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Discussion Starter #1 (Edited)
So the video is clear on the question but....

I have my wifes TW apart. The head and the cylinder are removed.

This is the question:

The piston slides back and forth on the piston side of the rod. Is that normal? All else seems perfectly tight but I don't know if I've seen a motor which allows the piston to slide back and forth. Obviously the cylinder would prevent that from happening but it is worth an ask.

See video below.

Thank you,
Rob
Kent, WA

https://www.youtube.com/watch?v=LLMXgrUVBwg&feature=youtu.be
 

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Like you said.. " With the cylinder on, It can't slide back and forth " !!

You need a new piston and rings. Your cylinder will need honed and / or bored also.

You will also need to find out what caused the damage.
 

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Discussion Starter #3
Whoa hey....you have me confused. Its normal so it's ok to slide back and forth.

Buuuut whoa....what damage do you see in the vid that is damaged and needs all that replaced??
 

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Yes that side to side is normal but all that scoring on your piston is not. Looks like either overheating of the engine or poor lubrication. I imagine your cylinder looks similar?
 

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Discussion Starter #5
Yeah wow. I'm here to tell you I can tend to suck at this stuff! That's why I'm in the position I am in. I will save the long story.

Short story is I tightened the chain adjuster way too much. Tore up the plastic.

Wife riding...loses power....smoking and dead on the side of the road. Plastic from the cam slides everywhere. Put a cam in b/c it was smoked.

Starts and runs but there was still a knock. Fair to say that knock was piston slap b/c of the damage to the skirt and the cylinder?

Guys ...I am just good enough to screw things up so be nice to me :) IMG_0339.jpg
 

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Normal side to side play of piston on the wrist pin/rod.

As for the piston skirt, I agree either overheating (I think most likely), lack of oil, or piston was fit to tight when installed.

As for the cylinder wall, I bet there is aluminum transferred from the piston to the wall making in look really ugly but I bet it cleans up with some acid, emery cloth and patience. Maybe even scrap it off with a single edged razor blade.

As long as you need a new piston anyway maybe consider a high compression (10.25:1) Wiseco piston. The piston comes with rings, wrist pin, and clips to hold the pin in place. Simply gap the rings and install.

Wiseco 4292M0670 for the stock size (67.0mm). Also made in 67.5mm and 68.0mm

Let us know how it all turns out.
 

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Discussion Starter #10
Normal side to side play of piston on the wrist pin/rod.

As for the piston skirt, I agree either overheating (I think most likely), lack of oil, or piston was fit to tight when installed.

As for the cylinder wall, I bet there is aluminum transferred from the piston to the wall making in look really ugly but I bet it cleans up with some acid, emery cloth and patience. Maybe even scrap it off with a single edged razor blade.

As long as you need a new piston anyway maybe consider a high compression (10.25:1) Wiseco piston. The piston comes with rings, wrist pin, and clips to hold the pin in place. Simply gap the rings and install.

Wiseco 4292M0670 for the stock size (67.0mm). Also made in 67.5mm and 68.0mm

Let us know how it all turns out.
How did anyone work on anything before the internet? Raa

Ok...I am ready to spend the $100 for the Wiseco set. I see them on ebay. Nothing else needs changed / modded for that swap?

Also, after the cam chain catastrophe we cleaned everything as well as humanly possible without cracking the case. How can I rule out oiling being the problem once the new kit is installed? Can we say 100% for sure the old piston was a victim of the cam chain guide f up and now thats its cleaned up it will be ok?
 

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Discussion Starter #12
Yes. I think lack of oil was not the problem. The plastic cam chain guides shredded into the motor. I think that shredded "crap" got in around the piston and cylinder walls causing the piston to overheat and/or run out of oil.

I then cleaned the shredded "crap" out and started it. There was a knock. That is where we are now.
 

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I don't see how over tightening the cam chain caused the piston to scuff on the cylinder walls. Low oil, yes. Over heating, yes. The piston may have been that way when you bought it.

Breaking the plastic causes a lot of slop in the cam chain throwing the timing off and making it run poorly or not at all. Enough play and the valves and piston meet resulting in bent valves. If someone can explain to me how this could cause the piston scuff I would appreciate it.

Edit: You posted before I did. I am not saying it can't happen the way you said, I just don't think it did.
 

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Discussion Starter #14
I don't see how over tightening the cam chain caused the piston to scuff on the cylinder walls. Low oil, yes. Over heating, yes. The piston may have been that way when you bought it.

Breaking the plastic causes a lot of slop in the cam chain throwing the timing off and making it run poorly or not at all. Enough play and the valves and piston meet resulting in bent valves. If someone can explain to me how this could cause the piston scuff I would appreciate it.

Edit: You posted before I did.
It shredded the plastic like a cheese grater. That cause overheating due to oil flow/melting plastic? The whole bike smelled like burning plastic when I went to pick her up.
 

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Discussion Starter #16
Oh yes. There was plastic sort of everywhere. After the cam chain disaster I replaced the cam (was obviously damaged from heat). The bike then started and ran with a knock. That is where we are now.
 

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Plastic pieces may have caused a blockage to prevent proper oil flow. Take your cylinder to shop to have it measured with a micrometer to check for wear and possible out-of-roundness before you spend money on a new piston and rings. If its still within tolerance you can then order the parts and have the cylinder honed. If not, you can order a first or second overbore piston and rings depending on the extent of wear as determined by the shop and then have the cylinder bored to match the new piston. You may want to consider having the cases split in order to make sure all the plastic has been removed.
 

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Discussion Starter #19
Plastic pieces may have caused a blockage to prevent proper oil flow. Take your cylinder to shop to have it measured with a micrometer to check for wear and possible out-of-roundness before you spend money on a new piston and rings. If its still within tolerance you can then order the parts and have the cylinder honed. If not, you can order a first or second overbore piston and rings depending on the extent of wear as determined by the shop and then have the cylinder bored to match the new piston. You may want to consider having the cases split in order to make sure all the plastic has been removed.
Yeah this is my concern. Is there a way to assemble and confirm oil flow to the top end? Then if oil flow is not is not present maybe have someone crack the case. I am just afraid to put more money into this bike than what its worth.
 

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