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[binary]

5 psi was measured at the open breather hose end. We are not talking about much pressure here at all. The volume in the crankcase is very large in comparison to the air displaced by the 350 piston going up and down. There is nothing wrong with leaving the out side bearing seal in and if there was, mine would have "blown out?"long ago. This is a simple thing that is being complicated out of all proportions and confusing the issue.

[Tim NZ]

Chris.


The redditch 500 Bullets have a similar but different crankcase vent to the latter Indian engines; 2 x 1/4" holes on the Dside crank case that are the most part sealed by a pair of 'floating' steel disc, and are retained by a screwed-down cover plate. Your Indian motor has one nominal 9mm vent hole. (From the same location) Both have similar max total flow capability.


If your mtr is prone to leak or blow oil at higher rpm, first check that the return pump has a PERFECT seating for the pump disc. Not a single score or scratch, and that the plunger is a perfect fit into the disc; 0.0005" ~ 0.001" clearance, there should be no 'rocking'.


A Leak-down test with the piston positioned, and locked in place, @ 25-35deg ATDC on the Power stroke will soon revel if the Rings, Valves or Bore need attention...




Revband: It is possible for the RS seal to be blown-out of a Bearing, in situations where an engine 'breathes' through the free-space in between the rolling elements. Such as the like with post 1970 Trihard twins. It isnt going to happen on a Bullet, as the annular space outside the bearing is for all intents and purpose a sealed cavity.

[Bullet Whisperer]

As I have mentioned elsewhere, I machine away the annular lip outboard of the drive side main bearing cork 'seal' on the early type engines, to create a hole the same diameter right through. A steel backed Norton Roadholder fork seal will then be a good press in fit, but the mainshaft spacer inboard of the engine sprocket will need turning down by about 0.020", to ease its' fit a little in the seal. Out of several modified engines, I have done three 'in situ', without stripping any more than the primary drive, with a little device I put together to enable the job to be done without stripping a good running engine. Once done, there will be no more chance of the crankcase venting into the primary case. An often overlooked aspect of the crankcase being able to 'blow' into the primary case, is that it will also 'suck' when the piston is on the upstroke - air drawn in from outside will get blown out with considerable force and mixed up with oil, making a mess. If it can't suck air in to begin with, that's half the battle sorted. If anyone has ever put a finger over an open ended breather pipe on a healthy running engine, when your finger gets close to the pipe end, it will appear to be blowing rapidly in small pulses, but when you put your finger completely over the pipe end, it will stop and no pressure will be felt - this is because air is not getting in to get blown out again in the first place. Of course, if you have combustion gases passing the piston rings, these will need to get out via the breather, but you don't want anything going in. I use open ended breather pipes fitted with a proper one way valve, located close to the outlet from the crankcase, this set up works very well for me.

[Revband]

Hi Tim, Thanks for your explanation, I now understand why on these engines the seal cannot move.

Binary you are too sensitive?, but if you read bullet whisperers post you may understand that without specialist equipment it is impossible to get a true PSI reading on the crankcase, the pulse pressure will be far higher than you are reading with a pressure gauge on the breather, also the air space in the crankcase is far less than you seem to think it is in fact quite full of crankshaft/flywheels and con rod.

I have never said that this would not work merely advised that the spec of the bearing/seal should be verified prior to fitting to ensure it is suitable, I have spent more years than I care to remember tuning British singles for racing and know from this that you never stop learning.

[mustaphapint]

Many thanks for all the comments. I understand the difference between sealed and shielded bearings as per Tim's explanation. Many years ago I used to repair machinery and plant for a living. My intention is to use the sealed bearing rather than shielded but I take the point about whether the seal can withstand the temperature. My assumption is that it would be the same material as the common Gaco seals we see used in engines all the time but I will try check the spec with the manufacturers. I hadn't thought of the possibility of the crankcase pressure blowing out the seal but it would seem that probably isn't a problem. I remember you used to be able to buy sealed bearings with either 1 seal or 2. Now it seems you buy a 2 sealed bearing and remove one of the seals if you only want single sided. I have read of BW's method before on one of his posts and I thought my suggestion would be a good alternative to those of us without machining capabilities, especially when the engine is already stripped. I would be interested in knowing where I can buy the one way valve BW mentions. Currently I have an open pipe routed to the back of the mudguard as I got fed up with the standard breather lubricating the rear wheel and tyre.

[PO51UHD]

Hello All

I may be reading too much into this... but surely if a bearing is sealed on both sides, it must be lubricated for life so why would you need to pull the inner seal out?

Stephen

[Beezabryan]

I fail to see why all the fuss about shielded, sealed or plain ordinary common or garden bearings. Years ago as a precautionary measure prior to a a once in a lifetime ride I replaced the Indian bearings and seals with direct European equivalents. Only the wheel bearing were replaced with sealed items.
Mustafa, you say "Currently I have an open pipe routed to the back of the mudguard as I got fed up with the standard breather lubricating the rear wheel and tyre" I say you may have a problem that needs investigation

[mustaphapint]

PO51. A sealed for life bearing is filled with grease and is fine for low temperature or low revving applications. I wouldn't like to rely on the grease alone in a harsh environment such as an i/c engine.
Beeza. Using a single sided seal is to reinforce the antiquated felt seal and a known weak spot with a more modern solution. The oil on the back wheel of my other bike is not a serious problem. The oil consumption is not excessive but I wouldn't normally choose to use an oil can to lubricate the chain as it flings off very easily onto the back wheel and yes it stops the rim going rusty but looks a mess.

[Beezabryan]

Apologies Mustafa for my hard of reading that made me think we were discussing an indian rather than a redditch bullet