hole in piston

[Semi]

well i got my the head off my cbr today, and it dont look good at all. piston 3 has a hole through it, about 1-2 mm. valves and seats look ok, although im gonna have to check them. spark plug is uberfucked, looks totally melted. who knows where i can get some cheapish cbr pistons. Will i need new sleeves as well?

[TYSON]

Sounds like it leaned out, Was it detonating? Bores shouldnt need sleeves unless badly damaged. If all is well and bore wear is near minimal you could get away with pistons and rings and a good hone.

[Semi]

i didnt feel it detonating, but im guessing that it was running too lean, it looks melted rather than smashed. how much is a hone worth?

[duffman]

repco, auto one, coventry auto, veale etc should have them for about $20

check out the carbies before/ shortly after you get it all back together so you dont have to go through it all again

ps
picsorban

[Barfridge]

That's moderately terrible, but it could be worse.

Hope sorting it goes smoothly mate.

[shrike]

yup, that's about what I thought. Bit worse actually.

I was banking on a ring or a ring land...

[rgvlee]

Plug melted... hole in piston... sounds like it's got real hot in there

Post photos of destruction

Any idea what caused it? I agree with the leaning out theory, but any idea of cause... jetting... air filter... blocked carb etc etc

Cheers

L

[Rooster]

The offending Piston!

[lee]

eep

[sathid]

nasty.

[Semi]

wow, that photos pretty good for a phone pic
ill find the camera and take some now

[Semi]

piston


valves


kitty

[BigTim]

Bugger.
Oh well mate, at least you can pretty clearly see what your problem was. It would've been worse to pull it all apart, then not be able to find anything wrong. Good luck with the re-build.

p.s. Ur cat's ugly.

[Semi]

yeh i suppose so. anyone got an idea of how much a set of pistons is worth, and anywhere good to get aftermarket ones (if i can get them?)

[TYSON]

Google?

Could go supa cheap http://cgi.ebay.com.au/Y-M-D-HONDA-CBR-250...1QQcmdZViewItem

[Semi]

woo those ones even come with gudgen pins
id rather get a new set seeing as i have all the crap out, for piece of mind. would there be any point replacing the other 3 pistons with 2nd hand ones?

[Para045]

I would be inclined to get a genuine one unless you are going to change all of the pistons - more chance of getting one that is similar in weight and balance to the rest IMHO. It also depends if you need a rebore then you will need all new pistons, rings etc. Also make sure you stip it down good and clean all the metal out of your oil galleries etc

[sathid]

hrm...wonder if an rz350 engine would fit in a cbr250rr....

double the horsepower, less weight, and maybe cheaper?

[Semi]

hrm...wonder if an rz350 engine would fit in a cbr250rr....

double the horsepower, less weight, and maybe cheaper?[/b]

ooooh that would be farkin awesome!

I would be inclined to get a genuine one unless you are going to change all of the pistons - more chance of getting one that is similar in weight and balance to the rest IMHO. It also depends if you need a rebore then you will need all new pistons, rings etc. Also make sure you stip it down good and clean all the metal out of your oil galleries etc [/b]

the plan was to do the whole lot, but would it really be that much of a bad thing to just do the 1? Id probably just do the rings on the others if its not a bad thing to do

[lee]

step 1) import cbr400rr motor
step 2) shoehorn into cbr250rr frame
step 3) ???
step 4) profit