Blew a Hole in Muh Piston!

[csmutty]

Last year I had been riding my 87 EX250 home from work and as I was approaching a stop sign going up hill I lost power, it wouldn't idle, and smoke started pouring out of my crankcase breather hose. I got it brought home in a coworkers truck and it got put away until today. Couldn't fit my uncles compression tested in without removing the motor from the frame. So starting at 1pm I tore the bike down and removed the motor in under 3 hours..not bad. Took off the valve cover and thought to look down the spark plug hole with a flashlight..only to see a hole in the center of the piston on the right side.

Just a little history of the bike. My friend got it last year on craigslist for $50 and somehow tracked down a previous reg and got it titled. He then semi-fightered it with a 5.5" delkevic headlight and blinkers. Removed the fairing and filled in the bolt holes in the gas tank and painted it. He then put on Koso gauges and replaced the chain and sprockets going up 1 or 2 teeth on the rear. K&N pod filters went on as well as dual Delkevic cans. We also drilled out the jets. I rode it around for half a year and wasn't very nice to it. The local speedway has 100ft drags and I decided it would be fun to bring a spork to a gunfight. Turns out I beat some 600's and made it to the 5th round of elims haha. It would hit the limiter right at the finish line in first gear. But anyways...

So I am planning on getting 2 new pistons to refresh this beast and was thinking about getting some flat slides. Anyone know of any flat slide carbs for the 87 that are for sale? I looked on ebay and several EX250 forums and found jack. Thanks guys! And uhh..I guess I'll post an intro post too.

[n4mwd]

Were you using champion spark plugs? I've read that blowing holes in pistons is pretty common with them.

I'm not sure I follow why you need a new carb.

[ai4px]

Originally Posted by n4mwd

Were you using champion spark plugs? I've read that blowing holes in pistons is pretty common with them.

I'm not sure I follow why you need a new carb.

I'm confused by this... a spark plug can have different temperatures per the length of the nose. If it were too long, it could contact the piston, but it would slam the tang into the electrode and then wouldn't spark any more - the engine wouldn't run. So that rules out physical contact with spark plug (I think ).

So how does a spark plug cause a hole in a piston?

Also, how many miles on this bike?

[n4mwd]

HERE is an explanation of sorts. Essentially, they run too hot. At high speed, things melt.

[csmutty]

Originally Posted by n4mwd

Were you using champion spark plugs? I've read that blowing holes in pistons is pretty common with them.

I'm not sure I follow why you need a new carb.

Nope I was using the stock NGK.

I think jetting was off. These carbs were pretty finicky and were never completely right, so I had thought of going to flat slides for more power.\

Also...I look on the parts fiche and can't find the 1987 listed on the fiche. Are the 88-07 the same as the 87? Or am I out of luck finding pistons?

[n4mwd]

I've also heard people say that bikes that run too lean will have problems like that. Don't ask, I don't know why, but I did hear them say that.

[csmutty]

Originally Posted by n4mwd

I've also heard people say that bikes that run too lean will have problems like that. Don't ask, I don't know why, but I did hear them say that.

Oh yeah. Lean was the problem for sure. I'm going to drill out the main jet on that side if I can't find flat slides.

[csmutty]

And just got it apart and turns out that the cylinder wall is scored as well. So need cylinder as well as pistons, gaskets, washers, etc.

[n4mwd]

Check to see if the jets are partially plugged. You can have the cylinders bored. Kawi makes oversized pistons I think. You probably can add new rings to the list too.
Posted via Mobile Device

[csmutty]

Originally Posted by n4mwd

Check to see if the jets are partially plugged. You can have the cylinders bored. Kawi makes oversized pistons I think. You probably can add new rings to the list too.
Posted via Mobile Device

Jets are not plugged. Carbs were just cleaned when bike was built like 2 months before this happened. And I was riding it daily. Cylinders cant be bored because oversized pistons are not made for the 86-87 anymore. It was a major PITA to find the factory parts online too. Only site I could find was www.cheapcycleparts.com, which I was referred to by someone on ninja250.org.

Here is my order that I just placed with them.

Quantity Your Price Total Price
Kawasaki - GASKET,CYLINDER BASE
11009-1572 Kawasakigasket,cylinder base
1 $18.59 $18.59
Kawasaki - RING-SNAP,PISTON PIN
92033-1161 Kawasakiring-snap,piston pin
4 $3.34 $13.36
Kawasaki - PISTON-ENGINE,STD
13001-1325 Kawasakipiston-engine,std
2 $34.86 $69.72
Kawasaki - PIN-PISTON
13002-1097 Kawasakipin-piston
2 $15.10 $30.20
Kawasaki - RING-SET-PISTON,STD
13008-0025 Kawasakiring-set-piston,std
2 $31.46 $62.92
Kawasaki - GASKET,CAMSHAFT BRACKET
11009-1573 Kawasakigasket,camshaft bracket
2 $4.82 $9.64
Kawasaki - WASHER-PLAIN
411AA0800 Kawasakiwasher-plain
7 $1.07 $7.49
Kawasaki - GASKET-HEAD
11004-1312 Kawasakigasket-head
1 $23.53 $23.53
Free Cheap Cycle Rag Your order qualifies for a
Free Cheap Cycle Rag! Free!
Subtotal $235.45

[n4mwd]

RonAyers.com is cheaper, but they usually nail you for $10 shipping. Most of the parts your ordered were about $1 cheaper at RonAyers.

The pistons you ordered show they fit other pregens and those pregens listed oversize pistons.

13025-1120 RING-SET-PISTON L,O/S 0.50 $30.54
13029-1201 PISTON-ENGINE L,O/S 0.50 $32.07
11007-1111 LINER-CYLINDER $76.46

If the pistons were OK, I'd say just get the liner, but since they are bad too, you can bore the old liner and save $76 X 2. I'd have to check the manual, but I think "0.50" means "+0.5 mm."

Its been 10 years since I had anything bored, but it was $10/hole back then. Maybe more now.
Or you can just buy a used cylinder for $65 on ebay.

You can check with @choneofakind about the carbs. He seems to know a lot about them. I think it might be possible to throw some washers under the needle to make it richer, but I'm not an expert at rejetting. Better ask him.

[alex.s]

how did the piston break? on the head? did you already take the engine apart? you probably want to check all the bearings...

[csmutty]

Originally Posted by n4mwd

RonAyers.com is cheaper, but they usually nail you for $10 shipping. Most of the parts your ordered were about $1 cheaper at RonAyers.

The pistons you ordered show they fit other pregens and those pregens listed oversize pistons.

13025-1120 RING-SET-PISTON L,O/S 0.50 $30.54
13029-1201 PISTON-ENGINE L,O/S 0.50 $32.07
11007-1111 LINER-CYLINDER $76.46

If the pistons were OK, I'd say just get the liner, but since they are bad too, you can bore the old liner and save $76 X 2. I'd have to check the manual, but I think "0.50" means "+0.5 mm."

Its been 10 years since I had anything bored, but it was $10/hole back then. Maybe more now.
Or you can just buy a used cylinder for $65 on ebay.

You can check with @choneofakind about the carbs. He seems to know a lot about them. I think it might be possible to throw some washers under the needle to make it richer, but I'm not an expert at rejetting. Better ask him.

Thanks man. I picked up a used cylinder on ebay for $9 shipped after I used my $18 of ebay bucks. And my cousin and I are planning on drilling out the jet with bits to make it a little richer. Should make it more happy with the new pistons. If I have any questions I will pm him for sure.

And wish I knew about Ron Ayers...

Originally Posted by alex.s

how did the piston break? on the head? did you already take the engine apart? you probably want to check all the bearings...

Piston broke because of excess heat caused by the main jet being too lean. The hole was right under the spark plug. I checked the crank bearings for play and they seemed fine.

[n4mwd]

Originally Posted by csmutty

Thanks man. I picked up a used cylinder on ebay for $9 shipped after I used my $18 of ebay bucks. And my cousin and I are planning on drilling out the jet with bits to make it a little richer. Should make it more happy with the new pistons. If I have any questions I will pm him for sure.

And wish I knew about Ron Ayers...

Where did you find one for $27. I couldn't find that listing.

[csmutty]

Originally Posted by n4mwd

Where did you find one for $27. I couldn't find that listing.

Maybe you couldn't find it because I had already bought it haha. And I am going to see about canceling my order with the other place and ordering it from Ron Ayers. Here is the link to the auction.

http://www.ebay.com/itm/260901829186...84.m1423.l2649

[alex.s]

instead of drilling the jets, jetsrus.com ... a couple bucks per jet

[choneofakind]

alex is right. Don't mess with drilling the jets. Just buy new ones that are a little larger. It will be a lot more exact, and if you go too big, you can just go down a size. Drilling jets is too old school for 2012.

[csmutty]

Originally Posted by choneofakind

alex is right. Don't mess with drilling the jets. Just buy new ones that are a little larger. It will be a lot more exact, and if you go too big, you can just go down a size. Drilling jets is too old school for 2012.

Jets were already drilled lol. They came out of one of my sets of EX500 carbs and then we drilled them from there. So I have no idea what size to get besides putting bits in the jets at the shop haha.

[n4mwd]

Originally Posted by csmutty

Maybe you couldn't find it because I had already bought it haha. And I am going to see about canceling my order with the other place and ordering it from Ron Ayers. Here is the link to the auction.

http://www.ebay.com/itm/260901829186...84.m1423.l2649

Wow, $12, that's awesome. Looks like you'll need to hone it, but I didn't see any scoring in the photos. While you're at it....

http://www.ebay.com/itm/1987-KAWASAK...96b4c3&vxp=mtr

Anyhow, being that its Sunday, you can probably cancel it if you get on top of it. Ron Ayers is cheaper, but if you plan to just order the same stuff, its probably not worth canceling and reordering.

[csmutty]

Originally Posted by n4mwd

Wow, $12, that's awesome. Looks like you'll need to hone it, but I didn't see any scoring in the photos. While you're at it....

http://www.ebay.com/itm/1987-KAWASAK...96b4c3&vxp=mtr

Anyhow, being that its Sunday, you can probably cancel it if you get on top of it. Ron Ayers is cheaper, but if you plan to just order the same stuff, its probably not worth canceling and reordering.

Yeah I was pretty stoked about the price on that haha.

And I'd rather just get new pistons. But thanks for the link! And yeah..it's not worth the trouble to save $5 lol.