I haven't replaced the t-chain and as far as i know it never has been. Im 99.9% sure i put the filter in correctly, although even after dozens of oil changes im sure i could make a mistake at some point
Need help with 08 400ex frustrating engine problems
Ive got a problem with my 400ex and need some professional advise. Sorry about the long post but there is a lot of small details that may give more hints on what the problems may be.
I bought it with a head gasket leak so i tore it down to replace it. When i had it apart i noticed some abnormal wear on the piston and slight scoring on the cylinder(figured the previous owner ran it low in oil). So i honed the cylinder and replace piston, pin, and rings with new oem. While i had it apart i also cleaned out the screens in the oil cooler and in the bottom of the engine. I then replace oil filter and filled with honda oem oil(It did seem to take slightly more oil than normal but i didnt think much of it since i had the oil cooler and side case off to clean out the screens).
Started it up and it ran great. Did about 8 heat cycles and some mild riding on it and then checked the compression which was around 120. Then i rode it fairly hard for a while till i noticed some smoke coming from the pipe and a very slight abnormal knock/ping while under load (the smoke continued seep out of the pipe for a while after i shut it off. It was a used pipe i just bought and put on, maybe it had some oil residue inside and was just burning out).
After it cooled off i removed the valve cover with intentions of getting a look at the cylinder but then decided to do another compression test before tearing down. So put the valve cover back on and tightened a few of the 6m bolts, did the compression test and at around 50 psi the engine seized. Took the cover off the side case and tried to spin the engine backwards, and it broke loose fairly easily. I tried to continue spinning it counter clockwise, and after a bit it got tight again. I pulled the valve cover off and the found the timing chain was tight all the way around (with tentioner in). Then i pulled the tenioner out and whenever the engine would get tight the timing chain work get tense the entire way around. (Tentioner seems to be working correctly)
Ended up pulling the head and cylinder off and found some fresh scores in the cylinder(much worse than the previous scores). The top of the piston also had a thin layer of black residue in the center.
At this point im stuck and need some professional input on whats wrong. If your feeling extra helpful and dont want the confusion of commenting below please send me a pm ...thx
I bought it with a head gasket leak so i tore it down to replace it. When i had it apart i noticed some abnormal wear on the piston and slight scoring on the cylinder(figured the previous owner ran it low in oil). So i honed the cylinder and replace piston, pin, and rings with new oem. While i had it apart i also cleaned out the screens in the oil cooler and in the bottom of the engine. I then replace oil filter and filled with honda oem oil(It did seem to take slightly more oil than normal but i didnt think much of it since i had the oil cooler and side case off to clean out the screens).
Started it up and it ran great. Did about 8 heat cycles and some mild riding on it and then checked the compression which was around 120. Then i rode it fairly hard for a while till i noticed some smoke coming from the pipe and a very slight abnormal knock/ping while under load (the smoke continued seep out of the pipe for a while after i shut it off. It was a used pipe i just bought and put on, maybe it had some oil residue inside and was just burning out).
After it cooled off i removed the valve cover with intentions of getting a look at the cylinder but then decided to do another compression test before tearing down. So put the valve cover back on and tightened a few of the 6m bolts, did the compression test and at around 50 psi the engine seized. Took the cover off the side case and tried to spin the engine backwards, and it broke loose fairly easily. I tried to continue spinning it counter clockwise, and after a bit it got tight again. I pulled the valve cover off and the found the timing chain was tight all the way around (with tentioner in). Then i pulled the tenioner out and whenever the engine would get tight the timing chain work get tense the entire way around. (Tentioner seems to be working correctly)
Ended up pulling the head and cylinder off and found some fresh scores in the cylinder(much worse than the previous scores). The top of the piston also had a thin layer of black residue in the center.
At this point im stuck and need some professional input on whats wrong. If your feeling extra helpful and dont want the confusion of commenting below please send me a pm ...thx
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Heres a picture of the piston, thought maybe it might help....?
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Here some of them
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And some more
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And some more...
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And some more....
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Last one....
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Alright, lets have a conversation. Those photos raise more questions (in my mind) than they answer. But I did see a couple clues worth investigating further.... more on those later...
I just read through three chapters (Head/Valve, Cylinder/Piston, Lubrication) of the service manual familiarizing myself with the motor, so I could talk about this. Again raising more questions than answers, since I haven't gotten enough information yet to point any fingers at anything and say "there... thats the problem". :-(
So I'm just gonna bounce stuff off ya and see what sticks and what comes back... and end with a recommendation.
A possible (or most likely) explanation for why the motor seized up while cranking it during a compression test is, because you may not have had it at TDC on the compression stroke when you took the valve cover off, then put it back on for the compression test? The cam or decompressor plunger or something may have moved up out of place slightly when the cover came off, causing a bind when you tightened the cover back up and cranked it over. My money is on the plunger popping out, but from here everything I say is speculation cause I can't look at any of the motor parts. The TDC procedure for valve cover removal is covered in chapter 8:
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Now, what about that upper connecting rod discoloration? It looks like the wrist pin (either this new wrist pin or the old one, can't see this new one well enough in the photo) and the upper end of the rod has gotten pretty darn HOT at one time! It is discolored for what looks like about 1.25 inches or more down the rod beam, and the entire pin area is burned. Is that new wrist pin discolored from heat too? That don't look good... but the bottom of the rod looks like it hasn't overheated. I can't tell from the photos whether its been getting enough oil or not...
Answering your question about the side movement of the piston on the wrist pin... that is normal at the top of the rod. Thrust movement of the rod is controlled at the bottom of the rod where it connects to the crank throw. Any excessive slop at the bottom is a big problem, but not at the top. The bore holds the piston centered over the rod, not the rod itself.
Is the oil ring a one-piece ring or a three piece ring, that you assembled? If you assembled it, are the scraper rails fit into the expander right, rather than one of them put in alongside the expander? Is the oil ring free to move in the piston land or is it stuck? Does it seem to fit snugly in the bore? I have several more questions about that oil ring that can't be answered through a forum, so I'll leave it up to you to insure that it is good and that it is installed right and that it fits and that it works...
You mentioned the ring gaps being lined up in one of the photos... don't worry about that while the piston is out of the cylinder... The cylinder itself doesn't look very good to me. I see wear at the top of the bore and other clues that indicate to me that it should be mic'ed and if not in spec, bored to the next oversize as appropriate.
Now for some general commentary... The photos don't give me enough information... in some of the photos the cam lobes look a bit ugly, but in others not bad at all. Same goes for the rockers... didn't learn anything from them. Cam journals and the head look alright so its your call... was it getting enough oil up on top? Are the cam and rockers still good?
Also, in some photos I see fine black particles in the oil film on the parts. It looks like it could be grit from parts rapidly wearing and burning up from lack of oil, or it could be from old motor oil that was left in there for a few years too many... Your call.
I come away from all those photos with one nagging question... that seemed to be a common theme in most of those pics. It looks to me like there is a lot of grit in that motor. What that grit is composed of, or the source(s) of, I have no clue from here. Some of it is fine enough to be leaving stains... while some are particles. It looks like stuff is getting chewed up pretty quickly.
I'm not there to put eyeballs on it all and figure out what is going on... I know nothing about its history (and neither do you), so my best recommendation has to be this:
Pull the motor out of the frame and split the cases. Clean every part up in solvent so you can inspect it and proceed to make a list of things that need to be replaced/fixed/refurbed. Disassemble the head too, it probably needs valve seals at a minimum... Read the service manual until you understand it all, then put it all back together clean and right with appropriate lubes and sealants.
Hang in there...
I just read through three chapters (Head/Valve, Cylinder/Piston, Lubrication) of the service manual familiarizing myself with the motor, so I could talk about this. Again raising more questions than answers, since I haven't gotten enough information yet to point any fingers at anything and say "there... thats the problem". :-(
So I'm just gonna bounce stuff off ya and see what sticks and what comes back... and end with a recommendation.
A possible (or most likely) explanation for why the motor seized up while cranking it during a compression test is, because you may not have had it at TDC on the compression stroke when you took the valve cover off, then put it back on for the compression test? The cam or decompressor plunger or something may have moved up out of place slightly when the cover came off, causing a bind when you tightened the cover back up and cranked it over. My money is on the plunger popping out, but from here everything I say is speculation cause I can't look at any of the motor parts. The TDC procedure for valve cover removal is covered in chapter 8:
Now, what about that upper connecting rod discoloration? It looks like the wrist pin (either this new wrist pin or the old one, can't see this new one well enough in the photo) and the upper end of the rod has gotten pretty darn HOT at one time! It is discolored for what looks like about 1.25 inches or more down the rod beam, and the entire pin area is burned. Is that new wrist pin discolored from heat too? That don't look good... but the bottom of the rod looks like it hasn't overheated. I can't tell from the photos whether its been getting enough oil or not...
Answering your question about the side movement of the piston on the wrist pin... that is normal at the top of the rod. Thrust movement of the rod is controlled at the bottom of the rod where it connects to the crank throw. Any excessive slop at the bottom is a big problem, but not at the top. The bore holds the piston centered over the rod, not the rod itself.
Is the oil ring a one-piece ring or a three piece ring, that you assembled? If you assembled it, are the scraper rails fit into the expander right, rather than one of them put in alongside the expander? Is the oil ring free to move in the piston land or is it stuck? Does it seem to fit snugly in the bore? I have several more questions about that oil ring that can't be answered through a forum, so I'll leave it up to you to insure that it is good and that it is installed right and that it fits and that it works...
You mentioned the ring gaps being lined up in one of the photos... don't worry about that while the piston is out of the cylinder... The cylinder itself doesn't look very good to me. I see wear at the top of the bore and other clues that indicate to me that it should be mic'ed and if not in spec, bored to the next oversize as appropriate.
Now for some general commentary... The photos don't give me enough information... in some of the photos the cam lobes look a bit ugly, but in others not bad at all. Same goes for the rockers... didn't learn anything from them. Cam journals and the head look alright so its your call... was it getting enough oil up on top? Are the cam and rockers still good?
Also, in some photos I see fine black particles in the oil film on the parts. It looks like it could be grit from parts rapidly wearing and burning up from lack of oil, or it could be from old motor oil that was left in there for a few years too many... Your call.
I come away from all those photos with one nagging question... that seemed to be a common theme in most of those pics. It looks to me like there is a lot of grit in that motor. What that grit is composed of, or the source(s) of, I have no clue from here. Some of it is fine enough to be leaving stains... while some are particles. It looks like stuff is getting chewed up pretty quickly.
I'm not there to put eyeballs on it all and figure out what is going on... I know nothing about its history (and neither do you), so my best recommendation has to be this:
Pull the motor out of the frame and split the cases. Clean every part up in solvent so you can inspect it and proceed to make a list of things that need to be replaced/fixed/refurbed. Disassemble the head too, it probably needs valve seals at a minimum... Read the service manual until you understand it all, then put it all back together clean and right with appropriate lubes and sealants.
Hang in there...
I had a hunch that putting the valve cover back without having it set at tdc caused the seizure. What would cause the timing chain to get tight the whole way around whenever the the engine got tight (even after taking the tentioner our)? I thought only only the side of the chain that was holding the load would get tight.
Ill try and get some specs as soon as i finish up some other projects and make space to work.
Thanks for everyones help so far.
Ill try and get some specs as soon as i finish up some other projects and make space to work.
Thanks for everyones help so far.
Well now it makes sense why it locked up! Pull the bottom end out of the frame tonight and found this little guy sitting in the bottom of the engine next to the timing chain.... Must have fallen out when i pulled the valve cover and i never noticed it! Finally some progress.... :icon_ banana:
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