The New And Improved Unofficial R65 Forum V2
Technical Discussion => BMW Technical Q&A, Primarily R65 => Topic started by: Session101 on August 14, 2012, 02:31:54 AM
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well let start from the beginning
put new diaphrams on the carbs and put about 50 miles on the bike easy, and it was perfect
went for about a 100 mile ride with some friends and about mile 80 bike lost power and backfired twice, but made it back home ok.
took the bike out for another ride again and it just didn't have the power that it did before.
i checked my diaphrams and they are good, so i sprayed and cleaned the carbs so you could eat off them, even cleaned the passageways. Also cleaned and scrubbed the coils to ensure good connection.
now the bike is running really rough and the carbs are both acting weird, i don't know which one is the way it should be. the right side carb, vaccum secondaries is going up and down with small revs and goes up upon full throttle, but also bobs up and down on idle too. the left side isn't moving even with high throttle...wtf is going on, ill post up a vid shortly.
basically i need some ideas... Im going to start from basics tomorrow
1)compression test and test again with adding oil
2)going to pull the plugs and dry fire them to see if the spark is blue or red, new spark plugs?? (cheap) but mine are like 400 miles old...
3)Go through the carbs again? or maybe clean the heads as much as i can
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[media]http://www.youtube.com/watch?v=3EZMr-l-4zw&feature=plcp[/media]
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the right side carb, vaccum secondaries is going up and down with small revs and goes up upon full throttle, but also bobs up and down on idle too. the left side isn't moving even with high throttle..
(no expert, just guessing really..)
I've never watched the slides in action, but it looks to me like the right one is working correctly. My vacuum guage acts the same way.
Does the left one work when you pull the cable end? If not I guess it needs stripping again.
Hope you didn't swap any of the left & right parts, I've heard of that having strange effects..
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no i cleaned each carb one side at a time when they were on the bike
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the left side isn't moving even with high throttle...
Interesting video !
The fact that the good side bounces a little may be due to the fact that flat top Bings have no slide control springs. Flat tops only lasted 2 years in production and maybe that's the reason. Having said that I have no problems using flat tops.
If the left side doesn't lift at all, logically it's either excessive slide stiction or if the diagram is good with no leaks then there must insufficient vacuum reaching the top chamber. That could be because of a blockage or the fact that the engine isn't producing enough vacuum due to valve or piston sealing problems. Your compression test will tell or a manometer carb balance.
The communicating passage to the top chamber is a small hole on the underneath of the slide. The hole should be oriented towards the cylinder head on both carbs. The hole is not so small it blocks easily though.
Going back to the slide bounce this is a very long shot and probably unlikely but perhaps worth a mention. Harley owners and maybe others have been known to drill that hole out to a larger size to improve throttle response. I suppose it's possible a PO did it to your carbs which would result in more slide bounce as the hole size acts as a damper orifice by restricting the flow of air in and out of the top chamber. Sorry I don't know the correct hole size off hand without stripping a carb.
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here is a question... if you use your finger to slide the secondary up, should it fall right back down? or should it stay? or should it fall slowly?
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It most certainly shouldn't stay. It should pretty much fall right back down. There is not much damping effect even with the correct sized hole unless the movement is very rapid.
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Do you have cap on the vacuum port on the carb giving you the problem ?
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I'm with Barry and Bob's advice.
Additionally - A loss of power is often a result of slide/diaphram operation it seems, or lack of. Check the installation of your diaphrams to make sure the tabs are located correctly in their bosses. Did you use OEM Bing diaphrams? Any burrs or wear patterns in the slide or slide bore? Just some wild guesses...
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First off, they're not secondaries like car carburetors - it's a slide - just an air valve.
The left one is upside down - or was the camera upside down? It looks to me like the right side is operating normally, but I didn't get much of a look at the left one, and that's the one that needs watching.
The piston moves up due to vacuum and returns because of gravity. Either there's no vacuum, or the slide is sticking. If no vacuum, check the valve lash - actually a good idea since adjusting carbs is the last step in a tuneup after everything else. Valves too tight would have a huge effect on vacuum.
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lol, yeah im used to cars more than motorcycles.
so it should be boucing at idle? that's normal?
1) Diaphrams are fine and were working fine when installed
2) vaccum port on the bottom is capped with the screw
I chose to clean the carbs because i was getting oil in the carbs from the engine using the stock air cleaner, so ill check to see where the vacuum is coming from.
also yes i filmed it upside down, i just wanted to show one side moving vs the other.
i get home in the morning and will take off the carbs first for compression test, and bench tear them down.
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so finally got some time with the bike
1) checked compression seems to be good, within 10 of each other, the left side the rings are worn because i sprayed some oil in there and it went up by 10, to equal the right cylinder.
2) pulled both carbs, put them on the bench and basically cleaned and rebuilt both of them, and put them back on the bike, ensuring the choke is positioned as well
I did happen to look at this video to test the slides and make sure i have full motion and movement
[media]http://www.youtube.com/watch?v=Q5BGTi6OX1E[/media]
they did but question, what should i do if the slide goes up and doesn't return unless there's a vacuum on it? it doesn't seem to fall right down like in the video..
i switched sides on the spark plugs, they seemed to be blacker on one side than the other, so i bought some new plugs too to swap out just in case.
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Do you have springs under the top of the carb that push down on the slide ?
You may want to take emery cloth and remove any scratches on the slide and the area in the carb body that it moves over, might just be a bit of friction holding the slide up .
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no springs, i don't think my model came with any..
but i just double checked and both slides are now dropping and working perfectly fine.
So i started up the bike, and its running really rough...but both slides are properly working and rise and fall at idle
i pulled the plugs to check, swapped with new ones and bike still runs the same, i checked for spark and both are sparking with blue
now im stumped....
i used an IR temp on the exhaust and it shows that the right side is running hotter than the left side, right side at about 140F and the left side 98F but thats after about a min cool down.
so now i have no clue where to go from there.... Got fuel! Got spark! why is it running rough and why is it running hotter on one side than the other?
oh i forgot to add when i pulled the redid the carbs, i put the air/fuel screw at 3/4 turn out per haynes manual
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That adjustment is to start start with, you need to perform a full carb synchrinization after disturbing the adjustment screws .
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Flat tops never had springs.
Sounds like the slide stiction on the left side has gone away.
If it still runs rough, setting the mixture screws at 3/4 turns out might be responsible. I see Haynes says 1/2 for UK and 3/4 for US models but I don't understand why. It makes no sense as the pilot jets are the same size. Try turning them in to 1/2 turn out.
I'd try the temperature measurement after a long enough run for the engine to be properly warmed up.
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the bike feels more like a misfire though....
can i check the timing without a light?
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can i check the timing without a light?
With points - Yes static timing can be checked very accurately but the maximum advance figure is ultimately more important to the engine.
Ignition off. Disconnect the bean can lead and attach an ohm meter or buzzer between the the bean can spade terminal and any earth point like the barrel fins.
Not my preferred method but alternatively with the ignition on you can leave the bean can lead attached and connect a test light across the points but beware of coil heating and leave grounded plugs in the caps.
With the plugs out rotate the engine clockwise with an Allen key in the rotor bolt and observe the timing marks through the inspection window.
The points should open (buzzer stops or ohm meter shows open circuit or test lamp goes off) when the S mark is aligned with the notch in the left side of the timing window.
Ideally check with a strobe to ensure at 3000+ rpm the Z mark is aligned to indicate the correct amount of maximum advance. Once you have established that the maximum advance is correct and correlated that with the static timing then I find no need for further strobe timing checks except at long intervals to check for wear in the advance mechanism.
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so i think i checked it properly, and it was really retarded, i advanced it as much as i could, which it just about full advanced and still runs rough... it just won't stay idling and also the response time when i give it gas is severely delayed, i bet that i could stall the motor if i gave it full throttle and backed off then gave it full again..
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so i think i checked it properly, and it was really retarded, i advanced it as much as i could, which it just about full advanced and still runs rough...
When you you checked it and found it was really retarded. How exactly did you do it ?
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Help me out fellas for year/fitment on a 1980, points and condenser in a can?
If the carbs seem to be operating correctly...
Have you checked your coils for cracks, solid mounting? Condition of points for alignment and pitting? And the often overlooked condenser? Ignition wiring and connections? Assumed fuel problems often lead us to electrical. Just not sure of the particular ignition arrangement on a 1980.
Another thought and wild guess.
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did the ohm meter check method with the ignition off, and basically the points were open when the S was low in the viewing hole.
i advanced it and the bike just really feels like its just running on one cylinder
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Have you checked the condition of your plug wires and their connections at the coil? Resistance measurements with them removed?
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did the ohm meter check method with the ignition off, and basically the points were open when the S was low in the viewing hole.
If the points just opened when the S mark was low in the window then the ignition was 2 or 3 degrees too retarded (assuming your notch is mid window). You should advance from there until the S mark is in the centre of the window. Take care with parallax error and sight as low down as you can just over the top of the carb.
A small amount of timing error would not account for really rough running.
Mike
All R45/65's up to and including 1980 were points in a can with the condenser fixed to the outside of the can.
Edited to correct mix up with Advanced/Retarded
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i can take pictures, but the points were replaced about 400 miles ago, along with the condenser. I will check the wires but the coils were taken off the bike and cleaned, i had connection issues with them before but when i did the spark test i figured they were fine because i was getting a nice blue spark. ill test the wires as well
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Thanks Barry I should have known that,
I'm just trying to determine if the one side is not firing at all, intermittent or weak.
Process of elimination...
Have we determined the compression by a compression test? I always start with valves but it seems we've covered that. Curious of the condition of the tappet adjusters and if recession could be an issue. But if we know the cylinders are pumping adequately and in time, we can eliminate that part.
Have you done a flow test with the carb bowls off and lifting on the floats with a container below? If we can eliminate air and fuel - we can move on to the zapping.
This one has me curious.
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Thanks guys for your help by the way, im trying to take pictures and videos to keep you guys right there with me, so here is pictures of my coils. after that i have a video showing that i have spark and its good spark, 2nd video is the bike i tried to get to run today, the only way i can get it to run is off choke, pump a couple of times then give it gas when i hear it fire and keep giving it gas while its running or else it just starves out. mind you when i pulled and went through the carbs i have not touched the idle screw at all from when it was perfectly running before.
(https://bmwr65.org/smf/proxy.php?request=http%3A%2F%2F3.bp.blogspot.com%2F-qbV2NWojPTs%2FUDQFp5CulUI%2FAAAAAAAAAaM%2Fgh2zv3gANoQ%2Fs1600%2FIMG_0841.JPG&hash=8a53908b6b643c81729baa1894793056c20f7079)
(https://bmwr65.org/smf/proxy.php?request=http%3A%2F%2F3.bp.blogspot.com%2F-EyiIL7lZXpI%2FUDQFr_1OPWI%2FAAAAAAAAAaU%2FDqh-qzaGJx0%2Fs1600%2FIMG_0842.JPG&hash=f3104d2155d1d56407cfd2465a2987278d5c6b00)
[media]http://www.youtube.com/watch?v=PiGwgM_3Lt4&feature=plcp[/media]
[media]http://www.youtube.com/watch?v=xEq0c7Pl8A8&feature=plcp[/media]
Also did an Ohm test on the wires and both were 4.85, so i think they are fine, i even switched for good measure and still no difference...
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oh wanted to add the sound you hear is just strong on the right cylinder, but because BMW has the crossover i can't tell about the left side
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Session,
I have a feeling this is going to be a simple solution >>> once we find it! What are the condition of your plugs (hard to tell in the clip)? Is one wet? Sounds like a completely dead cylinder to me and the "visual" spark seems to be enough to light the jugs off if they're adequately compressing a fuel and air mixture (at the right time).
1.) Have you checked your valve settings?
2.) Compression Test?
3.) Fuel Flow test like I described earlier with the bowls off?
4.) Is fuel getting to the combustion chambers?
5.) Did you disassemble the needle jets and atomizers in the carbs? Enrichener circuits?
6.) Are you smelling raw fuel after running it?
After re-reading your first post; you put new diaphrams in the carbs and after ±80 miles it started running poorly. Hmm.
What do you think guys?
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haven't checked the valves on that side i will try to do that tomorrow
compression was good within 10 of each other, i sprayed pentrating oil in the cylinder, that's why the plugs were wet, but the left side the rings are worn but ok
flow test, yes fuel is going and shutting off correctly with the floats
i disassembled the whole carb and sprayed out everything including the atomizer and the jets
no raw fuel smell after running
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*update*
finally figured out how to do a valve adjustment *applause*
so both side set to .006 intake and .008 exhaust, took a bit to get that
i did a flow test on the carbs, gas flows with floats and shuts off when level like it should.
re-tested the spark plugs resting against the head
i went ahead and reset and unscrewed the air/fuel mixture screw to a full turn out this time instead of 3/4.
started her up, seemed to be easier to start this time, but still the exhaust sound is way more prominent on the right side than the left, also the exhaust head is much greater on the right side than the left. the compression is greater on the right side by 10psi per a compression test. i can kind of hear misfire in the exhaust when rev'd up to higher RPM, also after being in the higher RPM the throttle is more responsive, still having trouble getting the bike to stay idle even with the choke on, the bike seems to shake more than a harley....
so what is going on?? what is next???
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Have you performed a carburetor synchronization yet ?
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Sounds like a carburation issue to me.
I'll just bet the mixture screw o ring or idle jet o-ring is compromised. It's a very common problem.
The first step of the carb tune-up sequencee (after cleaning them up or rebuilding) is setting the mixture. Was this done?
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<snip>
Sounds like a carburation issue to me
+1. I would start by checking to see if the mixture screw has a rolled or damaged o-ring. To start with.
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ill have to see if i can find a carb sync tool.
i can pull the air/fuel mixture screw on both the carbs to show that they are in good health, i didn't see anything when i tore the carbs down a second time. Setting the mixture is only what i read in the book to have the screw turned out 3/4 and adjust from there, but i can't get the bike to stay idling long enough to mess with it, the bike rocks worse than a harley at low idle
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The adjustment you did, is a 'nominal' setting, to get you in the 'ballpark' area, you need to to accomplish a carb synch, all engines are different in the settings required to get a proper running engine .
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well timing light is in the mail should get here wednesday or thursday. My plan is as follows...
1)properly time the bike with a timing light (i think this is a 2 man job, holding the RPM's at 3000 i think)
2) replace the spark plugs even though they are showing good spark
3) check the dwell on points with the meter that is also in the mail
4) sync the carbs also in the works of getting
still not running right?
next i will do 2 rounds of seafoam treatment and see it that helps the valves seat and seal better
and if that doesn't work then i think the bike is cursed...
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Dwell is not something that needs to be absolutely spot on for our bikes. It's just not an issue as there is more than enough time for the coils to saturate.
One good advantage of a dwell meter is you can target a specific figure, set the timing once and at subsequent services just reset to the same dwell figure to correct for points heel wear. That should automatically bring your timing back to spec.
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ok update*
drained all the fuel out of the bike and ran a liter of alcohol to show a flow test and also to remove any water or bad fuel. filled up the tank with fresh fuel after 24 hours of evaporation.
New spark plugs
I timed the bike the way that it was running, its not running on one cylinder anymore, because when i pull the spark plug wire there is a change in RPM and sound
2nd i pulled the bike out to sync the carbs and the air/fuel screw has no effect on the left side *clue*
after that i started to cup my hand a certain way over the left carb and bam the bike sounds normal and great again
so, first what are some indicators on the carb? my first check is going to be the choke... and others?
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Here's a video, this is after i turned the choke around which i still doing know if its right or not but blocking the choke hole in the carb doesn't seem to do anything. I wish there was a way to show passage ways in carb, i think this little guy goes to the atomizer right? and also why is it backfiring out the carb?
[media]http://www.youtube.com/embed/mktlKoLfZoM[/media]
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There is some guidance on the correct choke orientation in the FAQ section. In the diagrams fuel enters via the small holes at the bottom and mixes with air before leaving via the top left hand port.
http://www.bmwr65.org/cgi-bin/yabb2/YaBB.pl?num=1291933920
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good news
i think the bike is running ok, however i think i need to re-time the bike because the idle is good @ 800-900 rpm but when you drive it the idle likes to hang at the 2000-2500 rpm range and take a long long time to come back down or just to pop the clutch a little and it goes down
should i sync the carbs then time the bike or get the carbs to idle fine then time then sync?
Basically i re-re-rebuilt the carb again but this time replacing the gaskets that are 300-400 miles old and the bike didn't want to start but then once i let her run and idle for a while it's easier to start but i still think there is a leak somewhere but i have replaced everything and still no luck, if the valves were leaking on the intake would that have an effect?
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Ignition timing has to be a fair way out to influence idle speed. In principle excessive ignition advance will increase the idle speed.
If your idle is set at 800 -900 rpm on a fully warmed engine then the hang up symptoms are unusual.
-There are 3 scenarios that can cause the hang up symptoms:-
Idle speed set too high or set when the engine is not fully warmed up - probably the most common reason.
Sticking advance mechanism - probably a less common cause than it's made out to be.
Throttle stop screws set too far in and then idle revs reduced using the mixture screws. This is absolutely the wrong way to approach tuning the carbs as the excessive opening of the throttle disc at idle causes the transfer ports to come into effect and that will cause the revs to hang up - This is an unusual senario but I mention it because I recall your throttle stop screw initial setting being 1 full turn in which sounds way too much to me. 1/2 a turn in is too much on my carbs. If you need more than 1/2 a turn in to achieve a stable idle I'd say there is likely something else wrong.
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[size=14]+[/size]1 with Barry's comment regarding high idle revs.
Before I built and began using my $4.00 Ghetto Manometer, I had the same high idle situation when the engine was at full operating temps. I would drag the clutch at stops to bring down the idle speed.
Doing a full carb tune protocol on a hot engine showed my mixture screws to be too far opened. The manual's mixture screw settings are only a starting point.
After backing off the throttle stops to a "no contact" position, I was able to close down the mixture screws while watching the fluid levels in the manometer. I set my idle at 900-1000 rpm.
From your carburetor performance description, I would bet Bengt Phorqs lunch money that your mixture screws are excessively open.