Oil leaking from.......?

[Mick D]

Hi

Worth having a look at the oil pump cover plates and lower rocker feed pipe union to the front plate too.

I'd be tempted to put it on the centre stand, pop it in gear and sit and watch, (strap the front down), - a torch and mirror will show what's happening around the back of the chain case.

Regards Mick

[Expat]

Hello Mick,

Yeah, had thought to sit and watch while she's running and as you suggest, slipping her in gear also will get everything splashing that oil around. Just need to knock up summat to tie her down, don't want all that power unleashed on me .

Will do at the weekend.

Cheers

[Expat]

Decided to fit the 'stay up' carb float and needle as it was in the kit and though didn't suspect any issues with the old ones' they were the only parts not yet replaced on the carb.

As Mick D suggested, got her running in second gear, front wheel anchored down (don't ask), and looked hard with mirror and torch everywhere I could. Only leakage was tiny at the crankcase joint underneath, but no signs from rocker box, pushrod seals, chaincase or anywhere Great!

A better test yesterday when riding to work and there were quite a few drips underneath when I took a close look lunchtime, also took several pics of the underside. Convinced now all gaskets and seals are doing their job, so very pleased with the results of the work done. Now sure the clean oil is coming from the mainshaft exit behind the clutch as the level has dropped in the chaincase and not in the gearbox. Alternator wire hole is dry, also breather hole.

The biggest revelation to me now is how much 'crisper' throttle response is now, with a noticeable improvement in performance compared to before, when frankly I was a little disappointed with it. She really barks and surges forward when given a handful at around 40mph in top.

Really pleased with the new lease of life, as aside from setting up ignition timing by measuring off the top of the piston, to 7/16" BTC and decoking without removing valves, the only other work done was rebuilding the carb and fitting a smaller main jet as there is an air filter fitted.

So just need to monitor oil loss and level in the chaincase, taking on board the many comments re as 'little as possible', 'only just touching the lower edge of the chain' etc etc.

Very happy bunny at the moment.

Steve

[Expat]

Going round in circles thinking about this so thought it was time to ask the collective for general opinions and advice.

Oil level in chain case. Admittedly I overfilled it after the recent strip down, as the level as viewed through the inspection cap was above the lower edge of the chain but since then, while riding only around 80 miles, oil has been constantly emptying out from behind the clutch, stopping only when the bike stops, when the oil flung out leaves a pool on the ground.

So now the oil level is way below the lower edge of the chain and while it's possible there is still some in there and in the area of the clutch, as the chain is lower at that point, it does bother me that there's possibly not enough to keep the clutch rollers and chain lubed up.

Or am I fussing over nothing? Less than a hundred miles doesn't seem a lot and it doesn't appear that others mention this happening to their steeds' much, if at all.

Oil is not leaking from the gearbox or exiting the engine breather to any great degree.

So, is the opinion that whatever oil is left in there will be enough to do the job, as there seems no way to see how much is there?

Thanks

Steve

[1608]

I would suggest there is more than enough oil in there to keep things lubricated. The chain and rollers don't need to be swimming in oil. When the bike is tilted over and generally jolted around there will be sufficient oil and mist to do the job. Also, when the engine is under load the lower half of the chain will sag even lower and still get oiled. If the primary chain case eventually runs dry then there must be a leak lower down than the g/box main shaft and needs fixing.

[Mick D]

Hi

Are you aware there should be a self centering 'seal' around the gearbox input shaft?

Chaincase Seal.png

Is yours missing or damaged?

Regards Mick

[Expat]

Thanks for the replies chaps. No Mick I wasn't!!

That's interesting, as I was led to believe previously that no seal was used due to the gearbox needing to move fore and aft and haven't been able to find any reference to one anywhere. I'll look at the spares site. Is it a loose fit in the case and close on the shaft then?

I know the PO renewed the gearbox seal, so would obviously have had to remove the clutch and inner chain case, I just wonder if he will remember now after all this time what happened re the seal.

So can the seal be replaced without removing the inner case?

[Mick D]

Hi

Whilst I didn't replace mine during the restoration I'd guess the inner case has to come off - it looked like the seal was assembled in a press but I reckon a large nut and bolt with some suitable washers would achieve the aim, (I could be way off the mark though).

There are two large circular plates. (you can see one in the photo), that sandwich the inner case and retain the centre part of the 'seal' - the plates can move relative to the case and allow adjustment of the primary chain by moving the gearbox back and forth.

Regards Mick

[clanger9]

The two plates are spot welded together. To replace the seal, you drill out the welds and it comes apart. The replacement seal comes in bits and can simply be pop-riveted together.

Here's what a replacement seal looks like on my leaky Lightweight:

IMG_0241.jpg

[Expat]

That's great, a picture tells a thousand words and shows how obvious it is. Thanks very much both.

Club spares are saying seal kit is in short supply but in any case I've got to get my head round taking the case off a third time, if only to take a look at what's there
Guess I have to believe all is not well by the amount of leakage present.

So to spur me on....or not, can some level of fix be done without removing the inner case?