edge of piston going well below exhaust port at BDC

[tonydevon]

so in theory this isnt good surely, theres a lip that gases will hit and swirl around

is it really bad though?

brand new Mugello kit, and at BDC the edge of the piston is about 1.8-2mm lower than the bottom of the exhaust port

if its bad enough that it shouldnt be used, then whats the steps to sort it?

[tarmac tickler]

and when piston is at top dead centre how far below the top of the barrel is it?

[tonydevon]

its below it, didnt measure exact amount, but squish appears to measure 1.3mm

time to go back through things I guess, cant beleive that the kits a wrongun, so I must have done something

Im using a base gasket but its a paper one, and beside if the squish is right then I dont want to be lowering the barrel anyway??

[tonydevon]

ok so panic over, just had a call from the shop that supplied it, apparantly they spoke with the supplier and Charlie someone?? they are aware of it but its not a problem

phew I can breathe.

MOD please feel free to delete thread if needed, save some space:)

[carlos fandango]

Like Eden asked, if its a 60mm crank ? The piston will/should be 1mm lower at BDC, if the barrel is ported for a 58mm crank.
However the port (and trans ports) SHOULD be level at BDC if the crank and kit are as intended.

they are aware of it but its not a problem

p

It will work fine , but it should be level, and if they are aware of it its a fault and should be rectified IMO.

Buying a kit off the shelf and a crank from some where else, with a case from one of three different countries , that all vary slightly, will always find discrepancies , but 1.8-2mm is quite a difference.

[tonydevon]

as far as Im aware its a 58mm crank, its just the MEC GP replacement one, top end kit and crank, along with bearings seals gaskets etc all came from same place.

I wouldnt do it, but what would the effect be of that port being cut out and lowered so that the bottom of the port was level with the edge of the piston?? I like to learn

[carlos fandango]

as far as Im aware its a 58mm crank, its just the MEC GP replacement one, top end kit and crank, along with bearings seals gaskets etc all came from same place.

I wouldnt do it, but what would the effect be of that port being cut out and lowered so that the bottom of the port was level with the edge of the piston?? I like to learn

It will/should run fine and you probably wouldnt notice and difference if it was level.
But thats not the point really , its not difficult to work out where the bottom of the port should be with the barrel in your hand, gasket face to bottom of port should be 58mm or as near as damn itfor a 58mm crank .
If its wrong it wrong and should be corrected, but thats up to you ?
I was more concerned about the dealers comments, if they are aware of it why are they selling them ? BTW i doubt that Charlie (Edmonds, Google him ) would settle for it in one of his engines !

[WINTERMODEL150]

Once the engines built make sure you pressure test it to make sure you don't have any air leaks,as this can be the route of most engine failures.

Dean

[tonydevon]

ok thanks all, will pull it apart tonight and check it all again, take some photos and measurements

I had planned to get it tuned at a later date anyway by someone that actually knows what they are doing.

going to measure the squish again and make sure that Im doing that right, then look at everything and decide what way to go forward

[tonydevon]

but is fixing it as simple as have the bottom of the port lowered?

from my basic understanding raising the top of the port affects the timing, but lowering the bottom of it should be ok??

its nikasil so I suppose that I have to factor in a replate once its altered.