Need some opinions on diagnosing engine failure

[FixxxerKH202]

Alright guys, I just went through my 01' 400ex and ended up buying one of those cheap "Niche" cylinder kits with a piston, cylinder, and gaskets for around $130 on ebay. Now I broke it in and everything sounded great. Went for a ride and about 4 hours in I started getting a tick, it stalled and then nothing. So I go to tear it back down and first worry is that my case had almost no oil in it, but the valve cover had plenty and I turned it over to check the cam and more came up the passages. Now I turned it over a bunch of times after it stalled and wouldn't restart and the bottom end looks fine, no play and no scoring, plus the clutch side still had some oil in it when I removed the cover. So I pulled the strainer from the oil tank and it was completely clogged with chips, so I think my oil pump just pumped the case dry and couldn't refill it because of the debris in the strainer which showed up from the failure? Does that sound logical, or do you think I should replace the oil pump to be safe? I checked the lines to the motor and cooler with compressed air and they are all clear.


Next I would like to understand what happened in the cylinder to cause this failure and if improper clearances(piston too sloppy in bore, or bore not done concentric) could have been the culprit. I attached some pictures showing the carnage. The piston is worn on the intake side of the engine, the rings were still properly spaced so the gaps were in the proper places that I installed them to, on the oiler and both compression rings and the exhaust side of the piston is completely fine no damage.

Now before any of you flame me for buying the cheap cylinder, I accepted this risk before buying because it had a money back warranty which they have already honored. I also have already bought all genuine honda parts to put it back together with.

[FixxxerKH202]

Just took the oil pump out and checked it out and it is completely fine, barely any wear inside it. So the motor was definitely getting oil until the strainer got plugged.

Also it was not running lean as I put a tailpipe sniffer in before I went for my ride and here are two pictures of the plug, which looks perfect. So I'm guessing it had to be bad tolerances on the "Niche" piston and cylinder and maybe an out of round condition on one or the other, just looking for someone else to weigh in since I have rebuilt a bunch of engines but never had a failure like this within the first few hours after break in, or any for that matter that weren't just worn rings from old age. What really threw me was the fact the rings are still intact just fused into the piston on the scored up side.

[ride red 14]

What caused you to rebuild the engine in the first place? Did the other engine come apart causing the chips in the tank? Other than something like that it would almost point to too tight of tolerance or something like that with the cylinder.

[FixxxerKH202]

Reason for the rebuild was small amount of blow by on the rings and a slightly bent exhaust valve. I opted to replace the cylinder because the kid I bought it from had stripped just about every bolt and I had to put helicoils for just about everything above the crank case the first time I rebuilt it about 5 years ago. I had flushed out and cleaned the whole motor during this rebuild so it definitely wasn't anything hanging around in the case. The stuff I found blocking the strainer was definitely from this failure.


Tolerances definitely weren't too tight because it had a little more slop than the stock fitment as I compared my stock set-up to the aftermarket before install(my stock piston and cylinder weren't in bad shape, just the rings had worn down and the helicoils which I don't like trusting). So I guess it must have been the cylinder possibly out of round and too much slop for the piston. Oh well, at least I got my money back and now have a genuine honda cylinder, piston, and ring set on the way.

[DragonGunner]

Your screen got plugged and you went dry without oil in tranny. In that short time it was like running no oil and thats what damaged your piston and cylinder, lack of oil flow. With that said I recommend staying away from cheap ebay rebuilds…..a friend on here bought a Macnamur kit off ebay and in short time it was toast. I would do a couple quick oil changes and pull that screen until the time comes its clean of any junk and you should be fine when you rebuild it again. Recommend wiseco or JE piston.

[FixxxerKH202]

Your screen got plugged and you went dry without oil in tranny. In that short time it was like running no oil and thats what damaged your piston and cylinder, lack of oil flow. With that said I recommend staying away from cheap ebay rebuilds…..a friend on here bought a Macnamur kit off ebay and in short time it was toast. I would do a couple quick oil changes and pull that screen until the time comes its clean of any junk and you should be fine when you rebuild it again. Recommend wiseco or JE piston.

The strainer, oil tank, lines, cooler and case were completely flushed before the rebuild, so the failure was definitely not from lack of oil had to be a flaw in the piston and cylinder. I was just trying to see if you guys think it was an out of round condition or too much piston to cylinder clearance. The bottom end still had a coating of oil and about 1/8-1/4 quart left in it, plus I would have definitely blown the bottom end if it ran that time with little to no oil getting in there. Chunks in the tank definitely came from this failure as it shaved a good amount of the piston off, it was making an audible tick and slapping sound for the last 10-20 minutes while I rode it out of the trail. The engine had nothing catastrophic happen before this rebuild and I had thoroughly flushed it 5 years ago when I rebuilt it the first time which was just a hone, new rings, helicoils for the stripped bolts causing oil leaks, and a bunch of work to the valve cover because all the rockers and cam were shot.

I already pulled both covers, removed the clutch, oil pump, lower screen in engine, and pulled the oil tank and removed the strainer and flushed and cleaned everything. I also poured 5 quarts of waste oil from my car and truck down in the case with a fine screened funnel in the opening where the cylinder mounts so it would flush anything hiding in the center of the case. Then poured a couple of quarts of fresh oil after to wash out the waste oil. So there is little to no chance anything is left in there now. Definitely not buying aftermarket unless it's a well known trusted brand again, and like I said in the OP all genuine honda stuff is on it's way to fix it now so this time around it should be good. I had bad luck with JE products and customer service in the past when I paid a **** load of money for a custom piston set for a car that they botched horribly and I do trust wiseco, but just prefer staying factory because I don't race it or anything it's just a trail rig.

Mainly I was looking for opinions because I want to write some reviews on Niche since there is really no info on them other than their own and I don't want someone else to go through this same situation if it can be avoided.

[DragonGunner]

I was running a XC Race when a oil line at the pump came off. I had failed to tighten that bolt earlier, well oil pumped out over about a half mile or so….guys behind me later said they knew someone was in trouble….LOL. My engine cut off because of lack of oil, it restarted and kept going but then quit soon after……boot was covered in oil….it had ran all oil out but was still trying to go. Only damage was the cylinder and the 10.5:1 JE piston…the ring had seized into the piston. Replaced and was ggod to go so running low or out of oil doesn't mean your tranny well be ruined…..sounds like you got a cheap piston that broke down with particles clogging your screen and prevented oil to return fast enough to lubricate your piston and cylinder.