300ex top end noise

[Fortman_400]

i got a friend that has a 300ex that he wants me to work on for him. it has had a decently loud ticking noise comming from the cylinder head, i figured it was the valves,, well one day it just got extremely loud, and all power on the quad was gone. so today i took it apart and just set the valve clearances to the same as my quad was, but the clearances on it were soo far off it didn't seem possible that they would all move that far, i mean i could move the lifters about 1-2 mm at tdc, on both the intake and exaust. so i set the clearances to what my 400ex is, and put it back together. i got the reallly loud ticking gone but the original ticking was still there, i didn't know if it could be something with the cam or not. i inspected the cam from what i could see while adjusting the valves and the lobes looked fine tho. i just cant figure out what the original ticking is, i know its at the cylinder head, i just hope its not a valve tapping the piston but not breaking through the piston's head!!:( any ideas?!?!?!?!?!

[mojoe2878]

does it have a decompressor on the cam?
sometimes they can get stuck and cause it to hold a exhaust valve open all the time and it will make a clicking noise.
put a socket wrench on the flywheel nut that you used to turn the engine over to get it at TDC, and turn the engine over back and forth some as fast as you can, sometimes this will disengage the decompressor if its stuck. if this doesnt work then pull the valve cover off to get a better look at things. the cam journals may be worn enough to let the cam move around in there.

[rneal]

Check to cam chain tensioner it may be bad.

[Fortman_400]

ya i talked to my cousin who has rebuilt his friends 300, and he says to check the chain tensioner, but never specified on how to do that! lol. i know its internal but im not exactly sure how to see it and make the adjustments. if sumone would post DIY for tensioning the timing chain i would greatly appreciate it.

[440exnacsracer]

not trying to flame, but do you know what you are doing, hope so. but it could be a number of things, assuming it is an older quad that has alot of hours on it, the lifters or cam could be worn and check the clearances with a feeler guage. you can set the clearances a little tighter than your 400 to see if it will take any out, but definately leave a little. also check to see that the cam chain is tight

[440exnacsracer]

also call honda and get the specs for clearances on the cam and lifters, check the cam with an OD caliper and the lifters' mounting hole with an ID caliper

is it a vibrating noise? on my POS 300 the pipe guard rattles.

[Fortman_400]

am just waiting for the cam and rockers to get shipped into the local honda dealer, the cam broke in 2 spots (both in the bearings),,, soon as parts get here should have the puppy runnign in an hour

[250X_project]

250X/300EX valve clearance is different than the 400ex. It is .004" for both intake and exhaust.
If noise is still there your best bet is the tensionor which is very easy-remove exhaust (optional) use an 8mm wrench to remove side mounting bolts from the outside of the cylinder jug. When mounting the replacement have the center bolt out and tighten the flat head screw inside to pull back the tensionor mecanism so it may be correctly tightened to engine. No gasket is really needed just some RTV gasket maker. For best deals I would try EBAY., hope I was helpful...