Hope this isn't a repeat question on the forum but new here. My son has a 2000 DXL90 that began to have carb problems, ie the auto choke sticking, hard start, etc. Today we purchaced a new carb, replaced the fuel filter, drained the tank and put in fresh gas, and cleaned the air filter. The problem we are having now, and had with the old carb, is that it runs great on level ground and gets into the power band, but the slightest of inclines, or to try and climb a hill, and it has no power. The motor will not rev up to get it into the power band. The quad was almost new when we bought it and has very few hours on it so I do not think the rings and piston would be bad.
I am at a loss and would appreciate any help. I have also viewed on here to clean the spark arrestor but it appears to be a sealed unit on this quad.

 

hi my son has the same quad, sounds to me like you better check the compression first,post the numbers here. also check your throttle cable adjustment and make sure the airfilter is real clean and the airbox is sealed tight , ours bogs real bad if the filter is dirty of the aibox is loose? my son rode his for months and it got slower and slower come to find out the adjuster on the throttle cable was loose and kept him from using most of the top end power , after i took about a 1/4 inch of play out its like a brand new quad


but it sounds like compression to me[img]i/expressions/face-icon-small-sad.gif[/img]

 

Thanks for the reply. I just checked the compression cold on it and it is 65#. I do not have the service manual on this quad so I do not know whats good. Thanks again for the help and I appreciate any advise.

 

You need to freshen or replace the top end.

 

If it really is only 65 psi that is pretty low.Our Viper 90 has about 125 psi in stock form..Before you tear it apart though make sure you don't just have a fuel delivery problem.Check to make sure the float level is set correctly and that the carb is still getting fuel from the tank when the bike is tipped up a little.You can pull off the gas line and verify the fuel is coming out properly from the tank...We ran our Viper once with an incorrect cylinder head(race testing parts) and it only had about 80psi compression..It still ran very well although the rider was only about 55 lbs which helped...If the compression is good the problems you describe could also be caused by dirty or worn transmission componants which basically won't let the transmission backshift into a lower gear when it needs to(like on a hill)..The older E-tons didn't have removable spark arrestors but also didn't seem to clog up like the new removable ones do..This became more of an issue after the 04 model year.

 

Hi all, I just bought a 05 viper50m for my son. I am having the same problem. Should the compression be the first thing to check?? Not to be a newbie here but my buddy has a compression tester but it had a rubber end that you just hold on the spark plug hole. Is that how all compression testers are made?? i feel a bit ignorant here. can someone go thru the process of checking comression the right way?? thanks in advance Kurt also what should a stock comression be??

 

I prefer the screw in type compression tester.You can get them pretty inexpensively at most automotive parts stores..You simply remove the spark plug and turn the kill switch to the on position so there is no spark..Screw in the tester and hold the throttle wide open.Crank the engine till the gauge will not climb any higher ...Make sure the battery is charged up good so the engine rolls over at full speed or else use the kick start...Release the pressure and try it a couple of times to confirm your results..You will want 80 psi at the very least..You should probably be well over 100psi with a healthy engine.Our 90 was about 125 psi.

 

Thanks Old Yellar, I will get one today. From doing more reading I will look to clean the spark arrestor(Of course the screw that holds it in is stripped). This machine is an 05 but it looks to be a bit beat on. it looks like the guy never did much maintenance on it at all. The air box is not really even connected to the rubber intake. Lots of oil around where it should connect to the air box. Also from looking where the CDI is, I seem to have two. one is a maroon color and i see the dial to have different settings. That little dial spins and spins. the other one is on the other side of the steering and it has that wire loop going in and out. Any other comments would be appreciated. What has been anyone's experiences with the 50m?? I also read where a hotter plug might be better too....Can anyone give info about replacing the CDI with a racing style?? Thanks, this is a great resource.

 

Yes by all means clean the spark arrestor.That seems to be a big problem on the 05 models...I don't understand how you have two cdi units???Anyway turning the dial should still work.You'll just have to try it to see which way to turn it to the highest setting..The good news is you don't need a new cdi.The highest setting on the stock one should work fine...If the air box truely is seperated from the rubber hose going to the carb the engine will be running very lean and sucking lots of dust and dirt...Get it resealed with some silicone before you ride it again....If your compression is low you've probably sucked in some dirt and killed the rings or piston and cylinder.

 

Well, I bought a tester....Haven't used it yet though. I took out the spark arrestor and fired it up....the guy had the carb adjusted all the way up...I guess to comensate for the clogged arrestor. Wow what a dirfference. Lots of power as in too much...even when i rode it and i'm 240. So i turned it back to its normal setting. put the arrestor back in and it was still way too fast for my son....he is just starting out. he rode it around the house about 50 times last night. I adjusted the CDI to about 1...and turned in the throttle screw so it is about half way. So at least it all runs the way i think it is supposed to. I do have a couple of questions about tires....Can or is there a hub that will fit onto this 50m so i can put bigger tires on it?? Both of the back tires have plugs and leak so i know eventually i will have to replace the tires. I'd rather get a little bit beefer ones but i believe the bolt pattern is different than the other style ATVs. Thanks for the help with my questions. Also as far as having two CDI boxes, I am thinking that one might be for the remote stop/starter. No real clue but that is just an educated guess.

Kurt

I am probably going to continue this thread with the appropriate topic....thanks for the replies again...