Hello Everyone,
I am trying to build a new 50 degree v-twin engine using as many custom Royal Enfield Parts as possible, but basing the design on the Series "A" Rapide (I am aware of the fact that the Seriies a was less than 50 degrees), to be honest the only reason is that I cannot hope to buy one, which means that I will get the following off the shelf of any Royal Enfield Dealre in India
- Cylinders
- Pistons
- Heads
- Carburators (Preferably will try to source a Kehin 28mm for wach cylinder)
- Hydraulic tappits
- etc....
The problem I am facing is with the timing chest .. I can re-design the entire engine case and will keep the oiling lines outside the casing on purpose to further the vintage look but have no idea on what the timing gear ratios are .. plus to add to that in a standard RE the pushrods are parallel to each other versus them being alligned in a "V" formation which actually increases the problem .. I will try to mill out the head and the bore to accomodate the "V" design .. to decrease friction and increase performance however still need help in term of the calculations for the gears for the timing chest .. can anyone help - (FYI .. the bore and stroke are the same for the RE and the Rapide)
Hello Mr Brahmi. Greetings to India.
The ratios for the timing chest on a 4 stroke engine are relatively simple.
The Cams (and ignition) have to travel at 1/2 crank speed.
whatever pinion (number of teeth) you use on your crank mainshaft, the cam pinions (and ignition)have to be twice the size to travel at half the speed. (try to use even numbers as this keeps things simple)
If you can drive cam and ignition off the mainshaft pinion, all well and good. If this doesn´t fit in with your design, then you will have to use a so called idler pinion. It does not matter what size this is as the ratio is calculated from drive to driven gear. Your single idler is in between so will not influence the ratio.
Hope this helps.