New rebuild engine problem

[ducati2242]

Ive had a problem with my newly built 1955 G9 engine . The cog on the timing side of the crankshaft split down its width above the key way groove . Anyway the internals of the engine ended up covered in fine aluminium grindings from where it had ran against the alloy casings . I decided to take it back out and clean it . so new shells purchased just in case and engine on bench .
On strip down one of the conrod big ends was quite firm to move so new shells are needed. Crank is ok so a light buff with 1000 gauge wet and dry and rebuild commences . This is where I remembered that I didn't like the lack of a center gasket so I made one out of gasket paper I had . I reassembled the engine and checked for end float as I was sure the 30 ish though gasket would have caused some end float but theres none evident .
Does the center carrier bearing and spacers take care of any end float . I am going to try the engine and it is back in the bike but ive decided to change the gearbox main shaft whilst its in bits as there was an obvious oscillating run out on the clutch which turned out to be a ,very slight , bent mainshaft .

So the 30 though gasket do you think i've over done it or is it worth a go anyway .

[Duncan]

Guy, exactly as you thought, the crankshaft end float is governed by the centre journal thrust washers so the gasket will not have any effect on it.

[ducati2242]

Guy, exactly as you thought, the crankshaft end float is governed by the centre journal thrust washers so the gasket will not have any effect on it.

Thanks for that . Sitting thinking about past actions and decisions and your mind starts thinking up all sorts of reasons why it could have been a mistake and if it were a good idea why didnt they do it in the first place , but , its done now . I also altered the filter tunnel whilst I was in there I machined it out and fitted a 1mm thick aluminium tube that goes 25mm into each casing and has a groove in each case to accommodate an O ring around where it would leak so hopefully it will be leak free .

I love that lathe and milling machine . Thank for your reassurance . Guy

[leswaller]

Putting a centre gasket on will almost certainly make the crankcase leak oil. It was designed to run without one and even the thinnest of gaskets will cause an oil seepage. Many people have gone down this road before you with the same results.

[ducati2242]

Putting a centre gasket on will almost certainly make the crankcase leak oil. It was designed to run without one and even the thinnest of gaskets will cause an oil seepage. Many people have gone down this road before you with the same results.

I'm willing to give it a try but the idea wasnt mine it came from here on this forum and he seems to have had success with it .http://www.jampot.com/forum/viewtopic.php?f=19&t=1347

[ajscomboman]

Putting a centre gasket on will almost certainly make the crankcase leak oil. It was designed to run without one and even the thinnest of gaskets will cause an oil seepage. Many people have gone down this road before you with the same results.

If Guy has made a complete crankcase gasket and I'm convinced he has by reading his post I'll say what you've written is utter tosh Les.

I've rebuilt several twin motors using a full crankcase gasket and various sealants (Three bond is my favourite for this job) and had great success with all of them. I've recently built a motor that had refaced joints and still a 1.5 thou feeler would go through in various areas. This I'm convinced was due to one case being welded where a rod let go. Sealant on it's own would never have done the job, I know as I tested it out before inserting into the frame but using a full gasket and Three bond the same cases are as dry as the Sahara desert.

[G15 Roy]

Putting a centre gasket on will almost certainly make the crankcase leak oil. It was designed to run without one and even the thinnest of gaskets will cause an oil seepage. Many people have gone down this road before you with the same results.

Where do get this infomition from Les, my 1955 has a full gasket and has no leaks but will burn a bit.

[Duncan]

Both my twins have a full crankcase gasket which are oil tight, if anything the original circular gasket around the oil tunnel is very inelegant.

[dodger]

Your G11 does'nt Duncan.

[leswaller]

Putting a centre gasket on will almost certainly make the crankcase leak oil. It was designed to run without one and even the thinnest of gaskets will cause an oil seepage. Many people have gone down this road before you with the same results.

Where do get this infomition from Les, my 1955 has a full gasket and has no leaks but will burn a bit.

From the person who rebuilt my engine and does them for a living... you know who that is without me mentioning names