Gearbox oil

[HxPaul]

I hope someone can tell me.I filled my gearbox with 0.7 litre of Rockoil ST/90.The very first ride the scooter smoked quite badly,so when I got home I removed the level plug and about 2 to 3 mil of gearbox oil came out.When it had stopped dripping I replaced the level plug.The scooter has been ok since then and I have done about 2 to 300 miles.Can anyone tell me if this is normal and if you overfill the gearbox can oil find its way into the combustion chamber and be burnt.

[ULC Soulagent]

I only fill with 0.7 lts of oil from a completely dry engine rebuild and 0.5lts for a change over.
The only way gearbox oil can get into the barrel if the seal fails, other than that it will come out of the breather

[Scooterdude]

Also make sure your breather is not blocked, in theory if it gets blocked and a bit of pressure builds up oil COULD be forced past the seal.

[Fast n Furious]

+1 on the advice above.
I like plenty of oil in mine to ensure the needle bearing on the mainshaft gets proper lubrication at sustained high speeds. I use a whole litre of oil without any problems.

[missing lynx]

I can't understand this preoccupation with quantity of gearbox oil as long as the scooter is on level ground just remove the level plug and full till it starts coming out then that's enough. if the engine is hot when you cracked the level plug oil should come out as hot oil expands in volume but as said if the breather is blocked this can force oil past the oilseal and if that's the case also check behind the back hub

[Fast n Furious]

Paul.
Are you using the dished oil thrower behind the drive sleeve?

[Scooterdude]

I can't understand this preoccupation with quantity of gearbox oil as long as the scooter is on level ground just remove the level plug and full till it starts coming out then that's enough. if the engine is hot when you cracked the level plug oil should come out as hot oil expands in volume but as said if the breather is blocked this can force oil past the oilseal and if that's the case also check behind the back hub

I don’t understand the preoccupation with putting 700ml in and only being able to get 500ml back out. On all the ones including my own that i know I’ve put 700 in i always get 700 out, why wouldn’t i? Ok I appreciate some may be on the clutch and some might be on the gears, but 200ml ? Maybe I’m doing something wrong then?

[HxPaul]

Paul.
Are you using the dished oil thrower behind the drive sleeve?

Yes.Its a newly built engine,so obviously I thought 0.7litre would fill the gearbox.But as I say it smoked really badly on the first run so I checked the level and 2 to 3 mil came out.After I replaced the level plug I took it for another run and it had stopped smoking.By the way.The filler/breather was clean and clear when I blew through it.

[dickie]

Some remade breathers don't have the internal baffle. This can let oil blow straight out and drip onto the exhaust thereby smoking.

With 200ml less oil in, it's obviously less likely to blow out.

Maybe that's your cause?

[HxPaul]

Some remade breathers don't have the internal baffle. This can let oil blow straight out and drip onto the exhaust thereby smoking.

With 200ml less oil in, it's obviously less likely to blow out.

Maybe that's your cause?

Thats an idea,but thinking about it,the area around the filler plug was free from oil and the plug hadn't been leaking.The filler plug is the earlier type with the baffle inside.

[Scooterlam]

if its a new build I would expect it to smoke on the first run. would be more worried I it didn't.
I guess you or whoever built it used 2 stroke on the rings, bore, bearings and seals as they assembled.
if its stopped smoking and you're not losing oil enjoy riding it.

[HxPaul]

if its a new build I would expect it to smoke on the first run. would be more worried I it didn't.
I guess you or whoever built it used 2 stroke on the rings, bore, bearings and seals as they assembled.
if its stopped smoking and you're not losing oil enjoy riding it.

The trouble is,it was white smoke.Too much 2T oil smokes badly at start-up but it normally has a blue haze to it.

[Knowledge]

At the Italian Euro Rally, I was able to get Nic Cicutti’s Scooter running with no oil seal in it at all. None whatsoever.

I don’t know what I am proving by saying this, but it was the ultimate low-primary-CR engine, and ran like a bag of sh!te in a fog.

I always fit sealed bearings, with the seal on the chain side removed. It just gives a bit of extra security.

[HxPaul]

At the Italian Euro Rally, I was able to get Nic Cicutti’s Scooter running with no oil seal in it at all. None whatsoever.

I don’t know what I am proving by saying this, but it was the ultimate low-primary-CR engine, and ran like a bag of sh!te in a fog.

I always fit sealed bearings, with the seal on the chain side removed. It just gives a bit of extra security.

I remember reading this,so when I built this engine I fit an SKF bearing with a seal fitted.The thing that really gets to me is the fact that it smoked badly and with draining off 2/3 mil of oil out of the level plug it stopped smoking.

[rossclark]

2-3ml is less than 0.5% of the total volume of oil - that sounds to me like less than the margin of error on whatever you're using to measure the oil in.

I'm not dismissing your observation, just saying that it seems unlikely that it's cause and effect.

[sunrisemac]

The trouble is,it was white smoke.Too much 2T oil smokes badly at start-up but it normally has a blue haze to it.

It might possibly have been unburnt fuel mix in the exhaust which would have eventually burnt off as the exhaust got hot

[Fast n Furious]

Or excess grease from an overpacked mag bearing.

[HxPaul]

Or excess grease from an overpacked mag bearing.

That is a possibility."sunrisemac"That is also a possibility because it was a KBA clubman I used on a different scooter a few years ago.What ever it was it has stopped now and I suppose where just guessing at the reason.Thanks for your responses.

[Danbretta]

Maybe put the 2/3ml of oil back in and see if it smokes again. At least you can eliminate that and put it down to the other suggestions. Althoigh j doubt it would make a difference as its a small amount.

[HxPaul]

Paul.
Are you using the dished oil thrower behind the drive sleeve?

Yes.Its a newly built engine,so obviously I thought 0.7litre would fill the gearbox.But as I say it smoked really badly on the first run so I checked the level and 2 to 3 mil came out.After I replaced the level plug I took it for another run and it had stopped smoking.By the way.The filler/breather was clean and clear when I blew through it.

EDIT.The ammount is 200mil to 300mil,not 2 to 3 mil.Sorry for the confusion.