ok here is how i have it as of now. 220 main, 40 pilot, 2nd down on needle, 3/4 of a turn out on air screw.
ok, it starts great. when its cold when you first start it it idles a tad high until it runs like 20 or 30 secounds then idles perfect, and the quad runs awesome across the board idle to wot, then as it runs like 8 to 10 mins. it starts to lose pep, for the first 7 8 mins, this thing will power up in 3rd gear even it runs very very strong , but as i say when it gets totally warm performance falls off a little, i relize that it should run best when it is at a cooler engine temp, but as it is up to running temp it also starts to get a boooaaahhh throttle response. the plug looks a med, brown color,and never has a fouling problem. what do ya'll think jet up down leave it or what? i also run a 50 50 mix 114 octane and 93 octane mix, with 32:1 yamalube mix. hardly smokes at all. i just would like it to have the performance that it has when its cooler as it does when its up to temp... ideas? whats ya'lls jetting set at? with what mods? and at what climate?

 

You're running lean. This is an excerpt from this article....
If you weren't running race gas it would be pinging and it would be easier to tell but you'd be damaging the engine more. Stock main size is 240 and pilot is 30, so it's probably only lean up top. The engine needs more fuel as it gets hotter. I'd bump up the main to a 240 at least.

 

its the oppisite of what you think, motor requires more gas when its cold, less has it heats up, thats what ive understood from everywhere ive studdied.. so does that mean im rich? the last jet changes i made were down and it did run better, so maybe i do need to lean it out more , atleast on the bottom that is..

 

ok,stock jetting for an 88 quadracer 250 is a "240" main,and a "30" pilot. i would think a 220 main would be running really lean for your list of mods. and a 40 pilot sounds maybe a bit hi. i can almost guarantee your lean on the main jet,especially with the needle clip on the second setting down from the top. i have an 88 quadracer,with about the same type of mods as you,and im running a 35 pilot and a 270 main. the 35 pilot is a bit rich for idle,and the 270 is perfect at wot. i bet if you dropped in at least a 250 main jet and put the needle in the middle youd see a great improvement. my 87 quadracer had a 230 main and a 35 pilot,it ran great but ran for like a week and then seized from overheating. remember,the more air flow you get from an exhaust and aftermarket air filter,the bigger main jet you need, and suzuki says 230-240 is for stock-so its obvious to me to move up on the main. do a plug chop too

 

oh yeah i just read that your at 32:1,you should be getting a decent amount of smoke i would say at 32:1 and dont forget the more oil you run in your gas the leaner it makes your fuel/air mixture,i would definitely move up on the main

 

I would jet up as well. I'm running a 35 mm TMX so my jetting may not apply, but I'm at 320 on the main and it runs clean at WOT. It can't hurt to try jetting rich, but if you go leaner it could. At 3 bucks each it worth trying. And when it's hot you could already be lean causing the top end to try to start siezing which could be your loss of power.

 

We have to be clear about what we're talking about. Your statement is true for air temperature. The hotter the air temp the less fuel you need because hot air is less dense than cold air. What I was referring to is engine temperature. As the engine's internal temp increases, more fuel is required for it's cooling effect inside the cylinder.

As Evil mentioned, 32:1 is pretty rich and you should be seeing some smoke, especially with the Yamalube since it is not the cleanest burning oil. I'm pretty sure you're fat down low and thin up top.

 

Yep, that's what she said!
Sorry couldn't help myself.

 

if you run race gas you will be around 6 or 8 jet sizes smaller than with pump gas...well everybody says so anyway, and thats what works best in mine as well if i go any bigger on the main it wont rev at all, cause its rich....