Project over my head is dead!! (edited) By Bashan (Read 4,779 times)

[monstergy6]

That is the way NCY bore their cases, we have sold hundreds of them, as well as all other NCY dealers throughout the USA. We have also built many many motors using the same cases, and we have never had an issue like this with any of the engines we have built.

[noday]

Hey GTi how about some more pics of the cylinder and engine case opening ?

can you get the piston out of the cylinder ?

how did the cylinder block fit into the case opening ?

sorry about the loss of your engine. I would be really bummed out too.

[justbuggin]

Aug 3, 2012 21:25:11 GMT -6 monstergy6 said:

That is the way NCY bore their cases, we have sold hundreds of them, as well as all other NCY dealers throughout the USA. We have also built many many motors using the same cases, and we have never had an issue like this with any of the engines we have built.

OK if this is the way all of ncy cases are bored can you post a pic of a new bored case for comparison

[Moat]

I hafta' agree with monsterGY6 - it's impossible to decipher from the provided pics so far, whether or not the case boring (doubtful) or cylinder mating surface (possible) had anything to do with the failure. We'd need more/better close-up pics - preferably with a back-lit straightedge across the surface - to be able to tell anything definitive from this distance.

And yes - that cylinder liner looks to be way, waay too thin to me - wouldn't doubt that as being the failure source.

Bob

[monstergy6]

Aug 5, 2012 8:29:39 GMT -6 Moat said:

I hafta' agree with monsterGY6 - it's impossible to decipher from the provided pics so far, whether or not the case boring (doubtful) or cylinder mating surface (possible) had anything to do with the failure. We'd need more/better close-up pics - preferably with a back-lit straightedge across the surface - to be able to tell anything definitive from this distance.

And yes - that cylinder liner looks to be way, waay too thin to me - wouldn't doubt that as being the failure source.

Bob

Thank you, Thank you, finally a voice of reason on this thread, not jumping to conclusions based on a photo.

[justbuggin]

if you have reason you will agree that that case was not bore correct and you will post pics of a new case that is bore so we can see the def.

[monstergy6]

Aug 5, 2012 18:41:56 GMT -6 justbuggin said:

if you have reason you will agree that that case was not bore correct and you will post pics of a new case that is bore so we can see the def.

I will post one as soon as I get them back in stock, NCY is currently out of stock

[justbuggin]

ok that will be nice do you have a clue how long that will take

[monstergy6]

I will check tomorrow, I will also check, I may have a bored out short case in stock

[justbuggin]

ok will be looking forward to see and thank you for the responce

two days and counting

[justbuggin]

ok i got in touch with the builder of this motor and ask for more pics of it so here they are tell me what you see please



























now i know from what i am seeing the two parts of this case was not bore as a unit

[Deleted]

i agree it seems like it was not bored together. the left side looks like it was not done perfect with a boring tool. Kinda looks like the case a friend of mine bored out with a hand grinder.

[Moat]

Aug 7, 2012 12:06:40 GMT -6 @scooterelements said:

i agree it seems like it was not bored together.

I agree too, but it really makes no difference. The case is bored to clear the cylinder liner - it's not machined to any kind of close tolerance fit, in order to support the portion of the liner that extends into the case bore. IOW - you could hack it out with a hacksaw, and it really wouldn't matter.

One proof of that being GY6 case halves are commonly available separately - as entirely separate parts, with no need of being machined as a "matched" set (unlike horizontally split motorcycle cases, where the bearing bores are close-tolerance machined in one pass, as a set). Such precision tolerances are impossible when manufactured like that (separately) - yet it's SOP for the GY6 makers.

www.partsforscooters.com/164-151_GY6_Right_crankcase?sc=2&category=124367

www.partsforscooters.com/164-150_GY6_Left_Crankcase?sc=2&category=124367

You guys are barking up the wrong tree, IMO.

I think a more realistic assumption would be that paper-thin cylinder liner was bumped during shipping/handling, and had a hairline crack that went unnoticed during assembly - letting go as soon as the OP ran it under load.

[Deleted]

Aug 7, 2012 14:23:59 GMT -6 Moat said:

Aug 7, 2012 12:06:40 GMT -6 @scooterelements said:

i agree it seems like it was not bored together.

I agree too, but it really makes no difference. The case is bored to clear the cylinder liner - it's not machined to any kind of close tolerance fit, in order to support the portion of the liner that extends into the case bore. IOW - you could hack it out with a hacksaw, and it really wouldn't matter.

One proof of that being GY6 case halves are commonly available separately - as entirely separate parts, with no need of being machined as a "matched" set (unlike horizontally split motorcycle cases, where the bearing bores are close-tolerance machined in one pass, as a set).

www.partsforscooters.com/164-151_GY6_Right_crankcase?sc=2&category=124367

www.partsforscooters.com/164-150_GY6_Left_Crankcase?sc=2&category=124367

You guys are barking up the wrong tree, IMO.

I think a more realistic assumption would be that paper-thin cylinder liner was bumped during shipping/handling, and had a hairline crack that went unnoticed during assembly - letting go as soon as the OP ran it under load.

I have to agree with that. We here inspect all of our cylinder kits for any defects and we do find some with a tiny crack in the cylinder wall or else ware. Given the fact that that cylinder kit the walls are soo thin it would have not taken much to break.

I once installed a 59mm Cylinder kit (Made in China) The second after we installed everything and started it. we heard a bad sound. Opened it up and it was the cylinder walls had cracked. without even riding it just turning it on and testing it. My current scooter that i have the bore was done using a hand tool grinder to open it up. and its been running strong for 3 years with a 60mm cylinder kit.

So yea Cylinder kit i think is to blame

[Moat]

Aug 7, 2012 14:33:36 GMT -6 @scooterelements said:

We here inspect all of our cylinder kits for any defects and we do find some with a tiny crack in the cylinder wall or else ware.

That's good info, scooterelements... and makes me wonder if it might be a good idea for folks to use a dye penetrant on their BBK liners, prior to installation -

www.zorotools.com/g/00035751/k-G1260612?utm_source=google_shopping&utm_medium=cpc&utm_campaign=Google_Shopping_Feed&kw={keyword}&gclid=COyNqZmx1rECFbEBQAodHHIAlA