Loss of midrange power after riding?

[alping45]

Every time I take my '07 EX out, I make sure to let it fully warm up before riding, and all is great for about 10 mins, then it just seems to lose a little low end and mostly mid range power and throttle response isn't quite as crisp. Its not a very noticable difference, I notice it most when
trying to hold a wheelie I need to give it a lot more throttle to keep it up than before. Any ideas?

Kinda seems like fuel is getting blocked somewhere, is there any type of fuel filter in the gas tank or petcock assy anywhere?

[drew416ex]

there is a screen in the tank on the petcock. Have you jetted it for your location? Air filter clean? Also how long has it been since you changed the oil?

[BlasterEaten250]

Mine seems to lose a little midrange when it is hot also.

[alping45]

Hmm, I will check out the screen. I have the jetting about spot on, I've spent countless hours tuning in every circuit. I have a 40 pilot, the needle is shimmed up about .035", running a 160k main, cant remember how many turns on fuel screw but spent alot of time tuning that also(I machined an adaptor to make it finger adjustable). The air filter is pretty good but not 100%, I'll clean it. Probly been about 10-15 hrs since last oil change, I plan on switching it over to synthetic this weekend since this will be my third oil change since new, got it about a month ago.



Originally posted by drew416ex
there is a screen in the tank on the petcock. Have you jetted it for your location? Air filter clean? Also how long has it been since you changed the oil?

[alping45]

Well, I've been running 89 octane, always fresh, guess I never thought to try anything higher. Think it would make any difference?
I believe the compression on these motors is only 9:1 so I couldn't imagine it would need anything better but definately worth a try.




Originally posted by my88r
what octane gas do you run? how old is it?

Originally posted by alping45
Well, I've been running 89 octane, always fresh, guess I never thought to try anything higher. Think it would make any difference?
I believe the compression on these motors is only 9:1 so I couldn't imagine it would need anything better but definately worth a try.

that could be why I ran a lower grade before on accident other than 92 or higher I think it was 87 but the tank still had a little bit of 93 in it. I went riding and the quad ran like crap bogging down and idk it just didnt run right. Everything was stock but not running 92 or 93 made it run like crap. I ran the tank out and put 93 in it... it ran like a charm. And its not in my head because I didnt realize that I had put 87 in it until I got home and my dad said my brother filled the ATV gas can with 87 and the lawnmower gas can with 93 lol.

[alping45]

Ok, well this weekend I am checking the screen in the tank, cleaning the air filter, changing the oil to full synthetic, and draining the tank and filling it with 93. Actually, come to think of it, I am pretty sure I only have 87 in it right now. We'll see what happens...:chinese:

[alping45]

Ok, I syphoned & drained every last drop of gas out of the tank and filled with 93, and switched to full synthetic oil this weekend and WOW!!!! Problem 150% solved!!!!!!! Throttle response is better than ever and nice and crisp. This thing is a torque monster! :D :D :D