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Discussion Starter · #1 ·
Hey KawieLovers!
Picked up a mint 012 650 sra some months back, w/300 miles on it. Love it so much we put 600 miles on it this summer. I added a UNI air filter right off the bat. I have searched this forum (and many others) up and down for weeks, and have also googled the topic spending countless late night sessions. Im still not finding a definitive.
Here is my question > I have a dynatech cdi, and a big gun full exhaust which I have not installed yet. Ive wrapped the exhaust, it looks gnarly as h*ll, and now Im getting anxious. I am going the Kiehin jet route( I have not ordered them yet), not the dynajet.
Can someone give me a good starting point?? I will order jets as soon as I can narrow a half a dozen down.
I have a friend with 4 decades of drag racing/carb knowledge to help out, but has never fiddled with atv carbs.
Im expecting the pilot to stay at 40# yes?
Any help will be greatly welcomed.

Off topic > I just picked up an 04 kfx700 with about 20hrs on it. Payed a pretty penny, but she is absolutely mint. I rode it 2x for less than an hour so far :D I plan to make a youtube vid in the near future, I think it might be one of the cleanest factory KFX's in the US. Ill post the link here when I do.
 

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Assuming you are at or below 3800 feet, grab the service manual. It will list the stock sea level jets that came with it. Go up two sizes front and back although the instructions ob the Big Gun may say to have the same sizes that's OK...if the rear is rich you can always drop it a size later. It should have #40 or 42 pilots so leave them alone. See to it both A/Fs are set the same. Start at 2.25 turns out and adjust as needed but not to exceed 2.75 turns out. Get a two-each .020 needle shims. Use these to fine tune the main jet needs. Understand that two shims under the needles is the same as adding or going up 1/2 jet size. .040 is the max you can go. Try without any shims at first but you should be very close with the main jets already.
 

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Discussion Starter · #3 ·
That is perfect, I appreciate! Im at 1000', yes. 138f / 142r stock ; and so Im looking at 142f and 146r correct?

"Understand that two shims under the needles is the same as adding or going up 1/2 jet size." Beautiful - I was slightly confused on the whole needle shim discussion, and now Im not.
 

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That is perfect, I appreciate! Im at 1000', yes. 138f / 142r stock ; and so Im looking at 142f and 146r correct?

"Understand that two shims under the needles is the same as adding or going up 1/2 jet size." Beautiful - I was slightly confused on the whole needle shim discussion, and now Im not.
Whatever the manual says it came with in Kiehin jets, go up two sizes as per their chart.
 

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Back to the off topic > heres a few pix of the brute View attachment 75475
Hey, Tell us how you like those SUNF tires?

Are they a good alternative to the high price big name brands?
It really erks me to find 12" rim tires for ATVs priced like off road tires for a truck.
 

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Clean machines right there.
 

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Discussion Starter · #11 · (Edited)
Hey, Tell us how you like those SUNF tires?

Are they a good alternative to the high price big name brands?
It really erks me to find 12" rim tires for ATVs priced like off road tires for a truck.
Ive run ITP mudlites on most of my U-quads here in upstate NY, for years. Plenty adequate for most every practical trail situation, and the $$ isnt too too bad. However, they wear down quickly on the road/gravel roads. Im not a road rider, but at times destiny demands it. The only way to the next leg is 1/4 mile down the road...lol On Amazon I saw these Sun F for 225$/set. I did as much research as google would allow. Ordered em. As soon I helped the FedEx guy unload them, I knew they were going to be just what I was hoping for. Much harder tread. Ive had all summer to flog these, and they are the perfect solution to every terrain Mother Earth might throw at you. If you ONLY ride in 5 foot mud pits(semi sarcasm) - look elsewhere. These will take you through the average mud section no prob. Ill be running these SunF's on all my quads from here on out. After 700miles now, the wear is very minimal. And I cant helping loving the orange SunF label, its as orange today as it was when I mounted. The SunF's are certainly a quality tire, no doubt.
 

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Discussion Starter · #13 · (Edited)
So here we are a year and a half later (life happens) > Did a valve adjustment before winter came, it needed it ; and we wanted to make sure when the big gun full exhaust went on, everything ran like it should. Before the valve adj it barely started, and when it did it would clank and clamor. After the valve adjustment it started up instantly. Flash ahead 7mnths later, now its warm and we have the Big Gun Full exhaust wrapped and mounted. Jets are 142 frnt and 148 rear. First Start after 7mnths of sitting and cleaning when warm weather allowed in upstate NY >
In the coming days well see what happens at WOT. Thank You NMKAWIERIDER for the comments to help this happen.
 

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Discussion Starter · #15 · (Edited)
2mrw we'll take the Brute up and down the driveway and see how the jets feel, just got to button a few things up to ride in skeleton mode...
Tonight I ran it at idle again, and noticed a minor exhaust leaks. The rear exhaust port; I see a small spot where it has sprayed carbon mist onto the crankcase. I tried 6 ways till Sunday to get the rear mounted flush. Ordering a new Donut Gasket...
 

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Discussion Starter · #17 ·
Got the new exhaust donuts > Should of just bought them new to begin with. smh. Exhaust leak fixed. Went for a decent mostly flat 30 mn ride earlier. Kawierider I think your initial jets are dead balls. 142/148. Not a single pop, blurp, burp, gurgle or gargle. Havent pulled the rear plug yet, But I only seem to have a rich state at idle, and even then it runs smooth. Rich state meaning; If it sits idling for some minutes I get some tiny gas droplets on the floor where the muffler meets the coupler > or when I start it semi hot I get a good whiff of gas but only breifly (more then Im used too) I will dial in the A/F screw 2mrw, something I havent done yet.
 

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Discussion Starter · #19 ·
Ok. So before I did the downhill slope of getting the plastics back on I wanted to check on the a/f screws real quick. Seemed a smidgen rich at idle to me, but even then it would idle a tank of gas if i let it. Got the caps off ez pz. Interestingly the factory setup was 2.5 r, and 1.75 fr. Ended up w/ 2.25 turns out each it smoothed it out a touch and I could still stab the throttle and have it settle down instantly like a top fuel dragster. Keep in mind I set the idle screw midway when I put the carb back together to have plenty of wiggle room either way.
2 days later, Start it and suddenly it doesnt want to idle. As it warms up I find myself turning up the Idle screw to compensate. Now the idle screw is maxed and it will die w no throttle input. More importantly when I hit the throttle it will hang on to the rev for about 8 secs, and die not long after.
My first thought was the throttle cable > and so I checked both ends and it looks perfect.
Next thought is an air leak. I looked around to make sure the carbs were sealed to the boots etc > and thats where Im at right now.
Any suggestions ???
 

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Sudden changes only happen when something suddenly happens. Do spray something like carb cleaner around the head-side clamps on the carb boots. Drain the bowls into a pan to see if any water or trash got in, Loosen the gas cap to see if there is any vacuum and if so, change the tank vent check valve..that will be your problem if it's stuck shut. Also check the valve lash just to make sure they are still OK.
 
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