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Discussion Starter · #1 ·
I was on the highway and had I car cut me off, so I slowed down and shifted into 5th. Once there was a open in traffic I toke off and forgot I was in 5th. (Yes I know im a dumbass) as I noticed I shifted into 6th but I lost all power and bike stalled. The 300 was starting and running but when you gave it power it sounded like a spoon in a garbage disposal. I drained the oil and found a lot of metal in my oil. Im trying to decide if its worth trying to fix or just by a crate engine. Any advice or opinions are welcome but I’m aware I messed up. Thanks in advance
 

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84' Goldwing Aspencade, 91' EX500, 98' Ninja 250 w/ 17' 300 engine, 07 EX500
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I vote replacement engine
 
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Are the pieces magnetic?

No matter really, as something let go in a big way.

You could start pulling it apart just to see what you find, but most of the time it's a much better idea to just find a used engine than it is to repair a damaged one.

The rod bearings on the crank will let go when they overheat, usually from a lack of oil. Pieces are mostly bronze colored from the heat. I don't think they would be magnetic.
 

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Discussion Starter · #4 ·
Are the pieces magnetic?

No matter really, as something let go in a big way.

You could start pulling it apart just to see what you find, but most of the time it's a much better idea to just find a used engine than it is to repair a damaged one.

The rod bearings on the crank will let go when they overheat, usually from a lack of oil. Pieces are mostly bronze colored from the heat. I don't think they would be magnetic.
Are the pieces magnetic?

No matter really, as something let go in a big way.

You could start pulling it apart just to see what you find, but most of the time it's a much better idea to just find a used engine than it is to repair a damaged one.

The rod bearings on the crank will let go when they overheat, usually from a lack of oil. Pieces are mostly bronze colored from the heat. I don't think they would be magnetic.
yes they are magnetic I’m thinking maybe a piston or a valve. I though it might have been the timing chain but I think it’s a deeper issue
 

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It seems to me the general consensus is a rebuild after catastrophic failures like this is way more expensive than a good replacement engine.
Plenty of these bikes get totaled by insurance companies because of cosmetic damage, so there seems to be a decent supply of used engines for cheap.
A motor swap is probably much less work than a rebuild, too.
 

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Something else was probably also going on (low oil?) as these things bounce off the rev limiter all the time at the track w/o issues

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That was my thought too, these engines can take quite a beating before giving up so there must have been some underlying issue that was the root cause.
 

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The death of most of these smaller engines is usually related to a small, but consistent, use of oil over time.

They are typically running higher RPMs, and lose a small amount of oil from the crankcase breather system. Over time, it adds up if not checked regularly.

Most can take constant abuse if the maintenance, oil quality, and oil level, is all good.
 

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84' Goldwing Aspencade, 91' EX500, 98' Ninja 250 w/ 17' 300 engine, 07 EX500
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The biggest killer of these small parallel twin engines is, lack of oil, lack of coolant and/or both.

Due to the engine does not require as much oil and/or antifreeze as the bigger bikes do.

On the 86 to 07 Ninja 250s only required 1.8 liters of oil. That is not a lot of oil and running low even half a quart you run the danger of killing the engine.

It's imperative that all owners of this 250/300 bikes check their oil every time before they take it out for a ride. It might seem overkill but it might save your engine.
 

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Second the oil stuff. Not that I have much experience with other bikes that much, but you should just check the oil level every time you start it up IMO. Small mistake that will one day cost you a motor like OP has.

Also seconding replacement motor.

As stated, these motors are plenty durable. Not quite enough power to destroy themselves, so long as the water and oil is flowing. If that were me, I'd pull the motor apart to learn a thing or two, but you could just dump it.

Im around 55,000 miles on my 300, and I put new piston rings at 40k. But while I was in there, checked how everything else was doing, and it's mighty impressive how tightly made this motor is. If you think about that, I calculated that my motor has spun around 400 million times. Not even joking. Lol. But yeah, top priorities on this bike was always to top off the oil and check the coolant res, do plenty of coolant flushes, and plenty of oil changes. And use a manual CCT, lol.

Good luck on hunting down a used motor!
-Mike
 
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