moparcolt wrote:
Also I just found on ebay a brand new short block and a new cylinder, it is one of the old cylinders without the decompression slots. I am anxious to get these to give them a try. I am hoping the new cylinder will boost the compression even more and hopefully get some more RPM out of the 18x8 Xoar prop. I may even do a little grinding in the exhaust port to increase the exhaust timing.
where do you usually have to grind it out , on the top or bottom of the port?
I tried the decompression slotted cylinder and found a significant difference in compression and output power (see post #145 in this thread). You will probably see a vast improvement as well when you run the non slotted cylinder.
As for porting the exhaust of the single transfer port runner cylinder, by my experiments you probably won't see a difference in performance. If you do try and increase the port size you will want to increase the hight or width (or both) of the port but it will do no good at all to lower the port lip. At BDC, the lowest point of piston travel, the top of the piston defines the size of the exhaust port. If you haven't yet read Gordon Jennings book, or at least peruse the section devoted to porting, I recommend it.[link]http://edj.net/2stroke/jennings/[/link]
diceco