penno350

Tom are you heating the hub? I normally find that a good dousing with boiling water is enough and then drift the bearing out from the opposite side. If you cant get any purchase on the inside face of the bearing another option is tighten a construction type expansion bolt into the centre of the bearing where the spindle normally sits and drift against that. Most extreme option is catch a bolt or piece of bar with a blob of weld in the centre of the bearing and knock it out against that. Hope this helps.

Super job well done you must be very pleased.

Thanks for the replies chaps, much appreciated.

Any top tips on repairing a cracked 198 Airbox or is it dig deep for a replacement? Any views on best source for replacement?

North Wales, between Mold and Llangollen new club with proper twinshock sections and really enjoyable, friendly trials with 3 routes. http://www.aqueductclassics.org/

Mine is at 2 threads showing on the Clutch Springs then a couple of mm free play at the operating arm, works a treat. If you dismantle the clutch make sure that all the plates are facing the same direction, if you run your finger on the inside edge you will feel a sharp edge and a rounded edge, fit the assembly either way but make sure the plates are all the same way.

Jets should be 125 Main, 40 Pilot, mixture screw should only be out about 3/4 of a turn. What is your needle position?

Any decent footrests available for the Sherpa that don't involve serious welding/machining/fettling or is this the only option?

Hi Lorenzo, the thrust washer was the same side as the scufing and the piston crown was damaged by a couple of big chunks of debris which made their way into the combustion chamber.

Thanks chaps, I can't tell with the naked eye if the rod is bent but at the lowest point of the stroke you can rub it on the flywheel (clutch side) which is where the scuff marks are. There doesn't seem to be any up/down play but I assume the excessive side play has put strain on the piston washer (same side).

My Sherpa has run well for a couple of trials but last weekend decided to 'eat' another piston thrust washer. On stripping down it looks as if I will get away with the bore which is +1.00mm (which I think is the limit) but the piston crown has been damaged and needs to be replaced. I am not clear why it has destroyed the thrust washer. Secondly, the conrod has no up or down play but some sideways play and on one side it looks as if it has been scuffed by the flywheels. Is it worth taking the engine down and having the crank rebuilt and could this be why the thrust washers have been failing. Any advice gratefully received from experienced Bultaco owners.

Rebuilt the top end of my 159 engine this weekend but not happy with the fit of the Aluminium thrust washers with the small end. In my spares I have thrust washers with both a large recess and a smaller recess (flange). I assume this fits over the end of the small end bearing which is a single 20mm bearing. On the first couple of fits the gudgeon pin seemed to push the small-end bearing deeper into the thrust washer allowing one of them to fit loosely on the gudgeon pin with no contact on the small-end. Is my reasoning correct that the small end should fit the recess/flange on the washers and that they should both be tight with contact on the small end? This would also position the semi-circular cut-outs in the washers on the inside against the con rod/small end. As I said it all seems to have gone together in the end but I am a bit nervous that it isn

Totally wrong, took the top end off and one of the gudgeon pin thrust washers has given up the ghost and been eaten! At first glance the piston and bore look ok.

Having a very enjoyable ride out at a local twinshock event yesterday, cut short by some horrible clanging and banging from the engine at the end of Lap 3. Symptoms so far kickstart is solid but I've taken off the clutch cover and that will all spin including crankshaft but if I select a gear the back wheel is solid. Assume it must be a gearbox problem.

Many thanks.

They had a bigger frame and a one piece fibreglass seat tank unit. Don't know where you would get one from now, sammy Miller used to do a one piece seat/tank unit for the original TY80.

Is there a standard/preferred size for the main jet in a Bing 84 as fitted to a 350 Sherpa. Mine has a 123 fitted, is that suitable or should I change it?

Is it feasible to convert a 159 to right foot brake acceptiing there may be some loss in braking power? I just find it more instinctive having ridden left foot gear change all my life and still riding on the road, I think I'm just too old to re-tune my brain and have enough to concentrate on in a section rather than which foot to press!!

John, should I strobe the timing to standard then, 2.7mm BTDC?

Perfect timing (no pun intended) I had just sat down to type a similar question. I have fitted electronic ignition to my 159 but although it starts and runs I assume that you should do some fine tuning of timing? Is this generally an experimentation or should I take it from standard timing against TDC?

3/16ths is near enough to 4.7mm which are available fairly cheaply from most good cycle shops or on line.

Fairly simple question but are there two types of fixing the front pipe to the barrel on later 350s? The first one being the sleeve and spring type but is there also a pipe with a captive plate that holds the pipe on against a flanged end?

Got a back wheel for my Sherpa with a brand new 400 x 18 Barum Trials Tyre fitted. Looks knobbly but are they any good?

Can anyone advise if it's feasible to fit a right foot brake set-up to a 159 Sherpa? If so any recommendations for suppliers of the required parts?