what happened? no oil. engine rebuild?

[udell85]

i bought a 98 gs500e with 10,000 miles on it. i rode it for about a month and the on the freeway it loses power and starts making a strange noise. i pull off asap and kill the motor. i check the oil and there's hardly a 1/2 quart. i checked it the day i bought it and it was perfect. i'm assuming the dude that sold it to me knew something i didn't. i've pulled the motor and found that a piston is really lose. i haven't taken it apart yet other than the head off. the bike shows signs of being screwed with prior to my teardown (weird wire routing, missing screws, ect)

what i need to know is should i do a total rebuild, bottom end rebuild, try buying a used engine or what?

if i do a rebuild what parts will i need, other that a new piston and possibly crank and bearings. i'll post pics as i take it apart. thanks

[joshr08]

well its your money but if it was me i would rebuild and for only 1 good reason.  if you rebuild your motor you know what you have if you buy someones elses motor your buying someone elses problems.  I have never been a fan of have a motor that ran just needing a rebuild and buying an unknown motor with unknown problems and most of the time unknown mileage.  If you could find a newer super low mileage motor from a good scraper you could get a good deal, or you could just get a motor that youll end up rebuilding with the same problem you already have.

[O.C.D.]

Weird that this happened?!  Mine ate a quart in less than a month.  I will be watching what you do as I am curious what you will find.

[ineedanap]

If you ran low on oil long enough to trash a piston I would bet lots of money that you trashed at minimum the camshafts and the head.  The price to replace those alone is more than it would cost to swap out the engine.  That, and who knows how the crank, balance shaft bearings and everything in the trans looks.  

I'm with josh on swapping out on a low mileage motor with a history that can be documented.  

[udell85]

no, i thought the head and cams would be gone too but they're fine still. i ripped up one of the pistons. i haven't split the case yet because i'm having trouble finding the tools to get everything off prior to spliting it. the bottom of the piston is where the damage is. i'll keep working and be back with more info.

[The Buddha]

Yea throw away that motor and get a new one ... easy for me to say, motors have become very very very hard to find ...
Cool.
Buddha.

[bill14224]

I'm inclined to agree with Josh and Buddha.  When you rebuild you know you have a good-as-new engine.  Otherwise you're gambling.

From your description, I would guess the PO blew his engine, bought a used one off a high mileage bike that burns significant oil, put it in, maybe rode it a while longer, then sold it to you.

It's easy to put 1,000 miles or more on a bike in a month when it's nice outside.  It's common to burn a quart of oil in about 500 miles with an air-cooled engine with some wear on it.  At that rate, in a month you can be down to a quart of oil in the engine or less.  The engine only holds a shade over 3 quarts to begin with.

Especially with an engine that's new to you, you should have been watching the dipstick like a hawk until you figured out how much oil it's burning.  By doing so, you'd probably only be looking at replacing rings and seals, and perhaps a valve job, rather than a complete rebuild.

Not checking that dipstick every week is EXPENSIVE, isn't it?

[udell85]

You're absolutely right. I was an idoit for not checking. I have to admit this is my first bike and I've never owned anything aircooled before. So here's the question. Excluding the damage. What should be included in a fully rebuilt motor. I want to know it's gonna be good for as long as possible. I know what goes into a chevy 350 but I know a bike is different. I talked to the Suzuki dealership and he quoted me good senario as $1200 and bad as $1800. Would it be cheaper for them to do this considering hey have all the specialty tools or could I do it for way cheaper and hope I don't screw it up. I am a novice mechanic. I've never taken my vehicles into dealerships for work but then again I've never rebuilt a motor. I've got $1500 to spend so any advice would be appreciated. Thanks

[dgyver]

Most of the time, low oil damage is limited to the crank and rods. Rebuild it yourself. Not really any special tools required for basic dis-assembly and re-assembly. Torque wrench, caliper or micrometer are probably the only ones. Take any required maching to a shop, and that would be cylinder honing and any valve work. Bearing sizes required are stamped on the cases & crank. The service manuals have all the info required.

Expect $200-500 with new & used parts...
new bearings $50-100
new piston rings $50
used crankshaft (GS540 is the same) $50-150
used connecting rods (GS450 are the same) $20-50
Hone/deglaze the cylinder if still good, otherwise used replacements can be had $20-50

forgot gaskets...
Head gasket $25
Base gasket $10
you can get a whole kit for about $75