port timming questions

[jay793]

I put these cylinders on and saw that there's around 1/16th of an inch of the piston dome sticking above the exhoust port, and from my experience this looks wrong. I dont know anything about port timming so I was hopeing someone could fill me in and tell me what to do with this.

[jbooker82]

That doesnt look right to be but I am not an expert.

 

Maybe you have a set of cylinders ported for a 4mill stroker crank. Builders start by lowering the ports about 2 mm because the piston falls down in the cylinder 2 mm farther.

[Coupelx]

agreed, it looks like it was ported for a 4mil.

[jay793]

if that is the case what do you think I could do, I measured the port and it looks like it is 3/16ths bigger than my stock ports

[blowit]

if that is the case what do you think I could do, I measured the port and it looks like it is 3/16ths bigger than my stock ports

 

 

If you want to measure the bottom and top of all ports relative to the deck, I can tell you if this is for a 4mil. You should be able to look down the barrel at BDC and see of the transfers align too.

 

 

Brandon

[jay793]

when looking down the barrel it seems the piston is above the ports a hair, as for as numbers, it looks like from the top of the jug i got 1'' 11/16 to 2'' 3/16 on the sides

[blowit]

when looking down the barrel it seems the piston is above the ports a hair, as for as numbers, it looks like from the top of the jug i got 1'' 11/16 to 2'' 3/16 on the sides

 

 

Which ports are we talking about? what is a hair? accuracy is key here. I recommend a digital caliper at the minimum. If using a ruler, you should measure to the nearest 64th.

 

 

Brandon

[Aussie Quad Racer]

when the piston is at bottom dead centre, the piston top should be level with the bottom of the exhuast port

[jay793]

from what everyone is saying, it looks like there ported for a 4 mil. So what should i do sell them and start over, get a 4 mil, or try to work with what i got? thanks for all your replys

[Bansh-eman]

rather then going off what everyone is saying, get a caliper and messure it to be 100% sure. would suck really bad to start buyig parts and end up not being what you thought it was. plus any mechanic needs a caliper

[jay793]

rather then going off what everyone is saying, get a caliper and messure it to be 100% sure. would suck really bad to start buyig parts and end up not being what you thought it was. plus any mechanic needs a caliper

 

where can i get one and how much do they run, is one better then the other?

[moneybags]

Most likely it was built like that by the builder. My pistions do the same thing on my 06. I have emailed a few builders about this. They have all given my veary detailed info about Y it's done like this. If I hadent trashed that PM I would have quoted it.

 

On a side note my 421 cub motor is dead evan at BDC.

[jay793]

Most likely it was built like that by the builder. My pistions do the same thing on my 06. I have emailed a few builders about this. They have all given my veary detailed info about Y it's done like this. If I hadent trashed that PM I would have quoted it.

 

On a side note my 421 cub motor is dead evan at BDC.

 

so with this being like that will it run like shit?

[moneybags]

so with this being like that will it run like shit?

 

My 06 hauls the mail. Would be alot faster if I had a better pipes. I am pritty sure the person who built MY motor set it up right. Did you put that motor together.

[flotek]

where did you get these cylinders from? this is why its a bad idea to buy ported jugs off ebay

its like a box of choclates yo u just never know what your going to get