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Post by lain on Apr 14, 2015 10:52:43 GMT -5
So, I noticed I have been losing so much freakin oil lately that I have been gettin oil every week now! So I've decided to finally do a teardown and I ordered some new gaskets.
Unlike the last time this was this much of a problem, I do not seem to be burning oil, just losing it. I am thinking it may be coming out of the valve cover drain hose since I can smell it at high revs under load while on the road, but it smells hot but not burning. It is not a problem at lower RPMs or if I keep around half throttle.
I found gasket pieces in my oil last time I did the change so I am thinking the base gasket tore or something, I don't even know. Once I get the new gaskets and tear down the head I will find out though, but if it is not the head or base I am not sure what it could be since I have not taken anything off the crankcase so those gaskets should still be intact. Plus the gasket pieces I found looked like they were too new to be one of the original gaskets.
What can I use to make my next gasket set stick and seal real nice for a long time?
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Post by urbanmadness on Apr 14, 2015 14:55:39 GMT -5
Just something to check.... check the valve cover gasket. If they have been reused a couple of times, they tend to leak. Not only that, they are easy to pinch if it slips while you have the valve cover off.
When a valve cover gasket leaks, usually the oil will leak down the air shroud on the bottom of the cylinder and from there either blow around all over the place or drip by the exhaust opening in the shroud.
I can't see how a base gasket would make it leak thru the valve cover breather.
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Post by scooter on Apr 14, 2015 16:01:52 GMT -5
When I got my first scoot it was blowing oil all over the engine bay. I adjusted the timing and put the valve cover back on with sealant. It did fine for about a day and then leaked again. I put a new valve cover gasket on and sealant, and it started leaking at the base gasket. I put a new base gasket on and it started leaking out of the valve cover again. Finally, I loosened up the exhaust valve from .004 or .005 to about .006-.007. It clicked some but the leak stopped.
I guess my valve was too tight and was opening too soon or staying open too long and pressurizing the case.
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Post by urbanmadness on Apr 14, 2015 16:10:48 GMT -5
I was trying to remember if valve clearance on the exhaust valve would cause over pressure of the crank case. In any event, it's something else for him to try.
It would also mean it would be harder to start, and I know when I had my 150, as that valve tightened up, it didn't like to idle as well when it was cold.
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Post by lain on Apr 14, 2015 17:28:20 GMT -5
I was trying to remember if valve clearance on the exhaust valve would cause over pressure of the crank case. In any event, it's something else for him to try. It would also mean it would be harder to start, and I know when I had my 150, as that valve tightened up, it didn't like to idle as well when it was cold. Well it currently idles well, but it does have starting issues after it's warmed up. I need to rev it to start it usually. I'll have to check the valves later, just got home from a long ride so they are too hot to adjust atm |
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Post by lain on Apr 15, 2015 12:20:49 GMT -5
When I got my first scoot it was blowing oil all over the engine bay. I adjusted the timing and put the valve cover back on with sealant. It did fine for about a day and then leaked again. I put a new valve cover gasket on and sealant, and it started leaking at the base gasket. I put a new base gasket on and it started leaking out of the valve cover again. Finally, I loosened up the exhaust valve from .004 or .005 to about .006-.007. It clicked some but the leak stopped. I guess my valve was too tight and was opening too soon or staying open too long and pressurizing the case. Well .006 and .007 seem kind of excessive to me, but what's the worst that can come from slightly large gaps? wearing down the tappets? I have spares so I'll be fine I'll check this out today. |
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Post by onewheeldrive on Apr 15, 2015 16:23:57 GMT -5
Just more unnecessary wear having extremely loose valves. It may not even run all that great on top of that.
.004" made my scoot perform worse. I can't imagine .006"-.007" on a 139qmb engine.
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Post by JerryScript on Apr 15, 2015 16:40:32 GMT -5
.007-.008 is recommended on the engine info plate on both of my scooter, but I find I get the best performance at .004-.005
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Post by lain on Apr 15, 2015 16:50:51 GMT -5
Seems to idle fine and start fine with gaps at 0.006 and 0.007. Will see how it does on the road soon.
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Post by scooter on Apr 15, 2015 16:51:49 GMT -5
Just more unnecessary wear having extremely loose valves. It may not even run all that great on top of that. .004" made my scoot perform worse. I can't imagine .006"-.007" on a 139qmb engine. I see that's a 50cc. I don't know if it matters. I'm not telling him what to set his at, just that mine seemed to be too tight at 004-005. |
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Post by onewheeldrive on Apr 15, 2015 17:03:31 GMT -5
Just more unnecessary wear having extremely loose valves. It may not even run all that great on top of that. .004" made my scoot perform worse. I can't imagine .006"-.007" on a 139qmb engine. I see that's a 50cc. I don't know if it matters. I'm not telling him what to set his at, just that mine seemed to be too tight at 004-005. I understand. Personally I set mine to .003 inches for both. The recommended on mine is .002 inches or about .05mm. Oh well whatever works, lol. |
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Post by urbanmadness on Apr 15, 2015 17:18:28 GMT -5
It differs a little from bike to bike. Loose valves are better then tight valves. Just know that if they are set too loose, they are more likely to break valves if run hard and they don't make is much power. You might end up with a little more low end, but you will be lacking on the high end.
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Post by lain on Apr 15, 2015 19:56:28 GMT -5
Seems to run the same but my starting issues went away! Sweet. I do not feel comfortable with the clicking noise though, I will try 0.005 and 0.006 tomorrow.
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Post by geh3333 on Apr 15, 2015 23:43:15 GMT -5
I hope you get I situated lain . you should be able to at least see some oil dripping if its leaking out that fast. I would wipe everything down , go for a ride , then check everything again. However I do believe you are in need of another tear down unfortunately . just be very careful this time , and do everything by the numbers. I would even record the tear down and build , so you can go back and make sure all was done properly. And so we can watch some of it ☺
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Post by urbanmadness on Apr 16, 2015 9:46:01 GMT -5
What style feeler gauges are you using?
I use "go no go" type gauges. Each leaf has a step in it so the tip, where you take the measurement is say .004" and the rest of the feeler "leaf" is .006". They really help to get it right. especially if you are working in a difficult to get to place, Like when you adjust valves on a scooter. You make it to where it just slides in the measurement portion on the leaf, and stops when it hits the step.
Of course I've adjusted so many valves that I do it by feel, then confirm it with the gauge. When I had my 150, I set both valves at .004" and it seemed to happy. It's where I set most 150's when I was working on them. Before they left my shop, I'd run them up to operating temp and if I thought it was too quiet, or too loud, I'd set looser or tighter accordingly.
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