Piston to valve and head clearance issue.

[cuong-nutz]

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

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:




stock 62mm 11.6 piston vs 64mm 12.5 piston

[alex.s]

[Motofool]

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

[mgentz]

I am running those pistons. No issues so far.

[cuong-nutz]

Originally Posted by mgentz

I am running those pistons. No issues so far.

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



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.

[accumack]

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?

[cuong-nutz]

Originally Posted by accumack

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.

[mgentz]

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?

[EMSRacer07]

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

[cuong-nutz]

Originally Posted by mgentz

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. So I pulled head off and I can visibly see the flattening/marring of the piston and combustion chamber inbetween the valve reliefs.

Originally Posted by EMSRacer07

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?

[mgentz]

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.

[cuong-nutz]

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

[EMSRacer07]

Originally Posted by cuong-nutz

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?

[cuong-nutz]

Originally Posted by EMSRacer07

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/showp...&postcount=146

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

[genosr1]

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

[genosr1]

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

[cuong-nutz]

Originally Posted by genosr1

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









Definite piston to head contact.

[tubarney]

Originally Posted by cuong-nutz

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

http://www.ninjette.org/forums/showp...&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.

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?

Let us know how things go.

[tubarney]

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

[cuong-nutz]

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.

[Motofool]

Originally Posted by cuong-nutz

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.

[mgentz]

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?

[cuong-nutz]

Originally Posted by Motofool

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.

Originally Posted by mgentz

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.

[cuong-nutz]

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.

[mgentz]

I was always instructed not to reuse rings. Sux.

[mgentz]

updates????

[cuong-nutz]

Originally Posted by mgentz

I was always instructed not to reuse rings. Sux.

Originally Posted by mgentz

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.

[cuong-nutz]

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

[mgentz]

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

[Racer x]

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.

[cuong-nutz]

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*.

[cuong-nutz]

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.

[EMSRacer07]

Originally Posted by cuong-nutz

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?

[cuong-nutz]

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!

[EMSRacer07]

Originally Posted by cuong-nutz

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.

[cuong-nutz]

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-...e94600&vxp=mtr

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

[EMSRacer07]

Originally Posted by cuong-nutz

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.

[mgentz]

Originally Posted by cuong-nutz

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-...e94600&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.

[cuong-nutz]

Here's the scratch:



crappy cell phone picture. :/

[EMSRacer07]

Originally Posted by cuong-nutz

Here's the scratch:



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?