I need MORE!....few questions, ideas?

[leasureryan]

My quad just doesn't have enough sac for me. I have everything under the sun as far as aftermarket protection and "bling" goes....but everything internal is bone stock. It is piped, air box mods, and jetted. While I was at work today, I went ahead and set aside the CRF450R cam chain, ordered the XR400 head gasket, got my 450R throttle cable for the carb I am getting ready to install. I'm just going to start ordering all my parts now, and come winter...tear into the motor and completely do everything I can to the top end. Maybe a 426 with 11 to 1 compression, hot cams stage 2, port and polish, , etc etc.


We went to Crow Canyon yesterday, And I was bummin, because I have ZERO low end. I do alot alot alot of hill climbs, trail riding, and a little MX here and there. I couldn't even get enough speed to hit the jumps properly when TRYING to go andond the track Just seemed like I was being drug down by something. I even checked to see if my breaks were sticking. Once I get to a certain RPM range it is fine....and climbs like a champ, but drop below half in that RPM range, and it is all over unless you downshift. Almost think it is running rich.....But there is no way. I still have one mean *** flame shooting backfire on decel...or if I just rev to the moon sitting still, and let off...8" flame shoots from exhaust, so to me, that screems lean, but my pilot is already way bigger than most people reccomend. I have a 48...4 sizes up from stock, and still seems lean on pilot circuit(backfire)

Is it always going to backfire with aftermarket exhaust system?
You think I am rich or lean?
any other suggestions, or minor details I should know?
suggestions on type of piston, cam, etc?

[xtullyx16]

try messin with ur air/fuel screw or put a bigger main in it.. when u rev it to the moon ur holding it wide open which would be using ur main jet, i think ... idk just .02

[AZ440ex]

Originally posted by xtullyx16
try messin with ur air/fuel screw or put a bigger main in it.. when u rev it to the moon ur holding it wide open which would be using ur main jet, i think ... idk just .02

+1 Wide open is definately main jet.

As far a your "backfire", could be lots of things. A 48 pilot seems pretty big but every bike is different. I run a 42 on my 440 with no problems. If you have flame I would say running rich.

Something just doesn't sound right.

Check for air leaks around the carb and air filter. How is the head gasket looking? When was you last valve adjust?

If all this is good and your still not there you could always have it dyno tuned, not the cheapest ($100-200) but can be well worth it. Most places can show your air to fuel mixture to see if your lean or rich. I know the honda store by me charges $75hr and usually takes two hours.

[leasureryan]

I know my jetting...pretty well anywys....And I know that 3/4 throttle is a main.....but the backfire doesn't happen until it gets down under half RPM ranges, then CRACK POP BOOM. Typicly...that would mean lean on a pilot....but there is no way it is lean.

And yes...I know how to mess with the air screw, actualy bought a $40 tool specificly for that....also, there are no air leaks, or anything of that nature. Valves were recently adjusted, and gaskets are all fine. My quad is practicly mint

Kinda odd

Basicly, The question is, is there a sweet spot? I know to lean causes backfire....but could to rich also cause backfire?

Dyno tuning just for jetting costs me about $55

[AZ440ex]

Originally posted by leasureryan


Dyno tuning just for jetting costs me about $55

:eek:

Do it! For 55 bucks its a steal. You will be able to get your air to fuel mixture set just right. Even if its was running good its still worth the 55 bucks. I was supprised how much more power could be had by a good Dyno tunning session.

[leasureryan]

I'm going to. I have a felling it's a little rich. I think it backfired less with the 45 pilot in it. Actually didn't backfire nearly as often or as loud, just a couple little pops on decel. I'm going to go back to the 45, see how it acts. I know the 42 was way to lean though. So a 45 should do it.

anyone else with a full system not been able to cure the decel backfiring/poping???