The New And Improved Unofficial R65 Forum V2
Technical Discussion => BMW Technical Q&A, Primarily R65 => Topic started by: quixotic on May 21, 2013, 09:50:03 PM
-
Above that, it runs as smooth as hot butter. And Idle seems OK. I'm going to start checking stuff, but was wondering what to check first. Carb balance? Valve clearance? timing? points gap?
Thanks in advance.
-
Valve clearances and ignition timing always before carb balance.
There is a very similar thread already on the go here:
http://www.bmwr65.org/cgi-bin/yabb2/YaBB.pl?num=1368969101
-
Hmm. Maybe it is just the "torque pulsing" that Barry mentioned in the other thread. It's certainly not as smooth as my old slash 5, though. A bit disappointing.
On a positive note though, I had terrible brake squeal yesterday, and found that the R65 had the easiest access to brake pads of any vehicle I've ever owned. Scratched 'em up a bit; put some brake grease on the backs of the pads, and now everything's quiet again.
-
A 60/5 is about the smoothest Boxer there was (that I've owned) but was very underpowered. But, you do need to give it a good tuneup, as Barry suggests, before passing judgement.
-
I looked at the plugs yesterday, and one was significantly sootier than the other. Is that a possible sign of carb imbalance?
-
A black sooty deposit on the spark plug, is the result of poor incomplete combustion .
It could be from a carb problem, or an ignition problem .
I see in your signature line, that the bike is a '79 model year .
There seems to be an issue with the contact breaker points type ignition system, the forward ignition coil mount, has the main grounding or earthing point for the bikes electrical system .
Not too uncommon to hear of this bracket cracking and causing electrical issues, may not be the cause in this case, but it's a quick check type item .
Other than that, you need to go through the carbs and possibly the ignition system to find the fault .
It just may be a case of cleaning the carb internal parts / passageways .
-
So I torqued the heads (and they needed it; the four long bolts on one of the cylinders were probably only at about 10 foot/pounds), adjusted the valves, installed a Boyer electronic ignition, cleaned all the connectors to the coils and grounds and used a bit of dielectric grease. Then I set the timing with a strobe light.
Then I started it up. It seemed to start more easily than before. The idle and everything below about 3,000 rpm is now VERY smooth. But from 3,000 up to about 5,000, it's quite rough.
(I'm not sure about 5,000 and above. I'll take it out on to the highway tomorrow.)
But the weird thing is that the tach tends to bounce all around above 3,000 also. Below 3,000, it does what it's supposed to do. Is there possibly a connection there? Or would it more likely just be a coincidence?
I still plan on balancing the carbs some time soon, but I'm wondering if that's even an issue (since the bike runs so smooth below 3,000 rpm).
-
The bouncing tach needle above 3000 rpm suggests an ignition problem.
-
It would probably be worth it to make sure that you have a strong spark on both cylinders using an external, grounded plug.
You can have different carb problems at different RPM's.
Idle circuits will mess with idle and low to lower mid range, while the slides and needles will mess with things at higher RPM's.
Carbs are always the last thing to adjust. With properly torqued heads and adjusted valves, and proper timing, you should now do a carb balance. If you carbs were adjusted to run ok on an improperly tuned engine, they will not serve well on a properly tuned one.
Also, make sure that your chokes are fully returning on both carbs.
-
It would probably be worth it to make sure that you have a strong spark on both cylinders using an external, grounded plug.
I assume this means taking both plugs out, inserting them back in their wires, making sure they're grounded to the fins, and then turning the engine over?
I just took the beast out for a spin on the highway. I think the tach generally works, but when I accelerate, it momentarily (ie, for a second or two), goes down. And it has a tendency to bounce around a bit (not rock steady, like the speedo). In general, I'm not even sure I trust it enough to do the timing at 3,000 rpm (though at 1,000 rpm, it seems quite steady and reliable).
I think I heard a bit of pinging (sounded like rocks in a can), so I'm going to double check the timing. This time, I'm going to put white-out on the flywheel indents (like I should've done in the first place).
-
WOW! The W6 plugs that the previous owner put in the bike showed a slight imbalance in soot levels. But when I put in brand new W5 plugs and did a quick highway run, I got the following. I suspect that a carb balancing is in order.
BTW, I checked the choke cables and the right and left activate at about the same lever position, and when shut off, the lever down on the carb is definitely shut off.
-
assume this means taking both plugs out, inserting them back in their wires, making sure they're grounded to the fins, and then turning the engine over?
That's the ticket.
Well, it could be an electrical/timing problem causing the unsteady revs, though with 20,000km I doubt your timing chain is worn so I'd look to ignition... but your problem used to be below 3kRPM and now it's above it, and you haven't done anything to the ignition system except set the timing and clean things up. I'd go to carbs if the sparks look good and you've set the timing again with white-out on the flywheel (syncing is free too).
Poorly balanced carbs can lead to unsteady revs. I'm willing to bet your problem lies in the main (needle) jet or the needle itself, given the rev range. If the cables were off I'd expect the engine to stumble once off-idle... but again, syncing is free, so why not see if it helps.
Could be a bad diaphragm, or it could be that one needle/jet is more worn than the other (the one with the sooty plug would be more worn and letting more fuel past) They should always be replaced as a set. If those parts are bad, you can't really sync the carbs perfectly, though you could probably still improve the smoothness of the engine
As you sync the carbs, you might find that the tach smooths out. If you have a digital timing light with a tachometer feature try using that while syncing.
I think the tach generally works, but when I accelerate, it momentarily (ie, for a second or two), goes down.
Does the engine bog down too, or just the gauge?
I think I heard a bit of pinging (sounded like rocks in a can), so I'm going to double check the timing.
What grade gasoline are you using?
-
Does the engine bog down too, or just the gauge?
What grade gasoline are you using?
It's just the gauge that flops back down. If it was the engine, I'd probably get thrown over the handlebars :o I re-set the timing last night, and indeed, with the white-out, I saw that I had previously set it a bit on the advanced side.
I only use premium, and of that, I only use the high-test at Shell.
I'll sync some time in the next day or two, but today, I'll also order the carb rebuild kit from bmw2valve.com. I see that they don't seem to sell needles and jets, so I'll have to try Anderwerks in Calgary.
-
One thing I noticed when watching this video (at about the 8:35 minute mark):
http://www.youtube.com/watch?v=HShbaC9ORSo
was that the F mark on the flywheel was rock steady under the strobe lamp.
But when I did the timing on my bike, the strobe seemed to catch the S mark at two slightly different spots. I assume that this isn't normal, but I also would have assumed that the Boyer ignition would have taken care of that. Or is that a symptom of something else entirely? Can a carb malfunction affect the timing in this way?
-
But when I did the timing on my bike, the strobe seemed to catch the S mark at two slightly different spots.I assume that this isn't normal, but I also would have assumed that the Boyer ignition would have taken care of that.Or is that a symptom of something else entirely?Can a carb malfunction affect the timing in this way?
The carb can have no impact on ignition timing.
Is it possible the boyer ignition plate is not centered in the bean can. Does the boyer have 2 magnetic sensors and are they exactly equal distances from the cam.
-
Is it possible the boyer ignition plate is not centered in the bean can. Does the boyer have 2 magnetic sensors and are they exactly equal distances from the cam.
I suppose anything's possible with the Boyer. I wasn't too impressed with the design or the instructions. The stator plate (I assume that's what it's called) was similar to the stock mechanical unit in that the two screws that went through the bean can were used to hold it in place. Now, whether the plate is perfectly perpendicular to the sides of the bean can is another matter; it's just made out of circuit board material, so it's not nearly as robust as the stock unit.
Yes, it does have the two magnetic sensors. I'm not sure about the distance to the cam, but it seems that they're made to signal to two metal prongs that stick down from the stator plate. I think the only adjustment possible would be via any gap in the bean can where the two screws go through to hold the stator plate (ie, loosen the screws slightly and see if the can will allow some extremely tiny movement of the plate) (and maybe also to confirm that the plate is perfectly perpendicular to the can).
-
I just came across another bit of weirdness. I adjusted the throttle stop screws so that there was a bit of a gap (0.03 mm's) when the throttle was off (there was none before). After that, I very slowly increased the throttle to about 1,500 rpm. So far, so good. Then, just above that, the rpm's (on the tach and the engine) would race up to about 4,000 or 5,000 -- even though I had only just increased the throttle by a tiny notch.
I'm not sure if that symptom was there before the throttle stop adjustment or not, since prior to that, I may have just been blipping the throttle instead of very slowly increasing it. I guess I'll know for sure later today, when I take the bike out on to the road.
-
You need to perform a carb synchronization, with a manometer or gauges connected to the carbs .
Do this on an engine that is at operating temperature, not a 'cold' engine .
-
Well, I disassembled both carbs and gave them a good cleaning. Then I made a manometer and did the synchronization thing. I found that the butterfly stop adjustment at idle and the cable housing adjustment around 1,400 rpm went well, but that the idle mixture adjustment was a bit more of an art (whether I'll eventually master it is anybody's guess).
Occasionally though, when I blipped the throttle, the rev's would climb up to an indicated 5,000 rpm and stay there. My hunch is that it's got something to do with the Boyer ignition that I installed a short time ago. I've also had problems with the tach, and although I've been able to tune to the idle mark on the flywheel, I've been unable to tune to the advance mark (can't seem to hold the throttle steady enough). Plus, I've consistently heard what sounds like marbles in a tin can when accelerating on the highway. This all leads me to believe that the Boyer unit is the culprit. So I think my next task will be to reinstall the stock timing unit and see if those issues clear up.
-
This all leads me to believe that the Boyer unit is the culprit.So I think my next task will be to reinstall the stock timing unit and see if those issues clear up.
I think that's a good plan as the ignition has to be known good and timing correct before you can finalise the carb settings.
-
Hello !
Start by checking the valve clearance (it has a big influence), then check spark plugs, points, and advance system.
Only then you can synchronize carbs and set idle richness.
As for the throttle, you should buy the screw to set the throttle handle where you want it.
It is item # 26 on the right handle fiche for model after 81 (I hope the previous model had the tapping for the screw...)
-
Hello !
Start by checking the valve clearance (it has a big influence), then check spark plugs, points, and advance system.
Only then you can synchronize carbs and set idle richness.
As for the throttle, you should buy the screw to set the throttle handle where you want it.
It is item # 26 on the right handle fiche for model after 81 (I hope the previous model had the tapping for the screw...)
Thanks Georges. Yes, that has all been done.
The good news is that now I've taken the Boyer ignition out and reinstalled the old mechanical system, my tach is working again. And no more knocking during acceleration.
And with that and the carb balancing, the bike is now running better than it did at any time since I bought it 5 weeks ago.
There's a bit of fairly loud valve chatter above 4 or 5,000 rpm on the right cylinder, so I'll probably re-check that. But all in all, I'm a happy camper.
-
Well, glad you've a running bike ! summer is coming !
The noise could be due to pitting at the rocker tip. (making the valve to re-close a bit after opening a bit).
Some workshop can re-polish the tip and harden it back but it is becoming somewhat of a lost art.
You could start searching for a couple of non pitted rockers.... Or a wizard...
-
When you are checking the valve clearance, check the gap of the rocker arm and the blocks at each end .
Too much clearance will give you more valve noise/clatter .
-
Nice tip Bob, I'll have to do that myself from now on.
Also, Quixotic, congratulations! Now that your engine has smoothed out, you can play with the inevitable higher end vibration (around 5K) by adjusting your motor mount torques.
-
Hello Luca,
Could you explain the torque influence ,
I've always bolted my engine "by the book" so I will enjoy learning a new trick to try on my poor R65 :D
Thanks a lot in advance !
-
Play with your torque values... a little up, a little down. Supposedly each engine/frame combination is different, so you will have to tinker yourself. I'm doing some experimenting myself. 45 ft/lbs front and 40 ft/lbs rear seems to have a narrower high speed vibration (The 65-75mph buzzing that turns many people away from the R65) than 55/50 or 50/45 torque values.
I've been meaning to put a thread up asking what people would consider the minimum safe motor mount torques.
-
I've been meaning to put a thread up asking what people would consider the minimum safe motor mount torques.
I'd use the 85 on torque values as the low end limit. Forget what they are exactly but a fair bit lower than the earlier figures.
The best explanation I can think of why toque values have an influence (and I believe they do to some extent) is that the high frequency buzz happens to be at revs where the engine vibration resonates with the natural frequency of the frame. Back In the day when special builders swapped vibratory Brit engines and frames it was well known that the same engine could feel quite different according to the frame it was installed in and that must have been due to coupling and resonance effects.
Changing the torque values may alter the coupling between engine and frame which perhaps moves the resonant frequency and amplitude around a little.