Some have had luck with seafoam in the oil. Others will chime in that have used it.

 

I would drain the oil, change the filter, put in 4 quarts of 20w50 oil, and some Seafoam. Seafoam has worked for me before for cleaning oil sight glasses. Oil that is too thin can cause low oil pressure, though a worn engine with loose bearing clearances will also cause a drop in oil pressure. There might also be a problem with the oil pressure sending unit. If the engine has not been properly maintained, and has sludge in it, the oil pressure sending unit could be full of sludge. I would remove the sensor and use some spray brake parts cleaner to try and clean it.

 

Is the thicker oil also part of the recipe or is it only the oil that you usually use? I normally use 10W40.

i will change oil filter and all. Are you suggesting to leave the Seafoam in the system? and not drain it afterwards?

I got the Liquid Moly engine flush shooter and that is not supposed to be left in.

The sludge in the system could actually very well be.

judging by the picture I sent, do you reckon I have a lose seal, or is it just overfilled?

 

Seafoam worked to clean my stupid window. About an ounce per quart of oil and run it for a couple hundred miles and change it. This is with the oil that is in it. I use 10w40 Valvoline motorcycle oil for wet clutches. It sounds like you're overfilliung it due to the leak. Dunno. Good luck.

 

I have always used 20w50 oil in every motorcycle I've ever owned, for the past 40+ years. For two reasons. I live in Arizona, U.S., where summer temperatures often exceed 110 degrees F, and winter temperatures rarely drop below 40 degrees F. The other reason is that motorcycle engines put a lot more load on oil than most car engines do, and higher viscosity oil has more load bearing ability than thinner oil. I see that you are in Germany, which is going to have much lower temperatures, so 10w40 oil might be ok.

How many miles does your bike have on it? If it has super high miles, it will have some engine wear. As an engine wears, internal clearances become larger, and oil pressure will drop. Also, thicker oil helps fill in those worn clearances and help prevent metal to metal contact. I've had three Vulcan 750s, the second one had over 108,000 miles on it before a cam chain broke and destroyed the engine. I used 20w50 oil, and changed it every 3000 miles. It never had an oil leak. Considering where you are, if your bike doesn't have high mileage, 10w40 should work ok.

Is your bike leaking oil bad enough to cause the oil level to be low? If the engine is overfilled with oil, the oil level can be high enough for the crankshaft to hit the oil in the sump, which can damage the engine. If the oil pressure light comes on while decelerating, that could indicate a low oil level. When you decelerate, the oil in the engine moves to the front, and could cause oil starvation at the oil pump pickup.

If oil is leaking around that elbow between the right engine cover and front cylinder, it will not be easy to fix. That is a coolant pipe, and removing it requires removing the entire right side engine cover. If the leak is not bad, it might be possible to clean the area where it is leaking really good, and put some sealer around it. Oil in that area in not under pressure, it's just splashing against that area and seeping through.

As for the sight glass, I would still change the oil and filter, you can go ahead and use 10w40, and put exactly 4 quarts of oil and put in 4-5 ounces of Seafoam. The reasons for changing the oil before adding Seafoam is because the oil that is in the engine is already dirty, it would be better to start with clean oil, plus if the sight glass is not usable, you have no idea how much oil in in the engine. If you put exactly 4 quarts, you will know that you have the correct amount of oil.

I would then run the bike for as much as 500 miles before changing the oil. If you still can't see the oil level in the sight glass, then drain the oil, put in 4 more quarts of new oil, and more Seafoam, and ride it some more. If you changed the filter when you first changed the oil and put in the Seafoam, you can just remove the filter, pour out the oil, and reinstall the same filter. 500 miles will not be enough to plug up the filter.

While you are at it, I would still remove and clean the oil pressure sending unit. If there is sludge in the sending unit, that would likely cause an inaccurate reading. The oil pressure sending unit is located on the engine case on the upper right side of the oil filter.

 

@VN750Rider/Jerry here we go again. You rant on about how the engineers design things like airboxes and exhausts for optimal performance and they shouldn't be messed with yet you do things like remove a front brake caliper and recommend a thicker oil than stock? The VN750 is designed to run 10w40 even in higher temperatures and during the higher loads you claim, which motorcycle oils are designed for. As for the higher loads, a motorcycle weighs a lot less than a car and are built for higher RPM usage than cars. And you tell @Andrea_on750 that they should be ok running what the factory recommends? The oil light, if you read the initial post, goes out when @Andrea_on750 adds oil, meaning that the oil light comes on because the oil is low, NOT because of internal wear. @Andrea_on750 keep on running the 10w40, as hundreds of thousands of other VN750 owners do. Here's a question for you @VN750Rider/Jerry , Would you use Dr. Pepper in your master cylinder if someone said that it works?

 

@VN750Rider/Jerry I have had three vn700's. I have also done more research on these bikes than a human being should. I've tried 20w50 in all three. With 20w50, all three had rougher shifts, ran rougher, and all three developed the coffee grinder syndrome. Others have also complained about the above three side effects of 20w50. A lot of people have had good luck with Rotella 15/w40, which is JASO approved to run in a motorcycle. I highly advise against olive oil. Your bike might smell great running on it for a few minutes, but I highly doubt that your main bearings will be happy for very long... And even though it has a tasty sounding name, I do not recommend using Rotella in your favorite steak marinade...

 

If you read the owners manual, on page 71, you will see that 20w50 is recommended for temperatures from 32 degrees F to well over 100 degrees F. 10w40 is recommended from 14 degrees F to 104 degrees F. It gets a lot hotter than that where I am. I have experienced smoother shifts and a quieter running engine with 20w50 oil. I have never experienced the "coffee grinder" issue when the engine is properly warmed up before taking off. Motorcycle engines have always been harder on oil than car/truck engines, up until recently, when they started putting 2.5L V6 twin turbo engines in 6,000 pound trucks. WAY too small for such a large vehicle. Pretty much all new cars/trucks have engines that are way too small for them, because of EPA restrictions on MPG. Such engines tend to have a very short lifespan, no matter what oil you use in them, or how often you change the oil. Modern car/truck engines also use oil as hydraulic fluid, to control things like variable valve timing and cylinder deactivation systems, which no engine should have. High viscosity oil does not work well as hydraulic fluid, but that is not a problem with motorcycle engines, not yet anyway. 20W50 oil is fine in a Vulcan 750 engine, down to 32 degrees F, something I never see in Phoenix, AZ.

There is absolutely no doubt that the stock design of the intake and exhaust systems is as good as it gets. I have owned two BRAND NEW Vulcan 750s, and they ran PERFECTLY with the stock intake and exhaust systems. Kawasaki went to great lengths to tune these systems for the engine. The Vulcan 750 engine is ridiculously complex for a V twin cruiser engine. It makes a lot more power than most other cruiser engines. Back in the '90s, a Vulcan 750 would outrun a Suzuki Intruder 1400 and a Vulcan 1500 Classic. The Vulcan 750 engine, intake, and exhaust systems are all part of a carefully engineered design, and they work perfectly together. I only ran into starting, idling, and running issues after modifying the intake system (doing the "earshave procedure") And I only did that because I had to remove the carburetors to repair a problem with one of them, and because, having severe arthritis, I decided not to try and reinstall the stock system. Everybody here said it would run ok that way. Even under normal circumstances it is an exercise in frustration. I was able to do it back many years ago, when I had to remove an engine to replace a stator. I do believe Kawasaki could have made it easier to work on without changing its functionality. But the overall design of the Vulcan 750 would seem to indicate they did not design it to be worked on. I didn't do it because I thought it would work better. I've always been a believer in "if it ain't broke, don't fix it". It did seem to run OK the one time I was able to ride it before the cooling system started leaking like the Titanic. But it will never run as well as it did with a new stock system. If that was possible, Kawasaki would never have designed such a complicated system, if it wasn't necessary.

As for @Andrea_on750's problems, Germany has temperatures way below anything we have where I live, so 10w40 oil should work ok there, as long as the engine doesn't have significant wear. As for the oil light, @Andrea_on750 said the oil light came on during deceleration, when the oil in the sump is moving forward. That definitely indicates the possibility that the movement of oil in the sump might be dropping below the oil pump pickup tube. Yes it might also be low on oil, but with no sight glass there is no way to tell, which is why I suggested changing the oil and putting in the correct amount, then seeing what happened. I also asked how bad the oil leak was. A very small leak will not cause the engine oil level to be constantly low. And if there is no bad leak, the only other way to lose oil in an engine is for the engine to burn it. Checking the plugs and the ends of the exhaust pipes can confirm that. Too much oil can also cause serious problems. I also suggested adding Seafoam to the oil to help clean the sight glass. As well as removing and cleaning the oil pressure sensor. It's a simple and easy thing to do, so I see no reason not to do it. I have seen engines show no oil pressure because of a plugged up oil pressure sending unit.

 

I'm finding out first-hand the hard way just how carefully the intake system was designed by Kawi engineers for these Vulcans. I've increased the pilot jets to #40s and the main jets to #140s. I'm still experiencing sputtering ~4k RPM/25% throttle, especially while trying to cruise at a set speed. So I just finished shimming and will try that. Fingers crossed. Sorry Kawi engineers for removing all your carefully designed hard work.

 

@VN750Rider/Jerry First off the op isn't from Germany. Most likely Italy, judging from the Italian flag in the op's signature and the word Ristorante Italian word for restaurant (German is
Restaurant)) on the background in the pic for the signature. You are in the minority of people who use 20/50. Even the oil cap says 10/w40 if I recall correctly. You also state not to overfill the bike, but state to use four quarts, not liters, to fill the bike, which will overfill the motor.

Where are all of these new vehicles that you state are dying because of overworked motors? A twin turbo V6 engine has more torque and horsepower than the v8's you supposedly worked on and has better technology and metallurgy than anything in the past. Don't these newer engines that use oil as a hydraulic fluid also REQUIRE (not recommend) synthetic oil, don't they?

As for your issues with getting your bike to run properly with an earshave. Why did you not include the fact that you had BOTH of your rubber carburetor boots leaking? I had a conversation with someone when you were doing your earshave and he said that you probably weren't going to get it running right and would use the fact in future conversations against the procedure. Looks like he was correct. My degoated and earshaved 700 would eat up your stock Vulcan and Sportster ALL DAY LONG.

Now it's too RUBBER DUCKING early for this BS. I'm going back to sleep

 

I would drain a little oil out by burping the oil filter and letting some drain. Then add your cleaner or Seafoam for 100-200 miles before the oil change. Use the correct amount of cleaner, too much will dilute the oil.

 

@VN750Rider/Jerry roll your eyes and whatever me all you want. Regurgitating bs will get you called out every time

 

Addressing your edit.....

The inner clutch cover has to be removed, then the tube will come off with it. Coolant has to be drained to prevent leaking into the oil and it will most likely need a new clutch cover gasket or resealed with Motoseal.

The gasket may be hard to find.

 

I'm finding out first-hand the hard way just how carefully the intake system was designed by Kawi engineers for these Vulcans. I've increased the pilot jets to #40s and the main jets to #140s. I'm still experiencing sputtering ~4k RPM/25% throttle, especially while trying to cruise at a set speed. So I just finished shimming and will try that. Fingers crossed. Sorry Kawi engineers for removing all your carefully designed hard work.

I have kept my '03 box stock, except for disabling the vacuum peacock so it's totally manual, and putting in a

I'm finding out first-hand the hard way just how carefully the intake system was designed by Kawi engineers for these Vulcans. I've increased the pilot jets to #40s and the main jets to #140s. I'm still experiencing sputtering ~4k RPM/25% throttle, especially while trying to cruise at a set speed. So I just finished shimming and will try that. Fingers crossed. Sorry Kawi engineers for removing all your carefully designed hard work.

I've kept my '03 basically stock, except for disabling the vacuum peacock so that it's totally manual, changing the RR to the FO020, adding a windshield and a used Mustang seat. It had been sitting for awhile when I bought it, 14 years ago, and I put on rebuilt carbs. I burn regular gas, but add Seafoam. I also greased the splines. So far I've never had a problem with the bike. It's comfortable, fast, and powerful enough for me. And, to be honest, I haven't seen a bike that I would trade it for. I've seen a couple I might like to have, but I would still keep my Vulcan. I'm 84 and I don't ride often or much over a hundred miles one way, since I ride alone, but the Vulcan meets my needs just fine.