Is there an effective enough method that any members have used to repair hair-line cracks in the RH case around the bottom cam drive pulley area (JB weld for instance)?
I would like to avoid a total strip-down at this stage if at all possible. Failing that, once stripped-down has anyone successfully repaired with welding or bogging as I figure spare circa 1986 F1 cases aren't exactly "common"...

Personally I would replace the cases, if you are going to repair then strip them down and weld.
There may not be original f1 cases around but there are lots of cases that would work.
Good luck!
Paul

The Paso and later 750 cases are the same. Some differences in the trans shaft bearings/gears. I raced my F1 with a crack[s] around the jackshaft for a season with epoxy and a diaper. The glue slows down the leak but won't fix it, too much going on in that area of the case. Welding might work but finding a competent and willing welder would probably cost more than some good used cases.

The paso case is unique, at least around the swingarm pin. Inside it is same as the very late F1s, the 750 sport, and the 750, 600, etc. of the 1990s. But if you need the Pantah/TT/Alazurra/F1 swingarms and pins, then it must be modified.

MikeV

Thanks for responses. Widietz186, I think I'll first try a temporary bog job as you did meanwhile I'll start the search for replacement cases. Just a bit gutted that this ex racer is a bit like grandfathers axe and the only original part left IS the motor! The plan was to give it a once over and a tickle-up and turn up for a few events this season and assess how it handles and performs etc and give it an overhaul proper next winter. I have already found the GM -F1 cams to have had a badly ground profile meaning the closer clearances had to be run REAL loose to let the cam actually rotate so they're destined for the trash heap too! If was easy, everybody would be doing it, eh

If you do try to glue it, clean the cases with brake cleaner then heat the area with a propane torch. This will expand the crack somewhat and draw oil out of the crack, then drown it in brake cleaner again. Do that a few times and you will have a slightly longer lasting bodge. Roughing the area up a bit with some coarse sandpaper or a file will give the epoxy some "tooth" and it will stick better. I generously wrapped the cooler hose nipple area with strips of an oil absorbent mat that sort of looked like exhaust wrap to form a dam of sorts. It worked pretty well and raised no suspicions during tech inspection. I had forgotten about the swingarm differences in the later cases. I think the pivot issues can be resolved with some bushings in the swingarm to adapt the smaller pivot pin. If it is a racebike I wouldn't be too concerned about originality, it's just going to get abused.

The older cases are very susceptible to cracking in that area, even on stock motors. I always suggest going to 1999 and newer small case 750/800 cases as they are much stronger and of a more modern design. But they are not direst replacements. there are two major areas that need to be addressed and a couple of smaller areas depending on what you are planning to do with the motor. The swingarm pivot has to be addressed and the easy thing to do is run a late model cantilever swingarm (from an 800ss) but requires more swingarm room at the frame. The flywheel is the other issue as you need a late model carbureted flywheel which where on some of the later Monsters and some late carbureted 900ss. This will allow Kokoson ignition to be used. The cylinder heads will bolt on but the piston squish band needs a little work and the oil feed needs to be addressed. This swap can get you a 6-speed trans and a factory slipper clutch but it is a wet clutch. The later motors can be converted to a dry clutch but you do need too modify the oiling system to get it to work and not leak. If you do convert you won't have to worry about cracked cases again.

Palmer

Thanks again. The motor is in a Bimota db1 and has been raced most of it's early life and is destined, I hope, to continue it's legacy into retirement. The ignition has been converted at some point to Lucas Rita off the cam drive pulley, if that is the sole reason for requiring the later flywheel with later cases. Do you mean that the barrel oil holes need aligning to later cases or is there another issue with oil feed?

Hi luigi2,

Yes, so the flywheel/ignition would not be a problem then. As for the oil feed holes, if your are running the stock oiling where it feeds the heads up the cylinders then what you run into is that they are in the exact same location but Ducati change the o-ring placement from the head to the cylinder, so yo have too much clearance for the o-ring. Both the head and the cylinder are for o-rings. I have found that some 8mm flat washers that I epoxy into the cylinder o-ring hole and dress with a fill to solve that issue. Hope that helps.

Palmer

I think you'll find or I have found all the cams for these motors do that to some extent. Closing clearance isn't the same through the rotation. Best way to set closing shims is pistons down and belts off. You can rotate the cam by hand back and forth through the whole valve closed area. You want it to almost touch at tightest spot and it will be looser everywhere else. If you set closing shim clearance without doing this it will be dragging too tight part of the time. I highly recommend MBP collets, not the stock wire ones.