Dan53 Posted February 8, 2012 Share Posted February 8, 2012 This is my first post (other than my introduction). Forgive me if this is not the appropriate forum for this question. I am getting my dad's old 1968 Yamaha YL-1 back on the road. Hasn't been driven in decades. I restore vintage Volkswagens but I know nothing about motorcycles, so I appreciate any help greatly. I don't have the owner's manual so my question is simple, what oil should I use in it? It has a "Twin Jet 100cc" in it. Also, I'm a little confused. The bike fell while in storage and bent what I now know to be the oil pump cover on the side of the bike and all the oil leaked out. I bought a new cover for it (on its way) but it's strange to me that there's no seal or gasket that goes here. Amazing to me that it doesn't leak oil all the time (coming from someone that deals with how "drippy" old Volkswagens are). Anyway, what confuses me is that on the right side under the seat is a compartment with an "oil tank" and a sight glass on it where you evidently put the oil. However, there's also a plug on what I suppose is the transmission that looks like oil is added there as well. Can anyone shed light on this? This is the "oil box" I spoke of and if you look down below it you can see the silver plug I mentioned. Is one motor oil and one gear oil? What kind of oil should I use in either case? Thanks very much! Dan Link to comment Share on other sites More sharing options...
nayruf Posted February 8, 2012 Share Posted February 8, 2012 Hi Dan The oil I use in the tank on the frame for my DT is Castrol TT for two stroke motorbike engines (semi synthetic) The oil that I use in the engine is is motorcycle engine oil ( UK national motor factor I use is Halfords)see the link; the oil that I use is the 4 stroke engine oil 10/40, This is because the friction inhibitors in the equivalent motor car oils can mess up the wet clutch on a motorbike http://www.halfords....se+relevance||0 I would confirm the right grades/types of oil with the manual, If you don't have the correct manual then you will find that a manual from another 2 stroke yamaha of about the same era will also use the same oils (pehaps a yds7) Link to comment Share on other sites More sharing options...
Dan53 Posted February 9, 2012 Author Share Posted February 9, 2012 Understood. So it injects the oil into the cylinder rather than having you add oil to the fuel tank, and then the plug on the bottom is for the crankcase oil. I spent two hours last night cleaning up the fuel petcock (as I'm told they are called). It was like someone poured cement down there. Luckily it was switched to the STOP position so hopefully the carbs are pretty clean, which they seem to be. Though I'm a little concerned because the lever on the side, which I assume is a choke, won't budge. I might run into some problems. I've got some spark plugs and a battery on order so next week some time I should be able to see what kind of luck I'll have firing it up. Dan Link to comment Share on other sites More sharing options...
nayruf Posted February 10, 2012 Share Posted February 10, 2012 Hi Dan You are right it does inject oil into the inlet side of the carbs, I would bleed the 2 stroke oil pump first, on my bike it is under a little cover plate on the right hand side of the engine case, i would also put a little 2t oil in the fuel tank it will make the bike smokey but you can be sure that there is lubrication present, (I would put a drop or 2 of oil in the plug holes and turn the engine over with the plugs out to fill the crank case with fuel/oil mix and the drops in the plug holes will lubricate the upper bores) It will smoke and might oil up some plugs, but the plugs can be cleaned. Have fun, Link to comment Share on other sites More sharing options...
Dan53 Posted February 10, 2012 Author Share Posted February 10, 2012 How do you bleed the oil pump? It seems to be hooked up via cable to the accelerator, which looks to be one cable that splits into three (one for each carb and one for the oil pump). Dan Link to comment Share on other sites More sharing options...
Moderator Airhead Posted February 11, 2012 Moderator Share Posted February 11, 2012 there is normally a screw in the top of the pump, remove the screw and oil will flow out, replace when the bubbles (if any) stop Link to comment Share on other sites More sharing options...
nayruf Posted February 11, 2012 Share Posted February 11, 2012 Hi Dan I just want to tell you what happend to my DT, Like your bike it had stood for about 12 years in a shed, I too cleaned the carbs, tank, plug. points I over oiled the engine and it fired up fine no running problems and it would hold 65 mph, then about 150 miles later it sounded slappy and lost power and I limped it home, I removed the head,barrel and found the Gudgin pin bearing was loose (wrist pin), I figure that because the bike had stood the bearing had dried out and my over oiling might not of gotten to the bearing in time , So what I am trying to say that even though you will get the bike running ok I would still strip the head/barrels off and check out the main/small and big end bearings, If I had I might of avoided having to split the crank shaft, Hope this helps it is only food for thought. Link to comment Share on other sites More sharing options...
Dan53 Posted February 11, 2012 Author Share Posted February 11, 2012 Thanks for the story. My only concern about removing the head is that I don't know the torque settings or sequences to reinstall it. Would anybody be able to help me with that? Oiling the vintage Volkswagen engine is critical. When starting one for the first time after a build we leave the rocker arms and spark plugs out and crank the engine with the starter until oil pressure is established. We then continue cranking it for about a minute. Then we install the rockers and plugs and crank it with the starter for another minute before hooking up the ignition and firing it up. This way everything is nice and oiled. I can probably do something similar with the motorcyle. Obviously there's not an electric starter, but I can just crank the heck out of it for while with the pedal to make sure the oil is pushing through the passages and into the bearings. Dan Link to comment Share on other sites More sharing options...
Dan53 Posted February 11, 2012 Author Share Posted February 11, 2012 In another news, I'm currently sealing the tank with a Bill Hirsch repair kit. Dan Link to comment Share on other sites More sharing options...
Moderator Airhead Posted February 11, 2012 Moderator Share Posted February 11, 2012 Thanks for the story. My only concern about removing the head is that I don't know the torque settings or sequences to reinstall it. Would anybody be able to help me with that? Oiling the vintage Volkswagen engine is critical. When starting one for the first time after a build we leave the rocker arms and spark plugs out and crank the engine with the starter until oil pressure is established. We then continue cranking it for about a minute. Then we install the rockers and plugs and crank it with the starter for another minute before hooking up the ignition and firing it up. This way everything is nice and oiled. I can probably do something similar with the motorcyle. Obviously there's not an electric starter, but I can just crank the heck out of it for while with the pedal to make sure the oil is pushing through the passages and into the bearings. Dan dan thats not quite how it works with a 2 stroke engine, there arent any passages as such, the oil is mixed with the fuel and lubricates the crank and bearings as this mixture is passed through the crankcase Link to comment Share on other sites More sharing options...
Dan53 Posted February 11, 2012 Author Share Posted February 11, 2012 These are the things I don't think about. Thanks, good call. Dan Link to comment Share on other sites More sharing options...
nayruf Posted February 12, 2012 Share Posted February 12, 2012 My DT 175 has a 4 stud barrel and the cylinder head shares the same studs as the barrel using sleeve nuts. The manual (Haynes)states 'tighten evenly in a diagonal squence and that the final torque setting is 18 to 20 lbs/f , this statement covers (LT,2,3 100 cc AT1,2,3, 125 cc and CT,1,2,3 175cc including DT125 ,175,) so if your bikes cylinder heads are of a similar set up although you have 2. I would assume the torque settings are about the same, (assumption is the mother of all F@@k up’s) so they tell me, so I would telephone any Yamaha specialist, if you don’t get an answer you will at least be able to make a very good guess, Link to comment Share on other sites More sharing options...
Moderator Airhead Posted February 12, 2012 Moderator Share Posted February 12, 2012 This is what i'd do if it were mine Buy gasket set first, dont tackle anything until you have one (availability?) Drain the oil remove the clutch cover and magneto cover remove the engine from frame take off the barrels, heads and pistons / small ends for inspection, check for gummmed rings and also for ring wear, decoke piston crowns and note any oversize number and mark the pistons somehow L & R fill the crankcase with diesel for at least overnight to check the crank seals integrity (important) improve / replace and faults, carefully remove old / broken gaskets place piston pins in the freezer assuming alls well with everything drain diesel out place rags in the crankcase mouth (important in case you drop piston circlips) clean off old cyl base gasket, grease and fit new one oil small end bearings and bores refit pistons into bottom of barrels but leaving the gudgeon pin (wrist pin) accessible very carefully lower the complete assembly down and fit the pin and clip ...remove rag from case mouth when clip is safely home (use helper if needed) complete final assembly etc. grease paper gaskets before installing, they come off easier and can often be used again Link to comment Share on other sites More sharing options...
Dan53 Posted February 16, 2012 Author Share Posted February 16, 2012 Thanks for all the advice. I'm not convinced these throttle cables are working correctly, and the choke is also jammed on these carbs. How do I remove these cables? I don't want to go turning on things until I know for sure. Thanks! Dan Link to comment Share on other sites More sharing options...
blackhat250 Posted February 16, 2012 Share Posted February 16, 2012 Yeh dan " these carbs will need stripped, if your choke plunger is seized , the jets will be rencrusted too , unsdrew the big knurly [ carb top] slide every thing out , then you"l see how to diconect the cable , Link to comment Share on other sites More sharing options...
Dan53 Posted February 18, 2012 Author Share Posted February 18, 2012 Thanks. I took the carbs all apart and cleaned them. Took hours to do. It would have never started, all the jets and passages were plugged up. Should be smooth sailing now, though. Tomorrow morning I should be ready to start it up. I've made the necessary preparations and I'm going to give it a go. Wish me luck! Dan Link to comment Share on other sites More sharing options...
Moderator Airhead Posted February 18, 2012 Moderator Share Posted February 18, 2012 Dan Link to comment Share on other sites More sharing options...
up.yours Posted February 18, 2012 Share Posted February 18, 2012 awaiting with baited breath? Link to comment Share on other sites More sharing options...
Dan53 Posted February 18, 2012 Author Share Posted February 18, 2012 Ugh, well it's not going to happen today. This fuel petcock is no good. I might rig up some way to plug the port for it and then route the cross-tank ports to the carbs to see if it will start, but we will see. Disappointed. Dan Link to comment Share on other sites More sharing options...
Moderator Airhead Posted February 18, 2012 Moderator Share Posted February 18, 2012 whats wrong with it dan, it may be blocked and need the same cleaning regime as the carbs...it's very likely Link to comment Share on other sites More sharing options...
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