This is what happens when you decide to chance it and not clay the motor before assembling :eek:

Currently trying to figure out the issue. I don't know of anyone else running the 265cc 12.5:1 Wiseco Pistons. valve adjustments good, single base gasket and single head gasket were new. Head was not shaved nor was the the cylinder block. Wiseco hasn't been much of help so I'll try calling them again next week.

Here's where the piston is hitting the head along with the obvious exhaust valves:
http://i2.photobucket.com/albums/y5/cuongnutz/Ninja%20250/265cc%20build/piston.jpg

http://i2.photobucket.com/albums/y5/cuongnutz/Ninja%20250/265cc%20build/5FB021BA-3B87-4CD9-B9DF-082A05D13611-2258-00000284AC0366B9_zpse415dcfc.jpg

stock 62mm 11.6 piston vs 64mm 12.5 piston
http://i2.photobucket.com/albums/y5/cuongnutz/Ninja%20250/265cc%20build/pistoncomparison.jpg

http://i2.photobucket.com/albums/y5/cuongnutz/Ninja%20250/265cc%20build/5548032F-4684-4C73-930E-31FDB9374AA2-2258-000002D1186680E2_zpsd355cc8a.jpg

http://i.imgur.com/jWyKfY5.png

It seems that the piston has some tolerance's errors from machining.
Hopefully, the manufacturer will replace it for you.

I am running those pistons. No issues so far.

I am running those pistons. No issues so far.

Mike, by chance would you happen to have the build/run number of your pistons?

http://i2.photobucket.com/albums/y5/cuongnutz/Ninja%20250/B60B873E-EE6F-460B-8BE6-459AE116541B-39498-00002137624477AC.jpg

It's the last line of numbers and letters on the left box. The last part of the number should be 4 numbers and a letter which is the same as stamped on top of your piston. Mine is 6331K although the K is not printed on the label.

Dumb question. Are the pistons facing the correct direction? What direction is the arrow supposed to face engine front or back as the pistons don't look symmetrical?

Dumb question. Are the pistons facing the correct direction? What direction is the arrow supposed to face engine front or back as the pistons don't look symmetrical?

Yes, they are facing the correct direction: arrow towards exhaust.

6331K. Arrow toward exhaust.

I had a picture of my pistons to confirm....how can you tell its hitting without having done the clay method?

did you make sure timing was correct? Might be why yours are hitting and mgentz arent

6331K. Arrow toward exhaust.

I had a picture of my pistons to confirm....how can you tell its hitting without having done the clay method?

I ran the the motor and heard tapping. Definitely not the smartest thing to do ever. :banghead: So I pulled head off and I can visibly see the flattening/marring of the piston and combustion chamber inbetween the valve reliefs.

did you make sure timing was correct? Might be why yours are hitting and mgentz arent

I could possibly see how the exhaust valves could hit the piston if my timing was off but it still doesn't explain why the pistons still hits the head.

Is it possible to have stretched connecting rods or somehow damaged my connecting rod bearings?

http://i2.photobucket.com/albums/y5/cuongnutz/Ninja%20250/265cc%20build/8FA9A7B0-43A0-4184-B3A6-B84CBFD4D596-3058-00000336511882CB_zpsd134c3e8.jpg
http://i2.photobucket.com/albums/y5/cuongnutz/Ninja%20250/265cc%20build/89D59013-3340-4C39-AAA3-936DA31D2F4B-3058-000003363905693E_zpsedf79d7f.jpg
http://i2.photobucket.com/albums/y5/cuongnutz/Ninja%20250/265cc%20build/ACECCF73-9E54-4B8B-BE11-A5C9EC1C1CDC-3058-000003363ED5E777_zps4615cc9f.jpg

Did the motor spin freely by hand before you started it? I can see where it is hitting the head but the valves look ok in the pics.

I will be pulling my head soon and I will check for this issue as well.

The motor spun freely by hand and I couldn't feel anything binding or holding the piston up.

The motor spun freely by hand and I couldn't feel anything binding or holding the piston up.

best thing to do is make sure timing is correct and clay it. If you still see contact, what I have done in the past, take the pistons out and have a machine shop cut more into the piston for more clearance.

Also arent the piston numbers from yours and mgentz different?

best thing to do is make sure timing is correct and clay it. If you still see contact, what I have done in the past, take the pistons out and have a machine shop cut more into the piston for more clearance.

Also arent the piston numbers from yours and mgentz different?


Piston numbers match up. I verified it with the photos he took in his build thread.

http://www.ninjette.org/forums/showpost.php?p=663766&postcount=146

At first I thought Mgentz cleaned up the combustion chambers and deshrouded it but his combustion chamber is still stock in shape.

do any of you guys have the piston to valve clearance with the stock pistons, i'd like to know before i tear mine apart, thanks

also did you have either the head or cylinder decked, if so that might cause your clearance problem

also did you have either the head or cylinder decked, if so that might cause your clearance problem

head and cylinder did not need to be decked.

Clayed it and got some weird results so I'm going to try it again tomorrow. What kind of clearances should I be getting?

Piston #1
Exhaust 2.25mm/2.27mm
Intake 2.01mm/1.95mm

Piston #2
Exhaust 2.28mm/2.15mm
Intake 0.70mm/0.80mm

http://i2.photobucket.com/albums/y5/cuongnutz/Ninja%20250/265cc%20build/363F46BB-45B2-487E-8642-71A884068A8A-3467-000003BEB540E8EA_zps7b3d414e.jpg
http://i2.photobucket.com/albums/y5/cuongnutz/Ninja%20250/265cc%20build/5249F6FB-A390-4E90-8BA0-DF1E80DB2627-3467-000003BEAF793154_zpsafc63ad1.jpg


http://i2.photobucket.com/albums/y5/cuongnutz/Ninja%20250/265cc%20build/2799EBAC-6362-41BE-9342-34400C8FD256-3467-000003BED0C03CD9_zps73d7a8bf.jpg
http://i2.photobucket.com/albums/y5/cuongnutz/Ninja%20250/265cc%20build/D6EA8AD0-9E09-4B3B-BBD1-9A4396067C15-3467-000003BEC06F68EE_zps45b21a8a.jpg


Definite piston to head contact.
http://i2.photobucket.com/albums/y5/cuongnutz/Ninja%20250/265cc%20build/6A5DDBEE-23C3-422F-BF73-447B960CE538-3467-000003BEA9C7A8C5_zps6559397c.jpg

Piston numbers match up. I verified it with the photos he took in his build thread.

http://www.ninjette.org/forums/showpost.php?p=663766&postcount=146

At first I thought Mgentz cleaned up the combustion chambers and deshrouded it but his combustion chamber is still stock in shape.

Sorry to hear the bad news.

Can't understand how you didn't smash everything into a thousand pieces.:confused:

Conrod's have a bit of wobble, this is probably what saved you.

For some reason your valves are deeper than mine. You can see mine sit almost flush with combustion chamber. I had barely minimum clearances.

Leave your pistons alone and de-shroud that chamber. Might as well gain power than lose it right?:thumbup:

Let us know how things go.

1.6 mm - intake
2.0 mm - exhaust

These are minimum.

Piston 1 is good. Plenty of clearance on that baby.

I would double check piston 2. Then if need be, fly-cut that bitch

Definitely will have to cut back that area on the head. HOPING when I reclay #2 piston that the intake checks out. I'm still boggled as to why I'm getting that low of a clearance there.

I need to pick up some more dremel bits.

Piston #2
Exhaust 2.28mm/2.15mm
Intake 0.70mm/0.80mm
..........
Definite piston to head contact.
...........
Definitely will have to cut back that area on the head..........

Before doing that permanent modification, I would swap pistons and re-test.

The intake valves of cylinder #2 may be abnormally low, but the piston to head contact shouldn't have never happened, unless that piston is defective, as I presume.

The last thing you want is to end up with different compression ratios in both cylinders.

Any play in the bearings means higher readings of clearance, always.

I'm with them. Something odd going on with #2. However, both pistons are hitting right? If I have time this week I will pull mine apart to show. Could there be anything wrong with the cam?

Before doing that permanent modification, I would swap pistons and re-test.

The intake valves of cylinder #2 may be abnormally low, but the piston to head contact shouldn't have never happened, unless that piston is defective, as I presume.

The last thing you want is to end up with different compression ratios in both cylinders.

Any play in the bearings means higher readings of clearance, always.

I'll swap the pistons and remeasure. I really don't want to split the cases to replace bearings.

I'm with them. Something odd going on with #2. However, both pistons are hitting right? If I have time this week I will pull mine apart to show. Could there be anything wrong with the cam?

Yep, both pistons are hitting the head. I don't think anything is wrong with the cams either but I'll measure them and strip the heads again.

I pulled the pistons out earlier and found out that I had a bur on the edge of #2 skirt that left a good scratch on the cylinder wall. Hopefully the rings and wall are still salvageable. :banghead:

I was always instructed not to reuse rings. Sux.

updates????

I was always instructed not to reuse rings. Sux.
updates????

I brought my junk over to a bike builder/racer and it looks like one of my pistons was cut wrong. He showed me that the compression heights are different between the two pistons. I think he might have not have seated one piston all the way in the pin hole so I have to go home and verify them both with each other and with the stock ones. Method used: Attach the two pistons together sharing the piston pin and compare.

The guy also noted that it wasn't my skirt that caused the scrape but possibly a ring end or something got lodged inbetween the rings since the scrape goes all the way up where the rings sit.

This is definitely one biggest learning experience I have had with a motor build.

So, compression height is all the same between the both Wiseco and stock pistons. hmm.

http://i2.photobucket.com/albums/y5/cuongnutz/Ninja%20250/265cc%20build/BED515FA-32A1-4392-B394-099A21DFB742-9276-00000BB3F3257C30_zps9440d94f.jpg
http://i2.photobucket.com/albums/y5/cuongnutz/Ninja%20250/265cc%20build/534B025C-F3F3-4B44-BB21-67FE403900DF-9276-00000BB3EA53235A_zpsd53b4e40.jpg

I think its the way the done is cut. Look at the difference between your pistons and je domes.

This is a shot of the top of a std bore 13 to 1 piston. In the back ground is 13 to 1 and 12.5 to 1. Both seem to have the same room for valve clearance. The 13 to 1 pistons have a dig out in the center for the spark plug.

13.5 to1 only comes in 64 mom.

That's the only thing I can think of. The angled cut was probably started too soon for the squish band for the exhaust side.

I measured the squish angle for the head and pistons and Exhaust is about 19* and intake is 15*.

http://i2.photobucket.com/albums/y5/cuongnutz/Ninja%20250/265cc%20build/32D1AE61-7037-45E1-A8C4-007C68554A04-9276-00000BBB5FF4A87E_zpsfb37475f.jpg

I tried calling Wiseco again but powersports tech was already closed for the day so I left a message via Wiseco website putting as much information as possible. Bob Defranco(sp?), Wiseco street bike parts manager, called and left me a voice message stating that he wants to send me two new pistons. He saw the pictures I linked in the message and says that the pistons I have were from an early production run which they have made revisions to the design since then addressing the issue I'm having. Looks like somehow some from the early batch made made it out to the market. Lucky me :/ He asked that I call tomorrow and speak with the returns department so they can make good on the parts.

mgentz I know you have the same batch as I do but I'll give Bob a heads up about you having the same batch of pistons as me. I'll shoot you a PM with my cell phone in case you want to get in touch with me faster.

I tried calling Wiseco again but powersports tech was already closed for the day so I left a message via Wiseco website putting as much information as possible. Bob Defranco(sp?), Wiseco street bike parts manager, called and left me a voice message stating that he wants to send me two new pistons. He saw the pictures I linked in the message and says that the pistons I have were from an early production run which they have made revisions to the design since then addressing the issue I'm having. Looks like somehow some from the early batch made made it out to the market. Lucky me :/ He asked that I call tomorrow and speak with the returns department so they can make good on the parts.

mgentz I know you have the same batch as I do but I'll give Bob a heads up about you having the same batch of pistons as me. I'll shoot you a PM with my cell phone in case you want to get in touch with me faster.

Dang thats rotten luck. Well at least you know it wasnt the timing, valves, or cams. Did you tell him that the bur on one of the pistons messed up your cylinder?

I didn't mention it but I'll give him a call back tomorrow. My last resort was to tear the whole motor down again to reinspect all bearing clearances to rule out any error on my end. It's a good thing I didn't have to do it. That saved me some more time and money. Maybe they'll help me with a new headgasket and stuff.

Finally the build can progress again!

I didn't mention it but I'll give him a call back tomorrow. My last resort was to tear the whole motor down again to reinspect all bearing clearances to rule out any error on my end. It's a good thing I didn't have to do it. That saved me some more time and money. Maybe they'll help me with a new headgasket and stuff.

Finally the build can progress again!

Was the scratch on your cylinder wall something your finger nail could get stuck on? And yea mention that to him see what he can do. Or even with cost of supplies and materials.

The scratch could be caught with my fingernail.

Seems like there are other Wiseco pistons with the same issues:

http://www.ebay.com/itm/10-Kawasaki-Ninja-EX-250-Wiseco-Pistons-4mm-Over-w-Cylinder-EX250-104-/281218205184?pt=Motorcycles_Parts_Accessories&fits=Model%3ANinja&hash=item4179e94600&vxp=mtr

Take a look at the photo of the piston head. I am just in shock.

The scratch could be caught with my fingernail.

Seems like there are other Wiseco pistons with the same issues:

http://m.ebay.com/itm/281218205184

Take a look at the photo of the piston head. I am just in shock.

usually a scratch that can be caught by a fingernail cant be made smooth unless you bore. You might have to bore up a size to make sure your cylinder walls are sealed otherwise you will burn alot of oil.

The scratch could be caught with my fingernail.

Seems like there are other Wiseco pistons with the same issues:

http://www.ebay.com/itm/10-Kawasaki-Ninja-EX-250-Wiseco-Pistons-4mm-Over-w-Cylinder-EX250-104-/281218205184?pt=Motorcycles_Parts_Accessories&fits=Model%3ANinja&hash=item4179e94600&vxp=mtr

Take a look at the photo of the piston head. I am just in shock.

Holy s^&/! Glad I'm switching to JE.

Here's the scratch:

http://i2.photobucket.com/albums/y5/cuongnutz/Ninja%20250/265cc%20build/5107739B-707C-4154-9D0B-CC4EDF55A21A-10466-00000D37A10CDE39_zps7fc5b4be.jpg

crappy cell phone picture. :/

Here's the scratch:

http://i2.photobucket.com/albums/y5/cuongnutz/Ninja%20250/265cc%20build/5107739B-707C-4154-9D0B-CC4EDF55A21A-10466-00000D37A10CDE39_zps7fc5b4be.jpg

crappy cell phone picture. :/

doesnt look deep but if you can catch it with a finger nail might be bad.

Any update with the company and see if they can help?

Wiseco will be replacing the pistons with the updated ones along with any damaged parts caused by it. As for the cylinder scratch, I think I will have to take that out of my pocket. It's possible that the shop who did my bore/hone job might have left that mark during the process. Options for that right now is either to get a new cylinder and have it bored and honed or have the block sent it to get it fixed and plated.

Wiseco will be replacing the pistons with the updated ones along with any damaged parts caused by it. As for the cylinder scratch, I think I will have to take that out of my pocket. It's possible that the shop who did my bore/hone job might have left that mark during the process. Options for that right now is either to get a new cylinder and have it bored and honed or have the block sent it to get it fixed and plated.

My thoughts where that you had the wrong piston. Great that they're covering it for you. The scratch in the cylinder wall doesn't look that bad in the photo, would lightly honing the cylinder get rid of it ? You might want to send the new pistons and cylinder block to the machine shop and have the piston to wall clearance checked. In the event the clearance needs to be increased that may eliminate that scratch.

The picture I posted was after it was honed to see if it would clean it up.

.........Options for that right now is either to get a new cylinder and have it bored and honed or have the block sent it to get it fixed and plated.

I would leave it as is. :)

I would say that that scratch is insignificant for that engine and rpm's, and that you will not note any smoke or any lost performance.

Compared to the 125 cc trapped above the head of the piston, how much gas can escape through that little gap in 0.006 second, which is the time that each compression and work strokes take at 10K rpm?

............I have been wrong many times before, however. :angel:

I would leave it as is. :)

I would say that that scratch is insignificant for that engine and rpm's, and that you will not note any smoke or any lost performance.

Compared to the 125 cc trapped above the head of the piston, how much gas can escape through that little gap in 0.006 second, which is the time that each compression and work strokes take at 10K rpm?

............I have been wrong many times before, however. :angel:

I'm so tempted to test the it.:smile-beerglass: