Hanging idle

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flying_fin

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Jul 26, 2003
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Howell, MI
I took my sled out for a shake down ride (1st of the year) yesterday after getting the rebuilt rear suspension back in and noticed my idle was hanging (comeing down real slow after throttle is let off). Unhooked the TOR's and allowed it to run but idle was still hanging as expected.

I did add a 3/4" riser block to the handle bars so this might be the issue. I plan on looking at it tonight but wondered if there could be anything else in the carb that could be causeing this? It seems that if my throttle cable is preloaded now due to the riser, it would just keep my idle high not necessarily cause it to hang and come down real slow.

Any input is appreciated,

Da Fin
 
turn down your idel screw so you ideal about 1300-1400 and it should go away ..or just turn it down enough until the hang up goes away ..
 
You are most likely lean, open up the fuel screws 1/4 turn and it should go away. If the cable was too tight it would never come down.
 
Right way to fix...turn richen fuel screw to 2.5 turns

Easy way to fix...lower idle to 1400 or so until you get into the carbs either next year or your bored :)
 
Nothing has changed since last year except the riser block and it was running fine at the end of the season. Idle does come down to correct range just takes a few seconds. My thinking was also if the cable was too tight, it would not come down fully either. Think anything might be plugged in the carb causing this. Used Stabil instead of pulling them and cleaning.

Da Fin
 
Just went out and adjusted the idle screw so it was a little lower(1100) not that it was bad before (about1300) and still have the same problem. When just sitting in garage and I give it a quick throttle it goes up to pre-engagement and then pretty much comes right back down.

It seems to hang at about 3500 rpm when it is loaded (riding) and then I let off throttle. It holds 3500 for a few seconds and then slowely comes down to normal idle.

It sounds as if I may need to get into the carbs again and give them a good cleaning. Why does this always happen a day or two before you are going to go riding!

Any othe ideas, please let me know.

Da Fin :o|
 
i just went through the same thing with the idle hang. i was thinking a carb cleaning might do it too, so i cleaned them and it still does it. my fuel screws are 2-1/4 turns out, so i think i'm gonna have to do exactly what kinger said and back them out another 1/4 turn. i really didn't want to richen it any more because the stock spec chart says 1-7/8 turns. i wouldn't turn the idle down too much- they shake pretty bad. does anyone know what causes this idle hang/ lean condition?
 
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I am wondering why mine would change from last year for no reason since I did not reset my screws this year? hmmmm

Did you re-set your screws this year before it started happening?


Da fin
 
no, i didn't touch the screws till i cleaned the carbs. i just put them back where they were and hoped the carb cleaning took care of it. it actually started to hang at the end of last season. this year i took it for a ride and the idle wouldn't come back down until i blipped the choke-- last year it came back down with the blip of the throttle. the funny thing is, is that i just happened to put a 1' riser block on this year too!
 
I'm not sure if its normal for the rr's to drop like a rock after coming off throttle, last year my idle would hang near the engagement point (3500-3800) and just stay there. This year I adjusted my fuel screws to 2.5 turns out and idle back up to 1800, now it comes down just slow. It will not just sit there and hang anymore but they definitly do not drop real fast.

The idle back to 1800 eliminated all the shaking I had when I had it set to 1400 just to get through last season.
 
Here's my 2 cents on this issue from my own experiances with this problem. I would say that if the only thing you changed was to add a riser block,your throttle cable is probably to tight. I had the same problem when I added a riser to my 700MM. There should be a little slack in the cable at idle. I had tried to adjust the throttle so it would open the carbs the second you touched the throttle and had this problem. You will find that with a little slack, the carbs will still open all the way. I also had a problem with my idle hanging when I made some changes to my sled like thinner headgasket, and reed spacers I had to open up my idle screws from 1 1/2 to 1 7/8 to cure this. Also I have read on this site that if you have to open your idle screws more than 2 turns you should be changing your pilot jets to the next size, because they can jiggle loose. I would do a search on this subject on this site to make sure. I have had these problems before, made the changes I have outlined, my idle drops right to idle. One more thing, I always use stabil, but I alway pull my carbs and clean them, drain the gas in my tank and put fresh in before I fire it up for the first time. I put the old gas in my car. Hope this helps. Soc
 
[I had to open up my idle screws from 1 1/2 to 1 7/8 to cure this. Also I have read on this site that if you have to open your idle screws more than 2 turns you should be changing your pilot jets to the next size, because they can jiggle loose.

sock... i'm assuming you're talking about the fuel screws on the bottom of the carbs?
 
Sock - Slack in the cable is ok - first thing I checked - plenty of play in the cable at the carb. "Changing the pilot jet to the next size because it is wiggling loose" Can it just be retightened? Trying to remember what everything looks like inside and it is a little foggy as it has been a few years since I have had it apart.

Thanks for the help,

Da Fin
 
flying_fin said:
Sock - Slack in the cable is ok - first thing I checked - plenty of play in the cable at the carb. "Changing the pilot jet to the next size because it is wiggling loose" Can it just be retightened? Trying to remember what everything looks like inside and it is a little foggy as it has been a few years since I have had it apart.

Thanks for the help,

Da Fin
Click to expand...

He means the fuel screw jiggling loose if you have it turned out too far to compensate for a too small pilot jet. I think. There's some pics in this link to refresh your memory. http://www.totallyamaha.com/snowmobiles/aaTECH/carbs/cleaning_carbs.htm
 
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You dont have to change the pilot jets until you get to 3 turns out on the fuel screws. If you set them at about 2-1/4 turns out you should be real close.
 
When I put Bender triples in a couple of years ago, I rejetted according to their spec with PJs at 52.5. I had the same slow RPM return. I backed the air screws out farther, which helped, but when I put 55 PJs in, put the air screw back to 1 7/8, the problem went away.

Last year I noted that Bender now recommends #55 pilot jets for rejetting with their triples.
 
Screws are 2 turns out. Sounds like one of my pilots is slightly clogged? Will clean carbs tomorrow. Does anyone recommend changing the pilot size on a 2000 SX600r with otherwise stock jetting, mods: clutched, reed spacers, drilled can. Has always had a little bog which would be nice to get rid of, would this help? If so what size pilot is reccommended?

Thanks,

Da Fin
 
As far as changing the pilots, I have never had to go out further than 2 turns. This is just info I have gotten of this site. If you haven't cleaned your carbs lately I would definately do it. I'm no expert, but I have always cleaned mine at the beginning of the season and have never had an issue. Go to the tech pages under "cleaning carbs" and "carb photos and parts" you will find excellant pictures showing you what each part is inside the bowls. Be sure to blow out all passages, jets, including the overflow hoses. I also always pull the floats (carefully) and clean the needle and seat, which isn't outlined in the carb cleaning section. It's just one more place to get clogged and it's very easy to do. Hope this helps. Again, this is just my experiances with these carbs and not intended to upset others who are trying to help you. Soc
 
BigMac said:
When I put Bender triples in a couple of years ago, I rejetted according to their spec with PJs at 52.5. I had the same slow RPM return. I backed the air screws out farther, which helped, but when I put 55 PJs in, put the air screw back to 1 7/8, the problem went away.

Last year I noted that Bender now recommends #55 pilot jets for rejetting with their triples.
Click to expand...

you mean fuel screws?
 
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