New to me Viper - why is choke way too aggressive?

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kielbasa

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Hello, new guy here.....just got myself a 2004 viper - love the sled. Carbs had plugged pilot jets, so I cleaned them out and sled runs real nice. Maybe a touch rich on the bottom end (fuel screws two turns out), but acceptable - I may end up going 1 size leaner on the pilots maybe to clean the bottom end up. Anyways, when cold and trying to start with full choke, it just totally floods after popping off for 1/2 a second. I suppose I could adjust so the choke plungers don't pull all the way out but I have a hard time believing that would be the correct way to set. Any ideas why the choke is so aggressive? Thanks for any info!
 

I adjusted mine by adjusting the cable all the way down, so the choke is closed all the way, then go up till it starts opening and back it off a little till it shuts. Also check that all the plungers are aligned, hope this helps!
 
Here is a pretty good thread on where to set the needle position. 3.25 seems to be where most people set them. I had mine at 3.5 and found it a bit too rich at bottom to mid range. Choke or fuel enricher should be set so when it's off there is some free play on the cable. Also there is 2 positions on the lever, one for starting and one for first minute or so.

http://www.totallyamaha.net/forums/showthread.php?t=103667

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choke is adjusted, I even disconnected the cable so no tension at all on the plungers and tried that, same deal.....I'm beginning to wonder if the o-rings under the mixture screws might not be sealing well? where else could an additional fuel source be? it gets so flooded with fuel that it takes several pulls of WOT to clear it back out and get it restarted.....hmmm, two positions on choke lever? mine just has a sliding lever with infinite adjustments...
 
The aggressiveness of the choke is dependent on temperature. When it's below 20F, I use the full choke to get it lit then quickly flip to half choke for no more than a few seconds (you'll hear it start to load up), then blip it to half 2-3 times (or more if it's 10F or lower) until it'll idle on it's own.

Above 20F I use half choke to start it, quickly flip to no choke then blip to half a few times until it'll idle on it's own.
 
10 degF here.....full choke (2 to 3 pulls), will pop off for 1/2 to 1 second max, then dies because I physically can't get to the choke lever in time to turn it off. Another 3 pulls at WOT (no choke whatsoever) and it will fire up. Once it's running, then I am able to feather the choke. But anything near full choke just totally snuffs the engine out immediately - weird. Been sledding for the past 40 years, never seen a choke this sensitive. Has to be something else going on.
 
I would not go to a smaller pilot, you would most likely get a lean idle hang when the pipe is hot. My sled has always been blip the. Joke on and off when cold and no choke full throttle after a quick stop trail side. I won't even let others start it for fear of flooding out a cylinder and fouling a plug.
 
kielbasa said:
choke is adjusted, I even disconnected the cable so no tension at all on the plungers and tried that, same deal.....I'm beginning to wonder if the o-rings under the mixture screws might not be sealing well? where else could an additional fuel source be? it gets so flooded with fuel that it takes several pulls of WOT to clear it back out and get it restarted.....hmmm, two positions on choke lever? mine just has a sliding lever with infinite adjustments...
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I have a 2003 Viper and the choke is a lever. I assumed it's the same for a 2004. One other possibility is float level, or leaking float needle.

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kielbasa said:
choke is adjusted, I even disconnected the cable so no tension at all on the plungers and tried that, same deal.....I'm beginning to wonder if the o-rings under the mixture screws might not be sealing well? where else could an additional fuel source be? it gets so flooded with fuel that it takes several pulls of WOT to clear it back out and get it restarted.....hmmm, two positions on choke lever? mine just has a sliding lever with infinite adjustments...
Click to expand...


I guess I'm at a loss. I assumed you had a 3 position cam lever (off, 1/2, full) that actuates the plunger cable. Perhaps you should take a pic of what you have.
 
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When you say cold start, is it after an overnight soak or after an hour or two or doesn't matter? Where are your bowl vent tubes routed? I would agree that something else is going on if your issue is after an overnight soak. If after a lunch break or such (less than two hours, ambient dependent), I'd suggest 1/2 choke to start and flip it off right after it starts.

Generally speaking - I've perceived my Yamahas to be a bit more sensitive then the triple Polaris' and Cat I've owned to choke engagement. The fact most Yamaha riders here (me included) occasionally have to crack the throttle to restart after short (10 minutes or less) hot soaks suggests something is causing a fat restart. I rarely, if ever experienced this with the off brand triples.

YMMV
 
overnight cold start is what I'm talking about....the time when you would normally use full choke....choke lever is just like one would see on most street bikes, a lever with no detents but with infinite sliding (never owning a viper before,I assumed this is stock, sure looks factory to me.
warm starts are typical flat slide yamaha, crack the throttle slightly and lights right off, no problems there.....
I really don't think it's float positions, jetting, etc....since it does run so nice and is carbureted quite well, like I said, the only thing I would like to experiment with is a leaner pilot jet to clean up the EXTREMELY light burbling/four stroking at light throttle, I don't wanna mess with lowering the needle just yet - in no mood for a midrange burndown and it runs clean in the midrange anyways....
bowl vents are routed to a tee in the airbox - again, I'm assuming that is how it came from the factory...
here is the kicker, my brothers viper (we bought these as a pair this past weekend) behaves EXACTLY the same way - both are 2004's...both sleds appear to have been very well taken care of with zero evidence that a butcher has ever had his hands in there and messed with stuff...
 
That choke lever does not sound like the factory setup.

Pics would really help, but you sound like you've turned a wrench before so if the choke is opening and closing correctly that's all it's supposed to do. I'll assume you tried all different amounts of choke at cold start with the same result ?
 
oh, forgot to mention, it doesn't flood at all positions, just at full....for the time being the easiest way to start is set choke lever to approx 1/2 and it lights off in 4~5 pulls and quickly ease choke lever off.... i can limp around this quirk, I just have a hard time believing yamaha would send these out the door acting like this.....
 
Never had any of the symptoms you describe on my 04, it has never flooded or fouled a plug. Are you sure the plungers are clean and moving freely? For adjustment I make sure choke is fully open with lever all the way open also. That is the stock choke.
 
kielbasa said:
oh, forgot to mention, it doesn't flood at all positions, just at full....for the time being the easiest way to start is set choke lever to approx 1/2 and it lights off in 4~5 pulls and quickly ease choke lever off.... i can limp around this quirk, I just have a hard time believing yamaha would send these out the door acting like this.....
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I've had a similar problem on my 02 it was o-rings that seal the fuel screws was bad quality very easy starting when cold, sometimes when idling, it would drop rpm and sometimes die when on throttle, it would clear up. Worth checking.

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If you drop pilot size when you get the pipe good and hot it will will have an idle hang. My sled has always been touchy, if i dont keep it running by blipping the throttle and manipulating the choke it woud die and be kind of a bitch. It is not that difficult really just sucked.
 
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