#5). The vent tee from the carbs is vented to atmosphere, as is the tank vent.

Now, if I'm following the air flows correctly, while the motor is running, the purge valve (behind the radiator) is open, allowing the intake (#5) to draw air from the evap can. Now, it looks like the air can be fresh air from the evap can (#2) or from the fuel tank (#1). If I plug these lines (#5) wouldn't I cut back bigtime on my air flow, thus making it rich? (which I have).

Now, I'm considering leaving #5 open to air, but I'm concerned it will draw in too much air, because maybe by the time the air passes through the restrcitions in the evap can and valve not much air is flowing....

Can someone please give me a hand with this? My bike started like crap before, but now starts fine but runs like [email protected] at any throttle positions past 1/2. Like I said before, I plan on keeping this system on, but need to see if it was causing my hot starting issues. Feel free to PM me if you don't feel comfortable posting.

Thanks!



I have the 93 vt1100

 

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Discussion Starter · #2 ·
Just went and looked at my evap can... If I blow air into #4 (or suck) it easily comes out of the vent #2 or the drain. It does come out of #1 going to the tank, but not much pressure, and I'm guessing its because it passes through the charcoal. So, should it really be these easily flowing? If so, when my engine is running, the carbs are actually pulling air from the drain or #2 line from open air and into the intake...
 

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I have read through this and am still unsure what your exact question is or for that matter whether I can answer it. But I do have a Cali bike and when I switched tanks the new tank had no vent nipple (or vent) so I was confused at first what to do. I ended up just capping the hose that would have connected to the tank with a small homemade filtering cap (so it could still draw air). Other than that the system is 100% intact. And it has never seemed to effect performance or running characteristics.

So…if you are concerned that your emission system is sucking fuel from the tank, just disconnect it from the tank (and plug the tank nipple). I think you’re overcomplicating it, but what do I know. :oops:
 

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Discussion Starter · #4 ·
Sorry for the long post. I guess plain and simple, my bike was having a hard time starting hot. I suspected the emission system. When I pulled lines #5, there was raw fuel in them (being sucked into the intake). I read on a Rebel forum that a guy had this problem, especially when he filled his tank over 75% full. I removed mine to see if it helped. It hasn't had a starting issue since, BUT, it runs so rich it misses at higher throttle settings. Looking at the airflow, if I blocked the ports on the carbs #5 attach to, wouldn't that actually reduce the air flow, thus making it richer? I say this because while the engine is running, it appears air flows from the atmosphere and fuel tank, into the evap can, and then into my motor.

Also, I thought of your situation last night after I posted. I could leave it all intact, just unhook the fuel tank line, that way no raw fuel could get in the system.
 

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Discussion Starter · #5 ·
Still not sure if I was clear on my questions.
Lets try again.

1. Does what I say about air flowing through lines 5 while motor running correct?
2. Would just blocking those lines into the intakes cause rich conditions?
3. If I disconnect the fuel vent line, will my tank dribble gas out of the little vent nipple on the bottom of the tank?

I'm thinking that on a non-CA bike the carbs must be set up differently...maybe same jetting, but air flows are different???
 

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Discussion Starter · #6 ·
noone has any advice/experience with this? or maybe someone can explain exactly how the air flows work and then I can go from there?
 
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