hi, i am trying to adjust my valves on my 400ex, so far i have been able to find the exhaust and the intake TDC's, and i have it on the intake TDC right now. The problem is when i try to insert the feeler guage it bends all around, and i tried to bend the feeler guage to get it to work, but i still feel like i am not getting an accurate reading... does anyone know and easier way to be able to check the valves??? could i smash the feeler guage in between the rocker arm and valve, then tighten the bolt to where it is snug against the feeler guage???? BTW, i broke 2 sets of feeler guages trying to bend them into an L kind of shape to get them in there.... those small .004 and .005 blades don't stand up to much. Help is needed, later

 

Whoa, there, c400ex1234; you say you're on the "intake" TDC? There is one and only one TDC for adjusting your valves; the same for intake and exhaust. You want the compression stroke TDC, determined by removing the spark plug, inserting your finger in the spark plug hole, and feeling for a rush of air when you pull the engine through with the starter cord (if any) or by cranking the flywheel/rotor bolt with a wrench; when the piston reaches its zenith (determined by feeling its ascent with a piece of wire or something in the spark plug hole, or by the alignment of timing marks with their index), you are at the proper point to adjust both intake and exhaust valves.

I definitely think your feeler gauges should survive a valve lash setting; your problem may be you are NOT at TDC for the compression stroke (valve spring tension would prevent insertion of feeler gauge to measure valve lash if you are not at compression stroke TDC).

Assuming you have the flat, metal, tongue-shaped (round-ended) feeler gauges, the trick you must master is setting the clearance wide enough so the gauge can pass between the rocker arm and the valve stem/pushrod/lifter (at compression stroke TDC) with acceptable friction.

Tree Farmer's tune-up tip of the day: At TDC on the compression stroke, both the intake and the exhaust valve are COMPLETELY closed.

If you can't reach the valve lash adjustment and measurement position conveniently with your wrench, screwdriver, and feeler gauge, you must remove plastic, tank, whatever to obtain access.

As to loosening the adjusting screw, inserting the feeler gauge, and then tightening the screw to the proper clearance and cinching the lock nut, you can get in the ballpark this way, but you must ultimately be able to pass the feeler gauge between the rocker and whatever lifts it with the adjusting screw set and locknut tight. One often must re-set clearance after the locknut is torqued, taking some "Kentucky windage" on the clearance so when torqued down, the clearance is correct.

You'll get the feel of the right degree of drag on properly-adjusted valves with the feeler gauge with experience. Congratulations on having the guts and intitiative to adjust your own valves; good luck!

Tree Farmer

 

tree farmer, hahaha, thanks for the info, i am goign to get new feeler guages right now. and BTW i already have everything off... gas tank, plastick, even the carb. my manual isn't very helpful, it always shows pictures of the 300ex, then says 400ex similar. thanks man, i'll tell you what happened after i get it done!

 

problems.... problems.... the right exhaust valve was soo tight that i had to loosen it so much that it was banging off of the valve cover. I am taking it into the shop to get it porfessionally done... o well

 

Could be that the compression lobe on the cam isn't letting the valve go down.

Just happened to mine.

Had to take the cam off and use a press to remove the lobe.

RM

 

i just did this procedure, theres an easier way of finding TDC, theres a cap on the crank case that you remove, thru there you can see the flywheel, it has timing marks, F and T if i remeber correctly, you want the T and you want it on the compression stroke, use the finger to spark plug technique. Real easy with a socket to the crank to turn over. its got a cap also for access. When you can see the "T", your ready for adjustment (make sure and not to go backwards if you pass the "T",keep turning till it comes up again) to confirm, your rockers (both intake and exhaust) should have play in them, if not, your on the wrong stroke, spin her over 360° to the "T"
and check the rockers. If theres play, and your "T"is lined up, your ready for adjustment. Remeber, .004-.005 is very little so practice and double check twice be before you button her up.

 

"Kentucky Windage" LMFAO!!!

 

i think that my cam is ****ing up my rocker arm... cuz there is play in all the other rocker arms exept for the right exhaust one... i took it to the shop just now, thanks for the replies, I told them what was goign on and they said that they had a couple of ex's have this prob. they're fixing it tho, i don't know when it'll be done... later dudes

 

You are turning the motor over the wrong direction. You should turn the motor counter-clockwise for the 400EX. The right front exhaust valve is the decompression valve for the 400EX. The proper way to adjust the valves for a 400EX.
1. Remove the spark plug
2. Turn the motor over counter-clockwise untill the motor is top dead center.
3. Adjust the intake valves, and then the left exhaust valve.
4. Turn the motor over counter clockwise very slowly away from top dead center (at this time the right exhaust valve is barely opening up to let the compression out) till you hear a click (at this time it just closed). Then STOP immeadiately!!
5. Adjust the right exhaust valve at that point.

The problem with the right exhaust valve being tight is because the motor is still in the decompression mode when you have it a top dead center. The only way to keep this from happening is to turn the motor over the correct way.
Hope this helped.

 

Good post, XC426; thanks for sharing interesting and useful info about the 400ex valvetrain.

Tree Farmer