My bike got 52kph on the flat standard, after some basic tuning and drilling some holes in the exhaust. With the shift kit, I can get about 70kph max on the flat and about 80kph on a gradual downhill. I only weigh 50kg, though.
If you accurately calibrate your speedo by sitting on the bike and rolling forward one turn, then entering that value / pi as the diameter, you can calculate rpm from your speed using JPilots Gear Ratio Calculator.
The primary ratio is 20:82, (4.1:1) and the secondary ratio is 10:44, (4.4:1), for a 44 tooth rear sprocket. (Adjust to suit your rear sprocket.) Leave the third field at 1:1.
You'd find that any further refinements of the pipe would result in minimal gain. You'd get a much better improvement with some balancing and a high-compression head at this stage, along with a decent carby. Not CNS etc, but Mikuni or similar quality.
I have a Rock Solid Engines billet head, but at 16:1 CR compared to the stock 6:1 it makes the engine very hard to turn over.
yeah, i could be anywhere between 35 to 55 on the flat before i did any tweaking, but most of the time in the lower regions.... only another 16 kg here
temperemental? yes. right time of day when the humidity is just right, she would scream, then a few hours later? hmmph. the sort of times you wish you had spent some time setting up the derailleur properly... cant do much in granny gear.
interesting that with the now much leaner settings, its less grumpy, and in fact, sorta prefers the heat... i shall see as the days get longer i suppose, if it stays that way...
80 on a pushie.... nah, ill wait til i get my license back to do 80+ again
one last thing while i think of it.
indexing spark plugs. ideally, the open side of the gap should face the exhaust port. i have no idea why, but its one of those things that can make a marginal difference, and is far more noticeable as the cylinder size increases. i noticed my head was on 180 degrees out.
shame i always have to make three or four tweaks at a time so i can never really point at one thing alone.
Hi Steve, heres some info for anyone who ever wants to split the cases or replace the main or countershaft bearings. Case bolt torque setting 75inch/pound, crank end float 0.003" to 0.008". Recomended to change all the case fasteners for automotive grade or high tensile socket head. Cheers