Who's the expert on pistons? Pistons with holes!

Yup. I have a hole in my piston! Well, it's not MY piston, but anyway...

Can I link to an existing thread on another forum? Let's see...

www.intruderalert.com/cafe/index.cfm?page=topic&topicID=144894

That's a thread I started at my normal home 'IntruderAlert.com' (a shameless plug) after my son-in-law's little KZ-550 had an 'issue' on a ride back from Nova Scotia. The pics are actually hosted at...

s179.photobucket.com/albums/w310/IA_Cuban/Technical/


Any relevant information would be greatly appreciated. I'll try my best to answer any questions. I do know my way around a toolbox...

Thanx!

Cheers!

With what you said over there, I'd have to say serious lean condition causing her to run very hot, melt the piston, and then detonate, blowing it up. A couple guys on intruder alert said coolant, thats obviously not it on an aircooled engine.

Since your valve looks ok, lean cond then detonation is the most likely culprit. Was the carb syncing connection left off on that cylinder? Main jet plugged?

Thanx Man! I'll certainly have a look at the carb synch assembly tonite. I wouldn't have thought of that right away. I'm gonna pull a main jet to have a look anyway, 'cause I believe he was probably running rich. He was using more fuel, about a dollar a tank, than my VS750. That's why this hole is confusing me. (burning me up?) :lol:

Cheers!

77_650B1 wrote:

With what you said over there, I'd have to say serious lean condition causing her to run very hot, melt the piston, and then detonate, blowing it up. A couple guys on intruder alert said coolant, thats obviously not it on an aircooled engine.

Since your valve looks ok, lean cond then detonation is the most likely culprit. Was the carb syncing connection left off on that cylinder? Main jet plugged?

droped a vavle?..



thats what happen to my 1000.


let me know if u guys need any 550 motor parts.. i got a whole motor that i would love to get out of my way(its already been taking apart)

Maybe his burning more gas is because that cylinder wasn't making any power, so he needed to crank her a bit more to get the revs. Something must have been going on to allow a bunch more air into the cylinder.

The most common reason that a piston is holed is that fresh air is being drawn in and focusing on the piston crown. This is normally because the carb holder seal is bad or the carb holder is cracked. You didn't mention if the bike has the stock air box or pod air filters but the plugs were pretty lean looking; especially 2 and 3. This may be due to jetting but more likely, a major air leak. Also make sure that any vacuum fittings are either capped or connected.

RollingStock wrote:

droped a vavle?..

thats what happen to my 1000.

let me know if u guys need any 550 motor parts.. i got a whole motor that i would love to get out of my way(its already been taking apart)

:ohmy:

What the hell am I looking at? Is that the top of a piston? Our valves are still in place. Thanx for the kind offer for the engine components. I'll keep it in mind!



77_650B1 wrote:

Maybe his burning more gas is because that cylinder wasn't making any power, so he needed to crank her a bit more to get the revs. Something must have been going on to allow a bunch more air into the cylinder.

Agreed!



wiredgeorge wrote:

The most common reason that a piston is holed is that fresh air is being drawn in and focusing on the piston crown. This is normally because the carb holder seal is bad or the carb holder is cracked. You didn't mention if the bike has the stock air box or pod air filters but the plugs were pretty lean looking; especially 2 and 3. This may be due to jetting but more likely, a major air leak. Also make sure that any vacuum fittings are either capped or connected.

Thanx. Yeah, the airbox was removed before we got the bike, there are 4 new cone shaped pod filters (not K&N's) that we got from eBay on there now. Honestly, the bike was running pretty damn good, until this. Oh, those spark plugs you see @ photobucket are from a Honda V45 Magna. I don't have a reading for the little Kawasaki. Wish I did. I'll double check the carb holders. I know the vacuum fittings are still capped, but I'll have a good look...


Cheers!

Here I go, disagreeing again

I don't believe that was caused by detonation, I believe that was caused by the cylinder overheating and the rings seizing to the cylinder walls, thus ripping the ring lands off the piston. Look at the sharp edges of that piston, that hole was made by fracture, not melting.

A lean mixture may very well be the ultimate cause of the overheating condition, but detonation didn't do that to the piston.

Holly Crap!

Ok, I've got to ask the stupid question here....

To accomplish the severity in those images (holes/melt down) to that level, am I wrong in thinking there would be some tell tale sign that things weren't right?

I mean hollyshit, extreme pinging, grinding noises, running like crap, smoke, loss of compression something.... :blink:

OMR

look for a very bad air leak or a completly plugged main jet. something was causing it to run insanely lean on that cylinder.

Old Man Rock wrote:

Holly Crap!

Ok, I've got to ask the stupid question here....

To accomplish the severity in those images (holes/melt down) to that level, am I wrong in thinking there would be some tell tale sign that things weren't right?

I mean hollyshit, extreme pinging, grinding noises, running like crap, smoke, loss of compression something.... :blink:

OMR

i was thinking the same thing....even at highway speeds with/without a brainbucket,something would have made enough of a racket to signal the riding party
that something was rotten in denmark....

What did I say? AIR LEAK... CARB HOLDER cracked or leaking air because of a bad seal. You WILL NOT have major noises or banging. The piston will hole without much fanfare and you will be riding on 3 cylinders and an inexperienced rider might not even know the difference.