Flushing the crankcase after a holed piston

[Scotchmist]

My beloved 650 has recently decided to blow a hole through one of it's pistons. I've removed the top end to expose the damage. It looks like the piston was holed by detonation (oddly it only seems to have taken place on one side???). My question is; the bottom end doesn't appear to have sustained any damage but obviously there must be plenty of swarf kicking around in the engine. How would people recommend I flush the cases of the debris?

 

[Tomterrific]

Use higher octane premium from now on. I don't care how many people say they use 87 octane swill. They don't know what detonation is! You can ride around for years and just as you hit teh freeway for a trip, you blow a hole through a piston 20 miles later. Spending 20 cents more at teh pump is the easiest way to protect your engine from detonation when it is going to hit.

Tom Graham

 

[angus67]

[/IMG]
this was in my engine when i got it.
i went thru 2 cases of brake cleaner, had to split the cases, take aprt the trans, rebiuld the top end with a 1.5 over kit.
runs well. but i will never buy a bike that dosnt run ever again. the seller told me it had a kiker problem, and wouldn turn over.

 

[DogBunny]

I don't know if this is a good or bad idea, but if you have an air compressor and a spray gun, spray the interior down from all of the various openings with kerosene while slowly turning the crank. Then squirt motor oil all over the interior.

I actually did this once to an XS650 bottom end that a bunch of dirt had gotten into. I'll admit that I haven't reassembled that engine yet, but I think it will be okay.

 

[irristeve]

split the case's, it's no biggie I would also look at carb on holed side good lck

 

[mick71b]

The same thing happened to an RD350 I owned. When we split the cases, all the caged bearings on the crank had "piston" in them. Make sure you fix the cause of the problem too, or you will hole another one.
Mick

 

[Scotchmist]

I'll have to get a photo of the damaged piston so people can offer their opinions of the cause. The other pistons seems to be fine. The hole on the damaged piston is around 20mm diameter and is in the very centre of the piston. It happened after around 20 minutes of sustained low throttle cruising. Obviously I really need to determine the cause so it doesn't happen again. I'm not sure my wallet can handle the strain.

 

[gggGary]

Is this is a points bike?
The advance arms wear and allow the ignition to over advance boom, holed piston.
Air leak on the intake on that side.
Best is full tear down. dip rinse all parts in paint thinner blow dry till chunks stop showing up in the bottom of the pan you are working in. Worst is do nothing but hope. Your course will likely be somewhere between those two. At a minumum pull flush both filters remove sump and tranny drain plug. spritz/spray paint thinner till it runs clean, dry, preoil, reassemble, hope.

 

[hotdog]

Get 2 big containers & 5 liters of solvent, pull the gearbox sump bung & the crank trapdoor & flush...it may be more reassuring to just split the bottom end - post some photos, there's plenty of people here who will help you through the process.
Good luck.