Hello to all on this great site. I recently Rescued a '66 Yamaha YDS3 and am looking forward to getting it running. I hear that these are the street versions of the TD-1 factory racers. I'll try to put up some pics. I've got plenty of questions. Hope there's some answers here because I haven't any 2-stroke experience and I'm tired of missing out on the fun I know these machines can be to ride.
Thanks. Was left out in the rain for awhile and was running on one cylinder. Rebuilt the top end and now I'm trying to test the oil Injector pump. Makes me nervous to depend on that pump and all those little hoses to deliver the oil. I think that's what melted the left piston.
someone with more specific knowledge will be able to overrule me... However depending on how the cases split and any potential areas for leakage it's possible for something like a crank seal for instance to have leaked affecting just the one side, both side will be sealed from one another... sealing intake, exhaust and pressurising via the spark plug hole will allow you to do a leak down test
Leak down test it is then. Probably the right thing to do after having it apart anyway. The base gasket was in shreds when I took it apart. Oil everywhere. I did do a compression test which was good and equal both sides. Thanks.
Could have been a carby blockage (twin carb's), dried up gum restricting the jet's, low float level etc etc Yeah a leaking base gasket could do it too, too much air causing that side to heat up till the piston went. Guess you need to rebuild the oil pump and check out the oiling system. In the mean time you could try it on premix if the oil line's don't run down to the crankcase
Welcome. Looks a nice bike. Left side seal would have filled the cylinder with gearbox oil. Sounds like your base gasket was the problem. The oil pumps are pretty reliable, but remember on the '3' they are driven from the clutch and if you sit at the lights with the clutch lever pulled in you will get no oil from the pump. If the engine has been apart, I like to run a Litre of premix into an empty tank and hold the oil pump cable up ( so the pump is at full stroke) while the engine is running and let it go when the exhaust (both) start billowing clouds of smoke. Then you can be sure that the oil lines have purged all the air out. Yamaha's do not have the oil feeds to the main bearings as others do so if you choose you can run premix with no problems other than may have to adjust jetting because of the thicker mixture. I suggest using a synthetic oil at 50:1 ratio as this will not leave much smoke behind or carbon in the engine, which is great for spark plugs. Good luck with the build, great to see another one being restored not butchered/bobbered/cafe/etc.
Hi Murdo, how do you know all of this stuff ?, i have problems remembering AHH where am i again . Hi FrankYDS, Welcome to forum , that's one super cool bike you have there.Like the bike stand also , it's very narrow that's for sure.
I can remember 'all this stuff' because I recently rebuilt a YDS-5 (similar bike but with better clutch/oil pump set up) in one of my threads. http://2fiftycc.com/index.php?threads/1967-yamaha-ds-5-250cc-rebuild.2185/
Hi Murdo. Thanks for the link ,WOW !.That is one super cool rebuild , especially how the bike was rescued and to the final stage.I cant believe anyone would just crush a bike in the first place especially an older model that looks to be nearly all there.
Thanks. This method worked well. I could see the oil moving thru the lines. It's taking me a bit of time to figure out how to adjust the throttle cables to work correctly. I can't get the carb slides to bottom out even though the adjusters are all the way in. I removed the jam nuts from the carb tops and now the slides rest at the bottom. Could the cables be too short? Thanks again. I feel better knowing its delivering oil.
If both of the carbs wont close, then I would take a guess that the top cable (the one from the twist grip to the junction under the tank) may be your problem.
There is slack in the cable from the grip. Top cable has slack but the carb cables are stretched at the fittings which makes the casings a bit longer. Parts for this bike are rare and pricey on eBay--top dollar for questionable "NOS" and used items. Is there someone out there producing parts for these?
