Your stock bike went 49.8 mph? Since you used GPS I am not doubting that.
Please list all the mods. Gear ratios, engine, engine externals, etc. in bullet/outline. Thanks.
Hello Pablo, one thing I want to clear up first off is that the bike or engine is NOT stock as in Box Stock.
Ok, I'll try to be a thorough as I can here Pablo.
1. Bought a "Gen IV" lower from Thatsdax last year, I do NOT do any mods to lower, crank rotated very smoothly and there was no detectable wobble in counter weights so I decided to use this one of the three lowers I had bought from him for this project.
2. I ordered a jug from mainland China that showed to have larger than average ports, turned out to be a nice clean looking jug, but port size was average, so I used my Dremel and carbide bits to slightly widen and work out ports, enlarged transfer ports and cleaned them up as good as I could to help flow but did not raise or lower them, I did lower intake very slightly and raise exhaust very slightly, probably no more than 0.5mm, I lapped the jug deck just enough to make sure it was true, but didn't remove any material.
3. I used two base gaskets between jug and case that measure 0.030" I make these myself.
4. The serious work I did internally was to the piston itself, I drilled 12 holes in the piston skirt, each hole is approximately 6mm dia. each area that is drilled is a vertical line which is directly between exhaust and transfers and intake and transfers.
5. Ramps on piston are ground and tapered 0.065" down from top edge of piston and the ramped area ramps from edge of piston toward center of dome, from edge to where tapper stops it graduates in length from edge to nothing at a distance of about 0.300" and each ramped area is the width of the port it aligns with. also used high quality upper needle bearing from bearingsdirect.com
6. Manic Mechanic shorty billet intake
7. Dax "RT" Carb, Dellorto Clone with jet 70 that came in it, runs a tad rich until engine warms up and then gives a perfect plug chop when engine is warm and has been run at high rpm's
8. HD's Lightening CDI & Stock kit CDI produced exact top speed result when checked multiple times with GPS on same stretch of road which included some slightly up hill, flat ground and slight down hill, the slight down hill area is where max speed and rpm was reached and flat land speed was a 1- 1.5 MPH less in my test, my digital tach went out so I did not get any RPM readings but I had seen 9400 RPM's on it before this engine had 25 miles on it, so I honestly do not know what my rpm's were at the GPS'd speeds, but it was really screaming that is for sure.
9. the Exhaust I found to give me the highest top speed was a modified stock type pipe, this pipe came from BGF a couple years ago and never had the catalytic mess in it, it just had one of those ugly diverter pipes in it which I removed and then cut off the little 3/8" ID stinger pipe and drilled the hole out with a 17/32" bit and replaced cap, I also worked the flange out as much as I could to get it port match as good as possible to the cylinder exhaust port.
10. OK the bike, its an old 1963 Western Flyer Strat Liner frame, it is a 26" frame, I have 24" MTB forks on it with simple but functional V Brakes on the front, the wheels I purchased at my local bike shop, not high dollar wheels but they are Whell Master steel wheels with 12ga spokes they turn very true and the rear is a Shimano E-110 coaster brake hub'd, wheels greased with high quality grease and bearings adjusted properly.
11. Current tires on bike are Kenda Kiniption 24x2.35 and tubes are Kenda Thorn resistant HD Tubes.
12. Chain, KMC 415 rear sprocket is a 30T chromed steel sprocket I purchased from you Pablo, its one that is designed for use with your shift kits, I used an old kit sprocket as a template so that I could drill the correct holes for a rag joint set up, I have purchased a couple of your sprockets for making them up like this, they hold up really nice.
13. I run Opti2 at 100:1 in this bike from the first time it started up until now, that is all I run in all my bikes and all I plan to ever run since I get excellent durability from my engines with it.
Well, Pablo not much else I can think of to say about the bike or the engine accept it has just worked out nice for me, the piston ramping has no doubt hurt the low end torque of this engine some, but it has enhanced the ability for it to really wind up and scream, I have consider putting a stock unmodified piston in it other than a notched skirt and removing one of the base gaskets to limit rpm potential and increase low and mid power a little and this will like detune this engine enough to put me at a max speed in the low 40"s mph range and I may need to jet the carb down a bit if I do those things.
Well, this about covers it Pablo, hope this answers your questions good enough.
Pablo here is a video I made a while back that shows the piston I actually have in this engine that has been drilled and ramped on top, the video is long and was mainly done to show a weight comparison between parts, but you can see the work I did to the piston in this video.
http://youtu.be/ggfJVPQbzhI
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