Leaking 2 Stroke Oil

[gerg]

Noticed my RXS100 started leaking 2 stroke oil. Not sure how severe it actually is, it's going down faster than usual now though. Haven't opened it up yet but it's dripping down from underneath the bit where the clutch is.

Anyone had any experience with this? Where is it most likely to be coming from?

[Doovy]

Check the 2 stroke tank (left side of the bike, behind the panel that is easily removable).

That's where I'd start.
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Yamaha RXS 100 > Honda CD 250 > Honda Hornet 600 > Honda CBR 600RR > Yamaha RXS 100 > Kawasaki ZX6R J2 > Yamaha FZ1

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Wont the oil pump be behind a cover on the clutch side of the crankcase too? pop that off and have a look. It might even be running down the hose from the tank to the pump.
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TZR250 2MA road, TZR250 1KT road, TZR250 2MA race, TDR250, YZF-750R Boost colours.
Jaguar S Type 3.0 V6 Sport R, VW Transporter T5 GP LWB Shuttle 140ps DSG.

[stinkwheel]

Worst case, it's leaking between the pump and the carb, in which case it may be compromising the oil supply to the engine. Even a leak in the hose from the tank to the pump could be causing it to draw air bubbles.

So it's worth checking out ASAP.

I presume there is still a slight blue haze from the exhaust during normal running?
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“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[gerg]

Yeah, I think it's still getting a good oil supply, a "slight haze" is one way of describing what comes out of my exhaust

I will check these things out, thanks guys.

[redeem ouzzer]

Possible the pump itself (or the gasket between the case and pump body), might be lucky as stinkers says and find its a pipe or the bleed nipple.
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Be a REAL MAN!

[Pjay]

Premix it into the tank and save yourself the worry of a failure.

[redeem ouzzer]

[wodge]

The oil pump is behind the round cover on the RHS of the engine. You can take this cover off without draining the gear oil. Inside you will find the pump, it pumps oil from the tank in the left underseat panel to the engine side of the carb. How much it pumps depends on engine speed (the pump is driven from a gear on the end of the crankshaft) and throttle position (i think that controls the stroke of the pump)

It could be that one of the pipes has come loose at the pump or the carb and needs refitting. There is also a bleed screw which could have conceivably fallen out of the pump body leaking oil.

The pump is an easily available part from places like yambits. If you need to replace the pipes consider a clear pipe, it is reassuring to see oil in the pipe..
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nolidge iz pouwur.
Yamaha RXS100 RS100

[Pjay]

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[redeem ouzzer]

[wodge]

2 stroke racing engines are rarely off the throttle. No throttle, no fuel/oil mix, no lubrication so it makes sense to save weight on a race bike by not fitting extra bits.

Autolube puts oil in the engine even if the throttle is closed, say on a long downhill run and a proportional amount for pretty much any situation. It is sensible on a little commuter like the RXS and on pretty much every road bike, Mr Yamaha didnt fit them cos they are crap, he fitted them because they worked.

Poor maintainance over the years, worn components etc are going to cause problems on a bike that is at least 20yr old and which is probably just suffering from a perished rubber pipe anyhow.
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nolidge iz pouwur.
Yamaha RXS100 RS100

[Pjay]

[redeem ouzzer]

Not the mixture screw you clueless spastic. You need to rejet (change main and also possibly pilot jets). Shows how stupid you are if you think the mixture screw has an effect throughout the Rev range.

Premix isn't a case of mixing oil with the fuel and cracking on. In some cases it even requires modification of the crankcases.
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Be a REAL MAN!

[Pjay]

[stinkwheel]

The mixture screw only affects the mixture at idle.

If you attempt to run some 2-strokes on premix, you'll kill them. Just try it on a GT500.

An RXS100 isn't one of those and will almost certainly run fine on premix but I don't see the point when there's a perfectly good oil pump in there.

The mixture may be screwed up a little by premixing one but I doubt by much since the punp is drip-feeding the oil directly into the carb just after the venturi anyway. At 50:1, the alteration to the fuel:air ratio is almost certainly negligeable and would fall between jet sizes. You'd need 0.02% more fuel in each charge to cope with part of it being oil.

Of more concern to me than the mixture is what you'd propose to do with the pump which is mechanically attached to the crank and, if it no longer has oil going through it, will eventually seize.

Where you run ito some issues with premixing a road bike is ensuring a good oil supply at idle or on going downhill. One way round this is to set the tickover low so you have to keep blipping the throttle to prevent stalling (this was MZs solution). You would also want to blip the throttle periodically when going downhill, not coast on a closed throttle.

The first three 2-strokes I owned were premix with optional autolube on more expensive models. They had a measuring cup inside the petrol filler cap which held enough for 5 litres of petrol. Slightly over or under filling wioth fuel (and hence over or under-dosing with oil) made no discernable difference. Which tallies with the experience of 70's autolube systems which can be shockingly erratic in the amount of oil they deliver.
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[Pjay]

My advice was specific to his problem, it wouldn't run with much noticeable difference with premix and the pump is a very simple affair and wont need to be oiled anything past what it will get naturally inside the crankcase. I have in the past run a similar engine for over a year on premix and had no issue. Just the odd clutch in and throttle at low revs and a tweak or two at lights and it works just fine.

He has a leak and it could fail at any time, he said it's getting bad.
Premixing even while he sorts what is causing the leak is sound advice.
Fucking a top end for the sake of a simple fix, even if temporary is not good.

I'm not sure what GT200Fan79 thinks would happen if he premixed, but it wouldn't be catastrophic. Not premixing could be though.

Anyhow, getting the oil supply sorted one way or the other is the best thing to do, as you wont know until it's too late if it fails.

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[stevo as b4]

Pjay, your advice to op is not a useful fix or possible solution to the leaking oil problem, it's just a personal opinion you are trying to force by saying manufacturers are wrong and you and a few forums have outsmarted all thier R&D for 35 years. Why would op not want to fix the issue without considerable modification to remove the system that's there to help and make the bike run best.

I've got a 2stroke that has been modified to run pre-mix fuel, and I have to say that all the negative points raised by Blue and Stinkwheel are true and it's s pain in many ways to not use the factory set up and keep it serviced properly.

One incorrect fill up/fuel mix can wreak an engine in a few moments, as can not changing your habits regarding how you mix up the fuel before starting and also when riding.

If I had a brand new pump, and all the pipework I'd be using it. The only thing I like better about pre-mix is the slightly lighter throttle action, but that's not worth scrapping a proper lubrication system for generally.

[Robby]

The bike has a small oil leak.

Fix the small oil leak.

[gerg]