Carb problem, need help

[Dontron]

Hi everybody,

New member here, looking for advice on a carb problem with my ‘79 R65.

I bought this bike a couple of months ago, 40k miles, it’s in great shape and ran perfectly, but it gradually developed a rough idle, then it would die at idle, and checking today I find that the left cylinder is making no power at idle.

With the throttle opened up a little the left side kicks in, and the engine runs rough until a couple or a few thousand rpm, at which it seems to make normal power and runs smoothly.

Where should I start?

Thanks in advance for any suggestions,

Don

[Justin B.]

Sounds like that carb needs a sok and rebuild.  There is probably a clogged jet causing this.  I had the same thing on the Junkyard Dawg.

[Lucky_Lou]

Check the idle jet , you dont even need to remove the carb from the bike to do this just drop the bowl and unscrew the jet there are alot of articals in the technical procedures or you can have a look at this for a diaghram
http://www.gunsmoke.com/motorcycling/r100gs/carb_rebuild/index.html
Its a small flat bladed screw nearest the engine intake the one with the hexigan head is the main jet.
Lou
ps we like pictues

[montmil]

Welcome to the herd, Dontron.

Lots of experienced carb tweakers on board so not to worry. We'll get you tuned and running smooth.

+1 on dropping the bowls and doing a bit of cleaning. Also, check for water and/or crud in the bottom of the bowls. Are you running a fuel line filter? All but mandatory to head off junk in the carbs.

Let me be the first... Post up some pics of your bike. We luv 'em. [smiley=thumbsup.gif]

Monte

[Dontron]

Here's a photo ... I hope



<sub>click for larger

There ya go, I fixed your picture!  Pretty bike! ~Rob</sub>

[Dontron]

Jeez!  Sorry about the size of that file!

Anyway, thanks Justin and Lou and Montmil for the ideas so far.  Yes, it has an in-line filter, no noticable sediment, I already dropped the float bowls and cleaned them, no noticable sediment there, I'll clean the pilot jet and report back.

I bought this bike from a gentleman named Gene in Eugene, Oregon, a guy who has a garage crammed full of Beemers.  One reason I like it so much is that it's almost identical to my first Beemer (and first full size road bike), a 1970 R75/5, SWB, 85th one made per the serial number.  The R65 is the same weight, same dimensions, but with a 5-speed and a disc brake.

Anyway, thanks again, I'll report back.

[Lucky_Lou]

Ohhhh its got white heads........must be a virgin
Lou [smiley=beerchug.gif]

[Barry]

Jeez!Sorry about the size of that file!

No worries most of us have BTDT

If you aim for a max of 640 pixels wide pictures will display OK.

Any of the free photo packages like paint.net or picasa will resize the file for you.

A good carb clean should solve your problem. For a quick fix I would remove the idle mixture screw as well as the idle jet for a clean.  Make sure to check the mixture screw setting first by counting how many turns out it is from fully in and maybe compare that setting with the other carb.  They should be around 1/2 to 3/4 turns out.  

[Dontron]

Thanks Barry.

Cleaned the idle jet, no improvement, will follow your suggestion re the idle mixture screw and report back.

Thanks again everybody!

[Dontron]

Well, I pulled the carb, disassembled and cleaned it, but no improvement.

I should mention that the previous owner, among other things, rebuilt both carb less than a thousand miles ago.

Any other suggestions?

Thanks,

Don

[donbmw]

How did you clean the carbs. If you used spray can carb cleaner this may not get everything clean internaly. You may need to compeletly take the carbs apart and soak the carbs in a cleaner. I fought a carb problem on my R65 like yours and it took soaking awhile to get it clean. I have also had ignition wires breaking down that fooled me thinking I had a carb problem.

Don

[nhmaf]

If after cleaning the carbs, you've seen no improvement, before you get too far into the adjusting of the carbs, I would recommend removing the valve covers and checking the valve clearances.  If the exhaust valve clearance has closed up to nil then one can also experience rough idling or a refusal to idle, with reduced power.   If you need assistance on how to set the valve clearances, then we can help you.   Clearance (intake/exhaust)  should be .006"/.008"   (thats inches) or .15mm/.2mm

The valves clearances should be checked/set correctly before one gets too far into adjusting the carbs, as the valve clearances greatly affects the vacuum in the carbs (which in turn affects how the carbs work).

[montmil]

Well, I pulled the carb, disassembled and cleaned it, but no improvement. I should mention that the previous owner, among other things, rebuilt both carb less than a thousand miles ago. Any other suggestions? Thanks, Don

Hummm... another PO, "rebuilt both carbs." Possibly, your carburetors may or may not have been fully overhauled. Definitions vary.

+1 on checking valve clearances. The left side sounds like a good suspect to begin with. Erratic running is often blamed on the Bings; ultimately traced to mechanicals or ignition / electrics.

I cursed two bean cans before discovering a 1/8 turn on the idle mixture screws cured the demons.

Monte  

[Dontron]

Thanks guys, will follow through on these ideas and let you know...

[Sergeant_Joe]

COIL!, check the coil, they are made of bakerlight type stuff and it gets little cracks in it and the spark will leak to the frame.
I had this happen to mine, replaced it with two GT 40's and it has run fine since .