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Hi, I've noticed since changing my cyl kit that I'm losing engine oil at a rate of around 50ml in 150 miles. There is no white lingering smoke like you get with a shot drive side oil seal, it is a bit more smokey on start up with the choke but this clears up. Have any of you knowledgeable chaps any ideas? It usually doesn't use much oil and i don't think changing the kit is the reason though this has prompted the extra scrutiny. The side gasket is new and there's no oil patch on the garage floor, also the rear hub seal is new.
Thanks

A blocked chaincase breather would do it, but this is really an unlikely secenario.
Fit a party balloon over the breather and warm the engine up. The balloon then acts as a visible expansion vessel.
When the chaincase warms up, the atmosphere inside should expand and inflate the ballon to some degree. If the balloon pulses with every stroke, then the drive side crank oil seal or Halite washer is the likely culprit.

Thanks for the reply, I'll give the balloon test a go

So i did the balloon test, FnF you are bang on the money the drive side oil seal was the culprit. New Viton seals have been ordered along with gaskets and bearings, I figured as I'm there why not.

If your oil seal plate is an Indian aluminium one, then I would advise ditching it and replacing it with an Italian steel one.

Fast n Furious wrote:If your oil seal plate is an Indian aluminium one, then I would advise ditching it and replacing it with an Italian steel one.

The plate is an Innocenti one a bit of good luck at last Thanks for your help

I went for a short (luckily) ride on Sunday for a bacon sarnie with my suzuki mate.

First ride of the year. Fresh fuel and plug, started second kick, lovely.

We both noticed that the gearbox was a bit rattley, so I opened the chaincase last night. It was as dry as bone!

Gearbox, chain, tensioner, clutch etc. trashed.

I haven't ridden it since September and remember no smoke last year out of the normal, but I'll bet there was some, as there's no oil on my garage floor.

New gearbox etc going in tomorrow night, courtesy of Torbay and barclaycard.

What's the odds that when I try the balloon test, the seal has gone?

Part of the issue with realising that a seal has failed is that failure used to mean ‘all or nothing’ rather than a gradual loss. Personally, I’m not a convert as far as Viton seals are concerned, not that I’m attributing failure to them in these instances. Part of my reluctance to use Viton seals is that none of them that I ever bought had any manufacturing brand details upon them. I actually removed them from a Group Four engine, reverting to Nitrile when that machine was running petroil lubrication of the flywheel side bearing.

The material utilised in Nitrile seals is not as vulnerable to attack by the chemicals contained in modern fuels as some may believe. If you consider the flexible tubing used extensively for transfer of fuel from the tank to the engine in virtually all automotive transport, there’s an awful lot of ‘black rubber’ tubing in use.

However, what does seem to be a problem to some seals - & tubing, for that matter - is when they are allowed to dry out in storage. Ask anybody that checks the fuel feed lines on, say, a petroil hedge cutter just how hardened they can become. Obviously quality varies in manufacture, but I wonder whether two stroke oil specifically might be an issue when seals are allowed to dry out.

My apologies for the rambling thoughts but I guess we’re all trying to avoid similar problems……

Mmm I'm not 100% sure i've got the job right. I took the scoot out Sunday and noticed when in standing traffic and in neutral there was a fair bit of smoke out the exhaust. I checked the oil level on my return and it was at the correct level but the plug was black ( idiot i didn't change the plug) so another run soon with a new plug and fingers crossed it comes back with the same amount of oil and a better colour plug. I did the leak down test when re building and it was holding air, not certain that's an indicator though ?

Before you go out again, just check that the choke is working properly since your rebuild.

Is it possible that, before your problems, you had overly rich jetting that was masking an air leak? An air leak test (at least the ones I do) are completed in the absence of the exhaust and carburettor so you could have still had had an air leak at exhaust and inlet manifolds. Now that you have partially rebuilt the engine, you have fixed the air leak and your jetting is now too rich

Or, did you replace the hallite washer and, if you did, was it sealing between the plate and bearing?

Just a few thoughts

Fast n Furious wrote:If your oil seal plate is an Indian aluminium one, then I would advise ditching it and replacing it with an Italian steel one.

That said, I've never had a late Italian GP alloy driveside plate warp... but have no experience of SIL ones.

Storkfoot wrote:Before you go out again, just check that the choke is working properly since your rebuild.

Is it possible that, before your problems, you had overly rich jetting that was masking an air leak? An air leak test (at least the ones I do) are completed in the absence of the exhaust and carburettor so you could have still had had an air leak at exhaust and inlet manifolds. Now that you have partially rebuilt the engine, you have fixed the air leak and your jetting is now too rich

Or, did you replace the hallite washer and, if you did, was it sealing between the plate and bearing?

Just a few thoughts

Thanks for the ideas. I changed onto a new kit recently ( Casa ss225) and ran it in before a dyno set up. I carefully watched the plug colour and mostly it was too rich but during the process had the plug too light in colour, in fact right up to the day before i noticed it was a little lean in its colour. So i'm pretty sure that the seal was ok when i took it in and it was run many times on the dyno with changes until it was right. I understand things can change so it must have blown the seal since dyno.
So i did the rebuild and changed my plan and used a Casa oil seal plate with the O ring that doesn't need the Halite washer and replaced the seals either side of the crank with Viton ones did the air test from the exhaust manifold and carb inlet using a spare mount with a set up so the innertube is firmly connected and sealed with silicone to be used each time i rebuild and that reading was rock steady.
I've now just read in a Sticky book that some Indian casings can be a little deeper in the plate seal area so a Halite has to be used with the oil plate. I'm now thinking this could be the case and that's what's wrong?
I went with the Casa plate option as i've had problems fitting the Halite Washer in the past
I'll check the choke for sure as that's the place to start and i'd not thought of it, but my luck will probably not be playing ball

Yep, just like I thought choke working as it should.
Balloon test here I come

Double posts
Mods please delete.

Just need to talk this through

I’m attempting to figure out where a considerable amount of my gearbox oil has vanished in the last 1,000 miles or so

I’m trying out FnF’s ballon diagnosis of a failed main oil seal for the first time.

Running the scoot up to temperature the ballon inflates as the air temperature in the gearbox side increases
It’s quite difficult to see the pulsing due to the normal vibration of the engine
Should the pulsing be really obvious if the seal has failed?

Secondly reving the bike from tickover where the ballon has inflated and the ballon immediately deflates
I’m thinking this deflation indicates air being sucked in past the oil seal - does this logic seem sound?

The balloon's i used were quite strong/thick so didn't inflate that much but looking carefully at it you could just see it pulsing slightly.

Stripped out the crank and two things are pointing to gearbox oil passing the main drive bearing
1: very heavy carbon deposits in the cylinder head. Almost like the engine has been burning gearbox oil
2: the halite gasket was soaked in what I assume is gearbox oil

nsaints wrote:Just need to talk this through

I’m attempting to figure out where a considerable amount of my gearbox oil has vanished in the last 1,000 miles or so

I’m trying out FnF’s ballon diagnosis of a failed main oil seal for the first time.

Running the scoot up to temperature the ballon inflates as the air temperature in the gearbox side increases
It’s quite difficult to see the pulsing due to the normal vibration of the engine
Should the pulsing be really obvious if the seal has failed?

Secondly reving the bike from tickover where the ballon has inflated and the ballon immediately deflates
I’m thinking this deflation indicates air being sucked in past the oil seal - does this logic seem sound?

As you rev the engine down, because the throttle is closed, then the crankcase will suck in air from anywhere there is a leak as indicated by the sudden deflation of the balloon.
Sussed.