Hi everybody,

I have a scrambler 400 1999. The mods are a dynoport pipe and a pwk 39mm carb. From bottom to mid range, it runs to rich. It is like it is on the choke. I tried a smaller pilot jet (35 instead of the 38). Nada. I tried lowering the needle to the first notch. Nada. Along with that, I turned out the airscrew 3 turns...Nada. I tried a bigger needle (EEJ instead of the EEH). Still to rich. It is a bit better but far from beeing perfect. I even tried a smaller needle (EEG instead of the EEH) just to make sure I was not crazy. It was a lot worse. Now, I have ordered the EEK and EEL needle to see if it could help.

Do you have any Idea what could cause that ?

It has always been this way. With everything stock (pipe, mikuni 34mm carb), I had to lower the needle to the first notch and REMOVE the plastic washer where the clip (from the needle) sits to lower the needle even more. It ran extremely well that way, strong power, smooth running not that ding, ding, ding noise. I checked the plug to see if the mixture was to poor and it was ok. But I don't understand why... Is that possible that something is causing it ? I talked to Rick Ritter about it and he does not have a clue... Help !!! My life is miserable... I wake up at night trying to find an answer !!! I consider now going to the church instead of hitting the trails during weekends.

 

OK only thing I can think of off the top of my head. Could you have a vent hose that is plugged or kinked? What is it doing exactly that you believe it to be too rich?? What kind of air filter you running and are you keeping it clean? OHHHHHH (ligthtbulb) How much oil you pumping in there?? Do you use alot of oil? Is your oil pump set correctly?? Maybe you should try unhooking the oil pump, mix 32:1 with your gas and see what happens?? Sounds funny though. <U>Exactly </U>how is it rich to you??

 

My air filter is a uni bought from ritter and the air box has no lid. The oil injection pump is set correctly - (lines are aligned at idle). As soon as I push the throttle, the motor start to do that ding, ding sound and disapear when I reach 1/4 to 1/2 throttle. It has no power also. When I try to climb a hill slowly, the motor goes ding, ding, ding so I have to push the throttle a bit more and then zooommm I climb the hill at 100 mph (well it feels like it...)... By the way, with the pwk carb, should I adjust the oil pump so it gives a bit more oil (since there is more gas going in) ?

 

No, the pump should stay the same. You are going to think I am crazy, but could it possibly be the clutch making it do that?? Some clutching problems will make you think it is the carb. OK, have you ever flipped the choke on when it was doing that to make sure it is a rich condition??? If not, try it, sometimes carbs can trick you into thinking they are lean, when they are really rich. Does it do this at startup or after the engine has warmed up, or all the time?? Another thing I would check is float height, but since it done it with your old carb..huh.....What altitude are you at??

 

I am at sea level. I tried to flip the choke often but it is only worse. It is not the clutch. With the stock part, I succeded to make it run great. It does this all the time... Could it be an electrical problem ? Just to know, what would it do if it was lean on the bottom ? I know when it is lean on top it does that boooooah sound when accelerating but I don't know for the bottom ?

 

OK here are some more suggestions. That ping ping sounds you say you hear could be from an airleak somewhere. Check the cylinder base, reed valve, magneto seal. What kind of shape are your reeds in, they can sometimes give problems in the idle to 1/4 range. To check for leaks, use WD-40 while engine is running, not hot, and see if the idle changes, if it does you have found a leak. Check around all the places I mentioned. Do you use much coolant?? You could also have a coolant leak arounf\d the head gasket messing up the mixture and causing a rich condition. Do you have the factory silencer??? Is it stopped up or carboned real bad??? If not factory, have you re-packed it lately?? That is really all I can think of unless you confirm or deny any of this. Did It do this when it was brand new or have you bought it used??? If so, check the condition of the piston skirt. Do that by taking the carb, boot, reed cage off and look into the motor while slowly pulling the recoil rope to turn it over.. See if it is cracked or broken.

 

Ok, NcScrambler ! Thank you a lot ! You have given me some real good clues. I'll do everything you said to see if it leads to something. I never checked the reeds and I bought my Scrambler used. Could be that. I also notice that my coolant was a bit lower . I have 2 silencers (the stock one and the other bought from Modquad). Anyway, I will let you know how it went. You have put a smile back in my face. I'm gonna sleep happy tonight !!!

 

OK, the stock choke cable has to have an adapter to work in the 39pwk carb. If you dont have the right one or if it's not adusted correctly, the choke could be held partially open. Just something else to check.Bubba

 

That is true too Bubba, didn't even think about that. With all that you are describing though, I really think it could be something wrong elsewhere and you are trying to correct another problem through jetting. I have had experience with a cracked piston and the 400's are known for this, and that can cause all kinds of heck on bottom end. Air leaks can also seem like a jetting problem. What really makes me believe it is something like that is that you said it happened before the carb switch, so........ Check all the other stuff and If you find a blown gasket or piston crack, then rebuild. It is relatively cheap and the Wiseco piston is so much more reliable. I would quit trying to fix this problem through jetting and find the root cause. If you were running a TMX I would believe the jetting to give that much trouble, but not with a PWK. Also, let me throw this in, the silencer probably wouldn't have that much effect on the bottom like that, but It is recommended to re-pack at least once a year if you ride pretty much, and up to 2 or 3 times if you ride every weekend, also getting the packing wet while washing will ruin it, so a plug is a good thing if you don't have one. LOL Glad you can sleep good because now I will wonder and think about it until you figure out what it is. One more thing you should check is compression if you don't see any damage to the piston. You should be at least at 115psi. Since that is a 99, probably wouldn't hurt either to go ahead and re-build the top-end then try jetting again with a fresh motor.

 

Do what the others said, if you need the choke adapter, I think HPD still stocks them. If not, I think there's a carbparts.com or some site like that should hook you up.