Question, Can you run the high compression head that they sell on various sites on a stock cylinder? I was thinking about bumping the compression with that and doing some mild port/clean-up with the stock cylinder and bore until I can get a professionally ported cylinder. I've got a pipe, cdi, 30mm carb and I'll rework the clutches. I just wasn't sure if that head would work with a stock cylinder and piston. Thanks for you help.

 

Sure it will.
Plenty of clearance when stock. [img]i/expressions/face-icon-small-smile.gif[/img]

 

Thanks Jack,

Good to hear from you again. What would the ideal squish be on that setup? I might be able to get a buddy to deck the stock cylinder for me before I put it back together.

Oh, while I'm picking your brain, I've got one more question. What is the advantage to a "full circle" crank that is the same stroke as the stocker?

 

Clearance will be difference depending on bore size and the stock stroke as a 45 mm crank will draw more air than a 42mm. A 47mm stroker crank will draw even more air bumping compression way too high with a 8-9cc head (like 280 psi). Your stock bore and stroke Dinli will work well with a 9cc head and about 22-27 thousandths squish clearance and compression will be where you want to be with premium pump gas and if you go racing you can run a 50/50 mix of race gas and 87 octane pump gas and it'll pull a little better. Compression will be somewhere in the 140-160 range depending on cond of rings/piston etc. You will end up somewhere about 70 thousandths before milling. I mill the cyl not the head and stock port timing is way off on stock cyls I usually change it quite dramatically depending upon the type of racing. We do 300' sand drags and dune riding. Since you'r in Mo I can help if needed and we race in Grain Valley or Lil Sahara when open.

 

Bill, I would not deck the cylinder over .030 with stock porting.This will raise the compression.You should run 93 octane then.
Over .030 may compromise your future motor work. Better safe than sorry. [img]i/expressions/face-icon-small-smile.gif[/img]
I care not to say on squish clearance as this may differ from one head to another (brand). I think you'll be fine as I suggested.

I will presume that the crank mentioned is a brand name. I also presume that it may be a stuffed crank. If so the purpose is more mass resulting in less crankcase volume. Stuffing has been around for years and a good idea when needed.