Fast idle after putting on pipes

snow guy

snow guy

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Joined
Mar 10, 2004
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146
Location
Fairbanks, AK
I just got done putting on a set of PI ends dumps on my '00 MM 700. The only thing I've done to the carbs is to increase the MJ one size and raise the needle from 2.0 to 3.0. I was thinking that I've raised the needles too far and there is too much fuel left over after a throttle blip, I was thinking of dropping it to 2.5. But from what others have said it's a lean problem not a too rich problem. Momemtarily closing the choke brings the idle down too. I understand that something is overriding my idle curcuit because it is too lean and the engine needs more fuel. Could it be that my pilot jets are too lean (45) and I need to increase them or will opening up my fuel screws help (1 1/2) ? Any other ideas?
 
I think the stock Vipers did the same thing and it was the fuel screws needed to be turned out a little, maybe try 1/2 more out? turn in first to count, then back out
 
Those pilot jets are stock on a 700 right? If so you gotta go up a size on the pilot jets. Fuels screw adjustments won't get rid of it, with stock pilots you could turn the fuel screws all the way out and it won't get entirely rid of it. I went from 40's to 45's on my 600 with PI End Dumps and i'm at 2 turns out on the fuel screws.
 
The details in the previous post will also help your bottom end. You may find that you are lacking a bit of power if you chop the throttle from a dead stop. Larger pilots will also help stop this.
 
change_up said:
Those pilot jets are stock on a 700 right? If so you gotta go up a size on the pilot jets. Fuels screw adjustments won't get rid of it, with stock pilots you could turn the fuel screws all the way out and it won't get entirely rid of it. I went from 40's to 45's on my 600 with PI End Dumps and i'm at 2 turns out on the fuel screws.
Click to expand...

right, but it's a fast first try...
 
change_up said:
Those pilot jets are stock on a 700 right? If so you gotta go up a size on the pilot jets. Fuels screw adjustments won't get rid of it, with stock pilots you could turn the fuel screws all the way out and it won't get entirely rid of it. I went from 40's to 45's on my 600 with PI End Dumps and i'm at 2 turns out on the fuel screws.
Click to expand...

Yes the 45's are stock, most everyone has said to go to 50's with pipes on the 7's so I will try that too, thanks.
 
I turned my fuel screw out 2 turns and it almost took away the fast idle, comes down on it's own, most of the time. I'm still going to change my pilots to 50's though and put my fuel screw back to 1 1/2 turns thinking that I will have a little crisper throttle response.

Also I was wondering if anyone has needed to increase the air flow to the carb via flow rites or such after putting on pipes, I wonder if it would help. I know about the air box mod but like the flow rites. I'm asking this because I just piped an RMK and added flow rites and it really woke the sled up.
 
I have the CPR pipes on my 01 SXR700 and I run my screws 1.5 / 2.0 turns out. I have remote adjusters so it's easy. I am running 47.5 pilots and it's spot on with them. I don't know if I would go to 50's due to your fuel mileage going down. My mains are 147.5 and I think my needles are staggerd and I can't remember where they are at. My center needle is raised the most per Jeff at CPR as he says that one runs the hottest. Your pipes are different than mine so my advice is just me telling you what I have. Always check your plugs and do your own fine tuning. Doug
 
When I went to get my pilots there wasn't 47.5's listed, it went from 45 to 50. I've read about others putting in 47.5's but don' know where to get them. My needles are set at 3.0 straight across now and the plugs look good, I've got a tempaflow so that helps. Where did you get your remote adjusters, that would certainly help to make an adjustment in the field.
 
MPI has pilots listed in 2.5 increments. I put flowrites in my dash and am happy. I'm not positive if there is a huge performance gain or not because I did them at the same time as a Haulk boost bottle. The intake noise is quite a bit more noticeable though so I would imagine there is a bit of difference.
 
47.5 are stock in vipers and srx's if I'm not wrong, sounds like your dealer is a little slow. What elevation are you running at. I ran 50 pilots in mine, and it ran strong. Maxdlx
 
I'm running about 1500-4000 feet, as I said opening up the fuel screws to 2 turns almost eleminated the fast idle but I still want to change the pilots and see what that does. I will look into the Viper pilots too. The problem getting them from the dealer he wants over $10 each and I can get them aftermarket for $3 each!
 
My setup is used at 250' - 2000'. I also have the tempa flow and it works great. I don't know about the higher elevations but I think you use a bigger pilot and smaller main if I remember (don't hold me to that). The 50's might be fine for you. If your climbing hills the 50's would be best IMO as they will give you better flow and keep you safer, the SX motor loves fuel. It's never a bad idea to go bigger on jetting. Too small and that can get real expensive real fast. I would go with the 50's for the cost savings as well. Doug
 
we ride from 8-10K and have ported motors with benders on 700MM. I am running 50 pilots in mine and 52.5 in my son's or 52.5 and 55 something like that. I was told these small carbs need bigger pilots at higher elevation where the air is thinner so they can get fuel. Following Benders set up exactly we had this bog off idle. The funny thing is you think the bog is a rich bog but it is a lean bog right off idle. I went to the biggest pilots I had in the box. The ones I ran in flat land and instantly no bog at all. I was riding by Steamboat colorado and a friend hit a tree with his Skidoo so we had to go to the doo dealer who used to be the yamaha dealer. Pretty funny when I told him how my sled was bogging and that I was running exactly what benders specs said he said and I quote "bender is wrong they don't test at 10-12k ft go with the biggest pilots you got." I re-jetted both sled seen him riding his 1000 doo the next day and thanked him for his advice they ran sweet.
 
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