A little bit of an update on the engine build (60mm crank 125*/-5*) in a stock 200 cylinder)...
I first mocked up the the top end up using a 1.5mm base gasket and a stock cylinder head. I did some measuring of the ports, and I came up with-
-1.5mm base gasket
-exhaust timing 170 degrees
-transfer timing 127 degrees
-exhaust port width 61% (41mm)
-squish (with USA head) 3.7mm
I ended up taking my engine over to my buddy's shop to get some insight on how far to go with the porting. He started to do some quick math in his head, then proceeded to tell me everything to do. I interrupted him after about a minute of him taking, and asked him to do the work for me. His time is money, so I figured I'd throw him some work.
I got the engine back two days later, and here are the results-
-1 mm base gasket
-180 exhaust timing
-126 transfer timing
-Exhaust port width 65% (43mm)
-squish (10.5:1 MMW head) 1.5mm
-blow down 27 degrees
-compression test showed a peak of 155 psi
My buddy wanted to do more porting to both the piston and cylinder, but he knew that I wanted something VERY conservative.
I also did some engine swapping around late last night. This stroked (208) engine is actually going to be going in my Allstate ( Project 61 Allstate 200 (now 208) with 2020 updates (Page 3)
). Reason being is that the current P200 engine that was in the Allstate was a non-oiler and I wanted to have an autolube engine. This 208 engine has autolube, so in it goes!
*NOTE that my compression in the picture shows around a 147ish psi. Both of my dogs were trying to attack the scooter while I was kicking it over today, so I was a bit distracted to REALLY put my foot into it. I pulled a few different readings of 155psi last night...which is higher than I feel comfortable with on a road going engine. I spoke to my machinist about how much more my compression might go up once the rings finally seat, and he thinks maybe only a couple more psi. I think all that compression will cause more heat than I want. Rather than installing a head gasket, I'm thinking about opening the cylinder head combustion bowl slightly to lower the compression...preferably down closer to maybe 145 psi?