The New And Improved Unofficial R65 Forum V2
Technical Discussion => BMW Technical Q&A, Primarily R65 => Topic started by: Dontron on July 08, 2010, 03:21:04 PM
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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
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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.
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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
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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
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Here's a photo ... I hope
(https://bmwr65.org/smf/proxy.php?request=http%3A%2F%2Fwww.pbase.com%2Ftomfarr%2Fimage%2F127315792%2Flarge.jpg&hash=6281e457debed919ea629f7707bc548730e214d3) (http://www.pbase.com/tomfarr/image/127315792/original)
click for larger
There ya go, I fixed your picture! Pretty bike! ~Rob
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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.
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Ohhhh its got white heads........must be a virgin
Lou [smiley=beerchug.gif]
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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. (http://)
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Thanks Barry.
Cleaned the idle jet, no improvement, will follow your suggestion re the idle mixture screw and report back.
Thanks again everybody!
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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
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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
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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).
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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. :D
Monte
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Thanks guys, will follow through on these ideas and let you know...
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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 ;).
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And the winner is ... valve clearances !!!
All the valves were tight, I adjusted them, now the bike starts and idles very nicely. Thank you nhmaf and montmil !
BUT - now the bike is losing power at medium engine speeds. WTF???
Standing by to accept more suggestions!
Thanks again,
Don
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A couple of possibilities :-
A flat spot at 3000 - 3500 RPM that clears at higher revs can be needle position is too low. Check factory position and maybe move up one click if needed.
Losing power at higher revs say at 60 mph is often torn diaphragms
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A couple of possibilities... Losing power at higher revs say at 60 mph is often torn diaphragms
UhHuh. That be me sometime back. Hit 60mph and the stutters began. Couldn't see any damage to the diaphragms but with new Bing rubber, it runs to the ton. Buy Bing originals. Don't care what some folks may say about repop diaphragms; they're not the same.
Monte
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Well, I can use some more help!
To recap:
Bike started idling poorly, not making any power on the left cylinder.
I cleaned idle jet, no improvement. Cleaned entire carb, no improvement.
Checked valves - all were very tight, especially the left side exhaust. Adjusted them.
The bike started better and idled very well, but now started bogging down very badly at mid rpm’s.
Checked the points, they were very tight, adjusted them.
Checked timing, it was a couple of degrees advanced, adjusted it.
Bike still lost power badly at mid range rpm’s.
Raised the left needle one notch (to the highest position). Checked the right needle and found it was already in the highest position.
Slight improvement but bike still bogs down and loses power at mid-range rpm’s.
What now? Time to rejet? It has #140 jets in it right now.
Thanks ... again.
Don
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Have you opened the top of the carbs and removed the diaphragms to check for tears or even the tiniest of holes? (bright light)
And on reassembly, don't forget to get the indexing tabs in place. There is one on the O.D. of the diaphragm for the outer rim of the carb, and there is one on the I.D. of the diaphragm for attaching to the slide.
Also, the white plastic ring can become loose, over time, if reused too many times.
Replacement rings are available from Bing. Very helpful, small, family-run business:
http://www.bingcarburetor.com/
(https://bmwr65.org/smf/proxy.php?request=http%3A%2F%2Fwww.pbase.com%2Ftomfarr%2Fimage%2F80793349%2Fmedium.jpg&hash=2b18be9299de03dad718266ce045e0507705ec34)
Inside diameter measured
Old Ring - 36.25 mm
New ring - 36 mm
(https://bmwr65.org/smf/proxy.php?request=http%3A%2F%2Fwww.pbase.com%2Ftomfarr%2Fimage%2F80793380%2Fsmall.jpg&hash=ac27787198f741e7e855c1a01b2a35d7547a87c5) (http://www.pbase.com/tomfarr/image/80793380/medium)
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Do not change jets before confirming diaphragms are good or you've replaced them.
If, as you say in your first post, "It ran perfectly.", then there's no need to suspect the jets. I believe you need new Bing rubber.
Monte
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I second that. Check the diaphragms.
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Raised the left needle one notch (to the highest position). Checked the right needle and found it was already in the highest position.
The needles should not normally need to be in anything other than position 2 or 3. (counting top groove as position 1 - weakest mixture and bottom groove as 4 richest mixture). One change of position has a quite a big effect on mixture and If you have to use 1 or 4 there is probably something else wrong. I'd be inclined to put all carb settings back to stock and start again from there.
Another thought given that "the previous owner re-built both carbs" - there is a small hole in the bottom of the slide which is the vacuum connection to the top of the diaphragm. You might want to check this is clear and also to check for correct slide orientation this hole should face towards the engine intake.
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also to check for correct slide orientation this hole should face towards the engine intake.
If both index tabs are in place on the diaphragm, the slide should be oriented correctly.
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Thanks Barry.
Cleaned the idle jet, no improvement, will follow your suggestion re the idle mixture screw and report back.
Thanks again everybody!
Mine did the same thing over the last 2 months then just refused to idle no matter what I did. Popped ran rough sound right so far.
Turns out my problem had nothing to do with the carbs at all but a very sloppy use of crimped connectors at the coils and the aftermarket MRK III electronic modual to sensor wiring by a previous owner/HACK, I replaced all 4 connections and soldered everything then heat shrank all of them then ran out the highway last night to fine tune the idle speed two adjustments to great running and no stalling. It's never been so smooth and now runs a whole lot better. Treat your ride like a boat and only use a crimp connector to get you to your soldering iron and heat shrink.....saves a lot of headaches in the end (OLD BOAT MECHANIC). Extra bonus should be better fuel economy without the annoying rough running engine. Already at 42MPG looking for better..
PS it's also a cure for wiring problems by LUCAS prince of darkness