The New And Improved Unofficial R65 Forum V2
Technical Discussion => BMW Technical Q&A, Primarily R65 => Topic started by: trolle on March 03, 2008, 05:55:06 AM
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I have now finished installing the Omega digital ignition control, I have adjusted the carbs (new needles and other stuff last year) and the electric system is OK. Never the less there is a very distinct loss of power around 4000 rpm. This is especially notable in strong headwinds (>10 m/s) in the fifth gear and I have to go down to fourth to get past 55 mph. As soon as the engine is running past 4200 rpm in fifth, there are no problems. The problem arises both with a cold and a warm engine. The ambient temp. was 40-45 F
I pulled the plugs to see their state. They looked a bit pale, i.e. the mixture might be a bit on the lean side.
I need some advice before I start pulling my carbs apart.
Other than this, the Omega works like a dream: No failing sparks at any level of rpm; for the first time in four years the engine is completely steady when idling, no stuttering and there is much more power for acceleration.
greetings from a norht with varying cloud cover and tolerable driving conditions (dry and 42F)
trolle
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Maybe switch the wires back to the stock ignition just to eliminate the Omega as a possible culprit?
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I have thought of that as the first step in my error finding procedure. No the second step, because I checked the ignition time setting and adjusted it, which did not make the powerloss go away. So my next step will be switching back to "normal" and trying that out.
BTW in my search for possible solutions, I came upon this: http://www.theultralightplace.com/bing.htm
greetings from a north with varying cloud cover and tolerable driving conditions (dry and 42F)
trolle
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When you adjusted the timing, had the full advance mark appeared in the timing window by the time you reached 4000 RPM ? If it had done so, and the
timing at idle was correct, I would suspect either an air leak somewhere in the carb boots to the intake or possibly a jet that is sticking (though also a
misaligned or punctured diaphragm in the carb could also account for this).
Please keep us posted as to what you discover !
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Classic indication of a leaky diaphragm. However do not overlook checking your spark advance is at full advance as you reach 3,000 rpm with a reliable timing light connected to a power source that is not the bikes battery. Valves adjusted? Head torque? floats not set too low? you might also try raising the needle jet a notch if all else checks out.
rich
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Thanks for the advice. I will start out with the easy things: Checking diaphragms and needle positions - I installed new diaphragms, needles and nozzles last year, and new floats. If that does not help I will go on and check the valve settings (I am quite anal about those, as Rob would put it) and when the tops are bare, torque the tops of course.
I have considered raising the needles one notch, as the plugs looks rather light in colour, but this may be due to a better burn caused by my new high performance coils giving a better spark and not a too lean mixture, although my new airfilter might let more air through than the old one. My logic or my intuition tells me that raising the needles will result in more power as the increased amount of gasoline will "fit" the better spark and the increased amount of air. Having no measuring tools I have to go by ear and intuition.
Any comments on my "logic"
greetings from a sunny and windy north with wet roads and temps of 40F, mediocre riding conditions
trolle
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Are you running a OEM factory spec air filter? If not, then some fiddling may be in order.
Do you still have those inline fuel filters on the bike? Are they fresh and flowing well?
Have you performed Justin's suggestion of removing the Omega from the equation?
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Hi Rob
Are you an early riser or a night bird?
The filter is probably made to OEM specifications - it says so on the box anyway, and I have no reasons to distrust the manufacturer.
The only filter in the fuel lines is the one sitting in the tank above the petcock, and although I have not checked it resently, I do not think it has been clogged.
I am rather busy at work these days, so I have not had the time to do all these fun things to the wh8la2 yet, but if the weather allows it, I will spend some time in the garage this weekend.
greetings from a still sunny and slightly less windy north, where the roads have dried and the riding conditions improved
trolle
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I was looking at your website to determine which air filter you use (flat) and I saw the photo with the inline fuel filter.
I guess that was an old photo, no longer applicable?
I am a night-owl that works 2nd shift. I get off around midnight. Last "night" I turned out the lights at around 6am...
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Hi Rob
May be I should bring my site up to date [smiley=nopity.gif]
I checked the diaphragms and their placing - they were OK. Thursday next week I am going for a round trip of 400 miles so let's see how things are then.
greetings from a grey and moist but warm, 43F, and calm north, conditions demanding careful driving
trolle
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Update of measures: Moved the needles up one notch and checked the valve settings, they were OK, a loose .15 mm on the exhaust side and a firm .10 on the intake. Took the wh8la2 for a short spin down the highway to test the power. Conditions were dry, 42F and a very strong headwind above 12 m/s. When we reached the 4000 rpm the throttle was wide open, but it did not feel like a drop of power, more like the top. After a few 100 meters the headwinds subsided a little and I was able to bring her up to 6000 rpm.
Then the ignition disappeared (due to a connector which worked loose and resulted in a major backfiring) and it was time to switch to the "beancan", no real difference, so I think that the Omega is aquitted. 650 cubic cm and 50 HP just is not enough to accelerate a 185 cm, 90 kg driver from 50 mph to 82 mph in fifth gear and in strong headwinds in an acceptable time. There is a flat spot around 4000 rpm which must be circumvented by going down one gear when accelerating the bike from 50 to 82 km/h under those conditions. (82 mph being the speed limit on our motorways or freeways [US])
On the return, with the wind in my back, I of course had trouble keeping the old gal below 140 kph ~ 88 mph.
After this short ride, 30+ miles, I checked the plugs to see their colour, which was a nice tan, not too light and not too dark.
Tomorrow I will make the final adjustments on balance and idle and fix the loose connection.
greetings from a percipitating north - bad riding conditions
trolle
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The backfire referred to in the my posting above opened the left muffler all the way along the welded seam! It must have been rather loud [smiley=1drink.gif] [smiley=rifle.gif]
I hope my problems are solved by the way: The missing power was probably due to the loose connection, which may have enhanced the natural? flat spot around 4000 rpm.
For those of you who wonders, why the left muffler and not the right as well? the answer might be a hanging choker on the left side, due to a worn cable, making the mixture richer on the left side and therefore more combustible.
Well after this experience my need for more exact tools than my ears, which may be damaged by the loud banging of my backfiring engine, became so great, that I had to drive to the nearest bigger town, where such tools are for sale. The shop lies 39 miles from my home and 35 of the 39 are on a motorway with very little traffic. (the result of a political deal made by a couple of very astute local MPs in the nineties, giving me and several others a perfect testing range).
On the way out I had a fair headwind and of course wind from the back on the way home. This time every thing worked precisely as I wanted it to. A steady 84 mph on the way out and a steady 90 mph on the way home. At one time I touched 103 mph still having power in excess. No signs of wobbling or other vices. Made the final adjustments of the idle and throttle, and exchanged the busted muffler with an old spare.
Well, I changed the needle position back to second notch because I found the gasoline consumption a bit high (170 miles on a full tank).
And what did I buy in this shop? One ignition test lamp (stroboscopic) and one compression testing device. The former showed that the ignition is OK and the latter has not been in use yet.
Status till now: Everything works as it should, the causes of the problems may be found and even though the wh8la2 looks like sh*, she is a very wellbehaved lady.
greetings from a precipitating (not again! [smiley=drowning.gif]) north with bad riding conditions = wet and cold roads
trolle
I am getting good at keeping my own threads alive [smiley=happy.gif]
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Trolle,
Your posts are often informative, and always entertaining - I mean this in a complimentary way !
Good luck with replacing the mufflers - what are you planning to replace with ?
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>:( I have just written the most funny and entertaining posting and then it disappears, just because I needed this link:
http://www.bmwandguzzispares.co.uk/bmw/products/product.php?f=i&code=BA_15_20_YA_60&shnew=New&model=R45/50/60/65/75/80/90/100%20(2%20valve)&shnewcode=15&part=Stainless%20steel%20fasteners&sub_part=S/S%20brake%20parts&modelcode=20&partcode=YA&source_code=BA_15_20_YA_60&spPage=1
Well that is life.
What I wanted to say was this: Having no children at home, a reasonable salary and a wife, who after a trip to our capital returned with the words: "I couldn't find anything to buy" I can afford to buy a lot of not very necessary things for the wh8la2, like new mufflers when the old ones look dirty, new electronic ignition although the old beancan is no more than three years old and works just like it should, superflous tools like the ones mentioned in my last posting and so on. The point is that I have not had a real hobby before and with the r65 I have found something which at the same time satisfies my love of problem solving and my penchant for dangerous but controllable situations.
Back to reality: I have a pair of old mufflers lying about, and they are quite usable. The only reasons for exchanging them with new ones was that the right on was newer than the left and that I found a new pair on Ebay, that I got at half of the store price.
This leaves me with a problem! Now I have to by a new pair because ...
greetings from a wet north - bad driving conditions, dark, wet and cold
trolle
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Do you have that HPN (...I think that's the company....) catalog? There's a way to spend money. ;D
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I have the same power issues atthe same range Trolle, 4000-4200 rpm
what was your solution in the end? (i read the posts bu think i missed it)
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I did not solve that particular problem yet and having no idea of the cause I can only guess:
Yesterday I made a roundtrip of 400 miles in strong winds (above 10 m/s and up to 17 m/s in the gusts) and showers. At some stretches of the road the wh8la2 had problems reaching 80 mph due to headwind and at other, where the wind came from the side or even from the back, there were no troubles at all. Now I measured the compression of both cylinders just before this trip and although the compression was the same at both sides, it is at the low end of the acceptable, ie. 123 psi.
My hypothesis is that the engine has a small drop in power around 4000 rpm, maybe due to the working of the carburettors, as described in other postings. Under "normal" circumstances this drop is not perceptible but under extreme circumstances, like strong headwinds, the need for fast acceleration in fifth gear from 50 mph and up, steep inclines and the like combined with the less than optimal compression, the drop becomes perceptible and at times a nusiance.
My next project, therefore, is to put in new piston rings at both sides. After 60,000 miles the rings might be worn enough to make the compression less. Another culprit could be the valves but as I have not done 10,000 miles on my new exhaust valves and seats yet and as the intake valves were judged OK by the shop who did the job, I tend to blame the rings. Having the nicasil walls of the post 81 engines I do not have to worry about cylinder wear and the last time I checked the walls were OK.
I have at this point checked ignition timing, torque of the head bolts, compression and for leaks in diaphragms.
The carbs have been fitted with new needles, jets and floats and new throttle shaft and butterfly on the right side.
The coils have been exchanged for a new set of high yield coils and the rectifier and voltage regulator have been exchanged with a new unit, comprising both rectifier and regulator, which gives a much better power supply. The battery charging begins at 1100 rpm and the charging voltage lies appr. 1 volt higher than that of the old system.
greetings from a grey north with good riding conditions, ie light wind and dry roads.
trolle
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Milkman, if you are "running out of steam", and not picking back up after that RPM, then it is likely a leaking carb diaphragm or two...
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right, thanks
i used to pick up noticeably after that rpm, but now its laggin somewhat
hope to look at it when i can take teh bike apart
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Hi Trolle,
The problem at 4.0-4.5 I had too, when I fitted the heads with the larger valves.
Combined with rough riding in that RPM area.
Because the spark-plugs were too light I raised the needles -> problem solved. maybe you should fit the old needle jets: they are a bit bigger. ;D
My experience with more or less worn bikes tells me that a worn engine loses power at low RPM's, but the high end is not so quickly affected, (when the heads are OK, and no bouncing valves in their guides)
IMHO this is a tuning problem.
So do not sink too much money in new part, but fiddle with the carbs, and pay some Euro's extra fuel. :o :o
I assume that the advance is finished at at most 3.500 RPM.
Our BMW's do not like a lean mixture! I am happy with 18 kms/liter in the summer.
Now she does only 16-17 kms to a liter, but I do mainly commuting 8.5 to, 8.5 fro. Not good for the bike. She suffers.
But even the battery of 5 years old let me down only once this winter!
P.S. My bike has lost power above 6000 RPM, since I changed the torn rubber tiny rings around the idle jets.
Too rich a mixture now? Those BMW carbs keep you busy.
wiemer.
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My bike has a power loss when it goes over 7K. I think there's something wrong on the seat.
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Well, Ed.
Our not-so-strong bikes should have their max torque at 6.500 RPM, (book), so in real world the bike should pull OK at 6.000 RPM.
And that is only 144 kms, or 90 miles/hour.
Every now and then I test if the bike still does. And she doesnt anymore. >:(
Am I demanding too much?
wiemer.
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Hi Wiemer
You have not been on for a while - nice to hear from you again.
Due to the rather harsh weather - snow and freezing temps - I have not been riding for the last couple of weeks so I have almost forgotten the feeling. Never the less your info on the powerloss between 4K and 4.5K eases my mind and, as you suggest, the rest is a tuning matter.
So now I will finetune the ignition setting and see if that helps. If it does, I will find other things to worry about :)
greetings from a sunny, white and cold north with dry roads - good riding conditions
trolle
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I feel that the problems at 4.000-4.500 have to do with the bigger valves from 1981 on.
The guys (and gals) who have the pre 81 engines might confirm this!
Also, I feel (subjectively) that the intake sound at that RPM doesnt sound good, sort of bad interference.
Maybe there is some backwards going pulse when the intake valve is not yet closed.
It is not easy to make a bike have a dip-less torque curve.
wiemer.
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Just the latest update: I had a suspicion that the ignition was a little on the premature side and changed it appr. 2 degrees. Quite an improvement in power at all rpm. The 4000-4200 as well although there still is a flat spot there but now it is acceptable. In the band from 5-7500 rpm it really flies.
Wiemer: My new Omega DICU stops at 3700 rpm
greetings from a grey north with good riding conditions
trolle
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Hi Trolle,
That is nice!
To feel a 2 deg change, you know your bike well! :)
Maybe you should go back another 2 degs! Those marking points are not sacred. ::)
It is kinda strange that our CR 9.5 bikes have the same ign timing as an r 75 CR 9.0 and an R 50/5 CR 8.6.
I am going to check my ign also tomorrow.
What I experienced with my benelli twin I rode for many years that too early an ign timing resulted in a less vibrating and more smooth working bike , but less throttle responsive and worse accelerating.
The Benelli also never pinked (detonated), nor does my R 65.
Wiemer.
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I do not know much about the relation between ignition time and CR but never the less I agree that it sounds strange.
The former ignition setting was set just at the beginning of the cycle - at the point where the diode on the Omega unit just lit up - and the new setting is at the middle of diode light. Maybe I was bragging a little there about the 2 degrees, it is probably nearer to 4 or 5 degrees.
The result is better starting, less use of choker, more power at all rpm and maybe slightly more vibrations. The last is hard to feel because vibrations in our engines IMHO are mainly due to faulty synchronization of the carbs. This is especially the case at idling; if the carbs are not properly in sync, the engine vibrates very much making the whole MC shudder, but when they are in sync there are no vibrations, even at rpm below 1000.
greetings from a showery north
trolle
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Yes, showery here too!
But there will be sun this afternoon, the meteo-site says. ::)
When the CR rises, the flame will burn quicker, the ignition can start later.
The form of the burning chamber (head, squish band, piston) is very important too.
I dont understand a bit of the way you set up your ign. A diode light lights up, when the flywheel is in the S position??
What is the beginning of the cycle you mention? TDC?
You still need a strobe lamp?
I bet you advanced the ign. ;D ;D [smiley=behead.gif]
Wiemer
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(https://bmwr65.org/smf/proxy.php?request=http%3A%2F%2Findian.no%2Fmotobins%2Fomega.jpg&hash=146cd800518a9811e7b4a343ec69b66216ea5500)
The red thing in the picture is the ignition control unit and as you can see, there is a rotating aluminium disk with an embedded magnet (visible in the picture).
When this magnet passes a feeler placed in the ICU a red diode in the ICU lits up and stays lit for appr. 10 degrees of the disk's rotation. At first I had set the lighting of the diode to match the S mark on the flywheel but this was to early and therefore I changed the position of the alu disk to match the midpoint of the diodelight's period with the S mark.
I have not checked with my strobe light yet but when I checked the old setting, both the S (at idling) and the Z (above 3700 rpm) where sitting too low in the inspection hole.
greetings from a sunny, part cloudy north with good driving conditions
trolle
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OOhh,
That is not simple to adjust! So small, one touch and the ign moves a lot of degs. :o
When the ign marking is low in the hole, it is late. the crank turns clockwise, looking from front.
You should check with the strobe lamp the actual setting, which MIGHT please you more than the factury setting!
What we learned now is that a late ign aggravates the 4000 RPM power dip problem.
Let us know!
Wiemer.
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Watching this for a while to see what resolved this loss of power.
Was the cause determined & I missed it.
Both my Airheads are pretty much dogs in fifth gear, unless wound up tight.
But in all other gears there is a rapid increase in rpm when 4000 rpm is reached, if I am at the same throttle.
I beleive that is when full advance of the ignition timing is reached.
Anyone else have the same happening?
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No, mine pulls from...ah-very low RPM's.
When not on the highways I make very low revs.
We in Holland are the people (of europe) the most fined for speed-doubtless for our own safety. ::)
Really riding is not very funny here. :'(
In Holland one cant judge a bike.
In France, with load, and hills, and twisty three-laners, max 110 kms, it is better to judge a bike.
But I have not had the occasion.(with this bike)
My advance stops at 3000, measured today (because I checked ign after Trolle's story- mine was also some degrees off.
Just one tiny wiggle of my beancan, just visible- on the flywheel 1/4 inch, I forgot how many degs that makes.
After that I had to turn down the idle speed, so I know there has changed something. 8-)
wiemer
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Just to report some results:
After having done app. 1000 miles with the new electrical system, new digital ignition module, rebuild carbs and having synchronized the carbs and finetuned the ignition the consumption of gasoline has gone down with 10%, the engine starts without choker, runs very smoothly delivering power evenly from 1000 rpm and upwards to 7500 rpm and idles smoothly at 750 rpm when warm. I am a happy man :)
greetings from a sunny and partly clouded north with excellent riding conditions
trolle
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Trolle -
I don't think that it gets any better than that !!
Good job on your final "tweaks" - I need to check the ignition timing on my LS - though I think that it is at least close to properly
set (performance and fuel mileage is quite good) I am the sort who "just wants to know" if it is correct..
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I had similar problems with an old BSA Royal Star twin which I fitted with a Boyer Brandsen set up. It had to be set at high revs (Can't remember actual figure!) in order to check full advance was working. This was a three handed operation and I only have two! You needed one hand on the throttle to hold revs steady, one hand to hold the strobe and the other (missing hand) to adjust the timing. This was further problematic in that the timing marks and adjustments were on opposite sides of the engine and the engine was revving its bits off whilst all this was going on! I eventually found that I had been setting the timing too much retarded and that threw out the tickover and pulling at high revs. The advance was built into the unit and the distributor centrifugal bob weights were no longer needed. (Another job to forget about!) A call to the very helpful folks at Boyer and help from my son to do the third hand work did the trick.
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My bike has a power loss when it goes over 7K. I think there's something wrong on the seat.
I think that is where the valves start to float...end of cam and valve train...unless you put in trick springs, retainers and a cam with light pushrods. Not to mention raising the compression and porting the head and going with bigger carbs. (lions tigers and bears and oh my)... :o
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My bike has a power loss when it goes over 7K. I think there's something wrong on the seat.
I think that is where the valves start to float...end of cam and valve train...unless you put in trick springs, retainers and a cam with light pushrods. Not to mention raising the compression and porting the head and going with bigger carbs. (lions tigers and bears and oh my)... :o
I forgot about this thread.... I was actually implying that I let off the gas. I'm the thing wrong on the seat. I do believe that it takes pretty much all of my R65's considerable horse power to push me, itself, and the big Windjammer through the air at over a hundred miles per hour. When I ride my naked Triumph at those speeds, it feels like the wind is trying to pry me off the bike. I try to hug the tank and tuck my legs in, but the kick lever on the right holds that leg away from the bike and my leg flops around helplessly. That's even with both feet back on the passenger pegs. Behind the Windjammer on the R65 everything is uneventful, unless there's enough cross wind to make the bike wiggle thanks to big saddle bags.
No I'm not in the Ton Up Club, but I do the try outs fairly often! Is the Reverend Horton Heat rockabilly?