Hey guys. I am looking for a little advice. As you know i have a pro 800 with htg twins. vf2, head rechambered, gearing clutched etc. The way i set my jetting was, i put 460 mains in and held wide open then deto light flashed, went up one size and flashed again. went to 480 andall ok. needle i started at middle position and shimmed until light stayed off. i have not done this with low speed. i find the sled hard on fuel but have come to realize it may be the nature of the beast. of course some people say they get 13-14 mpg. anyhow. my problem is my valves are always very carboned and wet even after 250-300 miles. i have checked my reed pedals and they look ok. as soon as i go down in jetting the light flashes. i have not checked the needle and seat for leakage. any opinions would be great. thanks. compression is 150 lbs if that makes any difference. what are your opinions on atacc. i ride from 0-2000 feet and big temp changes. 0c to -30c

Are you running premium fuel? The light detects detonation and not necessarily your air/fuel mixture ratio.

YES 91 AT LEAST

You might want to do a little experimenting with lighter VES springs if you haven't done anything there yet. They let the valves open up at a lower rpm. This isn't going to do anything positive for your gas milage though....

I'm running mostly stock (clutched/geared/Tempaflo '02 XC8X) with the pink RMK springs. Like what it did to my perfomance - mostly trail. Valves are now opening much more often at speeds I normally run at (500-700 rpm lower than the factory springs I'd guess). Really snappy performance - kinda like it comes on to the pipe when they open if that makes any sense. Side benefit is it's really easy to tell when the valve(s) start sticking. The loss of performance is really noticable. Downside is it likely cost about a mile to the gallon.

The ATACC will help unless you rejet for temp changes, and that includes needle changes as well. The ATACC will lean from your baseline settings from 1/8 throttle up to full, starting at anything warmer than -20F. If you are talking fuel mileage while lake running, or lots of wide open, do not expect much change, no matter what you do. You could try orange/white ves springs, they will stay open a bit easier at high rpm, which will let the pipes run more efficiently. The deto protection is on the safe side, and that is going to affect your ability to use the pipes to their full potential, as well as fuel mileage. If it cannot be reprogrammed for a higher setting to activate, I would look to a CDI without it, then go down 1/2 needle clip and 1-2 sizes from what the richest you ran last year was.

So if i have my jetting on the edge as it is (deto light wise) putting a atacc on will just cause the light to come on more often. correct. i dont ride in real cold temps. so if i do ride on a cold day the deto will be on non stop. My plugs are black and my piston wash is very minimal at the transfer ports and very dark in the centre. What cdi would work on it.

You'll never get 13-14 mpg with an 800 w/ twins. I would expect 10 on the trails and 6 off trail. These are US gallons. 480 mains sound plenty lean to me. Needles around 3.5, IIRC. If the sled is rich on the pilots, it will cost mpgs too. How does the sled act near 1/8 throttle?

No, the ATACC will not lean it at all at -20F from what you have now. If it is fine now jetted for -20F, you will not need to change anything. I believe hot seat, or Wahl Bros. can reprogram the CDI. If your plugs are black, I would bet that you are very rich on the fuel/air screw settings, which can affect your mileage considerably.

THAT WAS MY PLAN POCKETS. I AM LEAVING ALL JETTING AND TURNED FUEL TO 1 TURN AND AIR TO 1.5 AND TRY THAT. THANKS FOR ALL THE HELP EVERYONE.

what about my float setting, i dont have a air pump to put 5lbs in carbs. so i just held carbs upside down with bowl off and blew into the inlet and air didnt go in until i lifted the floats. the floats are on a huge downward angle with carbs upside down, is this proper for these carbs?? can and how do i check float height?? are they fixed from factory???

anybody out there

Normally if your needles and seats are worn, it will flood the engine overnight, and will start hard. As far as your valves becoming dirty, what oil are you using and is your pump adjusted properly.

i use interceptor and have my pump arm line up when carbs start to open. the valves are out of the motor now sitting on the bench with black cap off. they have been sitting there for a few weeks and actually have a small puddle of oil/gas mix around them.

A Polaris rep at an open house, gave me a tip on setting things up for cleaner valves on my 800.
He said the oil cleans the valves, and too much fuel causes them gum up. I set the oil up to use more oil, and turned the fuel screw in to clean up the low end, as it was very rich. This went to over 1,000 miles with out valves getting sticky, and before that, 500 miles would have had them stuck. It also really helped the fuel mileage. This was an '02. On the '03 XC's, I think the needle is even fatter on the low end and mid range which is what is hurting the mileage, IMHO. You also have the air screw to help tune it at idle though.
After much tinkering, my '02 got 14 to 18 MPG trail riding. It got as low as 10- 12 with misc clutch and carb settings along the way. Before richening it up too much for DET, have you tried adding higher octane race gas to your premium to see if the fuel is the problem with the DET? We find very poor fuel in some areas we ride, it says premium, but pinged until you turn the key off of premium mode. I will be trying to get my new one, an '05 800 XC, to run right and I have no experience so far with the DET, but have read a few posts from owners not real happy about the performance of them stock.