Replacing oil return pipe - but with what?

[Linegeist]

Getting the Skorp ready for the imminent arrival of spring out here today, when I found the oil return pipe from the crankcase to the underseat tank was pretty tatty and ready to be put out to grass. The question is, What to replace it with?

It occurred to me to replace it with a length of clear, thickwall, plastic pipe of some kind - I'll then be able to see the colour of the oil and check it's scavenging properly. But that oil gets pretty hot, right? But how hot is Yamaha 660 hot? I don't want to get the motor nicely warmed up and then find the pipe's melted 20 miles from the workshop .............

So, can anyone please give me any clues as to how clear plastic pipe is temperature graded, and perhaps where to obtain the right stuff in the UK?

[basser23]

Good point about the temp....I think I would opt for a hose designed to carry oil,like from an oil cooler..but then you could splice in
a piece of hi temp clear to check the color etc...I'd mount the clear close to the oil tank inlet as it will be a bit cooler....

[Bill Jurgenson]

oil temperature is or should be around 90°C. Good modern oils can take up to about 130°. The normal
oil tem. should not be less than say 85°
There is no pressure on the hose. You should however use a proper hi-temp. oil hose for the purpose. Your best bet is o take the entire hose to a shop that does hydraulics (e. g. forklifts, etc). Theybwill have the right stuff in the right size and can crimp a new length to the fitting for you.

[Linegeist]

Your best bet is o take the entire hose to a shop that does hydraulics (e. g. forklifts, etc). Theybwill have the right stuff in the right size and can crimp a new length to the fitting for you.

Hi Bill. Er ................. I'm rather puzzled by your reply.

On my Skorpion, both ends of the return pipe are simple push-fit and jubilee clip fitted onto spigots on the crankcase and oil tank respectively. I hope my bike hasn't been previously butchered in yet another area by its previous tormentor!

[Bill Jurgenson]

It has. The fitting under the starter has the hose crimped onto it. The tank is of course a push fit with clamp.

Since my racer had no starter, you can see the original hose with crimp at the top right:

My racer used the original plastic tank. I had not gotten smart enuf yet for the round one I now use.
Even so, I am still using the same original oil return line with crimped fitting:

and the tank is still a push fit with clamp;

the clear line is the pressure balance line, the one of plain rubber hose entering your tank next to the return line.
The much larger clear hose in the foreground is the breather line back to a catch tank since I do not have an airbox.

[Linegeist]

Dammit Bill! Do you HAVE to keep putting up pictures of your bikes? I was only admiring my nice clean engine last week, and thinking how tidy it all looked after all my hard restoration work - and then you go and post THAT! I really must do something about my own stupid plastic oil tank and that horrible crowded underseat area - the whole cramped layout just annoys me whenever I take the seat off.

It looks from your pics like I'll have to whip the starter off, and find out what the previous arschloch has done to the original oil return fitting! I wouldn't be hugely surprised if any threads are completely shot. Thanks for taking the trouble to inform me about that Bill. I'd no idea <SOB!>.