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Discussion Starter · #1 · (Edited)
I need to pick everyone brain a bit!

On our last ride i noticed my valves chattering a good bit. And i know its a honda so some tick is normal but this was more then normal. Being that over the winter i put the new valves in i figured it was the new valves seating in and just a quick adjustment would clear everything up. So i took everything apart and checked the clearance on all 4 valve adjusters. 3 were tight. Like .001 tight. And one was loose. Like .008 loose. Which i though was kinda weird to start with. But i have taken it on 3 good full day rides and im not afraid of the rev limiter one bit so i adjusted them to spec. I got the intake to adjust perfect and i struggled with the exhaust alot more than normal.(I adjust valves alot) everytime i would get them perfect nice drag on feeler gauge i would torque the nuts after snugging them and they would be loose again even though the adjuster screw didnt move. I did finally get them close enough to try and put it all back togeather and took for a test ride. Sounded almost the same as before.

After some thinking and research i decided the adjuster screw and nuts needed to be replaced. So i ordered some oem ones off rockymountainatv.

Got them and installed. I was able to adjust them alot easier again. So i though i was good to go. I adjusted all of the valves again and i did my normal test with my finger on the end of the tappet arm to see if they made any noise and all but one were silent. The left exhaust valve taps like its loose but with my feeler gauge says its perfect.(never had this happen before). Going exhaust valve to exhaust valve they both have identical amount of drag on the gauge.

Thought well maybe the oil will get in there and quiet it down. And i was close to being right. If i start it cold and let it idle they chatter like crazy. If i rev it up a few times or when im riding its completely quiet. That being said it struck a cord in by brain and i though oil pump! Figuring it was getting weak. Being that its stock and this engine had been rarely maintained before i got it i did the oil pump check outlined in the fsm. And it passed the test perfect. Took the 10mm bolt out below the 2 oil lines and zero oil came out. Not a single drop even. So now i am stumped. Should i even worry since its quiet when riding or if i even just rev it once at idle its quiet and sounds perfect. Im on the fence. Sorry for the long post but throw your opinions out there please. Thanks!
 

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I know nothing about the 400ex motor, but if had to take a wild guess I would suspect that an o-ring (or seal or oil pipe) were either cut, out of place, or missing somewhere. Another possibility is the oil pump intake screen is plugged off with clutch material and/or stator winding epoxy glue flakes.

Chances are if the topend is not getting a normal oil supply for some reason... the camshaft and rockers are probably wearing very quickly. I'd pull the valve cover off and have a look-see in there and consult the service manual for possible oil pressure leak locations before yanking the cover and checking the oil screen and oil pump/oil pump relief valve stuck, etc.
 

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Discussion Starter · #3 ·
I pulled the valve cover and cam and rockers look new. I forgot to add that part. Im leaning toward the secondary arms or there pivot shafts causing it but its still odd to me that if i crack the throttle at idle even one time it sounds perfectly fine and stays that way for a long time. I let it idle for 10 or so minutes and after one rev it was quiet that whole time. Also there is whole lot of clean oil all over the cam and rocker arms and in every corner of the valve cover. So much that when i remove the valve cover it dripped out the front onto the headers and made it to the floor even so lack of oil pressure i think can be weeded out. Thanks for the reply though retro. I really appreciate it!
 

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Discussion Starter · #4 ·
Also when i did the rebuild i cleaned the oil pump screen and it was clogged pretty bad with clutch material from previous owner putting car oil in it. And i also have cleaned the oil reservoir screen at the sametime i flushed the oil cooler and all the oil lines with diesel fuel for good measure. Wanted to make sure i didnt miss anything. Because my luck 1 tiny flake would block off the oil passage and toast the whole motor.
 

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Ya, OK sounds like you making progress. It could still be an insufficient oil delivery problem though... the pressure relief valve in the oil pump could be sticking open when you fire it up... or an 0-ring or pipe could be leaking... keep it in the back of your mind its still a possible problem... symptoms suggest something may be wrong with the oiling.

Hope you get it sorted out right away!
 

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Discussion Starter · #6 ·
Well guys i finally got around to hopefully getting to the bottom of this sewing machine ive been riding very little for fear of something really bad. So i pulled the valve cover off and had a look at the cam and rocker arms and they are absolutely perfect. Zero wear. Tons of oil under the cam and everywhere under the valve cover so im thinking no way its an oiling issue. So i pulled out my trusty FSM and had a look at the valvetrane section. And i find service limits for the rocker arm shafts and the rocker arms themselves. I can feel a ridge in the exhaust side shaft so i mic it and its passed the service limit by .001. So i started checking all the rest. All of them are at the service limit or just above it. But the one that was impossible to quiet was noticeably more. So ordering both shafts, all 4 rocker arms, and the sealing washers for both shafts. Will post back with if it shuts the topend up or not. Fingers crossed!
 
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Great find! I never give it a thought that it could be rockers/shafts. I'll bet a dollar for every nickel that you got it...!
 

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Discussion Starter · #8 ·
I appreciate the confidence retro. And i think i even know what caused the problem now that i think of it. After getting the +1 valves installed i have always noticed new valves seat in differently each time. So i always go back after a good ride and check valves. When i did the left exhaust valve(the one in question) was so tight i couldnt fit anything under it. The other exhaust valve was loose alittle. And both intakes were a bit tight but nothing crazy. So im thinking when that one tightened up it wore the shaft that was mostlikely already close to the wear limit. Since this engine has a ton of hours. And dude before me thought maintanence was putting car oil in it. Didnt know what the oil filter was. And rode it till the rear carrier bearings failed 3 times. He tried to do the bearings the last time before i got it and ruined not only the carrier but the axle aswell. I picked it up cheap though. Knowing all the problems but the car oil that ruined the clutch. But i will keep everyone posted on if it fixes it. And maybe save someone the headache if they cant get valves to quiet down.
 

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Discussion Starter · #10 ·
Ok guys and gals. Here is the verdict. One shaft is on back order till mid july. But i got all 4 rocker arms 1 shaft and both washers. So being that were going to a track sunday i got the 1 shaft and both exhaust rocker arms in. Adjusted all 4 valves and did my normal finger test. Both exhaust tapped like crazy and intake were silent. So i though CRAP. Thats alot of wasted money. Decided screw it im putting it togeather anyway. Started her up and absolutely zero valve noise. I took it for a ride and its night and day different. When i get the other shaft i will install it and re-adjust since im sure by then the new rocker arms will be broken in and need alittle adjustment anyway. Thanks everyone for the kind words of encouragment!
 
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Great news! I took the cover off mine the other day to measure and found both of the shafts/rockers right at the service limits. The cam lobes are pretty worn too, so I'm gonna replace them all. Thanks for the headsup...!
 

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Discussion Starter · #12 ·
The way i see it being at the service limit must not make any noise atleast. Granted it should be replaced. It was just that .001 over the service limit that made it sound like a sewing machine. The weird thing to me is why did only one wear? And thats what makes me think its because that valve tightened up on me.....must have just been bad luck. Thing that sucks is the contact surface is perfect on all 4 rocker arms......
 
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Ya, both of mine are junk. Looking at the worn cam lobes explains everything too.

You didn't have anything to clue you in on what was going on though... You definitely had your work cut out tracking that one down. When .001" makes the difference between quiet and clatter its an eye-opener for me. The geometry & angles of attack between parts up there on yours must be running on the bleeding edge... LOL
 

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Discussion Starter · #14 ·
Yeah im thinking honda never expected this part to wear at all. Brand new measures at 0.450 inches and the service limit is 0.449. Mine had one spot at 0.448. Nuts that such a small amount made such a racket. Im sure most people would have ignored the sound and i have no doubt it would have been fine for quite a while. But im anal about things being right. And when im bouncing the rev limiter i will feel alot safer knowing its all new. Once that last part comes off back order.....lol
 

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True that! Small base circle cam with max lobe heights, much higher rocker acceleration/speed rate caused by steep cam ramps, rockers working at the limits of their lever-angle-lengths on small diameter stock shafts while shoving against valve springs with nearly twice the full open spring tensions as stock... at increased (sustained) RPMs... and with all those extremes barely fitting under the cover...! I doubt Honda engineers envisioned you'd be doing just that to it! LOL

Sounds like a fun bike for sure!
 

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Discussion Starter · #16 ·
Yeah shes a fun little monster. Its like a sleeper. People always go thats just a 400ex? How? It sits right next to my brothers mild built kfx450r. At the fair race in my town last year i took 3rd out of 7 against all national built trx450s, ltr450s, and a ds450. I was expecting to get dusted when i saw who i was racing against lol. But thats what i get for racing open quad i guess haha.
 
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Discussion Starter · #17 ·
One final update. After riding at a track on sunday like we had planned it sounded great. No valve noise at all. Still in the process of 100% dialing in the tuning but over all it performed very well. As a side note one of the guys we ride with broke his z400 and ended up taking pictures the whole time. So here are a few for your viewing pleasure.
 

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