The New And Improved Unofficial R65 Forum V2
Technical Discussion => BMW Technical Q&A, Primarily R65 => Topic started by: mfrias2nd on February 12, 2012, 07:38:53 PM
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Hey guys,
I hope you can shed some light on this problem I came across today. I finally changed a float needle out of the right hand side today. It's been leaking for a while and it may or may not be related to my misfiring/backfiring issue but I went on a 10 mile ride today and after it warmed up it started to bog down on low RPM's. I would be high on the RPM's and then when i had to let off it would start to bog down and give me terrible throttle response. After another couple of miles it started backfiring on the low's then when i pulled hard on the throttle it would kick in sweetly and run back to the mids and through the highs without a problem.
I came home and decided it was time to re-sync my carbs which I did quite nicely. I got the bike to purr sweetly by doing the carb adjust but I still have a little of the backfiring and poor throttle response in the LOW's and my left plug is coming out very sooty. My right one is fine. My peers tell me it's getting too much fuel and there's a carb issue but The carbs should be fine and this wasn't an issue for the last few months after I rebuilt my carbs. I switched plugs and it's still the left side.
I read this entire article http://www.bmwr65.org/cgi-bin/yabb2/YaBB.pl?action=print;num=1307801301 and I have a few ideas to go on but based on my story can someone give me a few more tips. Keep in mind the bike has been running fine until today. So it's a next-day problem.
Oh one more thing. Keeping in mind I did the carb sync and the idles are matched and low...after I really get the bike going when I come to a stop it's idling crazy high. I can't imagine lowering the idle adjust any more without the bike not staying on...this enforces my peers to tell me there's too much fuel going in the (left) side. Related problems? I don't know. Like aways much appreciated for your time to read. I hope you guys can help.
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It sounds like part of your problem, the high idle speed at idle once warmed up, is performing a carb synchronization on an engine that isn't up to operating temperature .
If you had no problems before you replaced the float needle, you need to go back into that area and recheck your work .
Not that you did anything incorrectly, but is the small wire clip holding the needle to the float arm ?
By chance did you bend the 'tang' on the float, altering the adjustment there, maybe causing a low fuel level in the float bowl .
Is the float pivot pin fully inserted into the arm or leg of the carb, serrated end inserted in the correct position ?
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Well the bike was ran for at least 10 miles before heading back home for the carb sync. I started from scratch. pull the idle screws all the way out and half turning them in once they touched the throttle. I can try going for a longer ride and rechecking the idle screws. That can account, possibly, for the high idle while warm.
Any ideas about the sooty left plug? it's an '82....too much fuel, electronic issues? possibly ok on fuel but intermittent spark? Coil? Wires?
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If the plug has a dry soot on it, it's running too rich .
A not too uncommon problem that arises from time to time, is the 'choke'/enrichener, if it doesn't close all the way when the choke lever is in the off position, it can cause a rich condition on one plug .
An improperly adjusted float level can cause a rich condition, if it's too high .
As far anything else, a bad ignition lead is a possibility, or a corroded contact area in the coil .
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ok...
Bottom line. The bike rev's too high even though the idle screws are set pretty close to nothing. I will pull another 10 mile ride and re-adjust. I'm still getting some backfires/misfires in low RPM's but when throttle is given it clears up and runs smoother than ever. I could be in 4th if i let off for just a couple seconds when I try to pull the throttle again it roughens up and backfires/misfires. I tried swapping the plugs and determined it's the left side. Wires? Coil? Also...when backfiring/misfiring my tach is jumping like crazy...leads me to believe the carb is not the culprit. Electrical?
Let me know your thoughts.
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It sounds like a tuning issue to me. Go back over the carb synch procedure and I'll bet a step was missed somewhere. Was the float level set correctly? Why were the mixture screws run all the way out and then back in? They're supposed to be screwed in till they lightly seat, then back them out a turn or so. The idle speed is controlled by an external screw on the butterfly shaft. Were the cables given enough slack when first starting the procedure? Are both butterflies open a half to one turn at the beginning of the synch?
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Thank you for your response.
Yes the throttle cables were slackened. The idle screws were drawn out then in together going half turns until they equally keeping the bike on. Then I synched the cables and they're taught and pull equally. The carbs themselves were rebuilt about 3 months ago and until today they never gave me problems. After the sync I did today the bike runs even better than before but I'm still having that misfire problem. And since the tach is jumping when it's backfiring it leads me to believe it's got an electrical issue.
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And since the tach is jumping when it's backfiring it leads me to believe it's got an electrical issue.
That's a reasonable assumption bearing in mind that the tacho is driven by sensing the number of ignition sparks per minute so when it misfires and the spark is absent it would cause an erratic tacho reading. Problem is what's causing the misfire? You said it was definitely the left side even after swapping plugs so that does sound like coil or lead but to be sure it's not engine/mixture related can you make it move to the right side by swapping the plug leads over.
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Appears to be a bit of miscommunication regarding idle adjust screws and idle mixture screws. High percentages that the excessive idle speed is due to incorrect adjustments of the idle mixture screws. These rascals are the first items to "screw with" during a carb synchro job.
I would definitely re-visit the float and float needle repairs, particularly as said, the bike was running OK prior to that work.
Monte
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How familiar are you with tune ups on these bikes - and specifically, with the Bing carbs?
Reason I ask is because the mixture screws aren't adjusted by screwing them out and then back in! The setting is the number of turns from lightly seated.
It's ok if you're new to these things - Letting us know the actual condition of all factors involved will make it easier sorting it out. And knowing what exactly has been done helps a lot.
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Hey guys,
There is some confusion. I haven't touched the mixture screws. I've only ever meant the idle adjust screws. I will say that the bike runs really smooth now and idles quite nicely. It's only when taking off or letting off the throttle and giving it throttle again where it's popping and roughening up. Maybe I let it cool off too much before adjustment. I'll re-check.
Regarding switching the leads. YES. this was my next step. I heard for the later coil where it's the 1-2 style (NOT the individual coil style) will not work period if just one side is having problems. If I'm wrong please correct me. If I'm right this pretty much narrows my problem to the leads, which is my next test.
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What year bike do you have ?
You can add it to your profile, so we know what 'generation' bike we're dealing with .
Makes a bit of a difference electrical troubleshooting wise, if the bike is a'78-80, or '81 and later bike .
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It's a 1982 R65 about 30k miles. Strong Engine, good compression. Never had problems. Purchased with corroded carbs did the rebuild myself no problems since then except for some leaks (the rebuild kit didn't come with the float stop needle) purchased them later and replaced them yesterday. No more leaky carbs.
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I'll agree with the tachometer indicating very erratically, that you have some sort of electrical problem .
No easy solution here, about all you can do, is take apart all of the electrical connections, check them for security, cleanliness (corrosion, etc.) .
The ignition control unit (ICU), it's located under the fuel tank and has a heat sink attached to it, should have a heat sink compound applied between the ICU and the heat sink, it's available from Radio Shack for $5 or so for a small tube .
Though I doubt it's your problem, if the ICU gets too hot, it can 'act up' and cause problems .
Again probably not the source of your problem, but if the ignition coil on your bike is a black and grey dual output type, it would be in your long term interest to replace it .
It's commonly referred to as the 'crack-o-matic' coil, the plastic case cracks at the ends, moisture gets inside and causes ignition problems, most commonly during damp conditions .
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If you are brave try this to test for a weak spark.
Remove one plug cap and fit a spare plug.
Now I'm not liable if you have a heart attack so wear rubber gloves and hold the spare plug by the cap so that the earth electrode touches the top of the plug still fitted in the cylinder head.
You now have 2 spark plugs in series. Start the engine and observe the spark from your spare plug it should be healthy blue/white in color.
Rev the engine which will increase cylinder pressure which is more demanding in terms of the voltage needed to create a spark. The spark should not change color. If it turns orange you have a weak ignition coil.
Caution
Besides the electric shock risk you must keep the spare plug connected to the firing plug at all times while the engine is running or you risk frying the coil if it's output is open circuited. Perhaps a 2 man operation is called for. Better still it's not beyond the wit of man to devise a permanent connection between the spare plug earth and the running plug. I've done it with a length of cable and strong crocodile clips.
A lot of fuss you might say and if you don't understand the risks then don't do it but this is a brilliant diagnostic which is showing you how the spark behaves under load. It's way better than just cranking the engine with a plug lying on top of the cylinder head.
Actually I think you can buy a properly designed spark plug tester that fits between the plug cap and the plug. Where's the fun in that though.
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I think I'm brave enough to give the spark test a shot. Thanks! I think first thing I was going to switch the leads and while I was at it hit the connections with some ECC and wire brushing....my tail light went out a couple weeks ago and I spent all day puzzled at what it could be, taking apart the light housing checking for broken wires etc. etc. I just had to take the wire brush to the connection on the fuse box.
That gives you an idea in what condition the connections are.
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You may want to remove the main grounding point for the bikes electrical systems, it's located in the area with all of the relays near the 'backbone' tube of hte frame .
There's about 10-15 solid brown wires that are 'ganged' together and then secured with a single screw/bolt to a sheet metal bracket that's welded to the frame tube .
Wouldn't be surprised if it's corroded/rusted as well .
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Update...
Got home and fired up the bike. After not firing in a couple days I let the carbs fill up pulled the choke and it fired right up no problems. I'm still getting a bad shake. I swapped the leads and I'm still getting a sooty left plug. So far I think I've ruled out the PLUGS and the LEADS. My dad (an experienced car mechanic) said he believes it may require a valve adjustment...however! while riding my tach was jumping around like crazy which lead me to believe it was electrical and it acted like it wasn't getting fuel or too much (possible flooding) could it be the carbs? Should I try a cleaning and rebuild before messing with the valves? Keep in mind the bike never had this trouble before I swapped the float stop needles. My spark is strong on both leads.
Let me know your thoughts.
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How old are your diaphragms in the carbs? Try holding them against some bright light to see any pin holes/ tear in them. I recently had a bad diaphragm and the spark plug was always sooty. On close inspection found a very tiny tear in one of the diaphragms which could be only seen against bright source of light, and new ones from Capital cycle cured the problem. Good luck!!
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I'm listening to your dad. When was the last time valve lash was checked and/or adjusted?
Be it a fueling issue or electrical, it's important that the valves are set correctly. Could be the exhaust clearances have closed up preventing the exhaust valves from closing completely. That issue would definitely cause operational problems.
Valve lash checks are simple to do.
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Can't say I've ever done a valve check on the bike. I brought it back to life with the carb rebuild and it's been running fine. Can anyone give a link to instructions on how to do. I'm the least mechanically capable man in my family but I get by with simple to medium tasks. Dad and brother are experts.
I will check the carb diaphrams next. my kit didn't come with them so they are the ones that were in there.
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This link is a bit wordy but you did ask.
http://bmwmotorcycletech.info/setvalves.htm
If you want pictures this procedure for /5 is concise. Only real difference is shape of valve overs.
http://www.bmwscotter.org/procedures/valve_adjustment/valve_adjustment.htm
In summary
- Remove valve covers and sparkplugs.
- Remove rubber plug from the inspection hole next to the oil dipstick.
- Turn the engine over by hand * until 'OT' mark (Top Dead Centre) shows in the inspection hole.
- One cylinder will have both valves closed. Adjust that side. Inlet to.004" and Exhaust to .008"
- To adjust the other cylinder rotate the crank one full turn until TDC mark shows again.
* Method of rotating crank is to put gearbox in 5th gear and turn rear wheel by hand or alternatively and vastly preferred by me, disconnect battery, remove front cover and use an Allen key in the alternator bolt.
There are other things you should know (read the link above) like how to check/adjust rocker arms for minimal play but that's probably not necessary for your current purpose of getting the thing running right.
Although you may hear this suggested as part of the regular valve adjustment I would not recommend torquing the cylinder head bolts unless you have done quite some research on the pitfalls.
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Hi, sorry for not replying sooner, work and bad weather means I have not being paying attention to the forum for a while now.
There was a bit more to my story that is not mentioned in the thread you referred to. My misfiring woes did return, and in the end I think the root of all my problems was a failed voltage regulator.
The too high charging voltage (up to 17v) going through the electrics was probably making my points go off early, as well as possibly not being too kind to the coils.
Since I replaced my voltage regulator and coils (with a dual coil), my bike has been running sweetly.
More details in this thread: http://www.bmwr65.org/cgi-bin/yabb2/YaBB.pl?num=1312539150/0
( I never got back to try the rooster booster again, but probably will one of these days)
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Thanks RSMike,
very helpful since I'm everything in my gut has been telling me it's electrical, especially since my tach was jumping around like crazy. But since my plugs and wires came back negative I was leaning back to the carb or valves.
The only thing that has been getting me is while riding and letting off the fuel or stopped when I start its stumbling and almost wanting to turn off but when given hard throttle it would just cough and GO without problems. I just had to keep the RPM's up.
I'll check out the following this weekend...
Carb diaphrams (being replaced)
New Floats (being replaced)
I'll also take the time to do a valve check anyway and if I have no luck looks like i'll fork out for the electrical.
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You CANNOT properly balance a BMW R type engine without FIRST doing a VALVE SETUP..... I'm very surprised no one has mentioned this very inportant fact...
Sorry.. But you need to set the valves first... Then you can balance the carbs... You might want to check for a leak around the exhaust gaskets as well as the other things mentioned here..
Valves first always.....
Then, Ten miles is not enough.. Half an hour minimum ride before doing the carb setup.... Do the rough setup.. Then ride for half an hour, Then do the final carb setup with a big fan blowing at the front of the engine... I have one of those big shop fans...
Good Luck...
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..... I'm very surprised no one has mentioned this very inportant fact...
They did....his dad.
...Ten miles is not enough.. Half an hour minimum ride before doing the carb setup....
If you really want to push the boat out on defining when is enough warming up to tune the carbs it should be when the oil temperature reaches a certain figure. I think BMW specify 80 Deg C. That could be 10 miles in a hot summer and in a very cold winter you might never get there with the bike in motion.
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very interesting! these are all things to consider and I'm very humble for everyones advice and tips. with this problem a good thorough tune up is in the works. My carb rebuild kit didn't come with floats or new diaphrams so I will tear them down again install the new components and rebuild. I will also check the valves. Proceed with a 30 minute ride around my house (in case i break down) and then fine tune the carbs.
If, however, my stumbling is caused by an electrical component then it will be useless to fine tune until the problem is fixed. I hope the problem is in the carbs. I'll keep you all posted. Wish me luck.
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You have my sympathy, I know how frustrating this can be.
I agree that I have found setting valve clearance, points and timing to be more productive than any carb adjustments.
Personally unless something is obviously off with carbs, I would leave those adjustments to last, (though I have not always practiced what I preach).
Now I am biased, but because of my own experience, I would encourage everyone who has not done so, to get a voltmeter and measure the voltage across the battery terminals with the bike running at different revs, you should not be seeing anything above 14.5v.
I failed to do this simple check early and all my other efforts were in vain.
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There's a rule of thumb that 90% of carburetor problems are electrical. While it's a very simplified over-simplification, you get the idea.
Sometimes the only way to attack the problem is to start at one end, work towards the other, and make right everything you touch. Eventually you'll find it, or at least will have enough data to make an educated guess.
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Barry, thank you for the simple instructions. I took off the valve covers, plugs, etc. checked for rocker play, NONE! The only adjustment required was the exhaust on the right side. Which isn't giving me problems. It was near touching. The other sides were spot on .004 inlet .008 exhaust. I had my friend double checking my work as I went.
On impulse i took apart my left carb (problem side) and rebuilt it and it fired up 100% better almost no problem. NO further time went into the bike.
Today I went on a 30 minute ride with my brother following on a GT185 and the bike was running a lot better. Problems are...I'm still getting a jumpy tach. This time it doesn't jump along with engine stumbles it was jumping even when the bike was running steady. More often I noticed it would jump when I left off the throttle and when i hit the throttle again it would try and even out. Other than that I'm still getting some popping here and there out of the exhaust.
Are my problems still electrical? What's going on with my tach what are the relations? I'm still going to rebuild carb with new diaphrams and floats when they get here if that doesn't solve the problem looks like i'll start replacing electrical components.
further thoughts please share.
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...I'm still getting a jumpy tach. This time it doesn't jump along with engine stumbles it was jumping even when the bike was running steady. More often I noticed it would jump when I left off the throttle and when i hit the throttle again it would try and even out
Well the tach just counts ignition pulse so even if the engine is running better unless the tach is faulty I would still say that it's ignition related. The tach needs a reasonably clean signal so a couple of obvious things to check would that all electrical connections to the tach are good and clean and then I would look to see if you have the correct resistance in the ignition secondary circuit. No resistance at all would cause a noisy signal that might cause the tach a problem. The usual set up is plain copper ignition lead with no resistance built in, Resistor spark plug caps and ideally none resistor spark plugs.
Mario, I forget which year your bike is. It should be 5000 ohm caps for the electronic ignition bikes and 1000 ohms for the points ignition.
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it's an 82. about 30k miles. to the best of my knowledge that is. All i know is it has those black NGK caps. Maybe it's about time to replace them anyway.
Bottom line is I'm getting a rich mixture in the left cylinder and for experiments sake I set the mixture for a really lean mixture and I was still getting a sooty plug. As soon as I rule out the carbs by replacing the floats and diaphrams and another cleaning I'm going to hit the electrical system.
Like someone said it's best to work one end of the bike first to rule it out instead of jumping around to different things half fast.
The tachometer reading works on a ground connection, correct? my wiring diagram shows a black wire from the ignition coils to the tach which if my problem is electrical would make sense. I disconnected the tach and didn't notice a major improvement.
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Causes of a rich mixture, besides weak spark, are float level high, leaky float needle, choke on or gasket leaking, jet needle too high, worn needle and jet, wrong size jets.
I can't think of any other reasons at the moment.
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Well the bike was running nicely and then I replaced the float needles then it started acting up! I can't imagine the float level is high because before I adjusted the float to compensate for old/faulty needles. If anything the float level would be low.
I'm really looking forward to seeing how the bike reacts when I change the diaphrams and floats. I hope that solves the problem.
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Were the floats adjusted after this work? Does the fuel turn off when they're parallel?
One thing I forgot to mention - sometimes I've seen the float tang gouged out from the action of the float needle. After a while it gets bad enough the needle doesn't slide anymore as the floats rise. What happens is it jams, preventing the float rising and then of course the fuel goes high or overflows.
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Hey everyone! thanks for your advice and tips. I replaced the diaphrams and floats and rebuilt both carbs again. The bike runs great! I took it on a 30 mile ride yesterday and didn't get a single misfire/backfire or bogging down at the start. I had smooth transitions from idle all the way through the powerband.
Only thing...The tach must have been a seperate issue because it's still jumping wildly. I'll try some contact cleaning.
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Check the front coil mounting bracket. On my 79 its the ground for the electrics. When it broke I got all sorts of weird electrical issues, one being erratic tacho.
I cable tied the coil to the frame and extended ( soldered and shrink wrapped the connection) the ground to the rear coil mounting bracket.
Problem soldered! Haha.
Just a thought as no one else seems to have mentioned it.
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The bike is an '82 model year, the dual coil setup was changed with the '81 model year, so the main grounding point isn't the front coil bracket, it was moved to the relay area under the tank, all of the brown wires are 'ganged' together at one connector and then bolted to the frame .
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I stand corrected. [smiley=deal2.gif]