idle problems

[jmd999891]

I just bought a 99' katana 600 with 4k miles about a month ago. I am noticing that I have to let it warm up with about 5min. of riding before it will idle ok. If i don't let it warm up it will die if i pull the throttle too quick. If i pull the throttle slowly it will sort of hesitate.( I am choking it for about 30 sec. before riding). I took the carbs apart and cleaned them. After i put them back on the idle was sticking around 4k rpm and sometimes it wouldn't even idle hardly at all. I was told that the carbs needed to be synched so i attempted to do that but all of my gauges were reading almost zero vacuum and the bike was running llike crap. I took the carbs off again and noticed that three of the throttle plates had a gap in them and the other was closed. I synchronized them the best i could by just eyeballing the plates and was able to get them close to even. I then put them back on and the bike was running halfways decent. I took the bike for a ride and it it ran good except sometimes the idle would stick around 2k rpm. Do I still need to sync the carbs properly or is there another problem? If I do need to sync them then what is the proper way to do it while keeping the bike running around 1k rpm? Thanks

[The CyberPoet]

(A) Sync them with the bike hot and the idle cranked up to about 2k RPM. Turn the idle back down after syncing.

(B) The temporary hanging idle on return-to-idle issue is normally caused by one of two possible issues, either:

1. Fuel residue build-up in the smaller carb passages (easily curable by use of a fuel-system cleaner such as Techron, run through with the fuel during normal use in the normal amounts -- 1/3rd bottle per full tank); OR

2. Throttle cable(s) set too tightly/binding/sticking. Loosen the throttle cables at the adjusters and see if it still does it. If not, then that's probably your issue.

Cheers
=-= The CyberPoet

[md86]

Don't forget a too lean pilot circuit . My idle was hanging up slightly because of that one .

[jmd999891]

When i sync my carbs where is the line that goes from the fuel valve on the tank to the #4 carb suppose to go. Also, will I be ok to ride the bike or is there a possible lean pilot circuit that may cause damage. I never made any adjustments to any jets in the carbs at all.

[Anonymous]

That sounds like a vaccum line to me...plug it up somehow...you don't want a vaccum leak during syncing.

http://www.katriders.com/forums/viewtopic.php?t=7433

[The CyberPoet]

Don't forget a too lean pilot circuit . My idle was hanging up slightly because of that one .

Dried fuel residues cause too lean a pilot circuit, and thus it's pretty much the same issue (unless something else caused them to go lean, such as install of an air filter with less restriction).

When i sync my carbs where is the line that goes from the fuel valve on the tank to the #4 carb suppose to go.

You leave it disconnected and either use an alternative fuel source or set the petcock to PRIME while syncing (and have the tank higher up). Since the connection to sync for carb #4 is the same place that that line normally connects to, obviously it can't be used to open the petcock's vacuum diaphram. I just use a small gas can set up on a shelf with a long fuel line hose to feed the carbs while sync'ing.

Also, will I be ok to ride the bike or is there a possible lean pilot circuit that may cause damage. I never made any adjustments to any jets in the carbs at all.

It may cause your plugs to foul if you tend to sit at idle a lot (or don't ride the bike very far and thus never let the plugs come all the way up to "burn-off" temp), plus it creates excess heat in the cylinders, but it shouldn't do serious damage under normal circumstances.
Question: have you done anything else to the bike that might lean out the mixtures, specifically:
1. Exhaust: Added an aftermarket end-can (muffler) or exhaust system, or swapped to a larger exhaust system (such as moving from the 600 to 750 headers), or ported & polished the stock exhaust header weld seams?
2. Intake: Changed air filters to Emgo brand replacements, K&N filters, Unifoam filters, or switched to air-filtering pods instead of using the stock airbox? Or made any form of modification to the airbox (such as drilling it -- highly unadvisable)? Or perhaps left the cap off the airbox drain tube?

Cheers
=-= The CyberPoet

[jmd999891]

no modifications have been made, the bike is completely stock. I am a mechanic and I had some left over BG fuel system cleaner that I am going to try. Has anyone ever used BG products on a bike? P.S., even though I work on cars for a living I know nothing about carburetors and this is my first bike which is why I am asking all these questions.