Oil leak with sprocket cover off !!!

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ChequeredFlagRacing
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Oil leak with sprocket cover off !!!

#1 Post by ChequeredFlagRacing » Mon Apr 27, 2020 7:05 am

Confused as to why this should happen. Anyone else had the same issue?
Took about six hours to notice it had shed about half an egg cup of gearbox oil with the bike on it's side stand
Hadn't drained the gearbox oil as I saw no reason to.
Looks like the oil came from the hole I've pointed to in the picture.
Doesn't appear to be any O rings or oil seals are needed for the screws

Image

Image
Yamaha FS1E 1975
Yamaha RD200 1976
Yamaha RD400 1977
Yamaha AS3 125cc 1978
Yamaha AS1 125cc 1979
Honda CX500
Honda MT125cc 1980
Yamaha TZ125G 1981-82
Zeger TC500cc 1983-84
Yamaha RD500LC 1985-87
Honda C90 1989
Yamaha DT175 1993
Yamaha RZV500R 2018

Motolli
Posts: 73
Joined: Tue Apr 18, 2017 7:10 am

Re: Oil leak with sprocket cover off !!!

#2 Post by Motolli » Mon Apr 27, 2020 7:48 am

You are right, the same mess happened to me. When you are working on the bike with this cover removed, just turn the screw back in place to avoid this leak.

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jackson.40
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Re: Oil leak with sprocket cover off !!!

#3 Post by jackson.40 » Mon Apr 27, 2020 7:51 am

Very common, most people put some thread sealant on the bolt.

ChequeredFlagRacing
Posts: 336
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Location: United Kingdom

Re: Oil leak with sprocket cover off !!!

#4 Post by ChequeredFlagRacing » Mon Apr 27, 2020 10:44 am

Thanks for the replies

Drained the oil after it leaked so not an issue now but will remember for the next time
Yamaha FS1E 1975
Yamaha RD200 1976
Yamaha RD400 1977
Yamaha AS3 125cc 1978
Yamaha AS1 125cc 1979
Honda CX500
Honda MT125cc 1980
Yamaha TZ125G 1981-82
Zeger TC500cc 1983-84
Yamaha RD500LC 1985-87
Honda C90 1989
Yamaha DT175 1993
Yamaha RZV500R 2018

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tacky1
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Location: Bay Area. CA.

Re: Oil leak with sprocket cover off !!!

#5 Post by tacky1 » Mon Apr 27, 2020 12:28 pm

I just fixed this!!!! Literally fixed it Saturday, I thought I had a leaking gearshift shaft seal or sprocket seal, Bike was leaking ever so slowly, I put some crankcase sealant on it and it seems to be fine..
1985 RZv500
1984 RZ500 Hybrid
1986 RG500 Walter Wolf
1986 RG500 Skoal Bandit
1984 RZ350
1984 RZ350 Hybrid
1981 RD350LC
1981 RD350LC Hybrid
2009 CR500AF Supermoto 250X
2007 CR500AF 250X
1988 YSR50 (2)
1989 VFR750R RC30
1984 GPZ750 Turbo

ChequeredFlagRacing
Posts: 336
Joined: Fri Mar 24, 2017 10:08 am
Location: United Kingdom

Re: Oil leak with sprocket cover off !!!

#6 Post by ChequeredFlagRacing » Mon Apr 27, 2020 12:57 pm

UPDATE
I'm now convinced it's because the two holes arrowed use the sprocket cover bolts to also hold on the gearbox oil cover and when the bolts are removed it lets the oil pump cover relax a little and the oil gets into the holes, hence the little bit of oil we see. What do you think?
Image
Yamaha FS1E 1975
Yamaha RD200 1976
Yamaha RD400 1977
Yamaha AS3 125cc 1978
Yamaha AS1 125cc 1979
Honda CX500
Honda MT125cc 1980
Yamaha TZ125G 1981-82
Zeger TC500cc 1983-84
Yamaha RD500LC 1985-87
Honda C90 1989
Yamaha DT175 1993
Yamaha RZV500R 2018

Motolli
Posts: 73
Joined: Tue Apr 18, 2017 7:10 am

Re: Oil leak with sprocket cover off !!!

#7 Post by Motolli » Mon Apr 27, 2020 1:19 pm

I would think, .... clean that smeary mess behind your cover 🤣

ChequeredFlagRacing
Posts: 336
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Location: United Kingdom

Re: Oil leak with sprocket cover off !!!

#8 Post by ChequeredFlagRacing » Mon Apr 27, 2020 3:08 pm

Motolli wrote: Mon Apr 27, 2020 1:19 pm I would think, .... clean that smeary mess behind your cover 🤣
That's why the covers off. Left over from the previous owners
Yamaha FS1E 1975
Yamaha RD200 1976
Yamaha RD400 1977
Yamaha AS3 125cc 1978
Yamaha AS1 125cc 1979
Honda CX500
Honda MT125cc 1980
Yamaha TZ125G 1981-82
Zeger TC500cc 1983-84
Yamaha RD500LC 1985-87
Honda C90 1989
Yamaha DT175 1993
Yamaha RZV500R 2018

steveho
Posts: 229
Joined: Thu Aug 20, 2015 4:01 pm
Location: Southampton, England

Re: Oil leak with sprocket cover off !!!

#9 Post by steveho » Mon Apr 27, 2020 3:35 pm

ChequeredFlagRacing wrote: Mon Apr 27, 2020 12:57 pm UPDATE
I'm now convinced it's because the two holes arrowed use the sprocket cover bolts to also hold on the gearbox oil cover and when the bolts are removed it lets the oil pump cover relax a little and the oil gets into the holes, hence the little bit of oil we see. What do you think?
Image
I agree with your suggestion. The oil pump cover is 'sandwiched' and uses the clamping force from one of the sprocket cover bolts.
Your engine sure will look nice without all that goo...!

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phildu31
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Location: Toulouse France

Re: Oil leak with sprocket cover off !!!

#10 Post by phildu31 » Mon Apr 27, 2020 6:41 pm

+1.
The cover will stop the leak.

ChequeredFlagRacing
Posts: 336
Joined: Fri Mar 24, 2017 10:08 am
Location: United Kingdom

Re: Oil leak with sprocket cover off !!!

#11 Post by ChequeredFlagRacing » Tue Apr 28, 2020 3:53 am

The goo will be gone soon.
I've had the bike since Nov 18 and just getting around to doing some jobs.
Wanted to ride it last year rather than tinker
Yamaha FS1E 1975
Yamaha RD200 1976
Yamaha RD400 1977
Yamaha AS3 125cc 1978
Yamaha AS1 125cc 1979
Honda CX500
Honda MT125cc 1980
Yamaha TZ125G 1981-82
Zeger TC500cc 1983-84
Yamaha RD500LC 1985-87
Honda C90 1989
Yamaha DT175 1993
Yamaha RZV500R 2018

ChequeredFlagRacing
Posts: 336
Joined: Fri Mar 24, 2017 10:08 am
Location: United Kingdom

Re: Oil leak with sprocket cover off !!!

#12 Post by ChequeredFlagRacing » Thu Apr 30, 2020 12:46 pm

And it's goo be gone

Temp bolt put in the oil pump hole that passes when removed. Good practice for next time I have the cover off

Image
Yamaha FS1E 1975
Yamaha RD200 1976
Yamaha RD400 1977
Yamaha AS3 125cc 1978
Yamaha AS1 125cc 1979
Honda CX500
Honda MT125cc 1980
Yamaha TZ125G 1981-82
Zeger TC500cc 1983-84
Yamaha RD500LC 1985-87
Honda C90 1989
Yamaha DT175 1993
Yamaha RZV500R 2018

smokamoto
Posts: 147
Joined: Thu Apr 06, 2006 12:18 am
Location: sacramento, ca

Re: Oil leak with sprocket cover off !!!

#13 Post by smokamoto » Sun May 03, 2020 12:52 am

Haha I also did that😄‼️

bokusouchi
Posts: 80
Joined: Sat Apr 13, 2013 4:36 am

Re: Oil leak with sprocket cover off !!!

#14 Post by bokusouchi » Fri Feb 09, 2024 6:14 pm

I also have this problem : ( when sprocket cover is off , the oil pump cover leaks quite a bit ).
But not only that : It still leaks a little bit when the cover is back ,now ....
I decided to replace the pump cover paper gasket . It is NLA , but I managed to find one on Ebay .
Failing that , Yam-bits has some refabs .
To Remove the pump cover , One needs to remove the generator cover , the flywheel (using a fly-wheel puller )
then remove the generator back cover ...
I put a very thin layer of liquid gasket on both sides of the new gasket , I hope it will make it more "leak-proof" .
When looking ar the 51x workshop manual (page 101 ) , I found that the oil pump cover has a "normal" fourth bolt ,
and that the sprocket cover has no pass-through bolt (!).
The pictures were probably from a pre-production model .
For Production ,Yamaha decided to put a pass-through bolt . My guess is that they wanted to beef up the clutch mechanism .
(the clutch mechanism pushes back on the sprocket cover ).
This shows that the design process of the RD/RZ/RZV was not at all smooth but rather with a lot of backtracking .
(But we knew that already ...)
By correcting a possible problem with the clutch ,they created a leak problem with the oil pump cover .
No wonder the gasket became NLA , as a lot of people probably tried to replace it .

Operation was completed this evening . I will do the oil refill later , and see if the leak is fixed ...

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