Right cyl. still not smoking

[Eddie]

Well I have gone throught everything like I have mentioned in other threads (oil pump, lines,etcc) and the right cyl still does not smoke like the other 2, Im wondering how long will it run without seizing if its not getting oil? I rode it about 50 miles and 40 of those was at about 80mph, I was thinking if it was going to seize it should have done it then right? I was going to run pr-mix but then I started thinking maybe I should run it like this and see if it does seize, that way I know for sure theres a problem, so when it does get rebuilt I need to figure out why its not oiling, If I run pr-mix and then later I rebuild it, it may still have the same issue annd that would reallly be bad, what do you guys think? I will not aske about this anymore I know im beating a dead horse now so this is the last time ,,,,I promise.... just thinking i should run it the way it is and see what happens, its going to be rebuilt eventually ( i hope)

[pearljam724]

Make a video and post it on here, bud. Pay someone to look at your cylinders and rings. A diagnosis of that first should be cheap. If they pass. Get the seals replaced. Remembering how old those original parts are it would be beneficial to do each when ever you feel is feasible. A video would help a lot. Record it when you start the bike and the motor is cold. If that one cylinder smokes, even though its less than the other 2. Its getting oil. That being said and all the other info you shared. I think its your cylinders and rings. Which is not detrimental either. As long as its fixed and that cylinder is getting oil. Another easy thing you can do is remove your exhaust. Shine a light inside the ports. You'll be able to see the pistons. Compare the ones to the one smoking less. If that cylinder is starving of oil the piston should be scared more than the others. Rotate the motor with the kick start and look them over. That or remove the cylinder head. But, if you do that you'll have to replace a 80 dollar gasket. Even though you'll get a better look. That wont be a diagnosis of the rings though.

[pearljam724]

How many miles do you have ?

[Eddie]

I just hit 15,000 miles, so pretty low mileage, i had looked in the cyl that doesnt smike when I had the exhaust off and it did seem scared but i did not compare it to the other, Im going to work now so I wont be able to take a video, but I will eventually it might be a while though becAuse im working alot now, plus I keep forgetting to take a video thats the biggest problem! my memory!!!! i think either one cyl is not getting , or the other two are burning to much oil!! so that being said im no closer to figuring it out, but when it is rebuilt I will replace everything for sure dont want to do it twice or three times, just once and replace everything, seals, pistons, rings, crank bearings, waterpump, everything that I can all at once, iv been buying stuff little at a time, so far I have two comlete gasket sets, 1st over pistons, rings, pins, I have a newtronics kit coming, and all i need is crank seals and waterpump...... I would like to know for sure whats wrong with it now before it gets torn down, but maybe ill have to tear it down to find out..

[pearljam724]

Like you mentioned with the buying of those parts. Have those ready for a complete rebuild should it take a crap. Knowing the original parts are old and perhaps worn. In between now and then. Add the oil to the fuel also. Ride it, enjoy it, maintain it to the best of your ability. Hoping to stretch it further. And dont worry as much about it. I suggest rebuilding all those things at once, like you said. For all we know. It could have that behavior for an additional 30-50k miles before it peters out. Or out live you. Lol ! I worry about those things too. But, then I stop to realize. At these bikes ages. Im thankful mine runs. Period. Lol!

[pearljam724]

Is it the middle cylinder your referring to ? Cause I'll tell ya. Both of my bikes smoke far less out the lower pipes. But, when I first got my 750. The right pipe smoked far less. I checked everything and ran it very often. And like I told you earlier. That went away.

[oldjapanesebikes]

I would like to know for sure whats wrong with it now before it gets torn down, but maybe ill have to tear it down to find out..

Have you actually checked to see that oil is or is not being pumped ? There are several easy ways to do this eh ? The easiest is to just hold the pump lever open and watch for increased smoke. Another is to introduce some air bubbles into the injector lines and then start up the engine and again hold the oil pump lever open - with the oil line cover removed you will be able to watch the bubbles get pushed along. Note that they do not all move at the same rate. If you can see the bubbles being pushed along in all the lines, then you do have oil being injected. Yet another way way is to use a different colour of injector oil - do the same thing again with the lever held open and watch to see the colour change in the lines.

Once you know oil is going in all three cylinders, and at similar rates (three lines will be faster, three lines will be slower) then you can start to thinking about why the left and centre are smoky rather than why the right isn't

[pearljam724]

Ian, I have a question for you. Do you have to have all lines completely filled in order for the pump to affectively start pumping the oil when you reinstall the lines ? Or should the pump be able to easily start the process even though a line could be empty and have air in it ? Not referring this to Eddie's problem, just something I have run across.

[oldjapanesebikes]

Do you have to have all lines completely filled in order for the pump to affectively start pumping the oil when you reinstall the lines ?

There are other folks on this board I'd consider to be far more expert than I am, so take what I say with a grain of salt :

a) you do need to ensure the mid-1973 and later pumps are bled to ensure they do pick up suction - on the GT750 pumps there is a bleed screw for doing this easily - if it has been bled (note that the 1972 and early 1973 pumps were a different design eh ? - see Richard's page at this link for details) and there is a bit of head pressure then if it is functional it will pump

b) whether the output lines are full or empty doesn't affect the pump's performance one way or the other - these are positive displacement pumps eh ? If they are working, and if they have suction then you can't stop them from pumping. But then why would you start up a rebuilt engine dry ? So you should have oil in the discharge lines, and I also ensure I can pump oil into the injector points (using injector oil from an oil can) before I connect the lines up to the banjo's. This allows you to be certain that the passageways are open and clear, that the gasket has been installed correctly and that no sealant (if you've used any on the gaskets - I don't - just on the crankcase halves) has partially plugged an oil way. A few air bubbles are good as they let you clearly see that oil is moving.

Just my tuppence worth.

[pearljam724]

Im not too sure about that. I mentioned to Eddie my bike smoked less on one cyclinder just like his when I bought it. The po had the oil tank off and regular motor oil in it, etc. I mentioned, I bled the pump of air, changed plugs, put correct oil in and ran the bike often and it stopped smoking less on one cylinder. My point is, being that corrected my problem and the manual states anytime the lines have air induced you must bleed the pump to get the suction going. Therefore, I would think the lines can not be empty. Because the line is full of air. Someone correct me if Im wrong.

[tz375]

Ian is correct. Think of the pump as having two "sides" input and output. Bleeding the pump clears any air bubbles out of the feed side. I allows oil from the tank to flow into the top of the pump and out of the bleed screw when it's cracked open.

On the outlet side, the pump is capable of pumping oil even if there are air bubbles. To give it an easier time, it is better to fill the oil distribution manifold aka the octopus with clean oil.

On an old bike it is quite possible that the wrong oil has been used or that one of the check valves may be clogged or stuck open. I would recommend that you disconnect the tank from the pump and drain the old oil of the tank. Then remove the oil pump and the cover over the oil lines.

Get two bottle of oil. One colored two stroke oil and the second, any oil with a different color. It can be 4 stroke motor oil, or a different brand of 2 stroke oil.

Get a hand oil can and pump the "second color" oil by hand into each of the 6 oil feed lines. The fresh oil should displace the oil in each line with little effort. It can be difficult to seal the oil can against the oil manifold and I find that putting the O rings back in their holes helps enormously.

Leave the bike for at least a couple of hours and see if the oil drains out of any of the lines into the engine. If it does, that's a sure sign that the check valve is sticking open. If all goes well, re-fit the pump and connect the oil tank and add the new oil to the tank- as long as it's a different color all will be well for the next step.

Start the bike and run it around the block or let it fats idle with the pump lever wide open. Within a few minutes the oil should change color as the oil from the tank replaces the oil in the lines. As the motor warms up it should start smoking profusely from all 4 pipes.

If one or more lines fail to change color, it means that something is blocked in the pump. If no lines change color pop the pump off and see if the drive pin fell out.

let us know how that works for you please.

[pearljam724]

This is a far reach. I had my lower pipes off to clean them on my 550. I heard something strange in one handling it. It turned out to be a huge wad of fiberglass packing. Similiar to whats wrapped around the baffles. But, mine has no baffles and they were all in tact when I removed them. I dont know if the larger pipes have this or 750's. That could possibly cause less smoke. So, could severe carbon build up. Mine was trapped in between the baffle chambers. You may not see anything shining a light in there. You may have to remove and shake the pipe. Its worth checking.

[Coyote]

My point is, being that corrected my problem and the manual states anytime the lines have air induced you must bleed the pump to get the suction going.

Suction? These pumps are not capable of sucking anything. Oil is fed to the pump by plain old gravity. These pumps only push the oil along as it is gravity fed by the tank. You could never mount an oil resiviour lower than the oil pump inlet. It won't oil period. Also there is a tiny vent in the oil tank cap to allow air in as the oil drains out. If the pumps had any suction, and that little vent got clogged, it would turn your oil tank into a pancake.
It would be nice if they had suction. There would be no need for the 6 pesky check valves.

[pearljam724]

You know what I meant. But, you had to bust my balls. Ah ha!

[oldjapanesebikes]

Suction? These pumps are not capable of sucking anything. Oil is fed to the pump by plain old gravity.

Chris - actually the pumps on the J and early K engines had a third plunger on the intake side for suction - in theory (note 'in theory' ), if you blocked the vent hole on the injector oil tank and of course if the line were primed to the pump, then it should be possible to suck the tank flat. Not something I'd recommend as it would more probably suck the feed hose flat first and you'd also need perfectly sealed connections. From a practical stand point in general, and specifically for mid-1973 pumps onwards you are correct as the design had just 2 plungers on the discharge side and so needed the head pressure of the oil in the tank, and all model year pumps need the suction side bled for it to work.