idle runs low after about 10 minutes riding

[dnargsiefil]

Hi, so I have been now through the carbs many, many times, the bike is actually running really good. Here is my usual procedure:

- start with half choke when cold
- can take the choke away after about 30 sec and the bike idles around 900
- now I get going to work and about 4 miles later the idle picks up and goes up to 1500, which works actually alright

once in a while when I take a longer ride (20 minutes+) the idle will drop again below 1000 and starts to stall on me when sitting at a traffic light.
starts right back up and will sometimes go back to 1500 idle (which btw I consider good enough), next traffic light it will drop to below 1000 and eventually die.

My work is about 7 miles away so when commuting I don't really see any issue, it is just when I go further than it becomes harder to idle.

Any ideas? thanks

[The CyberPoet]

What's the weather like there?
I ask because of the cold idle and the choke use...

As for dropping again -- the cable that sets the idle RPM on your carbs -- is it healthy (i.e. - sheath attached at both ends securely)?

Cheers,
=-= The CyberPoet

[dnargsiefil]

it is warm, happened yesterday for instances riding into downtown Minneapolis at around 7 AM which would make it 70th about.

the idle adjuster seems alright, it is not new by any means but I could say it's broken... and I do not change anything, next time the bike sits for about 1 hour it works in the same way as described...

[The CyberPoet]

If ambient is 70, your pilot screws are too small or set incorrectly (or the o-rings on them are toast), or the pilot passages are partially blocked again -- you should be able to start without choke in such weather.

Q: Airbox & standard OEM air filter?

Cheers,
=-= The CyberPoet

[sirdeity]

Your problem sounds a lot like mine. My bike also stalls a lot after riding for a while, but ONLY when I come to a stop. I'm sure it's not an operator error. The bike just doesn't want to run on its own power after a while. Only gas seems to keep it going.

[dnargsiefil]

If ambient is 70, your pilot screws are too small or set incorrectly (or the o-rings on them are toast), or the pilot passages are partially blocked again -- you should be able to start without choke in such weather.

That could be it, when we did my last carb cleaning and sync we did notice that some of the o rings were not looking so good anymore. Well got to wait on this one, since I need to schedule the carb sync tool to be in town again. Good catch

Q: Airbox & standard OEM air filter?

Of course OEM, I'm not going to make it that easy on you guys..

[kevin2502000]

Mine does the same thing, same bike. I just either beat the crap out of it which restores proper idle or just turn up the idle enough so when its at its low it still runs. It doesnt bother me enough to clean the carbs again and I do suspect the synch port orings but it runs great enough to live with.

[GytRDunKat]

I need to schedule the carb sync tool to be in town again

Let me know, we should probably plan another get together soon.

[belgum]

One possible cause that comes to mind is a vacuum forming in your tank. This will happen if the tank vent is blocked (not sure if Kats vent via the filler cap or not). To test, after a longer run when the symptoms show, open the filler cap and, as you do so, listen for a hissing. Basically, if the tank sounds like it just sucked in air as you open the cap then it isn't venting. Had this problem with my 21 year old VW Car.

Anyway it's the easiest thing to test. If the problem immediately goes after opening the filler cap (close it before you restart the bike), then you've found your problem.

Let us know how you get on with this one.

[dnargsiefil]

Checked for that vacuum today but it did not hiss.

I may have another symptom which I like to add to the list here.

When running around 4k RPM I have once in a while a back fire, just a soft one not a terrible loud one.

[katanachris]

Same thing happens to me, i was told to replace the K and N pods with a stock airbox. I ordered the stock 750 airbox on ebay but it doesn't seem to fit and it says 600 in sharpie on the top. Is there a differnce in size between the 600 and the750 airbox's Thanks chris