Topic: how do i locate a big oil leak?

[vrm]

I've been trying to get a 76 750 back on the road for a couple months. I swapped motors from another one and it's running fine but there is a major oil leak. So much that I can't really tell where it's coming from. About a quart every 50 miles. Some places that are not leaking are the head/valve cover, the oil filter and the sprocket shaft seal. After riding for any length of time everything behind and below the motor is dripping with oil. I tried running it in gear while on the center stand and got little or no dripping. The top of the motor is dry. In the process of troubleshooting a charging problem I had the shifter cover and the stator covers off.  The gaskets were intact and appear to have been put on dry with no sealer. I reinstalled them using Permatex hi-tack sealer on both sides of the gaskets and the gasket surfaces. I did do a search but didn't find anything similar to my problem. If I do need new gaskets where should I get them? Will the Honda dealer have them? 

[lucky]

I've been trying to get a 76 750 back on the road for a couple months. I swapped motors from another one and it's running fine but there is a major oil leak. So much that I can't really tell where it's coming from. About a quart every 50 miles. Some places that are not leaking are the head/valve cover, the oil filter and the sprocket shaft seal. After riding for any length of time everything behind and below the motor is dripping with oil. I tried running it in gear while on the center stand and got little or no dripping. The top of the motor is dry. In the process of troubleshooting a charging problem I had the shifter cover and the stator covers off.  The gaskets were intact and appear to have been put on dry with no sealer. I reinstalled them using Permatex hi-tack sealer on both sides of the gaskets and the gasket surfaces. I did do a search but didn't find anything similar to my problem. If I do need new gaskets where should I get them? Will the Honda dealer have them?

This is not a car.
It is normal on motorcycle to put on a paper gasket with no sealer.
Gaskacinch is the normal motorcycle sealer for engine cases.
There are copies like "Honda bond" or "Yamabond" but just get the real deal. GASKACINCH.
Read your manual. Many times the manual will show a letter or note telling you to not put sealer on that gasket.
Often Vasolene is applied to ONE side of the gasket to make it easier to remove later.

Now someone....maybe you is going to have to remove all that Permatex to get a clean surface and you will have to buy a NEW gasket.

Then if you gouge up the sealing surface with the wrong tool, the surface WILL need goo on it. from then on.

Now about the oil leak.
Check to see if your bike had a chain oiler. If it did you can close it up.
If you clean the engine it will be easy to see where all that oil is coming from. It could be a hole in the engine case if the chain has damaged the engine case.
Many of those holes in the engine case near the front engine sprocket can be cleaned with brake cleaner . Then sanded and repaired with JB weld epoxy.

Get rid of that big #630 engine "case busting chain" and go to a #530.

When and if the engine gets rebuilt the engine case can be TIG welded.

Often the front engine sprocket seal is leaking.

Do not go to the HONDA dealer for parts.
They charge extremely high prices!! Not kidding.

Go to Bike Bandit. They have most of the parts.
There are many other suppliers now of these parts.
The dealerships do not care about your bike.

[flybox1]

sermon aside  here's the answer to your question.
dip her in flour and check for the wet spot! 

spray your engine down with simple green
wipe dry with paper towels.
repeat.

spray whole engine with spray talc. 
run it and 'look for the wet spot'

[lucky]

I just want to say that when you swap engines all you have done is traded one set of problems for a different set of problems that may be worse.

Now this OP may have an engine with a hole in the engine case under a lot of dirt and grease in the chain area OR a countershaft seal that is leaking and it may be the type that has to have the cases split to repair.
Maybe that is not the case.
But it is always best to repair YOUR ENGINE.

Remember any other engine you get is 40 years old and has degrading rubber rollers,
and other worn out parts.
IF you rebuild your engine you will have a NEW engine with new parts and you will know what you have.
There is a lot less stress when you know what you have.
It is an investment.

[lucky]

sermon aside  here's the answer to your question.
dip her in flour and check for the wet spot! 

spray your engine down with simple green
wipe dry with paper towels.
repeat.

spray whole engine with spray talc. 
run it and 'look for the wet spot'

With that much oil coming out it seems that you could actually see it.

[Mooshie]

+1 on spray talc (foot powder) just make certain you do not purchase the clear kind (obviously it needs to be white so you can see it).  If you go that way when you spray it on it will not look like any has been sprayed--it needs time to set up white (when it dries) so don't keep spraying (like I did--ha ha).  But it will point you in the right direction very quickly

[iron_worker]

FYI to Lucky: Cycle X recommends installing all their gaskets dry. So it depends what kind of gasket you're using.

IW

[Henning]

A quart of oil per 50 miles sounds like it is blowing oil out of the oil tank, the oil tank to crankcase hose is broken or missing, or you put too much oil in. First up, you need to check your breather hoses are per spec and the oil level is OK. Then you need to cross fingers that it's not blowing from the oil tank due to too much crankcase pressure on this new and unknown motor.

[LesterPiglet]

+1 on spray talc (foot powder) just make certain you do not purchase the clear kind (obviously it needs to be white so you can see it).  If you go that way when you spray it on it will not look like any has been sprayed--it needs time to set up white (when it dries) so don't keep spraying (like I did--ha ha).  But it will point you in the right direction very quickly

I bet Dash smells lovely though. 

[Mooshie]

Why yes he does Les, and no more bothersome Athlete's Foot on our long rides

[scottly]

A quart of oil per 50 miles sounds like it is blowing oil out of the oil tank, the oil tank to crankcase hose is broken or missing, or you put too much oil in. First up, you need to check your breather hoses are per spec and the oil level is OK. Then you need to cross fingers that it's not blowing from the oil tank due to too much crankcase pressure on this new and unknown motor.

1+ The tank to crankcase hose is a drain from the air/oil separator inside the oil tank.
 

[vrm]

The tank to crankcase hose was in place. I disconnected it and ran the motor. There was no visible vapor or oil coming out. I held my thumb on the end of the hose for about half a minute and a puff of vapor came out but it did not seem excessive and no oil came out. The inside of the hose has an oily film but is not dripping with oil. When the motor is running there is some vapor coming out of the breather hose by the right passenger foot peg. I don't know how much is normal but it is not enough to feel with your hand. I have never seen oil drip from this hose. I think the leak is farther forward than that anyway. I have had the bike running on the center stand in gear at 3000 rpm for as much as 15 minutes and have not seen oil drip anywhere. That is, of course under no load and without the jostling of the road. The right side seems wetter than the left. The area around the chain sprocket is completely dry and free of oil. It is not coming from that area. I am going to pressure wash the whole underside and try the spray powder method. I am also going to order new gaskets and redo that. While waiting for that I am going to take a break and ride my scooter.

[lucky]

FYI to Lucky: Cycle X recommends installing all their gaskets dry. So it depends what kind of gasket you're using.

IW

Almost ALL motorcycle gaskets are installed dry.
It is just a tradition in the motorcycle industry.
Sealer is applied to engine case halves but that is about it.
Even Harley Davidson puts most gaskets on dry, and sealer only on engine case halves.

[Phoenix]

VRM
Mine just did the same thing for the second time.  It is that hose to the crankcase.  You checked it at idle.  At speed, it covers the whole ass-end of the bike in oil.  Trust me-and others.  My hose broke at the connection this time. Last time it was not connected after a rebuild.  I'm replacing both hoses and putting hose clamps on the fitting.  Rubber felt really soft. Good luck.

[scottly]

Since you have posted a thread about your bike being on the road with no major oil leak, would you mind filling us in on the fix???
http://forums.sohc4.net/index.php?topic=126077.0

[Henning]

Hear hear!

[vrm]

Phoenix was confident that it was the vent tube and it was. I had attached it with the stock wire clamp and it looked like it was still attached but the hose blew off and the end was resting loosely on the fitting. A proper hose clamp, some twisting and grunting fixed that problem. I have ridden more than a hundred miles since then an the oil level has not dropped. The local biker gathering meets the first Sunday of every month. I'm looking forward to showing off my new toy.

[vrm]

Seems I may have spoken too soon. The vent tube is still firmly attached and oil is dripping off the back.

Again.

Not as bad as before but not good.

Dang.