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Post by Corrosion on Dec 15, 2015 16:00:18 GMT -5
old school rule of thumb is doesn't matter as much what it looks like. If you can catch a finger nail on it, it is a no go. If it glide over it like it is not there. OK.
How did it get that way in the first place? So as not to repeat the scenario.
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Post by spaz12 on Dec 15, 2015 16:19:31 GMT -5
I can feel them with my fingernail. I wouldn't say they ''catch'' my fingernail though?
I'd let a buddy barrow a scoot and he forgot that it was premix. He bought me a new cylinder, so it wasn't that big a deal.
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Post by Corrosion on Dec 15, 2015 19:01:22 GMT -5
If it is raised, it is bad. If is a groove it tends to fill in with carbon above the ring and below doesn't matter quite as much. lower, hope it doesn't abrade the piston. But both will shorten ring & piston life considerably.
Take a compression test as a base line for later.
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Post by frank50e on Dec 15, 2015 19:48:25 GMT -5
For what it's worth I concur on all counts.The coarser grit paper will give you a somewhat different perspective.
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Post by spaz12 on Dec 15, 2015 21:48:40 GMT -5
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Post by FrankenMech on Dec 16, 2015 2:57:45 GMT -5
I think the question would be: If someone gave you this some odd dollar cylinder would you buy a 75 dollar piston for it and run it?
That answer for me would be: -Nope.
There is way too much scoring there. The rule of thumb after an 'accident' of some kind and some honing leaving a single or maybe two scratches that can be felt by a fingernail is 'maybe' run it if you can't afford to get a re-bore or sleeve. That is not the case with 100's of scratches.
-sorry
My experience is with damage to only one cylinder out of six or eight. The situation with one cylinder out of one would be like all six or eight cylinders being damaged. Definitely making it re-bore or scrap the block time.
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Post by spaz12 on Dec 16, 2015 7:00:03 GMT -5
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Post by Lucass2T on Dec 16, 2015 9:38:59 GMT -5
Why not put a cheap (not chinese though!!) piston in it? 75 bucks is very expensive!
Airsal pistons are cheap, 20 euros or so? A s6 racing piston is about 50 euros.
Its 47.6mm right? Maybe put a slight overbore piston in?
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Post by moofus02 on Dec 16, 2015 10:20:03 GMT -5
What Lucas said. It wouldn't look nearly that ugly if you didn't look that close lol. My thoughts are lots of small scuffing but nothing through the plating and nothing that will snag a ring. If you can find a cheep piston to fit I would run it. Yes piston and ring life might be a little shorter the big issue would be ring seal so power might be down slightly. If that is an issue just richen the oil up and re jet the carb. Used to pre mix my race sleds at 18:1 ring seal was never a problem
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Post by Lucass2T on Dec 16, 2015 10:58:44 GMT -5
Yeh i would just put a cheap piston in, run it and check it now and then. Check every 500 miles or so?
It's scarred yes, but i've seen worse and im sure it will run pretty good!
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Post by ryan_ott on Dec 16, 2015 12:55:42 GMT -5
Looks good enough for government work...
Some of my stock motors when opened up looked worse then that and still ran well.
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Post by Corrosion on Dec 16, 2015 15:10:45 GMT -5
That cylinder is a candidate for a porting experiment. or you could have it re-plated and then it would warrant a decent piston. It is pretty much toast as is, IMO.
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Post by spaz12 on Dec 16, 2015 16:03:02 GMT -5
For now I'm going to buy the Malossi piston that Ryan has so that I can do a compression test on it. A 35 dollar experiment I'll call it, and then I'll post the results so that others in the future might benefit? Although I think I should change the name of the thread? Who knows  I appreciate all of your opinions guys. I really do. |
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Post by niz76 on Dec 16, 2015 17:11:38 GMT -5
I ran one worse (Airsal) and it actually ran pretty strong after cleanup. It literally had a chunk missing out of the nikasil but that was below the exhaust port (didn't affect compression). Im almost positive pics are in the eton beamer flip thread and I ended up running it in a Zuma ( also has a flip thread) but on my cell phone right now so I don't really know how to link to it... With a nice tight squish I bet you'd still have pretty good compression!
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Post by frank50e on Dec 16, 2015 20:02:13 GMT -5
www.nrhsperformance.com/tech_cylinders.shtml Interesting read on this subject.Showed this to my partner in the shop.His recommendation was spend your time and energy elsewhere.After reading this article I sadly believe that to be good advice.Potential for damage to a set of cases would scare me off I am afraid.
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