090 clone porting and building.

[Maintenance Chief]

Anyone have tried and true formula for improving the 090 cylinder?

 

[redlinefever]

 

[smokey7]

Man that's a very odd shaped combustion chamber. Is that a kit cylinder or anyway or something

 

[Maintenance Chief]

Its a clone, but the oem has the exact same "D" shape.

 

[Maintenance Chief]

I saw a few issues why I was probably able to buy it so cheap
At least 1 out of 2 stacked correctly ain't bad?

 

[Maintenance Chief]

The cylinder was bolted down? With this gasket position.

 

[srcarr52]

 

[smokey7]

Both those gaskets look to have lines on them showing they were installed correctly at some point in their life.

 

[Nutball]

Put a Makita sticker on it.

 

[Maintenance Chief]

Both those gaskets look to have lines on them showing they were installed correctly at some point in their life.

That is true, but I received 2 broken rings 58mm with the saw ,and the intake side of the new piston had scuff marks on it ? Like someone was trying to run it without rings?

 

[Maintenance Chief]

Might have been a "key" part missing?

 

[Maintenance Chief]

I initially measured the squish to .065 and that seemed a little bit excessive for the possibility of a good build for pulling a long bar with Authority.
So I was pleasantly surprised to find a respected and generous porter with the tools and the skills to take .040 off the base and sleeve.

 

[Maintenance Chief]

After rereading the entire exhaust port thread this morning I started to ponder the shortcomings of the 090 exhaust.
I marked the piston skirt width, lots of room to grow. This is the port marked on the piston at TDC . I honestly don't have it carefully scribed out with an awl but with the kind of real estate I'm looking at I think ruffed in is ok.

 

[Maintenance Chief]

I choose to disable the air vane governor by cutting a slice from the top and folding it back, that way its still attached to the choke.

 

[Maintenance Chief]

So I originally thought about fingers going up towards the intake but I'm not sure what my capabilities are? I think it might be better for me to start by putting in a connector between the top/bottom. Also giving the bottom port some length and width.
The actual port casting on the outside of the cylinder doesn't allow for too much insanity but I'd definitely like to give the more volume.

 

[Maintenance Chief]

I'm not totally sure how long it'll take me to get a runner up and going but Ill try to shoot for before Christmas.

 

[Maintenance Chief]

I sketched out some ideas/guidelines for myself, basically a direction to go.

Little bites.

Mostly done except for clean up.

 

[Maintenance Chief]

I also thinned the back of the transfer divider.

 

[Maintenance Chief]

Basically left the uppers untouched because I wanted to increase the amount of volume that could be ingested into the ports but I'm not sure if I hogged out the uppers if that would make it lazy?

 

[Maintenance Chief]

Half the exhaust port
Then.
Minor amount of polishing