450 Seized?

[HondaHog 0]

Thanks for accepting me. Bought a 2004 450 this week with the engine locked. Previous owner ran it low on oil. I can crank the engine 360 degrees with a 17mm socket. Gets tight when piston is near TDC. My next step is going to be to pull the head/cylinder and see what is binding. Been told it's most likely top end because if the crank was seized I couldn't move it, but not sure that is good info. Hopefully I'm on the right track. I know these things are tough as nails. Has anyone else saved one in this condition? 

[toodeep 1,758]

I came across a lot of them that the shift shaft seal would leak and go unnoticed until it was too late. Yes, the crankshaft is fine but the rod is shot because the piston pin "welds" itself to the rod. Pull the top end off and see what's going on. A very uncommon and since it's known to be ran low on oil so it's probably not the issue, the bolts on the flywheel can come loose and lock against the stator. Most likely it's the first one though with the info given.

[SlammedRanger 1,556]

Welcome aboard! This a 450r or trx450? The options are kinda endless at this point. Topend needs pulled to see what damage has been done. Then the other question is why was it ran low on oil? Did it burn it all? Leak out? Removed and not replaced? Running low on oil on any engine damages almost always multiple parts. I would check the cam lobes, cylinder wall, piston skirts, piston ring gaps, wrist pin, rod bearings, oil pump. Clutch if its a wet clutch. The list goes on and on. That list would be where i start.

[jeepwm69 7,600]

You're the guy in Central Arkansas, right?

 

I am finishing up this one in the next few days.  My buddy had to order a new OEM carb for it as I couldn't get the original one to run right, but it was parked for the reason toodeep said; shift shaft seal was partially out which apparently leaked all the oil out, starved the engine for oil and ruined the top end. 

 

 

On mine the rod was still ok (which shocked me), so I put a top end, new timing chain, and new seals in it.  Runs great now with a good carb on it (I put one on it off of another machine till my buddy could get a new one).

 

Now if you're in Central Arkansas, and don't want to learn how to do it yourself, @shadetree is in NLR and might be willing to do it for you.  Honda dealers won't touch anything older than 10 years old, and Shade does better work than the dealers around here anyway. 

 

I would try to do it yourself.  These machines aren't terrible to work on, and if you have questions or a problem, you can post up here and we'll walk you through it.  You might have to buy a tool or two, but nothing expensive.