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Discussion Starter · #1 ·
I rebuilt the carbs on my 96 FZR600 and now I have a surging idle and need to keep the enrichment on to keep it running. I've rebuilt lots of carbs, so I have some faith in my skills. It sounds like a vacuum leak, but I wanted to see if I missed any tricky bits in the rebuild.
Any thoughts?
 

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Discussion Starter · #4 ·
I went all through the carbs again. Everything is sparkly clean and set to factory specs. Air screws are 2 1/2 turns out. No vacuum leaks that I can find with a can of brake clean. Checked sync as best as I could and the cylinders are pretty close. Still won't run without some choke.

One strange thing. After I get it warmed up, the cylinder header temp (measured with a laser temp at the exhaust manifold) for cylinder 2 (counting from the left sitting on the bike) is about 150 degrees f lower than the other 3. Three are at about 600f and one is at 450f. All 4 plugs look the same. I haven't done a compression check yet (I have to get a gauge with an extension).

This all started all of a sudden. One day it was running strong and the next, it was like it is now. My first thought was some junk got past the fuel filter, hence the carb cleaning/rebuild. On disassembly, there was some stuff in the float bowels. Since the problem continues after a thorough cleaning, I'm thinking it's maybe not the fuel system.

Any ideas? I love this bike and want to get it back on the road before the rains hit here in the PNW.
 

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Administrator "Loose Nut" - from Houston, Texas
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Sounds like something still not right with PSM screws or pilot jets. I would turn the PSM screw out about 1/4 turn or so on cylinder 2 to see if that helps. Did you double check the small holes on side of pilot jets were debris free?

11996


11997
 

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Discussion Starter · #6 ·
Well, I got it sorted out. Here's what I found. The needle you mentioned didn't look like what's in my carbs, but your comment did get me thinking in the right direction. When I did the initial clean/rebuild, I couldn't find my tiny, long shaft screwdrivers, so I didn't pull the 2 idle jets. I did run lots of cleaner and a small probe through them all and got what I thought was good flow.

This seems to have been not enough, as it didn't fix the problem. I took some time, found the needed tool, and pulled the jets. My rebuild kit had replacements for them, so after putting those in and reassembling everything, It's all better, runs great and idles as smoothly as it ever did.

Thanks for your help. It's always good to have another brain thinking about a problem.
 

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Administrator "Loose Nut" - from Houston, Texas
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Super glad you got it going. Make sure you sync the carbs first chance you get, it does make a difference. The next time someone posts similar issues, you can post what worked for you and possibly save them some headache. Again, good job.
 

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Discussion Starter · #8 ·
Super glad you got it going. Make sure you sync the carbs first chance you get, it does make a difference. The next time someone posts similar issues, you can post what worked for you and possibly save them some headache. Again, good job.
Thanks. I did a carb sync once I sorted the idle speed and got things up to temp. I also took your advice and played with the air mix screws and got the exhaust manifold temps pretty close. It was a mattter of making small adjustments, like less than 1/4 turn. I don't have any way to do the O2 probe thing to adjust mixture, so this and maximizing smooth idle and initial roll in will have to do.
 
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