RS 50 Oil Reserve Indicator Leak

[RedlineFX]

Well, I have been pleased with the perfmance of my big bore RS 50. I have started using it occassionally to commute to work and back. In the past 48 hours it has developed a rather annoying issue, leaking around the oil reserve indicator cap (the one with wires coming out of it). I clean up the drips down the inside, making its way all the way down to the chain, check to make sure the cap is seated properly and go again. Once parked, it has leaked again so I start the process all over. It has never leaked a drop until the past couple of days. Is this something that can be fixed easily or has it suddenly decided it needs to be replaced?

Dave (RedlineFX)

[RedlineFX]

Well it didnt leak last night, didnt leak this morning, checked again before lunch and as the day has warmed up just prior to noon the rubber seal had literally popped up. I pushed it back into place, cleaned up what had leaked down the side of the housing, and it has not leaked any more this afternoon. Based on this new discovery, I am assuming that it is the expansion from heat as the day warms up. The nights get down around freezing right now but the days are warming up into the 60s....not complaining for February....do not understand why the top filler cap that actually has a hole in it would not displace air from expansion/contraction due to temperature instead of this lower cap popping loose. Plan to check it again and again until I figure it out unless some of you have had a similar experience and can help out.

[RS_Patrick]

The Cap on the oiltank should have a little hole/channel trough it to balance the air presure, so maybe its blocked.

Are you sure you used the right type of 2 stroke oil? if you put Premix Only oil in the Tank it will affect the rubbers, so that could be an other thing that happened.

[RedlineFX]

I put Motul Ester 2T (what is recommended from AF1 Racing)....not premixed in tank, reservior under seat with and indicater (with a separate seal) at bottom edge of fuel tank. It is this separate lower cap that is leaking....I can get it to quit by messing with it but it will start again within a day or so. It is a rubber cap with two wires coming out of the top for the oil mix level indicator.

[RS_Patrick]

Wich Motul Ester based oil exactly??? because Motul 800 is Ester based and if you put that in your oiltank than its nbo wonder it starts to leak as it desolves most types of rubber and plastic easly...

The only way to fix the leak is to drain the oiltank, degrease the rubber and the plastic edge the sensor units seals on and use a oil and fuel resistand instand gasket, preferably one that hardens a bit and acts like glue.

[RedlineFX]

I will try that...Have always used Ester 710 full Synthetic 2T Injection Oil as recommended by AF1 Racing. Have never used anything else. I think you are correct, it is just a seal that has lived its life and needs to be replaced. It shouldnt be a big issue to replace it, other than draining the reservoir to replace it. It is a peculair design that the oil sensor cap is lower than the fill cap under the seat. Both serve the same reservoir but obviously gravity is an issue here. If I fill the reservoir completely, the oil is obviously putting pressure on the lower sensor cap so anything less than a watertight seal will leak. It is one of those situations where there are no issues for almost a decade and now it needs to be dealt with. Thanks

[RS_Patrick]

Motul 710 is good oil, one of the oils i usualy recomend.

One tip, if you fill it to far with oil and put the cap back on be carefull and put it on gently so air has time to get out trough the breader opening in there, if you just push it on there or/and acedently hold the opening closed the air and oil has no where to go it it might pop the rubber from the sensor if its already a little weakend

[RedlineFX]

I did clean the seal at the lower (sensor) cap and rubber seal. I added a fuel resistant o-ring which seems to fit perfectly. I first filled the reservior to the top level of sensor which only was about half way. With the engine being a 79cc, the 7 to 11000 rpm thrust creates enough surge that I notice my oil light would flash briefly, didnt understand why. Started another thread regarding the oil light to try to figure it out. The surge caused the oil to rush to the back of the reservoir momentarily causing the light to flash...I added one more ounce, still not completely full, and watched for leaks. The oil light issue went away so that fixed the light issue and I am going to slowly add more to the reservoir and watch the sensor cap for leaks to make sure that issue does not start all over again...looks like I may have resolved both issues. Again, I will always stay with the recommended oils for the bike...have a Ducati, was low on oil, supposed to use full synthetic Agip or equivalent...didnt have any so I added a little of another brand (not full synthetic apparently) which caused multiple seals and gaskets to start leaking...lesson learned...

[RS_Patrick]

Castrol TTS / Power 1(RS) Racing 2T, Motul 710 2T, Shell Advance Ultra 2, those are oils that are a lot better than the recomended one.

The only oils i can think off that would damadge the seals on the RS50 are Premix only oils like Motul 800 etc.

Please read my remark on your posts in the other topic mate...