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Base gasket?
http://www.pilotodyssey.com/PO/viewtopic.php?f=2&t=17751		 Page 1 of 3
Author:  Johnnyp23 [ Sun Nov 19, 2017 7:58 pm ]
Post subject:  Base gasket?
Do you guys know if this is the correct base gasket. Or is this one supposed to be metel. If so, where do i find it. Also is there anything suspect in the pictures. There is a burn mark in one of the rings? Thanks everyone.

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Author:  canadian oddy [ Sun Nov 19, 2017 8:55 pm ]
Post subject:  Re: Base gasket?
Oh my that looks like an original piston there. I bet it is a 78mm. I bet that thing has never been bored. WOW.
The piston looks good and so does that ring.
The base gasket is wrong. It needs to be metal.
Don't look like a basket case to me.

Edit: it has holes drilled in the piston for exhaust bridge but they are not parallel. That tells me it was probably bored once to 78.5 mm. That's probably why it has that fiber aftermarket base gasket.
I also see what appears to be a vent mod. Looks like the guy drilled and tapped the casing directly and added the hose barb.

Edit again: Based on the ring end gap there I don't think it hurt that ring. Its still good because the end gap is not closed up so it didn't get that hot. Still good -- use it.

Edit again: AVGAS
Author:  Johnnyp23 [ Sun Nov 19, 2017 9:25 pm ]
Post subject:  Re: Base gasket?
Im still lost as to why i only have 120 on my compression after i took it down to the thinest heas gasket. That seems low to me. The guy i bought it from said it was bored .20 over. Does that line up with the piston you see. A 25 in the center of the piston. Thanks CO
Author:  canadian oddy [ Sun Nov 19, 2017 9:32 pm ]
Post subject:  Re: Base gasket?
Johnnyp23 wrote:
Im still lost as to why i only have 120 on my compression after i took it down to the thinest heas gasket. That seems low to me. The guy i bought it from said it was bored .20 over. Does that line up with the piston you see. A 25 in the center of the piston. Thanks CO


Well it's possible that the ring end gaps are to large but there is no way for me to know that from way out here lol.
Sorry I did not answer that question you had on base gasket. Here is some reading: viewtopic.php?f=1&t=14418&hilit=metal+base+gasket
Some people here get the base from speedchaser: viewtopic.php?f=4&t=7565&start=0
I have actually made my own out of brass .010 shim stock and I now have home made ones made out of .010 copper shim stock that I bought. That stuff is expensive -- just to let you know.
Author:  canadian oddy [ Sun Nov 19, 2017 9:45 pm ]
Post subject:  Re: Base gasket?
That low compression could also be a result of a crappy tester. I know because I have two compression testers. One probably Chinese and the other American made. The Chinese one is out by over 10 psi. Did you try another tester before you ripped it apart ??
It could also be that the rings are worn or end gap to wide. I believe you need .012 end gap. You want .004 per inch of bore for your ring end gap but good luck getting that with a wiseco piston.
When you buy a wiseco piston I have never seen one show up that had that tight of a clearance. Every time the gap on a wiseco is around .020. Total crap and they don't care because they know that they are the only game in town for oddy pistons. They don't mill them anymore either to save money and even charge us more every year for their shyte product. Oooops I am ranting.
You can bring your compression up by running a single head gasket of .008 or .010 thickness and a .010 base gasket. Also have and Engine that is sealed tight -- no leaks.
Author:  canadian oddy [ Sun Nov 19, 2017 9:49 pm ]
Post subject:  Re: Base gasket?
Johnnyp23 wrote:
The guy i bought it from said it was bored .20 over. Does that line up with the piston you see. A 25 in the center of the piston. Thanks CO


Take a caliper and measure it :shock:
Author:  Johnnyp23 [ Sun Nov 19, 2017 9:57 pm ]
Post subject:  Re: Base gasket?
I dod try two different testers and they were both the exactsame. If it is worn rings how do i find the right ones for my Engine. Do i measure the piston or the cylinder. Can i buy bigger rings? I know im a greenhorn with wrenching lol
Author:  fully [ Sun Nov 19, 2017 10:13 pm ]
Post subject:  Re: Base gasket?
you don't want bigger rings, you just need replace the rings with the same size, might as well have the cylinder honed while you have it out. if that is a original art piston on the first over bore you need a set of 80.5mm rings. i highly doubt that's a 78.5mm piston but i could be, not sure what was all changed with the recall, would have to measure to make sure though. might be tough to find a set of rings for it, there are some hoarders on here that might have a set. 120 isnt that bad for compression, i believe 130-135 is what a stock unit is suppose to be. if you can't find a set of rings i would just put it back together and run it
Author:  canadian oddy [ Sun Nov 19, 2017 10:24 pm ]
Post subject:  Re: Base gasket?
I agree with fully on this.

If it is an art piston good luck finding rings. I sent an original art piston and rings to a member who is no longer here. They are rare as hen teeth.

You measure the piston.
Author:  Johnnyp23 [ Sun Nov 19, 2017 10:26 pm ]
Post subject:  Re: Base gasket?
Am i doing this right?

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Author:  canadian oddy [ Sun Nov 19, 2017 10:26 pm ]
Post subject:  Re: Base gasket?
Johnnyp23 wrote:
Am i doing this right?


Yes
Author:  canadian oddy [ Sun Nov 19, 2017 10:28 pm ]
Post subject:  Re: Base gasket?
That's what I thought. It's an original art piston. It's a 78mm based on what I see on that dial caliper.
No way that cylinder was ever bored.

Edit: You might have to hold that caliper directly over the top of the piston for a measurement because the jaws may not be reaching all the way over.
Author:  canadian oddy [ Sun Nov 19, 2017 10:30 pm ]
Post subject:  Re: Base gasket?
Please measure the cylinder for us
Author:  Johnnyp23 [ Sun Nov 19, 2017 10:43 pm ]
Post subject:  Re: Base gasket?
Pics

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Author:  canadian oddy [ Sun Nov 19, 2017 10:45 pm ]
Post subject:  Re: Base gasket?
Those are terrible pics. I can't see the numbers on the caliper and the numbers on the dial. I need to see both.
Author:  Johnnyp23 [ Sun Nov 19, 2017 10:52 pm ]
Post subject:  Re: Base gasket?
Lol sorry.

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Author:  Johnnyp23 [ Sun Nov 19, 2017 10:55 pm ]
Post subject:  Re: Base gasket?
It does say ART on it

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Author:  canadian oddy [ Sun Nov 19, 2017 10:59 pm ]
Post subject:  Re: Base gasket?
Ok 3.195 is 81 mm.
That cylinder is bored for a 81 mm piston.

So I think the caliper did not reach across the piston properly when you measured it.
Please measure the top to the piston again and hold the caliper directly over the top. Don't reach around the piston in the middle like the last time because it can't reach over far enough.
Author:  fully [ Sun Nov 19, 2017 11:00 pm ]
Post subject:  Re: Base gasket?
so you need to try and find a set of .20 over bore ring for art piston
Author:  canadian oddy [ Sun Nov 19, 2017 11:00 pm ]
Post subject:  Re: Base gasket?
OMG I see an ART stamp on that piston.
Author:  Johnnyp23 [ Sun Nov 19, 2017 11:08 pm ]
Post subject:  Re: Base gasket?
Is this better?

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Author:  canadian oddy [ Sun Nov 19, 2017 11:08 pm ]
Post subject:  Re: Base gasket?
canadian oddy wrote:
Ok 3.195 is 81 mm.
That cylinder is bored for a 81 mm piston.

So I think the caliper did not reach across the piston properly when you measured it.
Please measure the top to the piston again and hold the caliper directly over the top. Don't reach around the piston in the middle like the last time because it can't reach over far enough.


Sorry I think I just read that caliper wrong because it is upside down.
If it is a 3.095 then it is only 78 mm.
Your the one there looking at it. Which one is it ?? 3.195 or 3.095 ??
Author:  fully [ Sun Nov 19, 2017 11:11 pm ]
Post subject:  Re: Base gasket?
if its been bored once. then your need 78.5mm rings for an art piston.
Author:  canadian oddy [ Sun Nov 19, 2017 11:12 pm ]
Post subject:  Re: Base gasket?
I just had to photoshop this pics and flip them around for me.
You clearly have a 78.5 mm bore there.
And it is bored .005 over from what I read there on those calipers.

Edit: You will have trouble finding those rings but you can ask here on the for sale/wanted board.
Author:  Johnnyp23 [ Sun Nov 19, 2017 11:18 pm ]
Post subject:  Re: Base gasket?
Is that good or bad. Reading the caliper i think its a 3.095
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