Oil Leaks - 1978 XS Special

I can't recall.... If there were any pieces of black plastic.

I will check the oil and screens after I run up the engine this weekend. Looks like -4c here tomorrow... T Shirt weather. Good chance to get the engine warm.
 
Hello, could someone tell me if i need to put any sealent on the threads on the front cam chain guide bolts, i just rebuilt the motor and it is leaking oil from the bigger bolts that the 10mm bolts screw into?
 
No sealer needed there, just make sure the copper sealing washers are OK.
 
My bike sounds like its suckin in alot of air I hear it poppin in my exhaust what should I look for and what a good idea to catch the oil coming from the breather valves
 
when i got my 78 the head gasket would puff exhaust and spit oil, i pulled the head thinking the gasket was shot but it was just fine. cleaned the surfaces and put it back together, 3 years later it is still running fine, no leaks..

sometimes it may just be the PO torqued is down wrong
 
Well it looks like its leaking from the head.

I have had this bike up and running for about 4 months and its just making this noise you still think its the po tourqed wrong
 
skriblz i was responding the the first post about his head gasket..

but you should first make sure you don't have an air leak at the carb holders. it's good to retorque the head every 50-100 miles after a rebuild, probably do this about 5 times and they won't loosen up any more
 
The Tach Cable Adapter has 2 seals, an O-Ring on the outside of the Tach Gear Housing, to seal between the housing and the case and an Oil Seal inside the housing, to seal the rotating gear. Try to determine if the oil is coming from between the housing and case or from inside the housing. Both are easy to deal with. Remove the tach cable; then remove the screw threaded into the case that locks the housing in place and withdraw the housing. There's your o-ring. The oil seal is inside the housing under the threaded cable adapter. Unscrew the cable adapter from the housing and there's your oil seal.

Try as Yamaman suggested and re-torque the cylinder head nuts before resorting to removal of the engine to replace the cylinder base and head gaskets. If you do end up replacing these gaskets, consider replacing the stock steel/rubber head washers with copper ones to provide a more even torque load to the head. In fact, consider fitting these even if you do not end up replacing the gaskets. They can be easily fitted and also provide a great seal against oil leaks.

The areas INXS pointed out are common leakage areas to watch and address, if necessary. If you replace the clutch pushrod seal, check the bushing there for excessive wear and replace, if necessary. This can all be done without removing and splitting the engine, but care is necessary when doing it. Also consider a one-piece push rod here to reduce wear of the bushing and resultant oil leaks. If the seal leaks behind the sprocket, there is a kit available to allow you to replace this seal without engine removal.

Have Fun!
Hi, I'm new here and just purchased an XS and found some of the oil leaks referred to in these blogs. From these I assume the offending seals can be replaced without removing the engine and splitting the cases. You mention a clutch pushrod bush, is this in the end of the gearbox input shaft where the pushrod slides through. It doesn't show anything in the schematics in the haynes workshop manual.
The information that is available through this forum is far more helpful than any book I have come across. Keep it up.
 
SKRIBLZ, If you are getting a lot of oil out of the head breather you may just be running to much oil. The proper oil level on the dipstick is half way between the max and min marks.
They changed the dipstick marks in 75 to lower the oil level a bit to help prevent excessive oil out the breather. The new dipsticks makrs are different. If you measure from the max mark up the stick to where the steel goes into the plastic it should measure 140 mm or 5.5 inches. the min mark 25 mm or 1 inch below the max mark.
Any bike before engine #103747 of the 75 XS650B came with the old dipstick.If your bike came after that engine number of that year it has the new dipstick.
Just don't run it to full. Not only will it blow out more oil it can make the seals leak more
Using a HELP item #80190 Power Brake Check Valve, from the parts store, usually right on the racks. Put this in the hose from the breather. The large end of the check valve goes in the hose and fits just right. This lets air out of the engine as the pistons move down, but prevents air from pulling back in as the pistons rise. This creates a small vaccum inside the engine. This helps in a couple ways, it helps the rings seal better, and helps keep oil from leaking out of weak gaskets and seals.
Runs better, leaks less, A win win.
Leo
Thats with the bike up on the center stand on a level surface. If checked on the side stand it reads wrong.
Popping in the exhaust could be leaks in the exhaust. Check for leaks.
 
Thanks 650Skull. Just a matter of looking harder and I will find the answer to most problems. I,m still trying to find a NZ supplier of XS650 parts. I could get them from Mikesxs but the min. postage to NZ is $33 and thats a bit much if I'm only getting a few dollars worth of parts.
 
- installing a brake booster check valve in the crankcase breather line helps create negative crankcase pressure and serves to restrict leaking oil seals...early models have 2 lines, later models 1

- most good auto parts shops should have these valves

- crankcase breathers-found at the back of the head

ShortLong.jpg

I just did this mod. And noticed more oil then useally coming from the breather. Why?:D
 
As I said a fewposts up, you may be running with the oil level too high. Check it as described, is the oil level between the lines or at the top line?
Leo
 
An old thread,, but related to a problem I am having-- an oil leak at the cable. Removed the tach cable and the threaded adapter. The seal under the adapter is shot. Here is the question--what is the best (easiest) way to get the defective seal out. New seal will be here Friday. Don't want to let the shaft move and loose the washer at the bottom of the shaft. Thanks for any help forthcoming.
 
Old thread. You will need the rear oil screen gasket and the oil screen cap gasket, as well as a sump plate gasket if your going to do the sump filter which is a good idea since almost all of them tear and are almost useless. All are available thru Mikes Xs, I just ordered them and did mine a couple weeks ago. I got a new sump filter and oil screen too for good measure. My sump filter had a large tear in it.
 
Last edited:
"Unless the pushrod seal is puddling (as opposed to dripping) the dire necessity of changing isn't eminent, unless it's a green or clean thing for you.
I thought of one as an automatic chain oiler for 2 years."

Oh yeah? Try saying that to a gal that just had her brand new Blouse ruined by little oil droplets sprayed on her back from the chain!
My 75 XS650B is the only one of the 4 or 5 650s I have owned that does not leak oil onto the chain! In my opinion they are the first year Yamaha REALLY got all of the little bugs worked out of them. I don't know why but I have always thought of the 1975s to be the last of the true XS650s, and after that, they were virtually a different bike. I don't know why? The 1980 Special was really a fantastic bike, but people were drifting away from Parallel twins due to the vibration, but the extra few HP could be felt (at least by me) as I rode double in the City a lot..
 
The later 650s didn't have more HP than the early ones, in fact they had less. What you would be feeling on an '80 model is the slightly lower gearing the 16" rear wheel provided and the slightly better midrange power the smaller BS34s delivered.
 
Back
Top