Leaking carb - 81 R80GS

[Archie's dad]

Evening gents.... New to the site so please bear with me! Just bought a 1981 R80GS and I'm in the process of trying to get it back on the road. With a freshly charged battery I excitedly tried to fire the old girl up tonight and flooded the garage floor with petrol which was pi##ing out of the LH carb. I hastily switched off the fuel tap and eventually the flood turned to a drip. Lying on my back with a head torch I was able to ascertain that the fuel was leaking from the tiny hole at the bottom of the float bowl (it looks like the end of a very tiny tube protruding slightly from the hole) I tried to remove the bowl by easing off the wire retaining clip but it wouldn't budge. Two questions, why would fuel be leaking from here and how do you remove the bowl once the clip is released?.... The bike was subject to a restoration some years ago but has not turned a wheel for the past three years. Thanks

 

[nick.ct]

Hi and welcome

If it's a 1981 bike it's a R80g/s.

There is a drain plug with a rubber seal in the bottom of the float bowl. I think there is also an overflow pipe that comes into play when the shut off valve doesnt seat properly . Could be this is where the petrol is leaking out

Have a look here

http://www.realoem.com/bmw/enUS/partgrp?id=0348-USA-05-1981-2471-BMW-R_80_G_S&mg=13

 

[Bmmike08]

The leak is coming from an overflow pipe put there in case the float needle doesn't close properly.

You need to persist in removing the float chamber - the clip can be hard - and clean the needle seat and check the needle valve is clean and the tip is not damaged.

It is likely the leak was caused by the bike being unused for a while and some dirt getting in the needle valve seat.

Clean both carbs, check any filters in the fuel line and any in the tank above the petrol taps if fitted. Check both floats do float as over time they and leak and thus not float!

Add new petrol and try again.

Good luck.

Mike Davies

 

[ianboydsnr]

It's common to leak after a long time unused, it will probably be ok once used regularly, the little hole is the overflow, you just slide the clip off and the float bowl should pull off

 

[markjackson]

Welcome!

 

[Smug]

Switch off the fuel and start it. Let it run with the fuel swiched off and when it tries to stop because the fuel is running out, switch the fuel back on. The gush of fuel past a fully open needle valve will normally wash any crap off the needle valve seat.

If this doesn't work you will have to remove the float bowl.

 

[dr nosh]

When you unclip the clip the bowl may be 'stuck' to the gasket and will then require a little gentle tapping to allow it to release and drop......into your hands, not the floor.

 

[Beemerboff]

Just pulled my R 75/7 out of 11 months hibernation and had the same problem.

Wire clips were stuck too, but a little prising in the centre and the clip jumped off the carb , dumping the bowl on the floor.
Had to take the carb of to get the clip back on, didnt mind as I had a couple of intake stub rubber tubes to fit anyway.
Turned the tap on to flush the valve and it seemed to fix it, but some carbs seem to be fussy about being absolutely vertical and this one was.
Tank had been half full for a year so first tankfull was BP Ultimate 98, which in Oz has a bit cleaner in it too.
So far, so good, but it is only doing 16 Km/ L so looks like a bit more work is needed.
Might try a stiff dose of carb and injection cleaner before I pull them apart ----------.

 

[Rob Farmer]

it's usually little pieces of grit that get stuck under the needle preventing the fuel from cutting off. If it persists you may need to flush the tank out. Hopefully though it's only going to happen a few times before clearing

 

[Archie's dad]

Thanks very much for all the advice. I'll have a fiddle tonight and let you know how I get on. I'll also post some pics of the bike this weekend to see what you think.... cheers

 

[dr nosh]

Have you got fuel filter in line?

 

[Archie's dad]

UPDATE.... went with the easiest option first (thanks Smug!) Battery wasn't up to the task so wired it to the car, the engine wasn't catching so out came the plugs for a clean, back in and with a little persistence the old girl fired up. Left the fuel tap off as suggested until she cut out then fired her up again and HOORAY!! left cab as dry as a bone, only problem was the right carb was now copying its sisters antics from the night before �� So repeat of step one and hey presto both fine �� Engine was running as sweet as a nut even though it hadn't turned over for three years. New battery now on order and a couple of little jobs need doing before I book it in for an MOT (brake light stuck on, fork gaiters perished and front mudguard to be re-mounted in its 'high' position)
As I say, I'll post some pics at the weekend and look forward to viewing your comments.
Once again, many thanks for the advice chaps and I'm sure I'll be drawing on your expert knowledge again very soon ��

 

[markjackson]

, many thanks for the advice chaps and I'm sure I'll be drawing on your expert knowledge again very soon ��

The long term airhead owners on here are quite amazing with all the clever tricks and solutions, they'll pass on to us newbies, from years of fettling the old beasts.

And even though there's only about 100 of them, that's still at least 7,000 years of experience!

 

[ChasF]

And even though there's only about 100 of them, that's still at least 7,000 years of experience!

I had my first airhead in 1980, I've had a few since then and currently have two. I've only suffered leaky carb syndrome 3 or 4 times and each time it was fixed by unclipping the float bowl and gently moving the float up and down (with the fuel turned on - beware hot exhaust pipe) to clear any crud behind the needle valve. Works for me.

 

[tuftywhite]

Persist Archie's dad. I love my '81 g/s.

I know they're not the latest tech, but I love riding mine. I still take it off road occasionally.

Worth getting it properly sorted. There's enough folk on here that will help and advise.

 

[timeandtide]

Welcome.
Do you have a name apart from Archie's Dad . . .
We have a few dads on here -Andy's springs immediately to mind.
Seems like you've already benefitted from the collective expertise, to which, to my infinite regret, I can contribute very little!
Anyway welcome and enjoy your trusty steed!

 

[Archie's dad]

Neil usually, but the Mrs calls me a variety of others!!... looking forward to getting back to some 'retro' riding. Had bikes for over 30 years and I must say they've come on leaps and bounds since back in the day. Last time I rode an airhead was for a living back in the 80's so if I get this old girl back on the road it'll be like a trip down memory lane.

 

[dr nosh]

Neil usually, but the Mrs calls me a variety of others!!... looking forward to getting back to some 'retro' riding. Had bikes for over 30 years and I must say they've come on leaps and bounds since back in the day. Last time I rode an airhead was for a living back in the 80's so if I get this old girl back on the road it'll be like a trip down memory lane.

err, wouldn't happen to be a white one with a fairing and blue lights would it?

 

[Archie's dad]

For fear of being ostracised I couldn't possibly answer that!!

 

[Beemerboff]

Just refilled the tank of the R75/7 for the third time since I put it back on the road last Sunday.
Second tankful had a good stiff dose of carb cleaner, just the cheap stuff from K mart, and mileage has improved from 16 to 19 Km/L.
Next on the list are the in line filters - they have a paper element and and what with the inevitable water in the tank and a fair bit of petrol station rust /sludge are well due for replacement.
But they are a service item and if they are clogged 1500 km after they were fitted the have done their job!