So here’s the situation. Bought bike a year ago and one day lost all power to make that long story short it was a bad battery. Then the other day I was riding around and it died but I started it back up while still in motion, for about 100 yards, then was stranded. Opened the oil to check and it was smoking and pretty low like reeeeaaalll low. So I got a friend to go get me 2 quarts and I put it in but still no luck. Towed it home and decided to get 1 more quart, because Honda says it calls for 3 quarts, and a spark plug because it was pretty rough. Checked the compression it was at 120 put the new spark plug in, fires right up, check compression again and it’s at 180. I thought awesome problem solved. I went out my driveway and into second gear and boom, significant power loss and sounds like a ticking in the engine. Come back check compression, it’s at 150 now, decided to drain the oil and put 2.5 quarts in because apparently that is the actual amount and now it’s white smoking. My question is how serious is this? Did I blow some seals in my lower end after a few hundred yards? Or maybe something not so bad? Any help is appreciated thanks in advance

 

Why not check the level by the dipstick and fill until it reaches the full mark on the dipstick? That way you would have known, by the amount you put in, how much there had been in the first place. Alternatively, drain out the old oil first and see what was in there, then fill up. Now you don't know if you seized it from lack of oil or not. Anyway, too late now.

So, you could have problems from seizing, problems from overfilling or the problem may have been fuel related in the first place. Doubt if overfilling would do more than blow oil into the airbox, so check it isn't full of oil and drain it out if it is, then squeeze the filter dry. If your problem isn't that, it still could be fuel related, though a tapping noise would indicate seizure. If you think you may have seized it, 420s usually seize on a rocker shaft and inlet valve, though small end seizure is a possibility, and it may be prudent to remove the cylinder and check the piston/small end for seizure. If it is OK check rings for wear, if the oil did get low, it is because it is using it, and worn rings are the probable cause. Check the bore for wear, though a 3 year old bike is unlikely to have much wear there. If the valve stem shows a lot of wear on the end, change it. I have had a couple of 420s drop a valve due to the stem wearing down to the collets. Check rocker shafts too, usually just the shaft wears, rockers seem to be harder, and don't wear much.