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Discussion Starter #1 (Edited)
So out of nowhere the other morning, my ZR-7 started sounding weird and is super sluggish/almost dies below 4000RMPs, it had been running perfect up to this point. It sounded and felt like it was only running on 2 or 3 cylinders, but right after starting all for headers are evenly warm so all cylinders are firing. I even pulled the spark plugs to check for spark and color and all were ok. Once it's warmed up it is still super sluggish and crappy below 4000RPMs, but responds completely normal after 4000RPMs once warmed up. It's like how the ZR-7 is if you just started it on a cool/cold morning and tried riding without warming up or using the choke, but it stays that way even after its hot. The sound is like a knock or "chug".

It seems to be a fuel delivery issue, it just seems weird how it was fine when I rode it home, and then all messed up the next morning. Someone mentioned it could've been a bad tank of gas, but it was half full and I added a bottle of carb cleaner and a filled the rest with chevron premium and it didn't fix anything (I always use premium, but had gone to a questionable gas station for my prior fill up).

Has anyone else had a similar problem or have any ideas what might be the issue? I'm really low on funds right now so I can't just take it to a shop to have them do an expensive investigation.

Your help is much appreciated!!
 

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maybe the carbs want a clean out, may have picked up some dirt in a jet or jets that control it below 4k rpm.
 

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It seems to be a fuel delivery issue, it just seems weird how it was fine when I rode it home, and then all messed up the next morning. Someone mentioned it could've been a bad tank of gas, but it was half full and I added a bottle of carb cleaner and a filled the rest with chevron premium and it didn't fix anything (I always use premium, but had gone to a questionable gas station for my prior fill up).
Sounds like a gas issue. Can you get through it or drain the tank and flush it out? Pull the petcock assembly and check the screen. Pull the fuel line and check that. There is another screen on the other end of the fuel line before the carbs; check that. Maybe the combo of questionable gas followed by carb cleaner jacked something up.
 

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Also check the choke cable to make sure it works and ensure the air filter is clean.

I'm on the fence if it's a gas problem as poor flow at low speed would be poor flow at high speed. I agree it could be a low speed jet problem though.
 

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Did it "sit out" and get wet overnight? (heavy dew/rain). if so, could be nothing more than a evil wet electrical gremlin. (coil/plug wire(s) grounding) Does it start, run "normal" with the choke on? The seemingly running "normal" in higher rpms (4k+) could mean one of the carbs has a restricted/plugged low speed jet possibly, and it's only idling normally on the 3 remaining cylinders... for the most part...till the carbs open up into the mains. To isolate a suspect plugged carb, start it, and turn the idle knob up till it will just stay running, (doesn't have to sound/run smoothly, just to stay running) and then pull individual plug wires off one at a time, (rubber/insulated glove may help from getting ZAPPED. LOL) and each time noticing if it drops/stalls when disconnected. When you disconnect one that doesn't affect it much, or at all, you've theoretically found the culprit/offending carb. If it's a carb issue. Hope you get it figured out. And like Obo mentioned, checking on the air filter and choke operation is a good idea too.
 

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Mine had a dead miss once at low speeds...
Wound up being the boot from the carb to the head...
Had the carbs off twice and didn't catch it till putting them on the second time..
 

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Was it just not tightened down, or did it actually leak thru the rubber and aluminum sleeve inside and need replacement?
 

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Was it just not tightened down, or did it actually leak thru the rubber and aluminum sleeve inside and need replacement?
It was cracked but hard to notice until I spotted it pulling the carbs off the third time....
I replaced all four and noticed a big increase in power with the new ones...
The old ones were all cracked through in the end.....Good fix for under 100 bucks..
 

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Drain all the fuel in the system as completely as you can, and then flush a quart or more of fresh "trusted" fuel. Change the spark plugs. Fill up with the good stuff and now give it a try. Bad gas will just run bad, period.
 
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