Help Please !!! Cleaned carbs now extremely high idle at 10-11000 RPM

[JudahKat]

Hi everyone,

I am fairly new to the forum and am hoping someone can help me. I have a 1990 Suzuki Katana 750. My bike was running fine with the exception of the occassional rough idle. I decided one day to take the carbs off to clean them only to notice that the brass pipe for choke to carb one was broken. I found a local guy who said he could repair it for me. I took it to him and he replaced the pipe and used JB Weld to put it in place. The repair looked fine and I didn't think anything of it. When I replaced the carbs I went to start the bike and got nothing. Ended up draining the battery. Charged the battery and decided to suck the vacuum line to get gas into the carbs. Attempted starting and she cranked but the idle was so high it scared the crap out of me. Spoke to a few people and so far I checked the choke cable (completely released and started only to get idle at about 10,000 RPM), checked the throttle cable (completely released), Checked for vacuum leaks with WD40 and found nothing, took the carbs back out and checked for the O-Rings and seals and all look okay, checked the vacuum hose from the petcock to the carbs for breaks and it looks fine and now I am at a loss as to what the problem could be.

I recently read a forum that said this guys carbs floats were flooded and he had gas down inside the engine mixing with the oil. It suggested he drain the oil and replace it with the filter and try it. That was the next step I was considering. I looked at the oil and it does not look normal. It is kind of thin looking and yellowish. I am upset though because that was the high end racing oil at $9.99 a quart!

Please let me know if I am headed in the right direction. Thanks.

Sorry, forgot to also mention that I checked the idle adjust and screwed it all the way down so the butterflies are closed and still get the high idle.

[93_GSX600]

10k rpm idle? thats nuts man...

every butterfly is closed?

[Maxxrox]

I checked the idle adjust and screwed it all the way down so the butterflies are closed and still get the high idle.

If memory serves, tightening the idle adjust screw (clockwise rotation; at least on the 98+ Kats) increases idle? Back that lil' guy out a few turns.

I'd be more suprised if you tightened it all the way down and your idle was less than 10K *laugh*



--B

[scottynoface]

Yes, righty uppy lefty downy.

Did you get the boots back on the airbox correctly?

[JudahKat]

Hey guys. Thanks for the replies. Yup, 10K RPM is nuts! It starts at about 9 and starts climbing from there before I shut it off in a mad dash. Sounds like the engine wants to jump out.

I completely removed the idle adjust screw and cable to troubleshoot and no change. Went through the carbs to check all seals and can't find a thing. Checked the butterflies and they are all closing properly. I do think the boots to the airbox might not be on completely. They were seriously hard to get seated on but the rings did tighten properly so I assumed they made a seal. I am going to remove it again today and try to reinstall. I am getting so frustrated with this so any other ideas are definitely appreciated. Didn't get to take the Kat to bike week in Leesburgh, Fl. so the wife and I have been pretty down. Thanks again guys. I will try the airbox and let you know what turns out.

[suzukiray]

How do you know the butterflies are closed? Did you pull the carbs to see? If so, did you open a slide & look again after you re-installed the carbs to make sure the cable isn't hung up & pulling the butterflies open after you put the carbs back on? Ray.

[Wild-Bill]

Try running it with the tank off and the throttle cable disconnected. That way you can see the throttle position from above to make sure nothing weird is going on there. You can disconnect and re-connect the cable with the carbs in the bike. It just takes some patience and a hooked piece of wire to push the barrel out of the hole in the linkage.

[nater123]

Look at the throttle cable with the tank off. Mine did this same exact thing, the boot the boots from the air box to the carb, the clamp was getting in the way of the throttle so it was leaving on partial throttle. Try it and give it a try or make sure the inner two clamp screws are at the top so there not interfering with the throttle cable or mech. on the carb.

[md86]

You know , mine idled REALLY high ( like 6K+) when I had a shop clean my carbs . Forgot to close the float bowl drains ...

[JudahKat]

Okay. Thanks so much for the ideas so far guys. Checked the airbox and actually replaced it with another I have that I know seals and fits on good. Clamps all clamped great. Still same problem as well as she takes a long time to start now. A friend said I probably had gas on the plugs and that was why it took so long before it would start. My clamps are on the sides so I will check to make sure they are not opening the butterflies. Did take the carbs off and visually check the butterflies but when I put the carbs back on I can't see how I can check the butterflies. Can't see them. I will check the airbox clamps this afternoon and let you know what I find. Already tried disconnecting the throttle cable completely. No change. Thanks again guys.

[katana600Frider]

looks like you got a real headache on your hands man hope you get it cleared up in time.

[DumbLuck]

check the low speed jets. maybe the guy thought the hole was too tiny and reemed them way too far open. also, how about the needle jets? are they properly in the slides, and dropping down into the needle jet holders as they're seposed to? reemed open low speed jets, missing needle jets, or even the air/fuel screws way off will jump the idle badly

[arsenic]

not that badly

[JudahKat]

Hey everyone. Thanks so much for all the ideas and suggestions. I finally got it sorted last night. Turns out the throttle cable was being pulled because the adjustment screw at the grip was adjusted wrong. I released the screw and turned it all the way in and the throttle cable released tension and the throttle came way down. She is back on the road! Thanks so much everyone. I think I am a carbs expert now at this point, as many times as I went through my carbs!

[arsenic]

I could have told you that. All these people would tell me I was wrong so I didn't.