I have a 2002 325 Magnum and cannot determine why it is running rich. Fixing it for a friend. The unit sat for two years and had the usual fuel issues and clogged carb. The wiring harness was also damaged and burned up due to charging issues. Tank was cleaned out, Fuel shutoff vale replaced along with fuel lines and fuel filter, Carb cleaned 3 times. Moose Carb kit installed and the needle(Set to middle position)and jet have been replace. Choke plunger replaced since the rubber seal was damaged. Ignition, stator, pickup and coil replaced due to electrical fire causing part of the harness to burn up. Cam mic is within spec and valves have been adjusted to specs. Valve job was also performed on engine and the cylinder produces 155 psi. Stock unobstructed air filter with new filter. New Plug as well. I have no top end unit bogs. Checked all of the jets and they are to manufactures OEM size and specs. Carb pilot was adjusted starting at 2 ½ turns and then adjusted per manual specs. I read about the cam tempering issue and have replaced the cam since the exhaust lobe was not within tolerance. I re-timed the machine using the marks on the chain, cam and crankshaft and double checked with a timing light at the appropriate RPM. I also took an oscilloscope and checked to make sure the voltage outputs on the ignition system matched the manual and the CDI was replaced as well. I also bypassed the rev limiter to ensure it was not causing me grief and it is not causing the engine to bog. If I remove the air cleaner unit will run fine. Any suggestions would be appreciated. Also, the oil and filter were replaced since originally the unit sat for two years and fuel ran into the engine since the float was originally stuck. I am at a loss. Plug came back out black. I have no top end performance.

 

Look at this fuel section and see if it helps.https://www.google.com/url?sa=t&rct=...U2gGlaHJWSIlbA Often over looked is the air jet at the back of the carb. Make sure it and all passage ways are clean and blown out.Plus look closely at the slide diaphragm for any damage or worn spots.

 

Ill take a look at it tonight and give an update. Thanks for the information.

 

You need to do a plug chop to determine how it's running at WOT...that means killing the motor and releasing the throttle while at WOT for a good stretch...

 

Warmed engine up to normal operating temps. Swapped old plug with brand new one(gaped properly) and ran to WOT shifting through gears and shut down. Did a plug chop and the plug is essentially black. Not wet just soot. Bogging at WOT like it’s getting too much fuel. The air jet is fixed on this carb so there’s no adjustment except for changing it out. The diaphragm is not cracked, its pliable and fit in the recess properly. I checked it in good lighting lightly straching it. The slide does show signs of wear but seems to fully lift and drop while running the bike without the air filter. Read through the carb manual and essentially reevaluated everything I've done thus far. Also pulled the exhaust to see if there may be an obstruction causing it to soot up. Bike runs the same regardless. It is getting too much fuel from 3/4 to WOT. It will pulse at WOT like it gets the right amount of fuel then loads up then leans back out.

 

Also did a plug chop with the air filter cover off. The bike is still running a little rich but the plug looks acceptable.

 

Also the vent lines are not kinked and the snorkel is not being blocked by the foam under the tank. I can not figure out why its loading up. Any other suggestions greatly appreciated. I am use to a carb not delivering enough fuel not restricting airflow. Also FYI this carb has been cleaned three times in an ultrasonic cleaner and had contact cleaner blown through every jet. As well as having all the jets replaced with a moose kit and confirmed the sizes as they were installed.

 

I remember now that we had similar problems on the Trail Boss 325 and Magnums of that year model. The air box snorkel would look ok but as soon as weight was on the seat the snorkel pressed against the back of the tank restricting air causing bogging and rich running conditions. Not all did this,just a few. The way we solved this was to cut a sharper 45 degree angle on the tube end so the tank wouldn't interfere.May or may not be your problem,but just now remembered this.

 

Hello I'm a newbie and I'm having the same issue with my 95 Magnum 425 4x4. It was running fine and all of a sudden it just started to cut out at full throttle checked the plug and it's dry with black soot on it any ideas??

 

Oh and the etc is unhooked and the rev limiter and override button but it ran for a year fine with them unhooked it just started doing this the other day???