DragBikeMike
Serious Thumper
Offline
SuzukiSavage.com Rocks!
Posts: 4284
Honolulu
|
Removal and replacement of the cylinder head is straightforward. It’s like doing a cam swap (plus a few more steps). Part 5 of this series has good info on cam replacement. While the head is off, modify the ports as discussed in the links I provided. If you have an extra head, you can do the port work, then install it when convenient.
Set valve clearance to .005” and fill the crankcase with oil. I must confess that I switched oil. It was getting a bit too expensive. I’m into this thing every week or two and I usually don’t re-use oil. The Rotella T4 costs half of what Castrol V-Twin oil costs, and probably only one-fourth of what Mobile 1 V-Twin oil costs. The Rotella will do for now.
A quick compression test pumped 160 psi. No change. Makes sense. Same cam. Same 56cc combustion chamber. Same piston….. Didn’t really do anything that would affect the compression ratio. Ready for test.
How does it run? Just fine. Starts right up, idles smooth, revs quick. It will absolutely bury the 8K tach. No oil leaks. No unusual noise. The Cagiva valve adjusters survived a few laps around the block. It’s always encouraging when your trick parts don’t fail in the first five-minutes of operation.
It was time for WOT acceleration tests.
Let’s review the setup. Stage II ported head, DR 650 cam, 3” flywheel, stock piston, stock bore & stroke, stock compression ratio (8.5:1), modified airbox with K&N RD-0710 cylindrical filter element, PWK38 carb, stock exhaust header, LCGP high flow muffler. Except for the ported head, everything is the same as it was for the Part 6 flywheel test. I left the jetting as-is, a #35 pilot jet, #145 main jet, and the needle clip in the fourth groove (rich).
Second Gear 4K to 7K: 2.73 seconds 0.19 seconds faster than stock head
Third Gear 4K to 6.5K: 4.87 seconds 0.26 seconds faster than stock head
Third Gear 4K to 7K: 6.95 seconds 0.58 seconds faster than stock head
Fifth Gear 3.5K to 5K: 4.58 seconds 0.46 seconds faster than stock head
Fifth Gear 3.5K to 5.5K: 6.96 seconds 1.00 seconds faster than stock head
Wow! That’s one sweet modification. Nice fat improvements across the board. Fifth gear pull to 5500 rpm is killer. In addition, maximum rpm in third gear has increased by 100 (7550 vs 7450) and maximum rpm in fifth gear has increased by 400 (6450 vs 6050). The porting doesn’t hurt the low end at all, and it extends the top end a bunch.
What will happen when we throw on the Mac header?
|