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Discussion Starter #1
Hi,

The bike has 40.000 km (26.000 miles) and at each 1.000 km (621 miles) I have to fill about 130 ml (0,137 quart) with oil.
Currently running Bel-Ray semisyn 20W50, next change will be Motul 20W50 mineral. Bike is running well, only issue is to do not forget about oil refilling, specialy for longer trips.

Whant's your opinion / experience ?

Thanks
Marcel
 

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1. How long have you owned?
2. Did this problem just show up one day? (I am not sure it is even an issue...130ml/1000km)
3. How long since the valves have been checked?
4. Does the rear plug ever show signs of carbon fouling?
 

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What is the reason for using such a thick oil - 20W50? Do You have a very hot climate? Or engine problem with a poor compression? What is the API specs of Your current oil?
Does Your bike still has an afterburner?
Do You have any visible smoke when the engine is cold?
Any visible leaks of oil anywhere?
 

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Discussion Starter #4 (Edited)
1. How long have you owned? Bike is from 1995, I own it from 2003 (13.000 km at that time).
2. Did this problem just show up one day? (I am not sure it is even an issue...130ml/1000km)No, it's from years ago, and the quantity that I have to fill up (130 ml) didn't increased in time, it's quite constant since years.
3. How long since the valves have been checked?I have checked and set up the valves by myself, 15.000 km ago (3 years ago).
4. Does the rear plug ever show signs of carbon fouling?I don't know, need to check. The rear plug is CR6E.


What is the reason for using such a thick oil - 20W50? Do You have a very hot climate? Or engine problem with a poor compression? What is the API specs of Your current oil?
I live in Romania, in a temperate climate, my wife is riding (it's my wife's bike) only in the summer when temperature range is between 20C - 35C (68F - 95F). I don't know about compression. The oil is https://store.belray.com/products/v-twin-semi-synthetic-engine-oil-20w-50-12-x-1l-bottle/96910-bt1/
Does Your bike still has an afterburner?
No, I have removed the afterburner when I have scooterised the bike. Sorry, forgot to mention, I have scooterised the engine, but didn't notice some changes after that.
Do You have any visible smoke when the engine is cold?
When I start the engine, cold, there is a visible smoke coming from the rear cilynder. After warming up, the smoke disappear.
Any visible leaks of oil anywhere?
No oil leaks.
 

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1. Is the rear plug the factory recommended heat range?
2. You might be over the due date for the valves. Be aware that 800' are VERY fussy about valve adjustments and to ignore them will invite disaster.
 

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The valve clearance is not the reason for increased oil consumption (Same for a chosen spark plug type) These are different things. But You should definitely check the valves every 10'000 km!

When I start the engine, cold, there is a visible smoke coming from the rear cylinder. After warming up, the smoke disappear.
Well, that's the answer! :) Probably there's a problem with piston rings. The smoke comes form burned oil. Check the compression first!
 

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The valve clearance is not the reason for increased oil consumption (Same for a chosen spark plug type) These are different things. But You should definitely check the valves every 10'000 km!

Wrong... a hotter plug may have been installed to cover up a plug fouling issue.

When I start the engine, cold, there is a visible smoke coming from the rear cylinder. After warming up, the smoke disappear.
Well, that's the answer! :) Probably there's a problem with piston rings. The smoke comes form burned oil. Check the compression first!
Wrong again...the smoke could be from excess fuel in the rear cylinder (due to a faulty fuel tap) burning off.

I ask my questions for a reason, so please do not second guess them.

Remember, without a question, there can be no answer.
 

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OK. Then we both asked this question wrong. We should ask what the color would be that smoke :)
If it's black (dark grey), it's fuel. If it's white (light blue), it's oil.
 

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Discussion Starter #9
Thank you guys for the real debate here.

1. Is the rear plug the factory recommended heat range?
No, factory recommended is CR7E, but because of too often rear plug fouled, I have changed to CR6E and now is OK. I understood that doing this, we only are covering the real reason, which can be a NOK fuel tap)

The smoke is not white, is more like black/blue.

This winter I will recheck the valves and will do a compression test.

There are no visible leakeges, and the cooling liquid is not contaminated with oil. Means, the oil can "disappear", because of worn rings or worn valves guides (seals). As the bike is from 1995, thinking aging valves guides it can be a reason.
 

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If it smokes on start up, along with rear plug fouling, is a good indication that your fuel tap is leaking.
When that happens, raw fuel runs into the rear cylinder and makes its way down into the crankcase when parked.
This has two effects:

1. You get fuel dilution of the oil.
2. The cylinder wall is washed clean of any residual oil which results in poor sealing/increased wear on that cylinder/increased oil consumption.

It is poor practice to install a hotter plug to cover up a condition that could result in shorter engine life.

In "my opinion", this is what I would do:

1. Replace fuel tap.
2. Do the carb while you are at it. At that age and mileage, it is probably in need. Replace float needle.
3. Replace plug with correct one.
4. Check valves if they are due.
5. Ride
6. Monitor plug condition.
7. Your oil usage is not a concern at this time.

Of course, you are free to dismiss the above as crazy talk at any time.
 

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Discussion Starter #11
OK,

This winter maintenance items :

1. Order new fuel tap, out of the link from "tehnis" https://www.ebay.com/sch/i.html?_fro...etcock&_sop=15,
2. Reinstall factory recommended plug, CR7E,
3. Ride. If all OK, I will be able to confirm that the "notorious" rear plug fouling is because of NOK fuel tap,
3. Check valves.
4. Feedback here !!

I have two questions please :

1. Even the fuel tap is leaking, the "float valve needle" from the carb (see in picture), should stop the fuel. If leaking, means both are NOK, fuel tap & "float valve needle". correct ? I wanted to attach a picture with the float valve needle but the max picture size is 20KB ... this is ridiculous. or I do something wrong ..
2. Maybe I should use for my temperate climate a 15W .. oil, instead of 20W...that I use actualy. But why in the Service Manual is nothing written about the 15W.. ? Recommended oil grads from manual are : 10W40, 10W50, 20W40 & 20W50. Why 15W.. is not mentioned ?
 

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1. There is not a needle/seat in the world that will hold back fuel reliably when sitting.
That is why the tap is there in the first place.
2. Use Kawasaki recommended oil grades as outlined in your owners manual.
 

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OK,
1. Order new fuel tap, out of the link from "tehnis"
My link for a cheap replacement of original petcock should be like
https://www.ebay.com/sch/i.html?_from=R40&https://www.ebay.com/sch/i.html?_from=R40&_trksid=p2050601.m570.l1313.TR0.TRC0.H0.XLT80+petcock.TRS0&_nkw=LT80+petcock&_sacat=0
Don't forget that some petcock knobs are a little bit too long for Vulcan tanks and need to be slightly shortened!
1. Even the fuel tap is leaking, the "float valve needle" from the carb (see in picture), should stop the fuel. If leaking, means both are NOK, fuel tap & "float valve needle". correct ?
Sometimes it's OK, but needs to be cleaned from a limescale type deposits. The float needle has to be smooth and with no grooves. As the needle seat!
2. Maybe I should use for my temperate climate a 15W .. oil, instead of 20W...that I use actualy. But why in the Service Manual is nothing written about the 15W.. ? Recommended oil grads from manual are : 10W40, 10W50, 20W40 & 20W50. Why 15W.. is not mentioned ?
Technically 15W is absolutely compatible if it meets all the other API standards and You use it in appropriate thermal conditions. IMHO, it's not mentioned most likely because it's not very popular. And the range is already covered by other mentioned grades. Some oil manufacturers 15W have only on mineral oils. Some only on semi-synthetics. Some do not produce such grade at all, because it narrows the buyers choice and it's not worth for business.
 
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