GT500 oil leak.

GT500Andy · Post by **GT500Andy** » Tue Nov 03, 2009 2:26 pm

After having my crankshaft rebuilt with all new parts and rebuilding the engine its leaking oil on the ignition side. I’ve renewed the seal thinking it was a bad seal but with no avail. When I took a close look it seems like its leaking between the bearing and the casing. I can see no oil on the seal just a drop on the edge of the bearing and on the lower part of the casing. It doesn’t seem to leak when running stationary, only after riding for a few miles. Does anybody have any experiences with this problem or idea’s
Andy

Craig380 · Post by **Craig380** » Wed Nov 04, 2009 9:59 am

How much is coming out, is it just a drop or two? What's the spark plug colour like on the left cylinder, is it much different to the other side?

If the plugs look good and similar then it probably isn't sucking air ...

Post by **Suzsmokeyallan** » Wed Nov 04, 2009 12:22 pm

Well if its leaking there you have two choices, option one,,pull the engine and fix the issue OR???
Lean the bike over on its right side carefully so no more residue will ooze around the bearing then carefully clean the area of all residue with some carb cleaner etc and apply a smear of JB weld around the joint between the bearing and the case.
Take your time and do it neatly so it looks like a caulking bead run in with your finger.
Let it sit overnight and then try running the bike again, if it holds youre in business, if not well option number one kicks in full time.

Suzukidave · Post by **Suzukidave** » Wed Nov 04, 2009 12:59 pm

Do the 500 crank bearings have the hole for a pin like the 760's ? if yes could it be possible you didnt locate that bearing on its pin correctly and its keeping the bearing from seating ?

rbond · Post by **rbond** » Wed Nov 04, 2009 2:10 pm

Sounds like the 'o' ring may not be seated or is torn. I like jb-weld too, but for this, IMHO it would be better in the long run to pull the engine and check the '0' rings. Put some hylomar on them and the case halves should seal everything wonderfully. I know that's my plan when I do my GT500.

Post by **Suzsmokeyallan** » Wed Nov 04, 2009 2:15 pm

Its only a suggestion to use the JB weld to see if the leak is in fact coming from that location. Once you have verified it you can consider your next course of action.
If it holds for now then good, until you can get in the mood to strip the motor out again.
If not, pull the cases and investigate further.

GT500Andy · Post by **GT500Andy** » Wed Nov 04, 2009 2:56 pm

Thanks for the replies the plugs are the same light brown color. Compression is 10Bar on both sides
. I don’t think that the dowel pin is miss located seeing it’s on the bottom half, and the crank was laid in first and checked before putting the top half on.
May be the o-ring ? But the oil runs through the bearing doesn’t it. must be 2 stroke oil
Andy

rbond · Post by **rbond** » Wed Nov 04, 2009 3:06 pm

No, the oil leaking is most likely transmission oil. The 'o' ring is mainly to seal that oil from the crankcase and the outside world. There is a small chance it is 2 stroke oil, but that would be from the crankcase from where the the oil is being pumped to the crank bearing. If it is an improperly mounted or damaged 'o' ring, there is a strong chance it will get worse with use and you would still have to split the case to fix it. Do it now and get it over with so you can enjoy riding and not worrying about an oil leak and possible trans. problems too.

Post by **Suzsmokeyallan** » Wed Nov 04, 2009 3:30 pm

You stated its the ignition side in your original posting therefore its 2 stroke oil and not transmission oil youre seeing..

tz375 · Post by **tz375** » Wed Nov 04, 2009 5:41 pm

Now I'm confused. If we are talking crank bearing there should be no oil between the bearing and the cases unless the crank is sitting on the pin. And even then, no oil should get past the seal which is outside that bearing.

if we are talking the Countershaft seal, that could be the O ring behind the spacer or again the bearing sitting on top of the pin.

If it's a bearing sitting tall, there should be a gap between the cases and a visible gap under the bearing - between the bearing and the case.

Forget JB Weld this time. I understand that Allan was suggesting it as a testing technique rather than as a solution, but I wouldn't go there.

I'd push a feeler gauge into the slot and see where the gap is. It sounds like there's a 99% probability the motor will have to pop out and be stripped again. The good news is that it is much easier to strip and build a clean motor than an old dirty one.

Suzukidave · Post by **Suzukidave** » Wed Nov 04, 2009 6:19 pm

Ah , now i understand the O rings yall have been talking about #24 http://www.ozebook.com/compendium/gt500 ... arts41.htm

Post by **Suzsmokeyallan** » Wed Nov 04, 2009 6:29 pm

On a Titan fluid can get pass the bearings outer race if the o-ring on the bearing is bad.
Since the crank oil seals sit inside the face of the bearings, therefore the o-ring is the only source of sealing the bearing to the case.
I would strongly suggest any installation of the main bearings into the cases should have some sealant CAREFULLY placed around the o-ring section of each bearing.

bikegeezer · Post by **bikegeezer** » Fri Nov 06, 2009 6:58 am

GT500Andy wrote:After having my crankshaft rebuilt with all new parts and rebuilding the engine its leaking oil on the ignition side. I’ve renewed the seal thinking it was a bad seal but with no avail. When I took a close look it seems like its leaking between the bearing and the casing. I can see no oil on the seal just a drop on the edge of the bearing and on the lower part of the casing. It doesn’t seem to leak when running stationary, only after riding for a few miles. Does anybody have any experiences with this problem or idea’s
Andy

Andy,
I had the same problem with my GT500. Tore the engine back down twice and couldn't see any problems. I even tried the JB Weld trick, but it still leaked. It turned out to be a burred edge on one of the oiling holes on the bearing OD. Couldn't see it without a magnifier, and I could barely feel it with my finger. But it was enough to allow two stroke oil to seep over the O ring at that point. A couple of turns by hand with a chamfering tool cleaned it up and has stopped the leakage.

Stu

GT500Andy · Post by **GT500Andy** » Fri Nov 06, 2009 9:41 am

I tend to go with the theory from Bike geezer. I know its 2 stroke oil because transmission oil would only get there if there’s a crack in the inner casing. The oil seems to be pushed out under pressure with higher revs. With stationary running there was no leak, only after doing a few miles and re-removing the ignition plate I saw oil. I’m going to do a pressure and vacuum test to see if I can see it leaking only problem is the engine block will be cold.
I have tried to upload some photos; they are from the first time, before I replaced the seal. Note red grease around the circlip was done by crank specialist.
http://www.album2.com/events.php?action ... 4b72e66f75
Andy

bikegeezer · Post by **bikegeezer** » Fri Nov 06, 2009 10:02 am

GT500Andy wrote:I tend to go with the theory from Bike geezer. I know its 2 stroke oil because transmission oil would only get there if there’s a crack in the inner casing. The oil seems to be pushed out under pressure with higher revs. With stationary running there was no leak, only after doing a few miles and re-removing the ignition plate I saw oil. I’m going to do a pressure and vacuum test to see if I can see it leaking only problem is the engine block will be cold.
I have tried to upload some photos; they are from the first time, before I replaced the seal. Note red grease around the circlip was done by crank specialist.
http://www.album2.com/events.php?action ... 4b72e66f75
Andy

Can't see your photos, because you haven't made them public. You'll see the oil leak if you pump 6 psi into the crankcase to pressure test it. There'll be a few small bubbles visible around the OD of the bearing, probably around the 1 o'clock position.

GT500 oil leak.

GT500 oil leak.

Re: GT500 oil leak.