Super Jet Cutting cylinder?

[superjetchet21]

Just bought a 62t top end off here from a great guy it was re-sleeved with bb sleeves and was ported by x scream. It looks like a really nice job! The bore is at 85.00/771cc. And I noticed the bottom of the cylinder has been cut. I have seen talk about cutting cylinders down before. Im assuming itll just bring the piston hight up and raise compression/drop exhaust ports? Wont the pistons hit the head now? Im new to dealing with cut down cylinders so just curious as to whats safe and how I can tell if it was cut to much?!?!

 

[L.T.D]

You'll hafta assemble it and check your squish. You can achieve proper squish by machining the domes or different thickness base gaskets.

 

[restosud]

machine the domes for proper squish.usually done to lower port timing.rarely to raise compression as there are better ways to do that.

 

[TheBuzzard]

thicker base gasket raises port timing. kind of defeats the purpose of cutting the bottom off.

 

[JetManiac]

There should be matching domes for this cylinder. I assume you didnt buy them?

 

[Nuklear6]

^ x2

Def the domes for the cylinder should have stayed with it as they will likely be no good for anything else but that cylinder once the squish relief was cut to match.

Keep in mind a few things when going forward to match domes to that cylinder:

1. Measuring the overall height of the cylinder as compared to stock (off the top of my head 4.685" i think) will get you very close to how much the squish relief would need to be machined in a new dome. Even though your cylinder was likely cut on bottom and a little on top (to surface the deck with new sleeves installed). This doesn't matter as the depth of both of those cuts needs to be taken into consideration when machining the squish relief on the new domes.

2. Depending on how much was cut off the cylinders overall height you need to start with a larger cc dome to achieve your target compression. As you bring the piston pop up into the dome (even though your cutting material off to do this) you are making the actual bowl of the combustion chamber smaller. Im assuming your cylinder prob has somewhere around .060" cut off the bottom and only a few thou off the top. If this is the case you will want to start with about 2 cc larger dome then what your target compression would be at stock piston height (normally .030-.035" in the hole, now you are .025-.030" out of the hole). If there is more cut off the overall height then even larger domes will be needed to start with.


Hope this makes sense....