Forum

[Chris Tindal]

Not sure the floating bush in an achillies, my 'Bighead' engine when stripped had completely shot main bearings, worn driveside crankshaft and the oil pump worm had huge chunks out out of it. The bike had clearly had a tough life but the floating bush and alloy rod were sound.

[Bullet Whisperer]

I agree with Chris, we got four season's racing out of a [second hand] plain big end bush in our 350 Clipper racer. It was from a used Redditch crank bought from Hitchcocks and it was only meant to be in there short term, but it kept on going, until a failed oil pump drive saw it off at Cadwell. Nothing wrong with them, as long as they are getting a good supply of good, clean oil.

[Bomber]

In total agreement with last two posters my Bighead is used regular is on second oversize and replaced main bearings once (mostly worn cages) but still has factory fitted plain bush, certainly not the achilles heal!

[Norm]

Remember we are talking about Indian floating bushes here not the Redditch ones, good chance there is a quality problem with the Indian ones. Problem is not in the design but the quality of the bush and remember once the Indians started fitting the OPR valve the failure rate increased dramaticly, poor OPR seat or the slightest bit of something caught under the seat and it was all over in a flash, because the oil bypassed the bush, dumbest idea but what else would you expect from the Indians, do dumd things and blame it on the customer

[Bullet Whisperer]

The Redditch cranks have the OPR valve as well. I have rebuilt plenty of Indian Bullet engines, most of them tuned and many using the Indian bushes, depending on owner preference, some have had conrod, big end and mains upgrades, if asked for. One such machine [was my own a few years ago] can do 90 mph if you're cruel, lifts the front wheel in 1st and 2nd gears and has racked up many thousands of miles and even marshalled in local enduro events. While the top end has been off twice since it was built - once for a minor top end seiziure and once because a modified forged piston became holed after a partially blocked main jet weakened the mixture at over 80 mph uphill, the bottom end has remained rock solid. As I built this machine for myself, with no intention of selling it - I was pestered by a friend who gave me money and an AJS for it - I rebuilt the engine for my own use and fitted good but used Indian main bearings left over after someone else's engine received an upgrade. They are still in good shape, too, but the oil is changed every 1000 miles or so, along with the filter. The timing case is removed at the same time, to drain it and check on the oil pump drives and I fill the oil filter with good 20/50 oil while the timing cover is off and also prime the big end using an oil can pushed into the crank end feed hole. I also check / clean the crankcase scavenge and oil tank strainers every time.
The way I see it, you can have the best bearings you can buy dotted around the engine, but let the oil get dirty or the oil pump drive gears wear and any bearing will fail sooner or later.

[Bullet Whisperer]

Just to be clear, the machine I am referring to had the same Indian big end bush and crankpin put back in after I split the crank to lighten the flywheels in order to liven it up some more.

[Norm]

Hi Paul, as you would know the Indians introduced the OPR into the timing side shaft in around 2003/2004, nobody really knows when and this is when the floating bushes began failing in big numbers, particularly out here. Australia should never have had them because our temperatures never get low enough for cold oil to be a problem requiring the OPR to lift off the seat, but obviously many of them failed. I have only pulled down 3 motors that had not failed and rebuilt them because the owners were fearful of potential engine failures. The roller big end is a very forgiving big end