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1984 VT750C Oil Issue

2K views 22 replies 8 participants last post by  1984shadow750 
#1 ·
Hi, I checked the oil in my bike today and it was a little low (estimate 300ml) from the oil change I did about 400km ago. I don't see any leaks and I don't see any oil burning when starting up or riding, at least to my ability to look and ride at the same time. Do these bikes normally use oil as you ride them or should I be concerned?

Do I just need to top it up as it gets low? Is there a typical problem area I should be looking into?

Thanks for any and all help.
 
#5 ·
Thanks guys for all the input so far. Yes, the bike was on center stand and the oil was check about 5 minutes after a 45 minute ride. I bought the bike with 31,800km and now it has 32,200km. I did an oil change as soon as I got it and used Amsoil 20w50 synthetic. I used the amount specified in the service manual which put it just over half way on the hash marks after a 30+ minute ride checked on center stand. When I checked the oil last which was about 30 minutes before starting this post it was just below the hash marks. Maybe I should have let it sit a little longer before checking, but I figured 5 minutes was plenty of time for gravity to pull the oil back to the bottom of the engine. I have not check the plugs yet, but will when I have time later.

I did buy a new set of plus when I bought the bike, but have not had a chance to put them in yet. When I bought the bike, I changed the oil, changed shaft drive oil, changed radiator antifreeze and fuel filter. I do this with every vehicle I buy so I know where I am at from the onset of owning my vehicles and toys. I did get at the plugs as I did with the fluids because the bike is running good and since the riding season is almost over I was not in any panic to change them yet.
 
#7 ·
If you changed the oil filter at the same time as the oil change you need to allow for the new filter to fill with oil. It seems you only added oil per the non-filter change specs which would explain you're low oil level on the dip-stick. With the bike on the center stand add a little bit of oil at a time to the crankcase to bring the level just into the lower hash marks.
 
#6 ·
Someone please correct me if I'm wrong, but isn't the oil supposed to be checked in the vertical position while down on 2 wheels? Dipstick only inserted to the threads and not threaded in? Seems the son's old magna was to be checked that way.
 
#9 ·
You are correct but the factory maintenance stand keeps the bike vertical with a slight forward tilt much unlike leaning on the kickstand which will skew the oil level check.
 
#10 ·
The thing is after I did the initial oil change I rode the bike for over 30 minutes, plenty of time for the engine to warm up and the oil to circulate since it says to check the oil on center stand when the oil is warm (fully expanded) and the dipstick not screwed in. I then checked the oil and it was just above the halfway point of the hash marks and the filter would have been full. Then after 400km I checked it again and it is just a hair below the hash marks.

So even if I only put enough oil in for the engine without filter it had time to fill the filter after my first ride giving me the reading half way up the hash marks, if everything was the way it should be after 400km it should still be at half way up the hash marks, but it is just below.

I do not see any visible signs of leakage and when I start it up I do not see any smoke nor any while riding which is what is confusing me. I will go for a short ride to warm up the oil and then top up the oil as mentioned and go for a short ride to make sure it is all the oil is warm again and then monitor it again and see what happens.
 
#18 ·
I will go for a short ride to warm up the oil and then top up the oil as mentioned and go for a short ride to make sure it is all the oil is warm again and then monitor it again and see what happens.
Top it off before you go for a ride and the engine is cold. You don't want heat expansion or oil still draining back down into the crankcase to affect your reading.
 
#13 ·
Then after 400km I checked it again and it is just a hair below the hash marks.
"a hair" is not something to worry about. That amount may have leaked out through the shifter rod's seal or by evaporation or by the inhaling/exhaling of the breather tube.


Well, the oil just doesn't disappear.
it definitely does. There's been intervals where I've found the oil level a pint low for none of the obvious reasons.
 
#14 ·
"a hair" is not something to worry about. That amount may have leaked out through the shifter rod's seal or by evaporation or by the inhaling/exhaling of the breather tube.




it definitely does. There's been intervals where I've found the oil level a pint low for none of the obvious reasons.
Well, It didn't disappear any more than Houdini did. If it was gone and not leaked, you used it through combustion.
 
#20 ·
Hey Ron, what I meant was instead of it being just above the half way point of the hash marks (when I changed oil) it was a hair below the hash marks so about 3/8 of an inch on the dipstick low.

The mysterious oil missing has been solved. Before I even started the bike up (sitting for 2 days) I checked the oil and it was exactly on the bottom of the hash mark ( bike on center stand dipstick not screwed in on level ground in my garage).

I went for a 60+ minute ride. I parked it in the garage, put it on the center stand and instead of waiting 5 minutes I waited 12 minutes and the oil is exactly where it was when I changed the oil now 470km ago.

Apparently checking the oil after 5 minutes doesn't give it enough time for gravity to pull all the oil back down. Mystery solved and happy it is not burning oil or leaking any for that matter.

Thanks for all the suggestions and input.
 
#22 ·
Hey Ron, what I meant was instead of it being just above the half way point of the hash marks (when I changed oil) it was a hair below the hash marks so about 3/8 of an inch on the dipstick low.
Copy that. Actually I realized you meant "a hair" below the 'lower hash mark' abate after hitting the submit comment button, lol.

I went for a 60+ minute ride. I parked it in the garage, put it on the center stand and instead of waiting 5 minutes I waited 12 minutes and the oil is exactly where it was when I changed the oil now 470km ago.

Apparently checking the oil after 5 minutes doesn't give it enough time for gravity to pull all the oil back down. Mystery solved and happy it is not burning oil or leaking any for that matter.
My opinion on this is it's a sign that the oil is too old or most of the oil is too old. That is, the slug makes it take longer to settle down to the crankcase. Had this same problem last week. After 5 minutes, the oil level registered a certain height on the dipstick. Then after checking the level in half a minute later intervals, the level on the dipstick rose higher making me wonder if I actually overfilled the darn crankcase. So I drained the oil, put 4 quarts of NEW oil in (Valk), and the oil level that was registered after resting 5 minutes never rose above that. Nothing scientific.
 
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