ported head damage

[pacman696]

hi

i would like some information if poss ,first of all i have a 26cc cy engine which had been fitted with a 2mm stuffed crank and a 28.5cc head ,i was told this was done to make it a 30.5 cc ,but when i got the engine it was part of job lot, the head was cracked at the bolt hole ,so i thought i would strip it to see what had happened , i have just taken the head off and noticed that the gasket is a paper one ,i thought that it should have been copper and two of them to gain the 2mm back ,i am thinking this is why the head has cracked ??

what do you guys think................Phil

 

[MrFnisse]

Is there any damage on the piston ?

 

[pacman696]

Is there any damage on the piston ?

no none at all ,would it of hit the top do you think ? or could it have been the compression being too much? .....................Phil

 

[RFan]

Who did he head work? The head may have been machined in the dome area to compensate for the 2mm stroke. That would explain the standard gasket as opposed to stacked gaskets.

 

[whittron]

If the head wasnt machined for the 2mil stroker crank and the gaskets were not stacked that would defantley crack the head.

 

[pacman696]

If the head wasnt machined for the 2mil stroker crank and the gaskets were not stacked that would defantley crack the head.

i suppose if it wasnt machined out it would have made a mess of the piston ? so maybe it could of been just damaged or a faulty head.............phil

 

[Bigger the Better]

This is not uncommon. There are photos on here of that type of breakage issue with too much compression. If the head was not machined and one gasket with the 2mm crank would be too much for it and it would break. If it was machined then it could just be too much compression that broke it again.

 

[tongham runfold]

forgive my ignorance, but when fitting a 2mm stroker crank do you fit a 2mm copper gasket or a 1mm?
My understanding of a 2mm stroker is an extra 1mm up and 1mm down thus giving the 2mm total so would only need a 1mm gasket. 2mm up and 2mm down would give a 4mm stroke or am i barking up the wrong tree?