Seems cags are taking off in NSW with a few of the other elite racers getting them up and running so the class should be well under way soon. My cag has been going for a while and works well, but it still is running the stock one piece barrel with a woeful 8:1 compression and the timing is way off.
So to be competitive ill have to get a new motor going. about the only thing i have to do is make a new barrel / head combo as all the other parts from the old enging will swap straight over.
First i start with a much better barrel. I got a new one from Gray up in QLD. all the timings are actually pretty close to ideal and there isnt much to correct on it except the micro size exhaust port and the squish/compression area which isnt that great of a design.
to rectify the compression problem while keeping all the timings right the one piece design has to go. its going to be replaced with a seperate (much bigger) cylinder head and squish dome.
First job is to put the barrel in the jig which allows the barrel to be clamped in the lathe chuck. I only used the 3 jaw for now as there is nothing to indicate runoff from at this stage and accuracy isnt required for now.
Next the top of the barrel is hacksawed off. dawww look at the happy face.
From here its just a matter of progressively facing the barrel down until the brazed in compression area falls out. Took my time here because tenths of mm matter. Go too far and you can kiss this barrel goodbye.
All faced down to the correct height. My barrel is on the right. the one on the left is a premade chinese job. You can see that now i need to turn the top of the barrel down so the cylinder head can slip down over it as a press fit. The amount i need to turn down is 6.00mm in length and to a diameter of 24.88mm which is the size of the chinese cylinder head im using for now. Typical chinese tolerances :)
Now that the compression dome has been removed i have something concentric to measure from (the Cylinders bore) so i put the barrel and jig into the 4 jaw chuck which is much more accurate. You can see here that im using a dial gauge to read the "runout" (how many mm off center the bore is). I achieved 0.01mm of runout which is the limit of my gauge and pretty damn good for the kind of lathe i have. heres a video of it.
http://www.youtube.com/watch?v=Rd0RrZrS4Tg
With that centered the rest of the barrel was turned to size. I had to remove an extra set of fins on the barrel which i was hoping i wouldnt have to, but thats no big deal.
Done! and the cylinder head is a nice tight fit. When i get on to setting the squish and timing ill probably have to turn more off the cylinder height. so i left plenty of room to do that.
Heres the chinese cylinder on the left and mine on the right. couldnt ask for a better job then that :)
Next job will be to set all the timings, squish and compression level (i wont be posting those :P) and do any last machining before assembly.
There is going to be a flat top piston conversion in the works shortly so keep an eye out :)
Happy to convert one piece barrels to two pieces, drop me an email at Glen.M.R@gmail.com
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