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1990 TW200
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Discussion Starter · #1 ·
The reason why I'm posting this is to inform you guys about a problem that I had for the past 2 months that caused me

a) a LOT of frustration
b) some money {$100}
c) and time {2 months}

and I want to spare you all of this and I'm sure someone is going to run into a similar problem

It all started 2 months ago when I serviced the bike in anticipation of a December road trip, and took the bike for a test ride the next day and found a couple of drops of oil underneath the bike when refueling at the service station.

No problem at all, just replace the outer shaft oil seal as usual and I will be good to go, unfortunately the leak persisted and after replacing ALL the oil seals, gasket and the copper washer of the negative light pick-up switch the leak was still there!

At that time I was thinking that the new oil seals are of a inferior quality or maybe an old batch and that's why the oil is pushing past them all the time.

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So I went ahead and replaced the outer shaft oil seal a second and eventually for a third time, nothing improved.

The bike was using up a lot of oil, every 250 miles the glass on the side of the gearbox showed empty and I had to fill up again.

I then reasoned that maybe my engine oil is pushing past the seals because it's too thin because that was my only logical deduction that I could make before giving up.

211442


I've been using Castrol Actevo 10W-40 for the last 3 years and 30 000 miles without any problems, it's partly synthetic and my bike was running as smooth as butter with it and I believe it is the best value for money oil that you can get but they slightly changed the formula lately which caused the oil to be a bit thinner than usual and hence the oil leak that started after I serviced the bike with fresh oil.

This morning I have went to buy the thickest bike oil that I could get( Motul 3000 20W50) and put it into the bike.

Right now it's raining and I cannot go for a test ride but I will let you guys know if the Motul oil did the job, I but I'm positive it's going to work.
 

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Sorry about your gusher Cornelis. How many miles have you added since you rebuilt your engine? And how many total miles on it now? Let us know if the thicker oil fixes your leak.
 

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Are you sure its leaking the oil? Do you have visible signs of it leaking? You unloaded the parts cannon on it and it has not fixed it so maybe its not leaking it at all, is it possible its burning it?
 

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1990 TW200
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Discussion Starter · #6 ·
Check and make sure your vent tube is not stopped up.
The vent tube is still wide open.

Are you sure its leaking the oil? Do you have visible signs of it leaking? You unloaded the parts cannon on it and it has not fixed it so maybe its not leaking it at all, is it possible its burning it?
Very visible signs, I could see it seeping out of the seals and falling to the floor underneath but with the new thicker oil I'm sure it's going to stop.
 

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1990 TW200
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Discussion Starter · #7 ·
Sorry about your gusher Cornelis. How many miles have you added since you rebuilt your engine? And how many total miles on it now? Let us know if the thicker oil fixes your leak.
Hey, you still remember my rebuild bro!

It's been 3 years and 28 000 miles since the rebuild and hopefully at least 5000 more before I have to replace the rings.

I'm coming up to 60 000 miles (100 000 km) in total in the next 2 months, I want to do a special post about it!:p
 

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The vent tube is still wide open.



Very visible signs, I could see it seeping out of the seals and falling to the floor underneath but with the new thicker oil I'm sure it's going to stop.
That's really strange. Lots of people run 10w40 without seal leakage so weight should not be a problem. I wonder if the shafts those seals ride on are worn not? Also on the sprocket shaft seal, if you replaced the inner seal its real easy to tear when you slide it over the groove in the splined area of the shaft(this is one i have experienced first hand). One trick to prevent it is to put an o-ring in the groove to fill it.
 

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Discussion Starter · #9 ·
That's really strange. Lots of people run 10w40 without seal leakage so weight should not be a problem. I wonder if the shafts those seals ride on are worn not? Also on the sprocket shaft seal, if you replaced the inner seal its real easy to tear when you slide it over the groove in the splined area of the shaft(this is one i have experienced first hand). One trick to prevent it is to put an o-ring in the groove to fill it.
Yeah you're right 10w40 is just about the most common oil to use on the TW but Castrol changed the formula of their 10w40 and now it is too thin to use but I'm sure the other brands will be fine.

and yes, I double checked my shaft, it is still in a good condition and I was very careful with the inner seal, it was the second time I replaced it(y)
 

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Hey, you still remember my rebuild bro!

It's been 3 years and 28 000 miles since the rebuild and hopefully at least 5000 more before I have to replace the rings.

I'm coming up to 60 000 miles (100 000 km) in total in the next 2 months, I want to do a special post about it!:p
Yeah bud you’re one of the high mileage champs on here. I’d be surprised if anyone has a longer daily TW commute than you. Viscosity changes will definitely affect leaking. Hope that fixes it for you.
 

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My TW was leaking badly.... after i found the gasket that was the issue I checked my breather tube it was free and clear... but it was not connected on the airbox side. Shrug.... so i connected it. Fired the bike up and ran it a minute or two, removed the oil fill to add a little oil.... huge pSSSSSSSST of air rushing out. Found that the airbox hole for the vent tube was jam packed plugged with dirt.
 

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My TW was leaking badly.... after i found the gasket that was the issue I checked my breather tube it was free and clear... but it was not connected on the airbox side. Shrug.... so i connected it. Fired the bike up and ran it a minute or two, removed the oil fill to add a little oil.... huge pSSSSSSSST of air rushing out. Found that the airbox hole for the vent tube was jam packed plugged with dirt.
THAT makes so much sense! Classic case of going back to the basics while diagnosing a problem.

One of those cases where you think you are in the Twilight Zone right up til you finally really spot the culprit.
 

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If you have this bad of an oil leak it’s something mechanical wrong. Changing oil viscosity isn’t going to cause or stop a leak especially 10w-40 to 20w-50. I have run both in all of my bikes and small engines and no leaks.
 

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Discussion Starter · #14 · (Edited)
I'm glad to announce that my experiment worked and that my bike just about stopped leaking oil.

There was always a small puddle of oil underneath my bike after parking it in the garage every time after I went for a ride and now there is only 2 small drops of oil lying on the floor.

I'm sure it will completely stop leaking in the next few days as soon as the Castrol Actevo oil has been worked out of the oil seals.

211470
 

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Hey Cornelis! How is it going? Haven't heard from you in a long time!

The neutral safety switch can fail and leak oil. Its happened on both of my TW's. It leaks from where the red arrows are pointing and you have to replace the switch. Check it out. Tony

Household hardware Circuit component Auto part Gas Automotive ignition part
 

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Discussion Starter · #16 ·
Hey Cornelis! How is it going? Haven't heard from you in a long time!

The neutral safety switch can fail and leak oil. Its happened on both of my TW's. It leaks from where the red arrows are pointing and you have to replace the switch. Check it out. Tony

View attachment 211480
Hey Tony, I'm doing well thank you, yeah I took that switch out twice and inspected it very carefully, it's still fine but I'm sure my problem is fixed with the thicker oil now, I'll keep you informed (y)
 

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Lucas Heavy Duty Oil Stabilizer is good to thicken things up a bit and lubes gears great. I will add about 1 or 2 ounces only ever now and then. This stuff makes your clutches grab really good so I would try only one ounce the first go round. I have fixed slipping clutches with this for years. I used to run the oil not for wet clutches and added the Lucas for no slippage, about 4 ounces for that. I finally changed my clutches out but to my surprise they were actually still in spec. Good to hear from you Cornelis. I was wondering how the fastest TW street bike has been running.
 

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Lucas Heavy Duty Oil Stabilizer is good to thicken things up a bit and lubes gears great. I will add about 1 or 2 ounces only ever now and then. This stuff makes your clutches grab really good so I would try only one ounce the first go round. I have fixed slipping clutches with this for years. I used to run the oil not for wet clutches and added the Lucas for no slippage, about 4 ounces for that. I finally changed my clutches out but to my surprise they were actually still in spec. Good to hear from you Cornelis. I was wondering how the fastest TW street bike has been running.
I like that stuff too. Fixed leaks on a 1991 Suzuki Samurai with 150,000 on it. Doesn't leak or burn a drop of oil.
 

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Discussion Starter · #20 ·
Is the problem really fixed, though? Could higher viscosity merely mask the issue? Seems odd that that's the fix. Were you able to pinpoint the source of the leak?
Yes sir, I was actually seeing the oil dripping out of the oil seals and they are all brand new, so that's why I decided to switch to a thicker oil and it solved the problem.
 
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