Scooterotica

You mean for the crank / top end area?

It must be difficult to seal up the gearbox / transmission area? It's not airtight anyway?

It should be air/ oil tight once the breather is sealed (thats the reason the breather is there).

A top end leak test would require the crank seal to fail to allow air into the gearbox. The weld looks fine and the gearbox area isn't under a great deal of pressure as the breather allows air to escape. Personally i'ld just got for it.

B-Race Tuning wrote:It should be air/ oil tight once the breather is sealed (thats the reason the breather is there).

Yes but it's not intended to be under normal operation, hence the breather and shouldn't run under pressure otherwise one of the seal will eventually blow.

Get the test done or get the gear and do it yourself, 1 tin of dye, 1 tin of cleaner and 1 tin of developer. Clean area with the cleaner, apply the dye, clean off the excess then cover in developer - wait and see if the dye is drawn back from the crack/ weld area into the developer. Easy enough to do, not so easy getting the dye of yer mits. The engineering shops wouldn't charge much if anything at all for this I wouldn't think.

if you seal the crank bearing area and fit a gasketed chaincase, use the breather hole as your filling point then it will be 'gearbox end' not 'top end' sealed. I know it's not supposed to be under pressure, hence breather. But, hot oil WILL find is way out with no pressure through gravity/ capillary action. putting under pressure and warming with a heat gun should give you the peace of mind it's crack free/ fully repaired (looks a reasonable job though).

Well most of the welding on the casing is good, there is a small leak in this area though:

I can't open pictures but a leak is a leak, small or otherwise. It's surprising how thin sae90 gets once hot, and surprising how big a small leak can get once the casings get hot. Get it carved out and welded. Simon.

I was tempted to just take an easier option but your post has made me think again. Thanks

I've just been tracing/ tracking an air leak around the welding I did on a T5 casing that's been converted to the LML reed intake. It was easy to find the "out" side of the leak (it was in the clutch housing area) but a pig to find the "inlet" side of it. It was from the locating screw hole used to hold the original T5 carb box (that then becomes redundant) + porosity in the casing/ weld. Yours does look relatively easy to do from the outside, requiring no further machining. Definitely worth doing for what it'll take/ cost (negligible). Simon.