Flushing out the crankcase

Gmbond · Post by **Gmbond** » March 2nd, 2011, 7:34 am

Not a cr500 but figured this would be where to get the smartest answers.

Trying to put an 03 cr250 back together for a buddy. It was leaned out at WOT and a dime sized hole was put in the exhaust side of the piston. From what I can see, the majority of the piston went out the exhaust port and spray painted the inside of the headpipe.

The cylinder had some nikisil damage and is being replaced with a used one from eBay, and the piston is getting replaced with a namura kit.

So here's the question part

I've been flushing out the crank area and gotten some tiny silver flakes but no real material. If this was my personal race bike Id be splitting the cases but since this is on a pretty tight budget I'm trying not to open it up on him.

Any suggestions on how to flush better? I've just been using some premixed gas and spinning the crank then dumping it all upside down and repeat. The crank and rod seem to be smooth and moving freely,

Basically any good insight/input would be appreciated.
This was a very low hour motor prior to this damage, and afterwards it ha sat for at least a year with a bottle of ATF dumped into the crank area just to keep rust away.

Anyways, thanks !!

NightBiker07 · Post by **NightBiker07** » March 2nd, 2011, 9:05 am

it sounds like you are doing it right. just keep doing what you are doing, that is how I would flush it.

Maybe a can of brake cleaner?

Gmbond · Post by **Gmbond** » March 2nd, 2011, 9:18 am

Been messing with it since, I've now been using a compressed air powered vacuum brake bleeder with a piece of 3/16 brake line attached to suck out the bottom as the "flakes" settle while flushing.

The "flakes" look about like what you would see in metallic paint, very tiny and are getting less and less coming out,

I plan on keeping doing this until it's clean. I've been switching between the premixed gas and brake cleaner.

Kuma · Post by **Kuma** » March 2nd, 2011, 12:41 pm

I'd bite the bullet and tear it down, if those flakes made it into your bearing then I think you're going to have another rebuild in your future which may include a new crank.
just my

Tharrell · Post by **Tharrell** » March 2nd, 2011, 4:40 pm

You can flush one like that but, I wouldn't use fuel.
Matter of fact I did flush a CR250 '01 like that but put it in the parts washer to do it.
I didn't like it and wished I would have split the cases but it's still in one piece.
As you wash it, rotate the crank to make sure you don't have any pieces lodged in there.
The flakes, you're on your own with those.
I can see them getting in the bearing cages. Good luck.

2strokeforever · Post by **2strokeforever** » March 2nd, 2011, 4:50 pm

diesel might work good?

Gmbond · Post by **Gmbond** » March 2nd, 2011, 5:39 pm

Well I found a combination of penetrating oil and brake cleaner seemed to work the best. Lots of blasting it down the crank bearing lube holes while spinning it over then vacuum it out. And repeat and repeat and repeat...

See this is why I wanted people opinions on here. I searched on thumpertalk and some wingnut had told other people to pressure wash it out with water.

After lots of flushing and spinning and vacuuming i filled it up and spun the crank around and around and couldn't see any trace of any further debris.

The crank and rod bearings spin smooth and quietly. I'm just really hoping this can go together and not have to split it.

ridin4fun · Post by **ridin4fun** » March 2nd, 2011, 6:03 pm

I know that you are probably aware of the downsides of this, BUT.....you really need to make sure that your buddy knows that his bottom end is questionable if done this way. If this were a mini or even a 125, I would say never, ever go this route. A brand new top end, with like-new compression, will put extra stress on that used (and abused) crank. The same catastrophe that devoured the piston and cylinder also damaged the bottom end, though to a lesser extent. Two-stroke oils have a difficult time doing their job at melt-down temps, some more so than others. There is no doubt that your crank, crank bearings and seals suffered ill effects during the melt-down. You know more about the failure than we do, so you know just how bad it really was. The two vertical passages in the cases, one on each side of the crank, allow the oil-carrying fuel charge to wash through the crank bearings. In this case the metal flakes also washed through. You will never get all of the metal out without splitting the cases. That is, until you start that engine....then all of those pieces of debris will quickly be sucked through your new top end by a powerful 250cc air pump. I vote for splitting the cases and replacing the crank bearings and seals (and maybe crank). If not, then at least replace the scorched ignition-side crank seal and carefully blow out the previously mentioned passages which often fill up with debris during a melt-down. And, above all else, warn your buddy of the consequences and let HIM make an informed decision....it's one that he might have to live with. For what it's worth, all of this is simply one man's opinion. Good luck.

ridin4fun · Post by **ridin4fun** » March 2nd, 2011, 6:16 pm

Sorry, you posted your last reply while I was lazily (slowly!) typing my own reply. I see that you are aware of the debris which piles up in those passages. Replace that left crank seal. If it fails, it could fry that motor again. What was the original cause of the melt-down? Was it just a wide-open trip down the road, or maybe an air leak, or both?

2strokeforever · Post by **2strokeforever** » March 2nd, 2011, 6:31 pm

sounds like he learnt what happens when you run summer jetting in the winter

Gmbond · Post by **Gmbond** » March 2nd, 2011, 6:46 pm

Well number of factors caused the melt as I can see... Wide open down a road, cool weather and wrong jetting. And what I suspect may be a big thing was some massive chunks of crap in the float bowl which ive got a feeling were sucked up and blocked the main jet at WOT.

This bike has been apart for probably two years so I'm kinda speculating on the "true" story of it happening

Gmbond · Post by **Gmbond** » March 2nd, 2011, 7:00 pm

Carnage picture

You can see how the piston went outwards. I swear the exhaust pipe looked like it had silver spray paint all in the head pipe
Intake side

I'm pretty sure this is the original piston from this poor bike, the clutch basket looks like brand new not even the slightest notch. The magnesium/painted clutch cover has most of it's paint on still!! LOL

seanmx57 · Post by **seanmx57** » March 3rd, 2011, 6:04 am

I flush with diesel or keroseen. Only to clean things up after a rebuild. Then brake clean and compressed air. Are you filtering the liquid that comes out after a flush to check for particles?

hoofarted · Post by **hoofarted** » March 3rd, 2011, 7:47 am

I dunno - with all the effort you're putting into flushing this thing out and the uncertainty afterwards, you could of had it split and cleaned out proper, plus a few bucks for gaskets/seals.

Just my

oggo69 · Post by **oggo69** » March 3rd, 2011, 12:03 pm

a couple of gaskets , mains and seals wont be near any comparsion for a blown engine ... there is not much more time involved in going further than you have already for your buddy

dogger315 · Post by **dogger315** » March 11th, 2011, 1:35 pm

I'm siding with those that recommend a split and rebuild.
It's nearly impossible to get all the debris out of the crank
bearings by superficial flushing. What's more likely is you
are forcing the particles deeper into the bearings and seals.
Remember, the crank seal lips are full of grease - fly paper
for metal particles.

I know you are on a budget, but if the bottom end fails (better
than a 50% chance IMO), the repair cost will be much higher
than case gaskets and seals. Personally, I would not let a
friend loose on a bike repair I wasn't sure about.

Just another opinion.

dogger

http://www.youtube.com/user/500bigbore · Post by **Roostius_Maximus** » March 11th, 2011, 3:19 pm

I know if it were out of the chassis already i'd be apart in maybee 3 minutes, yank it, do it right or it'll bite you in the ass

rsss396 · Post by **rsss396** » March 11th, 2011, 5:28 pm

I have twice had to flush a motor out while away from home in order to run the rest of the weekend.

Both times I used a self-service car wash and flushed with lots of water.

Volumn is what will get the small particles out, then since I already have premixed alcohol in the trailer I finish flushing with a few gallons of alcohol premix to absorb any water .
Then straight oil on the bearings just like when I assemble it new.

But if the bike was home than it's worth disasembly but I still always use water to flush and clean parts. They just need immediate drying and lube.

bearorso · Post by **bearorso** » March 12th, 2011, 12:37 am

A mate of mine lunched a piston and barrel on his TM300 at the OZ 4day in Batemans bay a few years ago. 1st day. He was pretty shattered.

But, you could still continue on as a non finisher. So we snaffled a 250 top end from his TM team mates practice bike.

We then flushed the bottom end out, probably 25 times - the engine was in the bike still. He and I were in the team pits, turning the whole bike upside down, to empty the cases of crap, (and there was a lot of it), as the barrel was trashed. We had quite a crowd watching these antics.

It went the next 3 days, and another 2/3 months, before we replaced the big end and mains. There might have been something to the 'European Quality' claim to the engine (I'm sure my doofus mate stuffed up the piston replacement, resulting in the carnage).

Not that I'd recommend this tactic. But, it was amazing how the bike kept on going. The rod bearing and mains were jamming from the debris in the bottom end.

100hp honda · Post by **100hp honda** » March 12th, 2011, 9:36 am

i flushed this one out. crankshaft and everything else looked almost as bad as the cylinder. had alot of shit in the bottom end but everything spins freely now. its not the right way but i got the bike for free and im not going to put any money in it. with all the debris flushed out it should be just fine.

http://bannedcr500riders.com/board/view ... hp?t=10993

Post by **AlisoBob** » March 12th, 2011, 10:04 am

100hp honda wrote:i got the bike for free and I dont have any money to put in it.

Fixed

BannedCR500Riders.com

Flushing out the crankcase

Flushing out the crankcase