I'm helping my son in law to fettle his mid 70's Bultaco next week by all accounts it's stood in his barn for ages so first thing is change the oil,any advice on type of gearbox oil and correct quantity,many thanks

H

This will obviously open a can of worms as every owner has his own ideas but I use EP90 gear oil in the gearbox 600cc for a rebuilt engine as per book but for an oil change I put in 500cc. For the primary chaincase I still use Automatic Transmission Fluid (ATF) 300cc.

Stuart

Yes - Twinshock is quite correct.

G/Box 1 pint of EP 90 - if you can get a standard 90 eg SAE 90 I seem to recall that is a little kinder on the 2 bushes on the final drive shaft of your gearbox ( after 72 they went to 2 needle bearings - something like 2 small end bearings.

For the clutch use 1/2 pint ( 300cc) of Automatic Transmission fluid. Most handbooks will recommend a 30 - but ignore this - as while OK in warmer climes - TQF or similar works best for us.

Also - if the bike has stood for years I would recommend changing at least the Timing side crank oil seals - as although it will start OK - they will have gone hard and wil spin off a little material after a while.

It is an easy job on a Bultaco has they are housed in a carrier behind ignition stator and you just undo the 6 bolts - remove and replace the seal ( probably only 1 each side on yours). This is also a good chance to check - or for the price of them even replace the points - set gap at 15 thou ( I use a filed down feeler guage - in width not thickness! - through the window in flywheel when you see the points open at their widest)

Finally - if you have a circuit tester of electric test meter to tell you when the points actual open - you can check ign timing by using a simple depth gauge down plug hole. The points should open at about 2.8 mm BTDC.

Thanks for the excellent responses guys I've no idea what state the bikes in but he's keen to keep me out of mischief over Xmas may be I'll get to have a go.........I'll let you know.Have a good one

H