I have recently bought a 27 year old R80 G/S which has a 1000cc conversion and four spark plugs. After riding 120 miles two days ago with no problems, yesterday after a short run in the morning the bike, quite suddenly refused to rev. properly and will not accelerate past a certain point. The engine sounds as though it is 'choking' - like it cannot breath or has no fuel when I open the throttle.. Throttling harder makes no difference - the sound gets deeper like i have pulled the choke rather than the throttle.. In neutral it has trouble too and backfires a bit. I was able to ride home with no problems as long as I accelerated VERY gently..?!

At first I thought it was a blocked fuel line as there is some gunk in the tank bottom, so I opened and cleaned the float chambers bu to no avail. Fuel seems to be getting through fine although the LH chamber was lined with ochre coloured powdery stuff..

The bike had been standing for 6 months before I bought it and at first smoked a lot - the previous owner had WD40'd everywhere. This smoke stopped and only had a final burst when i was going up a STEEP hill during the long run..

The bike has loads of mods. R100 (I think) twin disk forks, ALL NEW wiring, a kickstart that nobody can successfully use, a HUGE rear frame for two really heavy STEEL Swiss ammo box panniers..

I am due to carry out a full service, the oil has been clean and steady at half way on the dipstick and there are no leaks other than a very small dirty film over the front of the carbs but I cannot readily see where it is coming from..

Could anyone help point me in the right direction for some diagnostic tests? Or tell me that it is something very common and easy to sort out..?

Toby.

ps. I have the bike as a first boxer to try out for a VERY LONG overland adventure in about 20 months time, so want to learn how to do all my own repairs, maintenance etc. as well as decide whether such a big machine is for me - I am quite small - so far I have succesfull replaced an over-engorged clutch thrust piston and fitted a Halfords £12 speedo to verify that the OEM one is reading 10 - 20% over.. Oh, and I am in North Dorset..

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