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Post by yknot057 on Feb 15, 2007 21:19:01 GMT -5
Hi guys,
I have read the previous thread on wet sumping and it seems to finish right before the good bit ... or the bit that I think I need anyway?
I bought a broken '78 (SR) Cafe conversion some while ago and whilst I have got it all back together and running I am now at the stage that if left, even 24hrs, I lose all the tank oil into the sump. Starts fine, hydraulics and then spews oil from various gearshaft and other seals on a continuing basis....
The last post on the original thread hinted at a non-return valve or similar that is failing. I have read both my service manuals and they do not mention such an item or where it is located. What am I looking for, or have I misunderstood?
Always happy to learn from the experience of others and thank y'all in advance for your assistance.
Best regards
Steve Campbell
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Post by colinjay on Feb 15, 2007 22:35:17 GMT -5
Hi Steve,
The oil check valve is located on the inside of the clutch / R-Hand engine cover. If you remove this cover and look on the inside of the cover, just to the rear of the oil filter housing you will find the check valve assy.
CJ
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Post by yknot057 on Feb 17, 2007 20:12:36 GMT -5
CJ, ..... many thanks
Steve
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Post by wotavidone on Feb 20, 2007 19:03:14 GMT -5
Guys,
I've had a brain wave. You can call me a wanker if you want, I'll not take offence, but I was wondering...........
If you have a wet-sumping motorcycle, do you have to pull the engine to bits? Can you get some sort of in-line check valve that you could put in your oil return line?
Just an idea for a quick cheap fix which might keep you on the road. Could be all sorts of issues I haven't considered - I've never had the case off for a look - but thought I'd float the idea.
Mick
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Post by frankyb on Feb 20, 2007 20:17:06 GMT -5
Hi guys, heres my dollars worth on this wet sumping business. The check valve on the rh side is to provide a non return functionto the out side of the oil pump.The oil doesnt reservoir in the spine or down tube, just uses them as a big gravity fed oil line. Park the bike up and the oil will run to the lowest point, which is the crankcase. Start the bike and if the oil pump function is ok, and you have no air locks,(very rare) then oil will start to circulate at a speed dictated by engine rpm. Correctly these engines are a semi dry sump, which was yamahas way of increasing ground clearance in the original xt design. yknot, if your engine leaks constantly from all its seals, then your crankcase breather is giving you grief in all probability. If the seals dont leak when the motor isnt running, then they are probably ok. Ive used these engines a lot in the last twenty odd years, and i have never had a problem with an oil pump in any of them. Hopes this helps, cheers Franky b.
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Post by wotavidone on Feb 20, 2007 22:02:54 GMT -5
So - crankcase pressurisation due to a blocked crankcase breather will cause leaks past seals when the engine is running? I can see that.
And the non-return valve will only prevent the oil that is above the point where the line connects to the spine of the frame from flowing back? I can see that, too.
So if the oil in the down tube at the front of the frame runs back into the motor when the bike is allowed to sit, this is not due to malfunction of the non-return valve? I can see that, too.
I've had a look at the pictures of the oil pump, and it appears to be a positive displacement job that will not flow oil unless it is turning. So I have to conclude that if the oil in the front down tube runs back into the motor, this would be due to wear in that pump.
Do you agree FrankyB?
Mick
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Post by wotavidone on Feb 20, 2007 22:24:26 GMT -5
Another question.
A dry sump motor has to have two pumps doesn't it? Or at least two separate rotors on the same pump.
I'm thinking one to take oil from the frame down tube to supply pressurised oil to the engine, and another to scavenge the used oil and pump it back to the frame/oil tank?
Mick
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Post by StewRoss on Feb 21, 2007 5:56:19 GMT -5
Hi Mick, Yep, spot on...both on the right side of the engine beneath the clutch. There are the early type and later type...and maybe some modifications on the latest SR's...but I'm not aware of any of the changes there. The later ones (G&H as I recall) have an extra screw on the cover that ensures better sealing and less loss around the edges of the rotors... SR  |
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Post by miker on Feb 21, 2007 11:40:57 GMT -5
As someone who checks oil before and after every ride I can say mine has never pumped oil out seals/breathers, even when there's some oil down in the crankcase. Usually what I get is 30 seconds of moderate smoking. Wotavidone - just removing the rightside cover isn't "pulling the engine to bits", now, is it?  But you're right, you can get inline anti-wetsump valves and guys with old English bikes are the ones to ask about that. Some of them even put manual valves on their lines to prevent wet-sumping... and usually only forgot to open them once. miker |
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Post by frankyb on Feb 21, 2007 18:14:47 GMT -5
Hi guys. For Mick, if you strip out all the oil lines from the down tube back into the l/h side of the motor,the only thing you will find is an inline strainer at the bottom of the down tube. Where the return line dumps into the crankcase is a fair way from where the oil pump is sited, so i guess gravity has its wicked way when nothing is in motion. I know that the pump is billed as a double trochoid design, which means it scavenges as well as pumps internally. To the best of my knowledge it only deals with oil that is returned to the crankcase by gravity action, that is it probably doesnt have a real strong pump back capability. Miker if your getting 30 seconds of smoke then your valve guides and seals are slightly worn. No drama, at least you know theres oil in the head. Years ago it was common to put these motors in hagon slider frames to make a handy dirttrack bike. A lot of these motors were wet sumped by putting a banjo fitting where the neutral indicator sensor is, and fitting a custom oil line across the back of the motor under the carb from theoutlet fitting. I never recall seeing one of these motors die as a result of this mod. Most of them expired due to overly ambitious comp ratios and rocketship cam grinds. Cheers Franky b.
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Post by wotavidone on Feb 21, 2007 18:41:10 GMT -5
Yeah you are right miker, it ain't really pulling the engine to bits. I assume you can get the rightside cover off without moving the motor in the frame?
Its just I have this pathological dread of opening engines. You always find more than you bargained for.
Like the time my mechanic mate said, that sounds like big end knock Mick, why don't you just slip the sump off your old commodore and slip a set of big end bearings in. Should only take a day. So there I am just taking the first big-end shell off, when I kicked the sump pan over. Lo and behold, when the last residual oil drained away there's half a piston skirt.
Or just lately a guy at work who blew the head gasket on his torana asked me to give him a hand putting the heads back on. Everything else is fine he said.
So far we have re-installed the heads, found a stuffed lobe on the cam, fitted a new cam, timing gears and chain, harmonic balancer was split along the keyway, timing cover has a big chunk of alloy missing where the crank seal goes, he dropped a manifold bolt down the extractors, we found a bolt broken off in the block that the last mechanic decided to just do without, the heads have been shaved that much the flaming valley cover doesn't want to seal properly, etc.
It all puts me off, so I'm always looking for alternatives.
Mick
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Post by wotavidone on Feb 21, 2007 19:51:08 GMT -5
I've been thinking some more. d**n these headaches Anyway, when I think about it, I still think the cause of all the oil draining out of the frame and into the engine has to be as much to do with oil pump wear as it is with non return valve, as the non return valve is only working the outlet side, and the only thing stopping oil gravity feeding from the front down tube is clearances in the oil pump. But, I reckon Frankyb is right with regard to smoking for 30 seconds or so. You would have to think this is valve stem seals. The old XT I bought had been sitting for 2 years. There was no visible oil in the tank, but I decided I would risk running the motor for a couple of seconds. As soon as I ran that motor, all the oil pumped out of the engine and filled the frame up again. My point is, even with all of my oil down in the engine, the motor did not blow any smoke on start up, its just happily pumped all the oil back where it belonged. It now stays where it belongs - unless maybe I let it sit for another two years. Now it seems to me that this might not be Steve Campbell's problem. Steve, did I read it right that your engine "hydraulics"? Do you mean it seems to lock up due to the amount of uncompressible oil in the engine? Have you drained every last drop out of this engine? And put back in only 2 litres. I'm just wondering if there is some way this baby is actually overfull? Like maybe it had an engine full, and then you topped it up on the dipstcik because you did not realise all the oil was still in there, just not where you expected it to be? Just looking for possibilities. Like I said, I'll try anything before I give in and open an engine. Mick |
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Post by miker on Feb 23, 2007 10:47:00 GMT -5
Wotavidone - LOL! Piston skirt in the oil pan... ouch!
Frankyb, I've been assuming my startup smoke is not guides/seals because it only occurs when I haven't ridden the bike for a week or so *and* the oil tank level is low (because of draining into the engine). If I ride it every 3-4 days I never have smoke and never see a significantly low oil level. Sometimes the oil level indicates no drainage even tho the bike has sat for a while, and then no smoke either.
miker
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Post by frankyb on Feb 24, 2007 20:18:20 GMT -5
Hi Miker, is it blue smoke or black smoke? If its blue then its oil burning, and that can only happen when oil gets into the combustion chamber. If it smoked all the time then it would be blowing back past the rings, but thats not happening. So the only other way that oil can get into the chamber is past the seals and down the valve stems, while the motor is at rest. If it gives a couple of puffs of black smoke on startup then its running alittle bit rich of the bottom of the throttle, which isnt a bad thing either. Cheers Franky b.
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Post by miker on Feb 26, 2007 11:19:04 GMT -5
Frankyb - blue smoke. My assumption is that when sufficient oil gets in my sump it causes a little blowby but not enough oil there to come out the breather or seals.
I guess I just feel like seal/stem leakage would be more regular. Last year the smoking thing happened maybe four times over the whole summers use.
miker
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But you're right, you can get inline anti-wetsump valves and guys with old English bikes are the ones to ask about that. Some of them even put manual valves on their lines to prevent wet-sumping... and usually only forgot to open them once.