300ex

[sneekypete]

I bought a 2000 300ex and it would start and it would run as long as you would give it some gas so I cleaned out the carb the best i could even though it already looked clean put a new spark plug emptied the tank and put fresh gas and nothing changed it pops a lot and doesn't idle i'm no mechanic i think i cleaned out the carb good but maybe i missed something. the guy that had it before me never had time to ride it. i took it for a spin seems to have plenty power but if you let off the gas it dies, any suggestions?

[the Z Man]

Check your valve adjustment, turn up the idle.
Clean the air filter, check for leaks between the airbox and carb, the boots have a tendancy to tear and leak.

[sneekypete]

what do you mean by valve adjustment? how do you turn up the idle on these things? this is my first quad as you can tell i don't know much about these things.

[Pojo450r]

first thing to do is buy a service manuel at your local dealer it is step by step basic trouble shooting and explains valve adj.
it is probably $25

[the Z Man]

Take off the plastics and tank, remove the 2 caps on the top of the motor, check the play in the rocker arms, should be.... .005 on both the front and rear, I could be wrong u=it has been along time since I have doen 300ex.
The idle, hhmmm. should be right below the carb. a black knob. or is that 400ex??
Don't forget to check your carb. boot while its apart, move it side toi side and look for cracks.

[bwamos]

0.004" intake and exhaust.

Idle adjustment is a ~3/8" diameter adjsutment nob w/ a slot for a slotted screwdriver in it. It is attatched to a bracket just below and in front of the carb float bowl.

Everything else was correct. ;)

[sneekypete]

how do i check the valve adjustment? i got the tank off and opened up the caps but i don't know how to check them. seems to be in good shape from the looks of it.

[300exOH]

Originally posted by sneekypete
how do i check the valve adjustment? i got the tank off and opened up the caps but i don't know how to check them. seems to be in good shape from the looks of it.

You need a set of feeler gauges. Make sure they have the proper size (.oo4) some sets will and some won't. You will want to adjust the valve until you feel a slight drag on the feeler gauge but not tight then lock down the lock-nut. If you aren't comfortable with the procedure I highly recommend picking up a service manual. You'll thank yourself later when you need to do other repairs and maintenance.

You may want to remove your pilot jet and make sure it isn't clogged. You should be able to see light through it. After that I would make sure you idle is set right and adjust the pilot screw (air/fuel mixture). It should be around 2- 2.5 turns out from lightly seated.

[sneekypete]

ok i took off the covers on the top and when i try to move the valve springs the back ones i can't move and the front ones i can move real easy how do i fix this i have a .004 feeler gauge to adjust the valves i just don't know how to do it

[the Z Man]

Make sure your on top dead center, the cam should be facing down, there is also a timing mark on the flywheel behind a big slotted screwdriver cap, left side, should be a T.

[sneekypete]

ok i cleaned out the slow jet put it back together and not nearly as much popping but i'm concerned about the valve springs being loose i can move the rocker arm pretty easy in the front how do i fix this? i'm sure that is the rattling i hear in the front. i think this is the last thing i have to do before i can actually ride and enjoy it. thanks for the help so far

[bwamos]

You remove the chrome plug on the stator side of your engine case (uses an allen wrench). You rotate the motor until the |T mark lines up with the slot in the hole. (Very very important)

You remove the tappet covers on top of the head cover. Both intake and exhaust rocker arms should have a little free play in them.

Slide your 0.004" (0.100 mm) feeler gauge between the rocker arm and the valve stem.

Use a 6mm box end wrench to loosen the locknut on the rocker arm. Once that is loose use a pair of needlenose to turn the rocker arm adjustment screw until it lightly grabs the feeler gauge. While holding the adjsutment screw in place w/ the needle nose, tighten the locknut back down.

Repeat 4 times for all 4 valves.

Reinstall tappet covers, sidecase plug, tank, and plastics.

It is important that there is a little clearance between the valves and rocker arms. When the engine heats up the valves expand reducing that gap. If it's tight against the rocker arms then the valves will be held open when the engine heats up resulting in burnt valves and/or damaged seats.