Author Topic: Need help---melted piston  (Read 3596 times)

KIAtech

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Need help---melted piston
« on: February 20, 2013, 03:45:28 PM »
Im new to the 2 strokes.  Im used to working on cars but trying to help out a friend of mine with his pilot.  He said he was riding it and it just cut off on him.  He brought it to me.  Had 0 compression.  So i pulled the jug off and removed the piston.  the side of the piston is melted and has a whole in it.  the jug looks pretty scared up as well.  What would cause this and what do I need to get it fixed and where to get parts etc.  And how do i find out what size piston/rings/jug etc. that i need.

Thanks in advanced.


LiveWire

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Re: Need help---melted piston
« Reply #1 on: February 20, 2013, 04:42:37 PM »
Measure the bottom of the piston from front to back to get the current size. Usually the next .5mm larger will clean up the bore. Standard is 80mm and they are available up to 82mm: http://www.aftershockmotorsports.com/Honda-FL400R-Pilot/Engine/Wiseco-Piston-Kit
http://www.aftershockmotorsports.com/Honda-FL400R-Pilot/Engine/FL400-Gasket-Kit

A 2 stroke cylinder should not be bored with a multi cutter boring bar because the interrupted cut at the ports causes a shadow on the opposite side. It cannot be honed with a spring loaded hone because it will snag the ports as well as make the bore out of round.

It was probably lean. What temperature is it where you are at? It would have been good to check for air leaks before pulling the jug.

KIAtech

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Re: Need help---melted piston
« Reply #2 on: February 20, 2013, 06:03:04 PM »
Thanks for the quick reply.  I will try to remember to bring my mic home from work tomorrow.  Also I believe this motor has already been bored.  If so can it be cleaned up and or bored again?  Where would I find a new jug if I end up needing one?  You asked how the climate was here.  Im in va.  When it failed it was in the fall.  70 - 80degrees.

LiveWire

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Re: Need help---melted piston
« Reply #3 on: February 21, 2013, 05:43:09 AM »
It can be bored 4 times over standard bore with Wiseco pistons. The jug is discontinued. It is is at 82mm now, then it can be Nicom Plated and a new 82mm piston put back in. It can then wear out 5 82mm pistons before being plated again.

KIAtech

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Re: Need help---melted piston
« Reply #4 on: February 21, 2013, 03:31:18 PM »
This is all great info.  Thanks again!  Where  would I get the jug Nicom plated if I need to go tht route?  Local machine shop?  How often do these things go through pistons?

LiveWire

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Re: Need help---melted piston
« Reply #5 on: February 21, 2013, 04:08:23 PM »
http://www.aftershockmotorsports.com/Service/NiCom-Plate-Cylinder

Depending on hours driven, each bore should last a few years.

KIAtech

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Re: Need help---melted piston
« Reply #6 on: February 21, 2013, 05:36:41 PM »
I take it if I sent it to Aftershock Motorsports they will be able to Nicom plate it and then send me whichever piston kit that will be needed after its plated?  I take it since you are recommending them to me that they are pretty good to deal with?

odypilots

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Re: Need help---melted piston
« Reply #7 on: February 22, 2013, 03:45:38 AM »
It should be mentioned that Livewire is Aftershock. Steve has helped me many times, and yes, he's good to deal with.
The usual 'my two cents' disclaimer applies. :)

KIAtech

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Re: Need help---melted piston
« Reply #8 on: February 22, 2013, 04:56:39 AM »
Good to know. Thanks!  I measures the piston.  It measures 80.2mm.  Hopefully it may be able to just be bored.  I will propably give Aftershock a call today and see how I need to proceed to get it done and get the other parts I will need.

LiveWire

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Re: Need help---melted piston
« Reply #9 on: February 22, 2013, 05:43:23 AM »
So if one were available, I would suggest an OEM 80.5mm, but I doubt you will find one. So a Wiseco 80.5mm

As odypilots said, if you send the cylinder to Aftershock, I'm the one who will be looking at it. I would have an 80.5 and an 81 on hand while boring. If it did not clean up at 80.5, then it would get bored to 81.

KIAtech

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Re: Need help---melted piston
« Reply #10 on: February 24, 2013, 09:46:38 AM »
I think thats what I will do.  I will send it to you one day this week.  Now do you recommend just trying to start by boring this one to clean it up and size a piston? or Nicon coat it and size up a piston? And should I just send the jug to you or?  How do you want to get started with getting this fixed?

LiveWire

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Re: Need help---melted piston
« Reply #11 on: February 24, 2013, 11:47:12 AM »
I would just bore it. If you can get an OEM piston, you could get it plated to that though. I have had people do that to be able to stay with Honda pistons.

KIAtech

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Re: Need help---melted piston
« Reply #12 on: February 24, 2013, 01:03:13 PM »
whats the pros and cons between Honda and Wiseco pistons?  Im not even sure what piston is/was in there.  Owner told me the previous owner had a lot of motor work done.  I did notice a lot of bolt ons.  Not sure about the internals though.

LiveWire

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Re: Need help---melted piston
« Reply #13 on: February 26, 2013, 05:27:31 AM »
OEM rings are thicker so will last longer. Wiseco is forged. Forged pistons are denser and expand to their full size sooner. This means you have to be more careful about warm up to not cold seize it. I ceramic coat the dome of the pistons I run though which slows warm up of the piston so it won't heat up faster than the cylinder.

KIAtech

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Re: Need help---melted piston
« Reply #14 on: February 26, 2013, 07:12:29 AM »
That makes a lot of sense now that you say that.  The guy he bought it from couldnt stress enough to him to let it warm up first BEFORE driving it hard.