Favour needed: BMW F650 Funduro owner

[imac]

Hi, I am after a favour (a big one actually) from an f650 Funduro owner.
I have a 94 f650 that is running like shit and I suspect that the problem is in the carbs but before I undertake the costly and time consuming task of pulling them apart and trying to fix them, I’d like to swap them out with a carb set from a bike that is running well to prove the problem.
So…. if you are in a generous mood can you PM me and we can have a chat.
I will of course come to you and do all the work – not that I am a mechanic. Thanks In advance
BTW symptoms are surging and gasping of the engine, especially when it is cold.

Thanks
Mac

[Taz]

Have you drained the fuel out of the tank to check for water?

[imac]

Yeah I have done all the basics, replaced fuel lines, drained and cleaned tank, replaced sparkplugs, checked HT leads, checked cables for free movement, repalced air filter ($30.00 for a $2.00 piece of foam), burnt my had on hot bits and got inordinantly large amounts of dirt and grime on myself.

[dino3310]

Have you drained the fuel out of the tank to check for water?

and the carb bowl.

hope someone comes through for ya mate, i hate pulling friggen carbs out

[JATZ]

If you reeeeealy get stuck I got a set in the DR 750 I'm not using at the moment (stator issues) but the bikes at the proffesionals. I could go and remove the carbs though
They are the Mikuni BST33 are they not ? I'm not sure what jets you have either.
I can't remember wether F650's are single or double carb, If they're single I have one here you could borrow

[marty]

if you'e gonna take the carbs off you might as well just drop the bowls and check the floats aren't full of fuel/water - that's not going to be that expensive

[warewolf]

BTW symptoms are surging and gasping of the engine, especially when it is cold.

A couple of things worth checking before you do a full carb swap...

Sounds like a lean condition - surging, gasping and worse when cold are all lean issues. Have you checked for cracks in the intake boots etc?

Mikuni BST carbs are renowned for emulsion tube & slide wear causing rich running problems (even some info here: Miscellaneous Carb Questions FAQ and may be more on that site, if you haven't found it already) but to be honest doesn't sound like your problem - although it could be a contributing factor to overall rubbish performance on an older bike.

On second thoughts, it is possible that you have a broken needle - extreme case of the aforementioned wear. It's usually a simple job to pop the carb tops and check the diaphragms and needles with the carbs in situ.