Hello All - first question

[raspersyd]

Hi All
I have just joined up as I have started the restoration of my 250 Desmo, 1974 with a drum brake. The bike was from the UK but I now reside in Adelaide and have owned it for about 30yrs but that is another story. I have started with splitting the cases and cooking them on the BBQ to get the bearings out, all well and good. However there is the one final one that can't be drifted out as it is behind the hole for the clutch push rod. Any easy suggestions?

I will keep looking through the old posts here and see if anyone has mentioned it before.

Look forward to conversing with you all

Cheers

Syd

[Bevel bob]

heat the lot , chill the bearing and bump the case, be carefull the seal flange is fragile.

[JimF]

Welcome to the list!

I don't know if this will help, but you can get a product in an aerosol can called 'Quick Freeze.' It seems to me that you could heat the cases and then spray just the bearing with quick freeze to facilitate removal.

http://www.ncmedical.com/item_576.html

Electronic techs use the stuff to isolate semiconductors that are in thermal runaway during troubleshooting,

Probably easier to find as a consumer are just aerosol cans of air used to clean keyboards...

http://www.outletpc.com/c7234.html

Look for this stuff at office supply stores. The difference is that you need to hold the keyboard cleaner air can upside down when you spray it and it works the same way as the quick freeze product. Be careful! This thing can cause frostbite!

Between the heated case and the frozen bearing you may just find the thermal difference needed to make the bearing come out easily.

Jim

[LaceyDucati]

Hello

The correct way to remove the bearing is by warming the casing up & if needed with the use of an internal puller. Normally these are an expanding lipped collet which you expand out into the recess behind the bearing. You then attach a slide hammer & a few taps & it will be out. Quality internal pullers are reasonably expensive, but I have seen budget sets at a reasonable price. Link below to give you an idea of what I'm talking about, I'm sure I've seen them cheaper. Can't have enough tools & these will get the bearings out the cam end cap & solve many other problems too!

http://cgi.ebay.co.uk/US-PRO-5-Piece-In ... 51959f2264


Another way that works (assuming the bearing is scrap & you have access to welding gear) is to weld a nut to the bearing inner & after warming either use a slide hammer or a spacer, plate,stud & nut to draw the bearing out. You could also weld a bit of steel across the inner race & after warming tap the bearing out using a 5mm pin punch through the push rod hole. With any of these methods you will need to put a reasonable couple of tacks on the bearing as the weld qaulity will be poor due to the bearing material being less than ideal for welding. Care should be taken to avoid any damage to the alloy casing. Ideally Tig welding, but with care Mig should be OK (stick welding is a No & also gas because of the heat).

Whatever you do, do not drill holes through the casing to knock it out!!!! I've seen quite a few cases butchered like that with araldite on the outside to fill the holes. One word NASTY!

Best Wishes Nigel

[raspersyd]

Thanks all, bought the tool and bearing now removed. Now to spend the cash and buy some bearings

Cheers

Syd

[dsmess]

I've got a small electric convection oven in the shop. It worked pretty well to remove the bearings. I think it is good to heat the case uniformly.
I set it to 250F-300F, and most of the bearings just dropped out of their bores. I removed the case and set in on the wood bench top, and smacked a plastic hammer on the outside case behind each remaining bearing, and they popped out.

Alternatively, you could wait for the little Lady to go shopping and use the house oven....but the oil causes a lot of smoke. You could get in trouble.
Women tend to have noses like hounds.

Scott

[raspersyd]

Well just to wind up this thread I bought a bearing extraction tool which did the job perfectly (although a bit expensive). The cases were heated in the BBQ and the new mains literally dropped in to place, I had heard of this before but until you see it happen it seems hard to believe.

I now turn my attention to the crank and bearings, the big one of which seems a bit too wobbly. More expense as I read you need a new conrod.

Syd