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Post by captaincaveman on Apr 15, 2012 21:45:54 GMT 1
Should i re use this?  This is my dilemma.. The bores and pistons seem ok small bit of wear but nothing really to worry about. So do i just get a set of new rings? Or should i get a new piston kits? If i get new piston gets i may as well get it re-bored but then that's a lot more than just a set of rings.  |
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Post by flames on Apr 15, 2012 21:49:21 GMT 1
dont re use it dude,theres bit broke on edge,the surrounding area will probably be brittle and break up and cause more damage.you need to know what caused it,but if the bore is ok,u may well get away with new piston and rings of same size.what is the head like?
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Post by loctite on Apr 15, 2012 21:54:09 GMT 1
hi mate that piston looks as though its at the last point before putting an hole in it,you can see its melted on top incorrect jetting to start with i think....
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Post by captaincaveman on Apr 15, 2012 22:03:26 GMT 1
I have no idea what caused it i'm thinking maybe it was running to lean?
The 150 would mean its 1.50? seen a few ring kits on ebay but there all point something.
I think the bit on the end your referring to that broken off is in fact a bit of molten metal probably from the center that's run down, But i will check it again.
What should i expect to pay for a top end rebuild?
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Post by marsbar350 on Apr 15, 2012 22:16:01 GMT 1
1.5mm over size
2 pistons and rings and gasket @£100 plus
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Post by flames on Apr 15, 2012 22:21:03 GMT 1
yes it means 1.50.re-bore and all the gubbins wont be cheap,but thats the nature of the beast im afraid.i dont think you have got many re bores left in her @ 1.5,cant remember off top of my head how far you can go.so if the bores are ok,i wouldnt bother personally.check the plugs,see what colour they are.i had a set of pistons go like that when mine was detonating due to lack of squish.one melted itself to the head.
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Post by arrow on Apr 15, 2012 22:29:36 GMT 1
Looking at that piston, I would also have a look at the ignition timing before I ran the engine again..
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Post by Tone on Apr 16, 2012 7:34:43 GMT 1
Other causes could be wrong plug grade, what plugs are you using? and a weak mixture.
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Post by Norbo on Apr 16, 2012 12:46:26 GMT 1
I would not use that pison id id look at your timing as well you may have ether a mixture problem or pri ignition
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Post by captaincaveman on Apr 16, 2012 19:25:42 GMT 1
I don't have a clue as to how the bike ran or anything like that.
I bought it as a none runner.
I have had it ruing since bur not for long because there was no water in it.
If i was to find and sort out the cause of the piston burning i would have thought it wouldn't get any worse?
or am i wrong?
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Post by flames on Apr 16, 2012 19:31:17 GMT 1
if you find and cure the problem,it shouldnt happen again,but that piston is beyond re use dude.it would be false economy because tho you may cure the problem,that piston is half wore up and will probably melt regardless.you will then deffo need a rebore,possibly a new head,and you wont be sure if it was because the piston was knackerd in the first place,or whether you never actually cured the original problem.
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Post by captaincaveman on Apr 16, 2012 19:38:55 GMT 1
Suppose your right enough. I,l have to find out how much bigger i can go with the barrels, Don't really want to take them out to the last bore if i can help it.
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Post by rdstars on Apr 16, 2012 20:28:45 GMT 1
What is the bore like, you maybe able to stick with the bore and just get some pistons at 1.50.
Piston sizes left are 1.75, 2.00 BUT at 2.00 the liner is starting to get a little thin. I have read some people have managed to get 2.25 over.
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Post by rdstars on Apr 16, 2012 20:34:18 GMT 1
I maybe a little wrong on my info, just realised you got an LC not a YPVS and I know nothing on the LC
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Post by flames on Apr 16, 2012 20:44:06 GMT 1
i agree,like i said earlia in the post,if the bores are ok,just go with the same sized pistons and rings,even go for a hone if you like.just because the top of the piston has had it,it doesnt mean you have to have a rebore.just that the top of the piston is thin,and will overheat/melt quickly.
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Post by stanlc7189 on Apr 16, 2012 22:45:53 GMT 1
I had a piston turn out exactly like yours, only worse - it scored the bore and was about to seize solid but the engine cut out when the spark plug got covered in molten alloy!
The cause - wrong grade of plugs! This caused pre-ignition as the plugs were too hot. I had fitted spannies, 2-stage reed valves and ported out the reed blocks, nothing more than that, but kept the standard B8ES plugs. BEWARE if the engine is even slightly tweeked. Play sfae and go for a cooler plug.
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