I am stumped, when I got my 98 form. deluxe 583 , it had a bog in the bottom end and i could only get about 120 km out of a full tank while trail riding

since then I have has new plugs gapped (br9es), rave valves cleaned, new stator/ volt. reg., garbs cleaned, belt deflection adjusted
tried it same poblem

so I moved the needle up a clip, same problem

so I dropped 2 jet sizes ( plugs were black)

seemed better in the bottom end when cold but then I rode it for an hr in 0 deg. to + 3 deg. weather, fresh snow on trail, and it once again had a bad bog below 5000 rpm ( 1/4 throttle) (not very convient for cruising!) and took over half a tank to go 50 km on the trails

whats goin on here?

any ideas??

How many miles on the sled? have you checked the spark and wires ?

just rolled over 10,000 km, compression is 135 in both sides, lots of spark ( when cold at least , I jsut checked when it was flooded lol)

choke or primer? Could the choke be sticking?

it has a primer, no choke

when you cleaned the carbs did you make sure to clean the pilot jets they very commonly gum up and cause a low rpm bog at ligt throttle and sometimes a dead cylinder if totaly blocked off that seems to go away at 1/2 to 3/4 throttle. Its the jet in the base of the carb body that is forward of the main jet closer towards the engine . remove it you should be able to see through it easely if you can't use a small wire or torch tip cleaner push it through. do not force it and open the jet more than it original factory size . or this will cause other concerns for you . tell us how you make out

actually I had them cleaned by 2 different shops, and then after that didnt work I had one size smaller new jets put in, I believe it was the pilots that we changed

I was wondering if maby it would be the coils? b/c it runs great for the first 45 mins then after it gets hot it starts acting up?
any thoughts?

Clickers on clutch. I think its #3. just to be safe, a quick check on belt to see how high it sits on secondary.any signs of over heating?

clickers are on # 3, it sits a few mm above secondary
temp gauge is reading right around the middle of the gauge, so it seems good

sucking air in somewhere it ain't supposed to??

does it seem like you are useing a lot of oil? check the pump for propper adjustment and see if it returns without sticking

oil useage is good, I am leaning towards a crank seal leak, anyone know how big a job this is, i have heard that it will probably be the center seal so I will need to split the block, any one know how many hrs this will take ( i dont have time so il send it to my mechaic) if it will be to much I may just upgrade and put a 670 engine in it and part out this engine, but if the seals arnt to much to get fixed il go that way
any thoughts?