stalling at idle

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stalling at idle

Postby CBJamie » Thu Jul 09, 2015 6:14 am

My 98 cat is stalling at idle after it warms up i pull up to stop light and it returns to idle it will idle well for 45 seconds to a minute then rpms drop and it will stall, it starts right up every time and runs very well going down the road, no flat spots and pulls hard during more sprited riding. If i adjust the idle stop up so it doesnt stall when i give it throttle it stays up at 3-4 k . No clue why its doing this. :dunno
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Re: stalling at idle

Postby cptchaos » Thu Jul 09, 2015 9:28 am

Pilot jets in the carbs - time for a cleaning. Pull a wire out of a wire brush and use that to clear the holes until you can see daylight through them. Soak the jets in gumout for a bit and dip your wire into the gumout to clean the gunk off. You'll probably want to adjust the idle mixture screws and sync as well. She's a whole different motorcycle when clean, adjusted, and synced!
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Re: stalling at idle

Postby deshpak » Thu Jul 09, 2015 4:34 pm

I had the same exact problem with my 98. I was pulling my hair out trying to figure out why it was doing this even after I cleaned the carbs and replaced all the jets with new ones. My solution:

1)pull carbs and make sure you put everything back correctly after first cleaning
2)check the float bowls are working correctly and set correctly
3)remove all the jets and inspect them to make sure they are really cleaned properly
4)drill out the a/f pilot screw plugs remove pilot screws (after remembering where they were set) and clean thoroughly in there (replaced pilot screws with new ones)
5)bench balance the carbs using the drill bit or wooden stick method
6)make sure you don't have any vaccum leaks in the intake boots
7)replace carbs
8)get the bike warmed up and balance the carbs using a carbtune or other tool of your choice


After doing all of that I think what made the difference for me was that I found my pilot jets needed to have a thin wire run through them to make sure they were really really clean (these were new jets when I cleaned the carbs the first time 6 months ago) and this time I took out the a/f pilot screws, replaced them and cleaned the area there really good.

Now the cat is purring at 1400 RPM like it did when it was new. Runs strong, no hanging revs and idles where I set it.
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Re: stalling at idle

Postby CBJamie » Fri Jul 10, 2015 6:11 am

Mine was working very well when i put it on the road this spring. Now after only 1400 miles started this idle problem and only after ive ridden 10 mile or so, when first strating out it idles well. I rode to work this morning and for the first time in a while its cool out 65deg, and upon ariving at work (20 mile ride) it idled a little low 900 -1000 but did not stall so im thinking this is something heat related. I did pull the plugs last evening and they looked good, nice medium to light chocolate brown maybe a tad rich. But the bike runs so well im inclined not to mess with carb settings. PS A/F pilot screw have been uncapped and i had the carbs ultrasonic cleaned when i got it running this spring.
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Re: stalling at idle

Postby deshpak » Fri Jul 10, 2015 8:10 am

It progressively gets worse. So you may be fine for this season but by next season you may have a bike that is no longer fun to ride. That is how mine progressed. But then again I didn't empty the float bowls when I put it away for the winter so maybe that could have contributed. All these things started happening when they mandated 10% ethanol in NJ.
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Re: stalling at idle

Postby KBacon » Fri Jul 10, 2015 9:55 am

Run a 1/2 can of sea foam to a full tank of gas through it...

Also adjust the idle up to 1200 rpm after the bike is fully warmed up
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Re: stalling at idle

Postby CBJamie » Fri Jul 10, 2015 11:55 am

KBacon wrote:Run a 1/2 can of sea foam to a full tank of gas through it...

Also adjust the idle up to 1200 rpm after the bike is fully warmed up
I added a 1/4 can of seafoam to a full tank this morning, and i have always had the idle set at 1200 rpm
deshpak wrote:It progressively gets worse. So you may be fine for this season but by next season you may have a bike that is no longer fun to ride. That is how mine progressed. But then again I didn't empty the float bowls when I put it away for the winter so maybe that could have contributed. All these things started happening when they mandated 10% ethanol in NJ.
I only run 93 octane, here in Pa they only put 3% ethenol in 93
72 CB750 café 72 CB350 bobber, 79 XS650 bobber, 74 CB450 café, 98 YZF600R
CBJamie
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Posts: 139
Joined: Sat Jan 17, 2015 5:06 pm
Last Visit: Thu Aug 03, 2017 6:43 am
Location: Hanover Pa
I Ride: 98 YZF 600R
Bike Color: flat black , silver
I also ride: 72 cb750 cafe
Bike Color: black
Bike Mileage: 21,200
Bike Mileage: unknown

Re: stalling at idle

Postby KBacon » Fri Jul 10, 2015 12:22 pm

I run a little higher concentration of Seafood like I said above... once it gets in & soaks... it should loosen things up and clear them out... I have had it take a couple of tanks to get everything clear...
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