Hey, so my next big project is to rebuild the carburator and rejet, of course. I have been having this problem for a while, and I'm hoping people can give me some things to look out for.

After the engine is warmed up, either with 2 minutes of choke on full or 30 minutes of agressive riding, whenever I approach a stop sign or a red light and have to stop, the engine RPMs usually drop down to 800-1k and the engine dies. It's always easy to start up again, but I have the same problem. If I stop somewhere (NOT at a red light or stop sign) to check/adjust the idle speed (it's usually 1.2k-1.5k but it fluctuates by about 200 at any given time) the bike is usually fine and idles strongly at 1.3k-1.5k. It's weird because it only happens when I'm stopping, like the braking force is causing it. I have the idle speed set a bit high to try and alleviate the problem, but it doesn't work too well. After setting the idle to 1.4k or above, the RPMs take a long time drop back to idle.

I'm in SoCal, so it's not usually colder than 50-60 degrees...  Also, sometimes when I'm taking off from a start there is some lag on the throttle response and/or backfiring.

What really pisses me off is that whenever I try and adjust the idle screw, it seems to work fine. Then at the next stop sign or red light, the RPMs drop and the bike stalls.   

Also, the bike always stalls when I turn off the choke if I don't goose the throttle.

anyone have any ideas? low float levels? vacuum leak? dirt in carbs? I dunno, hopefully you do!

Thanks,
-UnSaniTiZ

What year you got?
How long since a valve check?

2004, I haven't ever had/done a valve check. I was planning to do it along with the carb rebuild. What exactly will it do? Maybe it will fix my problem?

It's kind of senseless to try to fix carb issues if the valves are out of adjustment. It isn't that hard to check the valves to eliminate them as a potential issue. I'd check the float level too, and run carb cleaner through a tank or two of gas before looking any deeper into the carbs. Also, try running on prime for a while to see if the stalling goes away. It could be the vacuum diaphram in the petcock, or a leak in the vacuum line starving the engine at low speeds.

QuoteWhat really pisses me off is that whenever I try and adjust the idle screw, it seems to work fine. Then at the next stop sign or red light, the RPMs drop and the bike stalls.

Any chance that the idle screw is backing out due to vibration? (Maybe the spring that holds it is place is worn out?)

I think you should try and mark the idle adjustment screw to make sure it's not moving in between adjustments. A dab of nailpolish or similar might do the trick.

did i miss it? how many km or miles on the bike?

A bike that new should not have carb or petcock problems. Unless the carbs have been monkeyed with or the bike sat for a long time.
My money is on the valves. My 02 valves were so bad at 12k miles I  could not keep an idle at all. It is not as scary a job as it looks.
Get the proper feeler gauge for a few bucks. Remove the tank. Remove the valve cover and check your valve clearance. If all is good then muck with the fuel system.

How's your clutch lever?  I had that same problem with my bike the day after I bought it brand new and the lever needed adjusted.  Been fine ever since.



Or maybe you just shouldnt stop? :p

I tend to agree with everyone who says valves, my '02 sounds just like your bike minus backfiring, but everything else holds true for me too. I've pulled my carbs already and monkeyed with them so the valve adjust is the next thing for me too.

It's got about 10k miles. I just lubed/readjusted my clutch lever.

I was planning to do valves and rejet/rebuild at the same time, but maybe I'll just check the valves first. Can anyone link me to some good sites to order feeler gauges, that shim removal tool (in kerry's excellent vid), and shims themselves?

I still want to rejet though, so I dunno.

Thanks,
-UnSaniTiZ

HEY!! Ive seen this before. Thats EXACTLY what my bike was doing, 2-3 min choke warm up, stalls at every light/stop sign. A real quiet stall too, right? you pull the clutch and the RPM'S go down down down-stall, no buck or jerk right? Its your valves, and or a vaccum leak, mine was both. It started after the stealership did my 8k service, I didint figure it out until after my 12k service. What happened was they checked my valves while the motor was hot, and got bad readings they said they were all good, but really both exhaust valves had NO clearance causeing the valves not to set properly and the Main problem was they failed to reconnect the vaccum line that goes from the top of the petcock valve to a tee to that funny thing mounted to the left side of the frame. (I dont know what it is?) I only found this out after i Checked everything myself,drained/cleaned tank 1 time, cleaned carbs/jets 3 times, floats  height 3 times, synced carbs 2 times, 3 compression tests, 2 spark/ignition test on each cylinder, checked petcock valve 3 times, Needles to say turn you own wrench.  Check your valves & vaccum lines.

David-

Quote from: da602krew on February 26, 2008, 02:55:54 PM
HEY!! Ive seen this before. Thats EXACTLY what my bike was doing, 2-3 min choke warm up, stalls at every light/stop sign. A real quiet stall too, right? you pull the clutch and the RPM'S go down down down-stall, no buck or jerk right?

Yep, that's exactly how it goes

I'm not really sure how to check for vacuum leaks, though. Any tips?

-UnSaniTiZ

QuoteI'm not really sure how to check for vacuum leaks, though. Any tips?

Lean down and see if you can hear any hissing/sucking sounds,(i heard some!) second take the tank of and start inspecting the vaccum lines and boots(little gray ones) for any unusual wear, dry rott, cracking ,you know that kind of thing. Also check you connection make sure their good(I found a vaccum line just hanging, and a 3 way w/ one naked side. seemed odd) so what I did was bought one of those universal coolant overflow tanks (saw it in one one kerry's posts) and used it to run the bike with the tank off, so i could lissen for any sucking or hissing. And right away i was able to find the leak by sound, as soon as i hooked that line back up the rpm's went back to normal and it hasnt done it one single time since. NOTE: first i corrected the exhaust valve's clearance which helped alot but the leak was the key.  I Hope this is useful. Where are you? maybe i could show you how to do your own valve's and help trouble shoot.

Mega two-year bump, but did you fix this problem?

I'm having the same problems and am going to take it to a dealer for inspection.