86 Wr240 Piston Hitting Head Gasket After Rebuild

[maxbo]

Hi Guys, I am in the process of rebuilding my WR240 Have vintco rod, Gaskets from HVA, Wossner 71 mm piston. During assembly piston is protruding above cylinder by about 0.2 mm. HVA head gasket measures 69.8mm and fouls 71 mm piston at TDC What is the best way to rectify this.
I was thinking to cut another base gasket around 0.5 mm thick and add it to the one in the kit or I can machine a bit from the top of the piston around where it hits the gasket Dont know how all this will effect port timing/compression etc nor how much these gaskets will crush when torqued up. Any advice would be appreciated

 

[Crashaholic]

That sounds like a touchy area to venture into. I would think that if any of the new parts are not the same dimension as the OEM part you'll need to identify the specific part and address the problem from there. For instance, is the Vintco rod to long? Is the Wossner piston to tall? Are the HVA-Factory gaskets the wrong thickness?

I think your correct in that the gaskets will crush when the assembly is torqued down. So, for whatever its worth, attached is a service bulletin on the 81 430's that had an issue with the piston hitting the head from the factory, and how to test for the correct clearance, and how the factory suggested correcting it, in the case of the 81 430's.

 

[maxbo]

Hi Guys, I am in the process of rebuilding my WR240 Have vintco rod, Gaskets from HVA, Wossner 71 mm piston. During assembly piston is protruding above cylinder by about 0.2 mm. HVA head gasket measures 69.8mm and fouls 71 mm piston at TDC What is the best way to rectify this.
I was thinking to cut another base gasket around 0.5 mm thick and add it to the one in the kit or I can machine a bit from the top of the piston around where it hits the gasket Dont know how all this will effect port timing/compression etc nor how much these gaskets will crush when torqued up. Any advice would be appreciated

 

[maxbo]

The motor was apart When I got it. There are signs that the piston (Wiseco) that was in that engine had hit the head gasket as well. I am fitting a Wossner and the height from small end to top of piston is identical to wiseco. I think I will fit an extra 0.8mm base gasket in which will bring piston below top of barrel by about .2mm allowing for a bit of crush. Maybe someone has cleaned up the barrell surface at some stage although it looks original. Barrel is 117.80 mm tall if anyone has one laying around that they could measure. Thanx for the info

 

[2premo]

I would take the time to figure out what is wrong rather than raising the cylinder with gaskets
if the rod is wrong will throw off port timing as well, also would not make it so tight that worn parts will hit in the near future