The New And Improved Unofficial R65 Forum V2
Technical Discussion => BMW Technical Q&A, Primarily R65 => Topic started by: thessler on May 19, 2013, 08:11:41 AM
-
Hi
I have been fooling with this bike for a while now and can't seem to get it to run smooth.
When you give it gas from 1,000 rpm up to 4,000 rpm it will rattle your teeth. At 4,000 it smooths out real nice, anything below that it's just not a pleasure to ride.
I have been through the carbs twice and feel the is nothing left to do there, new plugs.
I used a home made clear plastic tube with colored liquid in it to balance the carbs and feel they are pretty good. I don't mind a little vibration it is a motorcycle after all, but this is unacceptable. I do own several other bikes and this by far vibrates the most.
Any thoughts on what to do next ??
Thank you, Tom
-
I think you'll find that they all have a slight roughness around 3000rpm. I'd hardly call it vibration though, more torque pulsing and only really noticeable in contrast to the super smoothness at 4000rpm.
Yours sound worse than normal so something must be wrong. How about other variables like valve clearances and compression ?
Try this as an indicator that vacuum balance is not producing the best results.
Lock the throttle open just a enough to lift the throttle off the stops by 10 - 20 thou. If you don't have a throttle lock you can tie or tape the grip to the brake lever. Now using feeler gauges compare the gaps under the throttle stop screws to see if they are equal. If they are not equal within a thou or two that suggest there is some mechanical reason why vacuum balance is being achieved with unequal throttle openings. If the difference is very small It can be something simple like unequal idle settings.
If everything checks out equal - valves, compression, mechanical and vacuum carb balancing then your are left with engine or transmission balance factors. Does it run as rough on no load or light load compared to wider throttle openings ? If it does (which would be unusual) that would indicate something mechanically out of balance.
-
Thanks Barry
valves are spot on, compression never checked.
I'll try that feeler guage test right now.
Tom
-
How many miles on the bike. Maybe a worn timing chain or semi-working timing advance (beancan) would cause unsteady ignition timing at idle and through the advance curve. By the time you get up to around 3500-4000 RPM, the ignition is fully advanced and no further advance is forthcoming, so it would be smooth then.
-
With the bike not moving and the transmission in neutral, when you increase the rpm's, does the vibration occur, or is it just when the bike is moving ????
When you have the manometer connected to the carbs, do you get any imbalance when the rpm' are increased into the range of rpm's that the vibration occurs ???
-
I set the balance at around 1500 or maybe a little more so it should be good.
This thing is mostly vibrating under a load while accelerating, if that helps.
Thanks, Tom
-
My first thought, is a cracked or torn carb diaphragm .
It doesn't take much of a crack/tear to cause an issue .
Another less likely condition, is the metal plug on the dome top of the carb, they on occasion come loose and may cause a similar condition to a diaphragm crack/tear .
-
Here's a few other things that may be present, there are aftermarket carb diaphragms that are a thicker material than the Bing parts, they are too thick and cause problems with the engine running .
Loose or missing screws that hold the round metal retaining ring on the diaphragm .
On one of my LS's, I found one screw that was too long and 'bottomed out' in the threaded hole, but there was still a gap between the screw head and the retaining ring, so it wasn't clamping the ring to the diaphragm and sealing .
-
Thanks Bob
Negative on the cracked diaframs. I have been through these real good and checked condition of them. No weird screws or anything out of the ordinary. No air leaks all clamps tight and boots in good shape.
Tom
-
Confirmed motor mount bolts torqued to spec?
-
Do you have a timing light? How steady is the timing at idle (~1000 rpm)
-
Thanks guys
Motor mount bolts are tight not sure about to spec.
This is an engine running problem.
No I do not have a timing light to check that.
Not sure weather to buy a light or sell the bike ! I am running out of patience with this thing. If I can't get it to run smooth ill sell it cheap and let someone more knowledgeable straighten it out.
Thanks, Tom
Will fool with it again today, I needed to walk away from this for a day or so.
-
I needed to walk away from this for a day or so.
Usually a good plan. Sometimes gives a new insight.
There is that story on the net of the guy that sells his vibratory R65 cheap and the new owner discovers that one cylinder and piston is from an R65 and the other is from an R45 hence the gross vibration. Not wishing to cause alarm. It would be near impossible for that to happen in a market that didn't get R45's but it goes to show that just about anything is possible.
Did yours ever run smooth ?
-
Barry
I don't know if it ran smooth, I got it a year or so ago with a swallowed exhost valve. I did get it running last year but never got serious about it .
Now it's registered and I'm ridding it around, I have done a lot of work messing with the carbs and lubeing up the advance weights. It has improved significantly since last month when I started fooling with it.
But this vibration under load is unacceptable, I am just starting to ride one of my other bikes and let this sit. Which is not a good plan, but the way this vibrates it's just not enjoyable.
Once I get it up around 4000 rpm it's smooth as silk, so I'm thinking its not a mechanical balance problem. More like fuel or electric but I could be way off .
Thanks for the interest, Tom
-
Why don't you look at the carbs for their Bing numbers, it's on the forward part of the carb on a vertical flange .
The number should read something like this : 64/32/325 .
Post the numbers here and we can give you the jets, etc. that the carb should have, no telling what previous owner(s) may have done in the past .
-
Thanks Bob
Numbers are (64/32/335 left side)
(64/32/336 right side)
I just remembered one of the needles that sticks out of the slide is new, I don't remember which side but I remember the new one wiggled and the old one was tight.
Not sure if it is set up right , or if this could be the cause just thinking out loud.
Thanks,Tom
-
When I get home from work in about 3 hours, I'll post the info from the Bing manual, unless someone esle has it handy .
I know it may not be of any help, just trying to eliminate anything that is a 'quick' fix .
-
have a look here :
http://www.bingpower.de/en/service/tuning-manuals/
Dial in your carb number (it is far down) and note the values.
What you report can be caused by some non symmetrical conditions between two carbs.
IMHO you should buy a set of jets, needle jet, and needles and replace them in both carbs (including the rubber).
It will pay in the long run by increased mpg
-
I just remembered one of the needles that sticks out of the slide is new, I don't remember which side but I remember the new one wiggled and the old one was tight.
Not sure if it is set up right , or if this could be the cause just thinking out loud.
The needles fit in one of four positions ( It should be position 3 in your case). Is it possible the needles are in different positions ?
If you measure the exposed length of needle that will tell you what position they are in. The needles being 1 position out wouldn't normally cause very severe vibration but it's got to be worth having them correct.
Length mm
1 42.37
2 40.57
3 38.79
4 37.10
-
The carbs came from Bing, with 138 mainjets, needle jet 2.64 if you can find a number on it, idle jet 45 and has been mentioned, needle position 3, this is numbered from the top .
On the /335 and /336 carbs you should have the upgraded parts where you remove a threaded plug from the top of the slide and the needle comes out from the top .
-
Ok thanks guys
Carbs are coming back off tomorrow, I know they are spotless but I really didn't check jet sizes or needle position.
I suppose if one needle was high and one low that might be problematic.
Otherwise I will post my findings.
Thanks, Tom
-
Hi
Just been through the carbs , I even used a magnifieing glass.
Idle , main and needle jets are what they are supposed to be. Number wise. Needles in third slot. Everything looks good and nothing out of place.
I noticed the cap on top of one carb a little loose ( I mean the little 3/4 inch cap ) not the big one. I put a little silicone on it but even that couldn't have had much of an air leak.
Ran it synced it and I would say runs 10 percent better, but really not good enough. Not sure why it runs better ,must have cleaned something somewhere. Or just an optimistic imagination.
During the test ride I really zeroed in on the tach. The worst problems are around 2500 rpm. It vibrates unacceptable from about 2000 to 3000 .
At around 3000 it settles down to a typical buzz then smoothes out real nice toward 4000.
Someone earlier mentioned timing and I'm thinking the timing should affect both cylinders at the same relative time and not cause excessive vibration so I really didn't go there, besides I don't have a light. Just thinking out loud, don't really know where to go from here.
Carbs have been off three times, that should be enough but my gut keeps going back to them.
Last thought change the throttle cable, maybe it's doing something weird while ridding I hate to just start changing parts, that is an expensive road to go down.
That's where it's at ! Thanks, Tom
-
It sounds very much like a carb balance issue to me- one side working harder that the other. I would start over with the cable tension and idle setting.
-
... I have been through the carbs twice and feel there is nothing left to do there...
Does this mean you completed a total strip down of both carbs? new Bing carb kits installed?
Did you run a single strand of copper wire -from, say, an 18-gauge wire- through every passage; then flush and blow them clear? Replace the multiple o-rings with new? Confirm fuel rate of flow and float bowl condition plus adjustment/alignment? Confirm condition of diaphragms? Needle position in each carb slide? How about those tiny holes in the venturi adjacent the slides -are they clear?
Unless the carbs were totally disassembled, there's still the possibility of a blocked/clogged fuel or air passageway. Doesn't take much to disrupt proper operations.
Also, are the fuel lines new-ish and not deteriorating internally and restricting fuel flow?
Are the vacuum take offs sealed after the carb balance?
There's carburetor overhauls and then there's carburetor overhauls.
-
During the test ride I really zeroed in on the tach. The worst problems are around 2500 rpm. It vibrates unacceptable from about 2000 to 3000 .
At around 3000 it settles down to a typical buzz then smoothes out real nice toward 4000.
I was actually thinking about your problem on the way to work this morning and watching the tacho in the same way. What you describe here is typical airhead as far as the characteristics at the RPM bands are concerned. They all rumble a bit and smooth out progressively above 3000. The only thing untypical about yours seems to be the magnitude.
On the assumption that vacuum balance isn't giving the best result I'd be inclined to try a plug shorting balance to see if there is any difference. If you lock the throttle at 1500RPM and then short each cylinder in turn, observing the fall off in revs, it should demonstrate if both cylinders are producing the same output. You can do the same at idle except the engine will only run for a few strokes so you are comparing how quickly it stops or in practice just listening to the difference for a couple of strokes and not actually letting it stop.
Another option after a vacuum balance is to mark the cable adjusters at each carb with a dab of paint. You can then experiment by turning one adjuster 1/4 turn in either direction to see if the vibration get better or worse.
-
I hope I will be corrected if I'm spewing bad information.
With your throttle set at at the notorious rpm that will produce the vibes: Reach down with your free hand and pull slightly up on the cable housing just above the carb. Do this one side at a time. If the engine vibes smooth out momentarily when the rpm increase (assuming it will increase) then you LIKELY have a sync problem; but if it doesn't, its something else to move on to.
-
Keep in mind that carb imbalances are often more noticeable at lower revs. A slight leak at 5% throttle is a greater percentage of the total air/fuel mixture going into the cylinder than at 90% throttle. It's one of the reasons we dont synch carbs at high revs.
Like Monte asked, did you overhaul the carbs or overhaul them? Often the butterfly shaft o-rings are neglected, and those can leak air. Also, make sure the butterflies are properly installed. They can be put in backwards or installed so as to not seat evenly. Both instances will give you more trouble at low RPM's than higher. Same with the dome cap that you siliconed. If the cap leaks air, the diaphragm won't have the proper vacuum on it and the slide will not lift enough. It doesn't need to be jiggly to leak air, so you might consider gooping up the other one as well. It's also possible that one of your new o-rings was damaged during installation.
One easy way to identify air/exhaust (a bad exhaust leak can also cause you trouble) leaks is to hold a lit cigarette/incense/whatever near various joints (not just the carb boots) and give the engine some revs. Look for a disturbance in the smoke. You can also use the old brake clean/wd-40/starting fluid trick on the intake tract. Spray that stuff at the joints and listen for an rpm change. Usually the engine will bog down and then the revs will gently rise as the spray stuff burns. Keep a fire extinguisher handy [smiley=thumbup.gif]
Also, confirm that your enrichener (choke) levers are fully returning at the carbs. If the spring is weak or the arm sticky, that can mess up your mixture too. Are they installed correctly? I'm not sure if installing the discs backwards can mess with the carb balance... hopefully someone who knows can chime in
Does your bike still have the EPA emissions system installed? As Monte asked about the carb vacuum ports... there could be a leak in one of the vacuum lines between a carb and the EPA valve. Also, less likely, one of the EPA pipes to one of the cylinders could be blocked up, have a leak, or have a loose fitting.
Are your plugs, plug ends, and wires the same and in good shape? Sometimes resistor plugs make their way into non resistor boxes. You can verify this with a multimeter. Same with your plug wires/caps. You could try reading the plugs at the most problematic rpm to see if there is an obvious difference in mixture.
Do you have much oil consumption? Are you using good, high octane gasoline?
While my experience has been that motor mount torque makes more difference on the upper rpm vibration (usually around 5K RPM), you could try experimenting with the motor mount torque. 5-10 ft-lbs can make a substantial difference. 55ish front 45ish rear seem to be popular figures
Sorry to go on at length... I just don't want you to give up :'(
-
And here I go again...
nhmaf suggested you check your timing at idle. Considering you recently had a problem with the bean can, it would be worth it to check the timing. A local auto store will probably loan a timing light to you for a refundable deposit.
IMHO you should buy a set of jets, needle jet, and needles and replace them in both carbs (including the rubber).
+1 Believe it or not, needles and needle jets wear with use
-
+1 Believe it or not, needles and needle jets wear with use
True true, but they don't all of a sudden wear, or do they? The rubber I can understand having a sudden rupture.
-
True true, but they don't all of a sudden wear, or do they?
no they dont, but he said
I just remembered one of the needles that sticks out of the slide is new, I don't remember which side but I remember the new one wiggled and the old one was tight.
so one is new and one is worn. That could cause an imbalance. IMO, probably most noticeable when the slides first start to do their work...
-
thanks Luca. I should know better than to jump in here...
Well, I for one am keen I learning what it turns out to be. I just hope he doesn't give up on this.
-
Those carb slide tapered steel needles are kinda loose for a reason. They "self-center" as they move into and out of the needle jet. If a steel needle is so tight that it doesn't wiggle at all, it may likely rapidly wear a channel into the brass needle jet and cause mid-range operation concerns.
Did you remove the needles during your carb overhaul? Are the cut-aways on the slides oriented properly?
-
Wow
This is a lot to digest. My carb job is just a cleaning, I have not installed any new parts.
My thinking and maybe this is short sighted is to get this thing running good and see if I even like this bike before I start dumping more money into it.
Maybe it's time for a rebuild kit for the carbs.
Can anyone suggest a good site to order carb parts from ?
You guys have given me a lot to read and understand so I will need to go back and re read all of theses suggestions and keep trying, maybe ill try that shorting system of sync. The carbs.
Being that I feel there was some improvement today this kind of points to these carbs as the culprit.
Diaphragms are good, chokes installed properly and returning, butterfly's checked.
I know what was suggested to replace the o rings on the shafts, I may be wrong but I can't see a little air leak causing this amount disturbance.
Between 1 and 3 k I can't use my mirrors, can a vacuume leak cause that ?
Thanks very much for all the help, Tom
-
Still at it.
I think there is a misunderstanding. I did not overhaul the carbs. I went through them to clean and inspect only.
I removed both needles to varify notch , and freed up the stuck one.
Slides are oriented properly.
Vacuume line is plugged good and the rest of the EPA system is gone.
Thanks, Tom
-
Well the EPA removes some of your woes IMO. (it doesn't seem to bug as many people as it should that it keeps the right carb bowl from coming off)
I think you should rebuild the carbs. If one needle is new and the other one isn't, it means somebody messed with em' and probably didn't do as thorough a job as they should have. It's gonna run you a few bucks, but it really sounds like it will be money well spent. Motobins has rebuild kits, but they'll have to get shipped from the UK. Not sure who has them in the domestic market, as I got mine from Motobins, but the one important thing is that you use BMW parts... especially the diaphragms. Some people sell (cheaper) Saab diaphragms as suitable replacements, but many people report problems with those diaphragms as the rubber is not the same in one way or another.
This is a lot to digest.
yep, I feel for ya. Carbs can be real a pain in the butt, and even worse when they're an electrical problem. The trick is to stay cool and methodical, which is why:I know what was suggested to replace the o rings on the shafts, I may be wrong but I can't see a little air leak causing this amount disturbance.
you don't assume anything. Put the wrong diaphragm in one carb, have a bad needle or needle jet on another... things can compound. Don't assume anything. Eliminate one potential problem at a time. It's gonna cost you a few bucks here and there, but you will chase your tail trying to sync the carbs to fix your problem if everything else isn't in proper order. Carb syncing is the absolute last thing you do when tuning an engine.
Best of luck. We're here for ya'
P.S. did you plug the vacuum ports on the carbs, or plug up the tee in the airbox? If the hoses are still in place, there could be a leak along the way.
P.S.S. thanks Luca. I should know better than to jump in here...
PSHHHH! give yourself some credit
-
I wonder if I'm in the same boat as thessler. I bought mine from a dealer about 2 weeks ago (not really a dealer, but a motorad specialist). It had been on the showroom floor for a few weeks, but when he started it up in the garage prior to me taking it, it sounded quite rough to my untrained ears. He revved it up to 5 or 6,000 rpm and frowned, saying something wasn't 100%. Then he took the float bowl covers off and fiddled with the floats a bit. Then he started it up again. Maybe it sounded slightly better; maybe not. But the money was burning a hole in my pocket, so I grinned when he grinned.
After I got it home (hauled it 100 miles in a pick-up) and rode it, I knew that it was FAR rougher than any other vehicle I'd ever owned. Even my old 1972 R75/5 was much smoother.
So, is the R65 significantly rougher than the R75/5?
I soon plan to check the points gap and then the timing, spark plugs, etc. Then on to the carbs.
-
Evan,
We don't want to hijack this thread but, yes, start with the points (perhaps a new set), timing and valve lash adjustment. With 20 thou kilometers, you, too, may be due for a complete carb overhaul.
We now return you to our regularly scheduled programming...
-
Good news today
I locked the throttle at 2500 and set the carbs. I did not have to adjust much they were close and it did help, not a lot but it helped.
Seems every time I fool with this thing I am gaining a little. Can't say it's right but it is getting better. I will continue to read up and follow your suggestions.
Thanks, Tom
-
Check the return springs on throttle and choke.
I had old springs not strong enough to return the choke off. So the engine had a few choke on all the time (and of course was not the same every ride...)
Buying 4 new one saves fuel ;D