Cylinder lapping?

[teton]

I just went to the machine shop and after cleaning the cylinder there was some irregularities in the mating surface that would match up with the head....I will be using a stock head for now with a new gasket
my pistons are 82.5mm
what is the most l could lap off the stock cylinder and keep my compression below 180 so i can still run pump gas.

 

[Mouthfulloflake]

the proper term is "decking" the cylinder to make it flat.

I have no idea what the max is though, my guess is NOT Much.

 

[Big Kahuna]

just remove enough material to acheive a perfect flat surface, but if it has run fine with a stock head before, then the stock gasket would probable take care of it.

 

[teton]

make the above term decking
still learning

 

[Big Kahuna]

typically you do not deck a cylinder to achieve a certain Compression Ratio, you would deck the head to do this, but that can involve re-cutting the domes and squish........ Your best bet would be to deck the cylinder to make it smooth, then install the head and check compression, then have your head cut by Chuckie at Team Scream, or any other reputable builder (I noticed he has said to contact him on another thread) or get an ADA Head with either 35cc domes or 38cc domes.

 

[teton]

i realize its backwards, i just want to make sure i dont deck too much

 

[teton]

so does anybody know what the maximum i can deck from the cylinder and not increase the compression too much?

 

[freestylegeek]

You can play around on both surfaces for about 0.001"-0.002" A lapping table is the best way to achieve flatness without removing tons of material. I've lapped two different sets of warped cylinders and heads and the squish barely decreased buy 0.002" Just make sure you check squish when you're done. There are some aftermarket head gaskets that can gain you clearance if you take too much off, but it shouldn't be neccesary.

 

[Mark44]

I actually had to deck my cylinder to achieve proper squish with ada head.

I believe I had to machine .015 off.

Mark44

 

[Big Kahuna]

so does anybody know what the maximum i can deck from the cylinder and not increase the compression too much?

every cylinder is different, there is not a set number.

 

[Mark44]

every cylinder is different, there is not a set number.

True, you need to know your squish it was very odd I had to deck mine.

Mark44

 

[SUPERTUNE]

Try and keep from removing more than .007 in off top of a stock uncut cylinder block...that way when you do get an ADA head, the squish would be almost perfect for a high performance set-up.

 

[Proformance1]

True, there are some general rules of thumb for certain motors, but always check what you are doing. Measure squish, piston to deck, etc. If you don't know enough, send it out. It will be cheaper in the long run. Just make sure that you send it to someone who knows what they are doing. Usually if the cyl deck is warped it was probably over heated and the piston to wall may be off also. I see where you went to the machine shop, so they probably measured the top deck with a straight edge and feeler gauge, etc. Take the whole assy in and have it checked. The head may be warped also.

 

[teton]

yeah its more or less like corrosion on the aluminum that seals the head, the sleeves look pretty good, they are all surface irregularities (pits etc...) and im actually wondering if the head gasket would make up for it. the sleeves don't look too bad. i just want to do it right