Weird Carby Problem

[Tony_T]

Here's the deal.........
My 1979 R65 came to me not having run for 10 years. It turned out that it had a seriously blocked pilot jet on the L/H cylinder. So blocked that I couldn't get the offending item out and had to buy a new jet. So I went the whole hog and rebuilt the carbys completely with new needles, floats, gaskets, o-rings etc. I also fitted new filters, points and plugs. I also flushed the tank and lines and fitted a fuel filter.
I fired it up today and it was running really sweetly.  8-)
Then, without warning, it started running on one cylinder at idle again. So I pulled out the L/H idle jet again and found that it was blocked again. and again, no amount of prodding with tie wire, then a tiny drill bit will dislodge the offending item.  :-?
Anyone got any smart ideas as to what could possible wedge itself so tightly in a pilot jet?
All ideas, crazy or not, much appreciated.

[montmil]

Hey there, Tony T...

With ten years of non-activity, there could be quite a bit of debris in the carb's fuel passages... deteriorated fuel hose bits, grit, etc. Not too surprising that you have a new "offender" on line. It may take a little time for all the crud to wash downstream. But...

Did you totally strip the carbs, soak 'em and use some air pressure to aid to clearing all passages? New fuel lines? Don't overlook the enrichener circuitry; fuel passages in there, too.

It's back to the bench with you, mate. Keep swinging. You'll get there. [smiley=thumbsup.gif]

Monte

[Barry]

Anyone got any smart ideas as to what could possible wedge itself so tightly in a pilot jet?
All ideas, crazy or not, much appreciated.  

What part of the pilot jet is it stuck in down at the bottom close to the screw driver slot or up the top where the aeration holes are ?

If it's a piece of grit or something similar it's hard to see how you would force it out without damaging the jet.  On the other hand it got itself in there with very little pressure so it should come out again. Know anyone with an ultrasonic bath ?

[Julio A.]

A wild guess would be that a metal piece of something that is related to fuel could have become brittle over time and started to crumble with the fuel. It happened to me once. My old petcock became brittle and had some large metal "grit" induced in the fuel lines. It only managed to get to the fuel filter.

[darrylri]

Don't try to clear the jet with anything metal, you'll open up the jet.  Use compressed air or a broom or brush bristle.

You don't say what you did to clean the carbs, but be sure to blow out all of the passages with air.  (Wear safety glasses!)

[Tony_T]

Many thanks, gentlemen. It seems I probably didn't go far enough with cleaning the carbys. I had them off and did blow them out with compressed air but I didn't soak them first.
Should I just soak them in fresh fuel or is there something else that works better?
Also, you were spot on Darryl. I did clear it with soemthing metal and it did open up the jet just as you suggested. So now it runs rich at idle on that one cylinder.  
Yes, it is back to the bench for me............  
Thanks again, fellas.

[Rob Valdez 79 R65]

And don't put that enrichener disk back in "backwards".  If you haven't already been warned.

[Tony_T]

And don't put that enrichener disk back in "backwards".  If you haven't already been warned.

I have now.  
Thanks a lot, Rob.

[Rob Valdez 79 R65]

And don't put that enrichener disk back in "backwards".  If you haven't already been warned.

I have now.  
Thanks a lot, Rob.

I think you will enjoy this thread, Tony.  Got pictures!  (Thanks again, Barry!)

http://www.bmwr65.org/cgi-bin/yabb2/YaBB.pl?num=1291890305/5#4


And that thread has a link to this thread, which also has a lot of good info:

http://www.bmwr65.org/cgi-bin/yabb2/YaBB.pl?num=1256755915/4

[Semper Gumby]

<snip> I also flushed the tank and lines and fitted a fuel filter.<snip>

You mistake was probably in not replacing the fuel lines.  I know that hose under the airbox is a PITA.  But replace them you must....Any hose today should be on a bike no more than 5 years.  For fuel lines probably less now that we have lovely ethanol in our fuel...

Remember to make sure the enrichening jet in the bottom corner of the float bowl is working as well.  People seem to forget that one.. :-/

[Julio A.]

Have you checked the fuel line connectors? Those might be perished as well.

[Tony_T]

Have you checked the fuel line connectors? Those might be perished as well.

No, I haven't Julio. But I will be replacing the whole lot now.
It's not so much that I got dirt in there that confused me, it was the fact that the jet was block so solidly.  :-?
Ah well, I'm armed with a lot more knowledge now, thanks to you blokes, so hopefully I'll have it back running sweetly early next week.
then I can start on the cosmetic stuff.  8-)

[Lucky_Lou]

My 79 had been stood for over ten years and i had endless carb problems untill i had the carbs ultrasonicly cleaned and fitted an inline filter i also replaced the fuel lines and steam cleaned the fuel tank.
Lou

[Rob Valdez 79 R65]

You mistake was probably in not replacing the fuel lines.I know that hose under the airbox is a PITA.But replace them you must....Any hose today should be on a bike no more than 5 years.For fuel lines probably less now that we have lovely ethanol in our fuel...
 

Even though there may be superior fuel line available on the market, I really like the braided cloth covered stuff, so I make a point of replacing mine every three years.

[Tony_T]

Thanks once again for all the words of wisdom, fellas. It's all sorted now and I've just been riding!  
A couple of observations from a BMW newbie.
The clutch seemd a little grabby. No problem and I quickly got used to it.
The indicator buzzer scared the crap out of me.  
It revs quite freely and performance was better than I was expecting.
Very comfortable seat, but I think I do want higher bars and maybe a small windscreen.
Shaft drive will take a little getting used to as well.
So all in all, I think I'm going to enjoy this bike.  8-)