Hello to anyone who passes my post im on here today asking for help with a 1973 Tiger 750 that i recently inherited. I need to do a full fluid change primary chaincase, oil tank, gearbox, etc. I haven't found concrete information on the fluid specs on these bikes and mine is a bit of a odd case. I notice the various plugs below the engine and i have spotted the main plug and what i believe is the gearbox plug. From other various sources mine seems to look a little different than other 750s. My gearbox plug doesn't have the big plug and the little level plug in the middle and i don't see a way to drain the chaincase. I have supplied photos below of my plugs and my oil system which is an external filter. If anyone has a source or know themselves on the specs it would be much appreciated.
welcome. i missed this your "unknown plug" is actually the housing for the camplate spring. no need to touch it. the allen head plug is an owner bodge for tbe original gearbox drain. maybe tbe plug hex was buggered? no telling if it has correct threads or was just forced in. if the threads are destroyed you can leave it alone and drain most fluid through the camplate spring housing hole. the "main oil plug" is the engine sump. very little oil is in there, as its a dry sump motor. some people never remove it. if you do, spray it perfectly clean first to keep sand out. you drain the engine oil by removing the half inch bolt in the middle of tbe square plate that is under the frame spine reservoir and is hidden when the centerstand is up. the cap screw behind the cylinders is to allow access to the timing slot in the crankshaft. dont fill there. your bike has a pot metal cap with a cross head in the top of the oil-in-frame oil tank, just under the very front of tbe seat. fill there until you can touch the oil with your finger. your "chaincase fill plug" is where you can pour in about 150 cc after you drain the chaincase. the primary chaincase level is maintained automatically by oil blowing in and out around the drive side main bearing, so an initial fill is all you need. the "gearbox fill" is the gearbox fill. the chaincase drain is tucked in at the bottom rear of the primary, the same hole you use to adjust the primary chain. i believe yours has a level plug just above it. it drains very very slowly. lots of people just vacuum out the oil with a mity vac style extraction pump. vr1 is an excellent oil, but it wont work in your machine, which has a wet clutch that shares engine oil. the friction modifiers and super duper additives in it will make your clutch slip. look for a 20W50 with a label that says it is formulated to work with wet motorcycle clutches. older formulations (SG?) will not have the additives. i cant remember the exact spec codes, but someone here will know. harley shops will have it. i think the lucas 80W90 will work okay. on these you generally want a GL4 or a specification on the label that says its safe to use with yellow metals. even GL5s are generally safe these days. download a manual and a parts book fron kyle at CBS: https://www.classicbritishspares.com/pages/workshop-service-and-repair-manuals someone will be along soon to correct any mistakes ive made here. there are lots of brains available to you in this place. cheers
wait i see now that you have a 73 wet frame motor in a 1970 or older dry frame. everything i wrote about the motor is valid, but your oil is in the octagonal tank. you will drain there by removing the rubber feed oil hose, the outboard one. its the one hose-clamped to the hex headed plug in the bottom of the tank. make a big funnel out of aluminum foil and put under it to direct tbe oil before you remove the hose. then unscrew the hex nut and wash out the metal screen.
Thanks for the reply the information you gave was very informative. The little hex plug in the gearbox did come out and it goes in smoothly, when I took out the sump bolt previously I did have a decent amount of oil come out and I took the time clean the screen. Last I checked I don't remember seeing the drain plug for the primary case only the tensioner bolt. I know its planted above the tensioner bolt so I got to take a better look next time I'm with the bike.
I copied this from a previous post regarding suitable oils for Meridan Triumphs: THIS IS CASTROL'S REPLY Good morning Clive, The engine on the Bonnie runs on Castrol Classic XL20w/50, which is a mineral low detergent oil, you do NOT require high detergent, and synthetic oils may leak over time, the unit construction gearbox used to run on Castrol Classic GP50 which is fine, however you can use Castrol Classic EP90 as it is a GL4 specification and will NOT affect yellow metals, I would synthetic, NOT recommend r"Te ourg0 80/90 as as again again it will be a and at 80 weight will be too thin The primary requires an SAE 20 oil therfore use Castrol Classic TQF All can be found at www.classicoils.co.uk Kind Regards Trevor Castrol Classic Oils Manager
beanbag's motor is a 73, so it shares the engine oil with the chaincase, unless its been modified. the oil in the engine and in the chaincase is always mixing. so you cannot use current SJ-SP API-spec oil in the engine or chaincase. pre-1970 you can use anything you want in thr engine, and old-spec 20W in the chaincase, or use Type F automatic transmission fluid, which is what i use. the oil that will work in a post-1970 machine is this: JASO MA API SF/SG/SJ SG was 1993. motorcycles with wet clutches need this earlier spec. i used to buy valvoline "4-stroke motorcycle oil," which stated on the container that it was good with wet clutches, but i havent seen it for awhile. i can buy SG oil at my local parts store. got to read the label.
heres the drain plug on a 66. yours wont be so dramatic. unscrew this and you will see up inside the hole is a slug of metal with a screwdriver slot. thats the adjuster. in the T140s over the years they changed various things about this and the level plug, iirc. i cant remember exactly what. https://i.imgur.com/CotQVDIl.jpg part 40 https://i.imgur.com/VIAQhDGl.jpg
