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[vince]

Hi, havent got round to that as yet, Depends what role I built it for. Did you have anything in mind? Vince

[Adrian]

Lighter flywheels for something sporty (well, by Bullet standards, anyway) or heavy ones for trials or a touring plodder. Not sure where our hosts' own super-dooper 500 crankshafts would be classified on those terms.

ISTRC something in the back of my mind about the 500's cases having better main bearing support compared to the 350, but as I often get tripped up by the subtle differences between Redditch and Indian Bullet engines, perhaps Bullet Whisperer or someone could confirm whether or not that is actually so. Don't think I'd want to trust a 612 kit to to a set of bored-out 350 cases.

A.

[John-M]

I ask re the flywheels as I don't think that the 350 flywheels would be balanced for a 500 piston and are quite a bit lighter, although I am willing to be corrected.
I think that Reditch 500 cranks are a little thin on the ground and Indian 500 cranks use metric bearings so won't fit.
I fear that there may be more to this conversion than first appears.
The difference between the 350 and 500 main bearings only relates to pre-1956 350 engines, i.e. engine numbers below G2/38101.
These early 350 engines don't have cooling fins on the oil tank, if yours is one of these then I suspect that the 500 conversion may be a non-starter.
I will watch this thread with interest.

[Wheaters]

Lighter flywheels for something sporty (well, by Bullet standards, anyway) or heavy ones for trials or a touring plodder. Not sure where our hosts' own super-dooper 500 crankshafts would be classified on those terms.

ISTRC something in the back of my mind about the 500's cases having better main bearing support compared to the 350, but as I often get tripped up by the subtle differences between Redditch and Indian Bullet engines, perhaps Bullet Whisperer or someone could confirm whether or not that is actually so. Don't think I'd want to trust a 612 kit to to a set of bored-out 350 cases. A.

The cases on my 2004, 350 Electra are stamped “C4 & 500”. I don’t know the significance of this but it might mean that later cases suit either capacity.

[stinkwheel]

ISTRC something in the back of my mind about the 500's cases having better main bearing support compared to the 350, but as I often get tripped up by the subtle differences between Redditch and Indian Bullet engines, perhaps Bullet Whisperer or someone could confirm whether or not that is actually so. Don't think I'd want to trust a 612 kit to to a set of bored-out 350 cases.

A.

I can confirm this is the case with Indian motors. The first donor engine I got for my 612 turned out to be an overbored 1991 350, not an 2003 500 as the logbook and registration would have had me believe.

I took it in past Hitchcocks in the back of my van and they confirmed it wasn't suitable for the 612 conversion. Apparently the later 500s have extra webs cast into the crankcases to support the mains.

[Adrian]

As far as I can tell with the later crankcases they had K/S castings which could be machined as 350 or 500, lean burn or classic, also E/S cases which could be offered for electric foot versions. From about 2001 some right-foot shift bikes already had the alloy cast in place in the oil tank for what would eventually become the tunnel for the gear change shaft on later left-foot shift 5 speed gearbox bikes.

Whether it's on a set of Redditch or Madras 350 cases, converting to 500 involves boring out the crankcase mouth, plugging the old main cylinder stud holes and re-drilling/taping to suit the wider spacing of the 500 cylinder studs, and on later Indian 350s, most likely machining the timing side to take the 30x20x7 oil seal behind the crankshaft timing pinion.

A.

[Chris Tindal]

Late Redditch 350 and 500 cases are identical apart from the machining for the barrels, it’s the same casting. I converted some 350 Clipper cases for my Bighead as the original has a cracked bearing housing. I just couldn’t find any original 500 ones at the time as they’re pretty thin on the ground. It works really well and they are just as good as genuine 500 ones. In fact maybe better because late Redditch 500 cases don’t have the little chamfer around the lip to ease getting the barrel in. Don’t forget to machine that on when you bore the cases out.

I put the original rebuilt 500 crank in with steel rod and roller conversion. One quirk of Redditch bikes is the timing side bearing runs directly on the shaft. If you want to avoid this our host provide a needle roller conversion that runs on a collar on the shaft and all fits in the bearing housing. It looks quite puny but seems to work well.

[Chris Tindal]

Just found some old pics.

[John-M]

I can't help thinking that it would be better to weld up the original stud holes, although your experience seems to prove me wrong.
I would be concerned that there is a potential for the cases to crack through the line of the old studs.

[Chris Tindal]

It’ an old school conversion that’s been done many times. It works well John and doesn’t crack, although I know what you mean about welding.

Apparently it’s more involved and means a large groove have to be cut where the stud was and the whole area built up with weld, then machined. Don’t know if anyone’s done Enfield cases this way but Lambretta ones are done with this method.