02. Viper erratic , searching idle problem

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Adam1231

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02. Viper (hanging) idle problem***

Hi.

I'm planning on buying my dads 02 viper. It has 2,400 miles and lhas been babied. Here's the problem, we cant figure out... Any help would be very much appreciated!


So after riding awhile and slowing to a stop, the idle revs up and slows down, revs up and slows down, and when it revs up it will actually engage the clutch. It's a pain in the butt, because when it's idling all over like that you can't use the reverse or it will slam hard when it engages.

( I should mention that when cold starting the machine, it idles perfect. )

What would cause this idle fluctuation problem? I think they call it a searching idle?

I don't think it's an air leak, seems more like a sensor problem of sorts?

Thanks in advance for any feedback!
 
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I will try that out this weekend... are you thinking if the choke makes it idle down to normal, than it probably is an air/fuel problem of sorts?

What if the choke makes no difference?

I will report back asap

thanks!
 
the vipers had a hanging idle problem that after running on the trail, the idle would remain high for an extended period after stopping. if you blipped the choke for a sec it would idle down to normal idle. my brothers 02 viper did this as does my dads 2005 sx venture with the same motor.
 
Ok, so I got some more info from my dad..

Sounds like it does get a hanging idle when warm and the reason
The idle drops is that it hits the clutch engagement and it kick the idle down
So I would call it a hanging idle not a stearching or hunting idle.

I will try flipping the choke when it revs and see if it makes a difference.
 
There are a few things that help with idle hang. You can turn out the fuel screws a little further on the carbs and lowering the idle a bit seems to help it come down a little sooner as well. And of coarse the choke flip helps as well. If it’s hanging so much to engage the clutch that sounds excessive. I’d look into the carb settings
 
Check the manifold for cracks, I had that cause high idle hang on a viper I used to have.
 
Thanks for the responses!! I'm picking up the sled on Tuesday and will have a chance to
Test it out and go through it and report back first hand ...
 
Put some miles on the VIper today...Awesome machine!

After the sled is warm it gets a hanging idle, around 3,500 rpms

When I flip the full choke it will go back down to normal idle for a few seconds,
Then climb slowly back up to 3,500-4,000 rpms.

After some hard riding the machine didn't seem to be overheating at all and runs strong.

Do I need to be concerned about this issue, or just deal with it as-is?

Any thoughts?
 
A couple of bucks said:
Hey Viper guys. As I've never had a Vipe, would raising the needles 1/2 a place improve this condition?
Click to expand...



Just the nature of the beast. I have my needles raised (should anyway for safety from today’s gas) and makes no difference. Turn fuel screws out 2 full turns and keep idle down at around 1200. I always blip the throttle comming in to a stop and this helps also.
 
Adam1231 said:
Put some miles on the VIper today...Awesome machine!

After the sled is warm it gets a hanging idle, around 3,500 rpms

When I flip the full choke it will go back down to normal idle for a few seconds,
Then climb slowly back up to 3,500-4,000 rpms.

After some hard riding the machine didn't seem to be overheating at all and runs strong.

Do I need to be concerned about this issue, or just deal with it as-is?

Any thoughts?
Click to expand...

Keep the idle down at 1200, Set after a good warm up. This is the best way to handle it. The pipe is so well tuned that it hangs up there when warm. It likes it there! LOL! Been a problem for these machines since the beginning and never been a issue.
 
It is normal to hang up when warm and coming to a stop. In my opinion it is not normal for it to climb back up after blipping the choke. Mine have always stayed down once I blipped the choke. Try like super1c said and turn the idle down after it is good and warmed up. That usually helps. Also make sure the boots from the airbox to carbs are all on properly. I have been just taking the airbox apart when I put the carb boots on. It is easier to make sure they are on good. If that doesn't help try spraying carb cleaner behind the clutch when it is idling and listen for a change. That would tell you if the seal is leaking.
 
Thanks for the feedback...

I will try turning down the idle. And checking the seals.

It just started happening out of the blue, no adjustments were made or anything like that..

Could dirty carbs cause this? I don't think they have ever been cleaned.

Rode it again today, mid range on this thing is awesomeness ;)!
 
Adam1231 said:
Thanks for the feedback...

I will try turning down the idle. And checking the seals.

It just started happening out of the blue, no adjustments were made or anything like that..

Could dirty carbs cause this? I don't think they have ever been cleaned.

Rode it again today, mid range on this thing is awesomeness ;)!
Click to expand...

If the carbs have never been cleaned that would be the first thing I would do. Check the pilots good and take the fuel screws out and blow carb cleaner and then air through. Be careful when you take them out. There are small parts in there. When you put them back in lightly seat them then turn them out 2 turns. When you put the airbox back on I have found it is easier to take the airbox apart to put the carb boots back on. It is easy with a long bit on a drill.
 
So i do have the same issue on an 04 viper, bought a sled that seemed it just needed carb cleaning and found a couple issues with it. So story is I pulled the carbs off, cleaned and reassembled and rode it 5 miles after installing a new piston and rings and well, another seize. Pulled down and rebuilt 2nd time and found I have more carb issues than I thought, same as Adam mentioned, engine revs up and down and engages clutch, idles down after a bit, hit the throttle and runs good, idles back down to normal then revs back up. So I went through all the carbs again, has all the stock jetting in it and the needle clip has been put on the 4th groove down, still does the same thing. So now I pulled the carbs off my wifes 04 venture which has all the same jets in it and it sits there and purrs like a kitten but I do get this little burp now and then when idling, thoughts anyone.
 
How about replacing the low speed jets? Another way I found works is to run a thin wire through them but replacing it the best. Also there should be a low speed circuit vent on the intake side of the carbs that needs to be clean with compressed air.

Sent from my VTR-L09 using Tapatalk
 
dgasper said:
So i do have the same issue on an 04 viper, bought a sled that seemed it just needed carb cleaning and found a couple issues with it. So story is I pulled the carbs off, cleaned and reassembled and rode it 5 miles after installing a new piston and rings and well, another seize. Pulled down and rebuilt 2nd time and found I have more carb issues than I thought, same as Adam mentioned, engine revs up and down and engages clutch, idles down after a bit, hit the throttle and runs good, idles back down to normal then revs back up. So I went through all the carbs again, has all the stock jetting in it and the needle clip has been put on the 4th groove down, still does the same thing. So now I pulled the carbs off my wifes 04 venture which has all the same jets in it and it sits there and purrs like a kitten but I do get this little burp now and then when idling, thoughts anyone.
Click to expand...

Very interesting. Been working on the hang for many years now. Pm sent to you.
 
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