Forum

[Chris Tindal]

I will soon be starting a rebuild of an old late 50's bullet 500 engine, it has been stood many many years. Three things are going around my head. Do I 1) fit a steel conrod?, 2) Fit a roller bearing instead of the floating bush?, 3) Replace the original split skirt piston?. The bore is still on 84 mm and seems in good nick but the rings are well and truly gummed up. I would like to keep the original piston but I'm open to suggestions. Is the floating bush/alloy conrod really as fragile as is made out? I have had a rod snap in the past so I'm a bit paranoid, but not convinced the design is that bad. There is no up and down play on the conrod so do I need to re build the crank at all? I didn't get its original 'bighead' so will be using a standard non tuned 'small' head instead. So while the engine's in bits whats the best course of action? Once its done I don't want to strip it again. Any suggestions and opinions wellcome.

[Bullet Whisperer]

Hi Chris, I have a 1955 500 which I rebuilt totally to green lane spec a few years ago. In a full engine strip I decided to keep the original type crank / conrod setup, although the big end in the original crank had play, I had another crank assembly that was ok so that went in. The Hepolite split skirt piston went back in with new rings fitted. I think the most expensive bit was getting the tired magneto sorted. Redditch alloy conrods can break, usually at around 6,000 rpm in a 500 [seen it happen], if you have any doubts try the Hitchcocks alloy conrod, it takes plain or roller big ends. I have fitted a few of these to some of the engines I have tuned and rebuilt and used the plain big end to date. Hope this is of some use to you. Paul.

[Mark M]

Chris, the Redditch rods are much stronger than Indian ones and are only really fragile under serious abuse or compared to steel. The floating bush is very robust too but it must have clean oil and not be slogged like a long stroke side valve, remember these motors are near square bore/stroke and prefer to be used at reasonable revs. The split skirt piston is probably the weakest part, it's not very strong and can give up if used hard. The split is for mechanical quietness only so fit a better modern one if you feel the need! While it's apart change all the bearings, they're cheap enough and check the fit of the crank in the timing side case. If there is no bronze bush in there (and there probably won't be with such a late motor,) consider getting one from the earlier models and fitting it: it will help avoid wet sumping. This is a proper engineering job as it must be line bored. Also consider fitting Mr H's adjustable timing pinion, this will give you tuning options later. You could also fit another breather on the oil tank filler neck while it's apart, if tuned you'll need it!
REgards, Mark

[Norm]

Chris, to help with the wet sumping, while the cases are apart it might pay to get the timing side machined to take an oil seal and we have now adopted to fit the steel rod and roller, fit and forget, bit expensive but peace of mind, because we keep busting things out here

[Chris Tindal]

BW, Mark and Norm, perfect, just the info I need. I'll report back when its all done, thanks for your info and advice.

[Mark M]

Chris, Norm is right about the oil seal mod but I couldn't do it on mine (which is very near yours in numbers,) because there just isn't enough metal in the crankcase in this area due to cutaway to clear cams. You might be lucky but I don't think so!
REgards, Mark

[Norm]

Mark,
You might be able to machine it on the inside and fit it in behind the bearing but that means you have to fit the seal and then heat the cases to fit the bearing. Maybe not such a good idea, not sure

[Chris Tindal]

Something I'll look at once the cases are apart, its still got the pinion on the crank at the moment. I thought Redditch ones had the bronze bush but early Indian ones didn't?

[Mark M]

Very late 350 and 500 Bullets (59 onwards? Not clear) had the bush omitted. Instead there was some rudimentary scrolling on the inner alloy face of the crankcase in this location,presumably to return oil to the timing cover. I doubt you'll get a seal inside, when you see how deep the cutaway for the higher lift cams is, you'll see why.
REgards, Mark

[grunda 12]

chris cut out the middleman throw the old lump away i can point you in the direction of a proper motor !!!only joking chris !!!