byron wrote:no, the side casings are different externally as said and the exhaust studs on anything but series Is and early IIs are M8
I stand corrected, I thought Rosscla meant the larger semi circular raised section. BUT the Indian side casing on the engine I'm putting together at the moment is a mixture of the 2 i.e. it looks the same as the one pictured on the outside but does not have the recess for holding the piston on the inside. It was an unused item off ebay mind you and took quite a bit of hole fettling to get it to fit so probably not genuine SIL
Edit: Just looked in Sticky's Spanners Guide and it mentions this at the bottom of page 67.
Thanks for all the info, it is a series one crankcase, because of the over extended kick start bump stop, so i imagine its the other half to the 1958 series 1 block.
if i choose to use the series one block, i will place new long silent bushes in it and use a SIL mag housing to cater for GP crank bearing and purchase myself a GP crankcase cover so to use a GP clutch setup and use the GP gear box end plate.
Am i correct in saying if i plan to use GP clutch & if i purchase a hardened clutch spider you have to use roller bearings in it than use a bronze bush.
Or i could just use old series 1 case with series one block, change to SIL mag flange for bearing and use an after market clutch pressue plate like used in SX so no centralise pin and hardened clutch spider.
You can use hardened clutch spiders in with a bush, but I don't think you need to change that part unless the one you have is damaged, you just need the GP bell with the flat pressure pad rather than the raised nipple.
As I mentioned earlier, I wouldn't personaly use the S1 case. You are intending to use a 175 stage 4 top end so I personally would not use the S1 case. As mentioned earlier, the 2 studs that hold the exause 'swan neck' bracket in place are only 10mm. If you compare the area where the threads are on both cases you will notice that the Indian case bulges around these 2 studs to accomodate the 8mm (thanks Jarv) studs that were introduced on later models. There just isn't enough metal on the SI to allow drilling out and re-tapping to the bigger size. The side case for the GP and any exhaust you may use will have correspondingly larger holes to fit the larger studs....not good. Also, whilst comparing the cases, look at the area where the chankshaft protrudes on the drive side. You will see that the Indian case has an angled recess around the drive side bearing wheras the S1 is flat. This was done to accomodate a dished 'oil thrower' washer to improve lubrication of the bearing. You mentioned that you wish to fit a stage 4 175 top end which will put additional strain on a design that Innocente deemed necessary to upgrade just for 125 cc usage.
The Indian case is a MUCH better proposition and would provide a solid base for your upgraded engine imho. Use the Indian end plate either with the ramp still on or better still, cut it off and drill and tap the casing (very easy job) to take an Li type ramp.
I don't have any experieance of the Atomic clutches but ScootRs stuff is GENERALLY ok ish.
