1962 YD3 -- Running 1 cylinder??

[nourydr12]

I have a 1962 YD3 I picked up very recently.It is in excellent originol condition with only 4500 miles. Everything works. Has not been run(really) since 1968.
The bike is not running on the left cylinder. I have--
-Cleaned sealed tank & carb
-Ignition timing is dead on correct
-pionts set and good (both cylinders have great spark)
-cleaned carbon from exhaust
-tested coils by swithcing cylinders
-both cylinders have about 140lb's compression

The left exhaust leaks oil/fuel profusly at pipe muffler joint when you try to run bike, which makes sense as it is not firing….  Someone suggested it is the left crank seal, and that it is sucking iol in from the "wet" left clutch….

ANY THOUGHTS WOULD BE GREATLY WELCOMED*****  AND IS THE LEFT SEAL ABLE TO BE REMOVED AFTER THE CLUTCH BASKET IS REMOVED OR DO THE CASES HAVE TO BE SPLIT… LITERATURE ON THIS BIKE IS HARD TO COME BY AND ONLINE SHCEMATICS I HAVE FOUND DONT SHOW THE SEAL.
Thanks
Bob

[mark2]

sounds like a gumed up ring , lift the barrels
http://www.yamahapart.com/oemparts/a/yam/54454051f870020ad8f5dc4d/crankshaft

[nourydr12]

Hmm- Do you think a gummed up ring would show up in compression test, I mean if its gummed up and ring is not moving freely it would affect compression??? Interesting, that would be easy….
Thanks

[chaterlea25]

HI,
If both cylindrs have 140psi than I would think the rings are ok
maybe the left crankcase is just flooded with fuel /oil??
A lot of older twostroke bikes had a crankcase drain screw for such events, I dont know if the Yam has??
If not, remove the sparkplug and exhaust on the left, place some rags on the head and in front of the ex port to reduce mess, ground out the lefthand plug lead securely
start the engine on the right hand cylinder and blow out all the excess fuel / oil from the cylinder
fit a new sparkplug and then see if the engine runs on both cylinders

The capacitors connected across the points can detioriate with age, when the engine is runnning seee if there is a lot of sparking at the points

HTH
John

[mark2]

has it a lower oil ring ? 3 ring piston ?

[murdo]

As it is a two stroke that has probably been left with the fuel tap on over the years, I think Chaterlea25 is on the money with it just full of old fuel/oil. I had a similar problem with my YDS5, caused by the needle of left carb leaking. I would suggest you remove the carb while trying to clear the cylinder so you are not putting more fuel into it.
Re the seal; get it running first and then watch the pipes to see if the left is excessively smokey. The seal can be removed without splitting the cases, just takes a bit of fiddling with two small self tapping screws screwed into the seal body for something to get hold of with pliers to pull out. Use good quality sealant when refitting the new one.

[nourydr12]

All good stuff, you all R writing….. All in all it boils down to elimination. Glad to here the seal can be removed…… with out splitting cases. The clutch needs work anyways, so………. I will save the ring option for last, as i dont see that as my first answer. Thanks much for the input. Lucky the engine is fairly simple to begin with.
The bike is really in excellent condition for original.

[nourydr12]

To: Mark2---- It is a 2 ring piston

[murdo]

So how did you get on? Running on 2 now?

[nourydr12]

Well Murdo---- No it is still on one cylinder. The left seal is gone badly… The entire crank case was full of oil from the clutch side. I havent had time to look at it any further. I have a 1962 BSA on the lift right now with the entire front end ripped off.
At this piont i'm thinking about taking the entire engine apart mainly to replace all seals, gaskets etc… The bike has been sitting since 1968, untouched so every seal and gasket on it has been dry long over.
Bob

[nourydr12]

I did get that intake at speed and sport by the way.. NOS and still soft rubber, which I was worried about. Cost me dearly tho

[murdo]

These blokes do seal kits plus other bits for the old Yamaha's

http://www.ebay.com.au/itm/Yamaha-YDS1-YDS2-YD3-engine-oil-seal-kit-/200819042937?pt=Motorcycles_Parts_Accessories&hash=item2ec1bf6a79

http://www.ebay.com.au/itm/Yamaha-new-centre-crank-oil-seal-YDS1-YDS2-YD2-YD3-YDT1-YDT-1-NOS-/200968016067?pt=Motorcycles_Parts_Accessories&hash=item2ecaa090c3

http://www.ebay.com.au/itm/Yamaha-YDS2-YDS3-YD3-YDT1-YM1-TD1-TD1A-TD1B-crank-centre-O-ring-NEW-/201179858329?pt=Motorcycles_Parts_Accessories&hash=item2ed7410599