Tue, 07/13/2010 - 16:38
I am having trouble getting my R69S to run, any adice would be appreciated. I can start the bike with a little difficulty & it will idle but as soon as I open the throttle it dies. The bike was running OK when the previous owner bought it, he didnt use it ( besides starting it now & then). I have cleaned & drained tank, clean carbys, checked float level, cleaned out pilot & main jets, changed fuel filters, new plugs, clean air filter, ensure slides are syncronised, run with fuel cap off, points gap good, coil gap looks OK, set mixture screws at 1.5 turns out (also tried 2 turns out etc). I can get the bike to run for a little (roughly & then dies) if I give it alot more throttle, this made me think pilot jets may be slighty blocked but thet look OK.
I do think this is a fuel problem as it was running fine when parked up, I have ordered a condeser & new points.
Thanks
Dominic
Sydney
Australia
- 747 reads
Tue, 07/13/2010 - 20:59
#2
Air leak at carb to head?
Remove the carbs and check the flanges for flatness. You may have to lap them to obtain a true flat surface. Then use new base gaskets and done overtighten. My R50 would hardly run until I did this. Good luck.
Thu, 07/15/2010 - 18:20
#3
Poor Running
Thanks for the responses, I have checked the floats out & they look OK (I fiiled the bowls with fuel & they float & dont seem to be taking in any fuel) , have taken air intakes off to watch slide action & that looks OK as I did initially have a sticking slide issue which turned out to be the throttle cable,had advace/retard unit off, spings look fine.
I now have a new set of points & condeser to fit & then I may need to face off carb flanges if this doesnt change anything.
Thanks
Dominic
Fri, 07/16/2010 - 01:41
#4
Spray some carb cleaner at
Spray some carb cleaner at the carb flanges with the engine running. It the engine speed changes, the flanges are a problem.
Bruce
Wed, 07/21/2010 - 18:40
#5
Poor Running R69
Thanks Bruce, I tried spraying Carb cleaner on the Carb flanges......no change in engine speed, I am not sure about changing needle settings or jet sizes etc as this bike was sorted & running fine (This bike has been restored with just about everything renewed/replaced).
Need to work out if floats are catching somehow, will install points & condenor after running through these carbs one more time, my gut feeling is a fuel issue, like its getting a gutful as soon as throttle is twisted, I aint givin up........
Thu, 07/22/2010 - 01:56
#6
Another issue with Bings is
Another issue with Bings is that the pressed in section just beneath the slide tends to rise up and sometimes needs to be reseated (tapped down). I believe Duane has a write up of this on his website.
If you compare a good carb to one where the center section has risen, it is easy to see.
I don't know if this could be the problem, but it is another thing to check.
Bruce
Thu, 07/22/2010 - 04:08
#7
As a professional mechanic,I
As a professional mechanic,I will be the first to say it is difficult to troubleshoot problems over the internet,but I will give it a try.
I would have a spark plug wrench handy,rev the motor,and as soon as it dies,QUICKLY remove a spark plug and see if it is wet /flooded,or dry.....that will start you off on where to move next.If it is a lean condition,and you are sure the
1.Petcock flows sufficient fuel
2.Gas cap vent not clogged.
3.Float not flooded/working
4.Needle seated/holding fuel
5.carb slides not too worn/slide pegs missing=slide rotating around
6.jets clean/seated properly
Then I would check the position of the slide needle,there are several positions you can adjust it to in order to cure a running condition,all else being in good order of course.
Sun, 08/15/2010 - 22:14
#8
Poor Running R69S
http://www.bingcarburetor.com/pdf/2x1.pdf
Having checked all of these things I was running out of ideas and took it to a BMW shop in Sydney . He said the main problem was that the slides where in upside down... I had them out (numerous times) & put them in the way I found them also checked the workshop manuals & Bing breakdown (above link) which looks to me the flat bottom of the slide goes to the bottom.
Also having now read jlibbys issues with carbs he states that his were in upside down "wire up plate down". If this is right then the breakdown details for these carbs are very confusing (Cymer included).
The mechanic also said the timing needed advancing alot and that full advancing could not be achieved without removing magneto etc , but it was close. I got the bike home & it starts & idles good, the bike now seems to have no power? I dont think that if the timing was a little retarded it would reduce the power noticibly. I think have replaced one issue with another, frustrating....
Thanks for the responses they all have been helpful.
Mon, 08/16/2010 - 05:52
#9
Slide upside down? I
Slide upside down? I wouldn't think that's possible given how the throttle cable attaches to the slide for movement up and down. Plus the jet needle placement...it would have to be clipped in such a way that it stuck out very, very far. Strange indeed...hard to imagine.
Just where is the timing set? Have you put a timing light on the flywheel marks? If it idles good, the S-mark (I forget if it's actually an S or not) should be in the hole at idle. Then with advancing throttle, that mark could move out of the window and disappear. As you near full advance, another mark should come into the window and remain at full advance.
I'd be sure that the advance mechanism is working. If the S-mark doesn't move, something is not right. Check out Duane's page about the advance unit.
http://w6rec.com/duane/bmw/advance/index.htm
About half way down he show pictures of early and late model advance units.
With the timing light and front engine cover off, you could start the engine and watch the advance unit work. Those bob weights should open up as the engine RPMs come up.
With the carb slides corrected, you might have to start over with all of the tune up steps to be sure everything is working right. Synching the carbs would really be needed now.
Mon, 08/16/2010 - 16:27
#10
R69S
Kurt,I meant that the floats were upside down not slides ....sorry about that,.....no wonder it seemed impossible, as it would be.
I will recheck the timing myself (It is an S that should be in the window) & recheck carb synching, the advance unit seemed to working & returning OK.
Thanks
Tue, 08/17/2010 - 01:20
#11
I would check your valve
I would check your valve clearances. If the rockers are too loose you would be experiencing tons of noise, if they are too tight it might not be noisy but there would be a lack of power. Lots of problems diagnosed with carbs are really just extremely out of spec valve issues.
Also check your rocker up/down clearance. Sometimes the valve clearance is in spec but the rockers are floating up and down and not allowing the valve clearance to be in spec while running, especially at high rpm's. Grab the rocker and see if it moves up and down. Little to no movement is good, ticking noises or grossly sloppy movement is bad.
Someone earlier described removing spark plugs from a hot engine?? This is a huge no-no on /2 bmw's. Read Duane's website on this issue- the spark plugs holes are dainty at best and removing plugs from a hot engine is the worst abuse possible. If you fall into the 62-68 pre LK heads (butterheads) you can literally pull out the entire spark plug threads with the plug and have a nice smooth bore hole left. I can understand this is a valid way of checking for fuel in the cylinder but it's just not possible on a bmw engine of this vintage.
Tue, 08/17/2010 - 05:48
#12
RE: up and down movement of
RE: up and down movement of rocker arms.
On the /2s, there's very little adjustment capability for these bikes if that's what you're suggesting, certainly not like the /5-on bikes. The rocker arms are indexed to the posts. If they do move a lot, then you have a whole bigger issue to deal with.
Thu, 08/19/2010 - 22:29
#13
On the weekend I am going to
On the weekend I am going to go through valve clearance & timing again, thanks guys.
As for carb floats they should be installed wire side up flat side down? Im not convinced this mechanic I took it too has got it right telling me they are installed upside down.......
Fri, 08/20/2010 - 06:00
#14
IIRC, there's a thin metal
IIRC, there's a thin metal shoulder that extends out past the circumference of the float. That should be on the bottom. It helps keep the float centered in the bore of the float bowl. You can sort of see that here, but you can also see the rounded top of the carb.
Fri, 09/17/2010 - 01:13
#15
A runner
Got the bike sorted out with the help of a guy who has alot of /2 experance & showed me alot of little things I had not quite right, the combination of all a liitle out combined to make it hard to start & run & very tempremental.
We replaced coil, new plug caps, Points & condenser, set timing advance by points backing plate method ( I had advanced timing by Clymer manual method & was not getting enough advance), tweaked carbs.
Running well know & took it on a classic run on Sunday which went well. Thanks all for your advice, I have learned a hell of alot over the past couple of months.
(There was NO WAY I had put the carby floats in upside down........ lesson learned on that one, professional advice is not always right.......)
Dominic -
Well, you've certainly done lots of things. I'm not sure what to suggest doing next. I would hope that the floats are cracked and filling with fuel. I suspect they're OK because you can start and idle the bike. Where are the needles set in the slide? Are the slides moving properly that you can tell? You might consider removing the air intake tubes and watch the action of the slides.
Another thing might be the advance mechanism. If the mechanism doesn't advance the ignition timing, then the bike might stall when giving it throttle since the spark isn't firing sooner for the faster running engine.
Hmmm...I'll have to think about it some more. A new condensor might be a good thing to try. I understand that condensors from the early '70s Ford 8-cylinder models are good substitutes.
Kurt in S.A.
'78 R100/7 '69 R69S '52 R25/2