The New And Improved Unofficial R65 Forum V2
Technical Discussion => BMW Technical Q&A, Primarily R65 => Topic started by: Lucky_Lou on November 06, 2008, 02:26:54 PM
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Well the rebuild is almost finished only got cosmetic stuff to do cranked her up for the fist time today got new points plugs ect but will only fire on the right cylinder definte spark on the left stripped the carb again again and all looks good anyone got any bright ideas!!!! any easy way to check compression?
Ta Lou
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any easy way to check compression?
Ta Lou
Lou,
You should be able to feel the pressure at the tail pipe by hand but with a crossover tube on the exhaust that might be unreliable. With the spark plug removed a thumb over the plug hole should easily be pushed off by the compression. Did a quick search of automotive stores by you but only came up with the A1 automotive chain, looked useless for a compression gauge. Have the intake tube off the carb to facilitate a look see if your getting fuel while running. Perhaps before all this have a second look under your valve cover while cranking.
rich
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After doing that you can swap plugs between sides then dribble a bit of gas into the non-firing cylinder and see if it at least coughs. All of my "running on one cylinder" issues always seem to have been carb related...
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Right. You can even swap the spark plug wires from side to side. With the wasted spark design, the engine doesn't know or care which plug lead (or coil) is which.
:-/
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Right. You can even swap the spark plug wires from side to side. With the wasted spark design, the engine doesn't know or care which plug lead (or coil) is which.
:-/
Could it be the dreaded "Crack-O-Matic" coil? Evil among us ;D
Monte
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I had exactly the same problem a week ago. Then I touched the coil and nearly burnt my hand off, hotter than hell. The right HT lead is charred where it went into the coil - Still waiting on a new coil, plug caps and HT leads from Motobins.
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Think ive sussed it when i partialy block the carb intake with my hand it runs fine going to rejet the carbs even though the old ones look ok thanks for the help anyway. Had a ride on her with one pot couldnt resist it after 4 months of tlc first time running for 6 1/2 years put a smile on my face in these days of doom and gloom i hope the old boy who had her before was looking down with a smile bless him{died in 2003 RIP}Will post some piccis soon and sort out an avatar
Lou.
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Still no joy rejetted the carb no better only firering intermittantly......has anyone fitted electronic ignition motobins have one for a reasonable looking 66 pounds mignt be my next step
Lou
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Any chance there is some sort of fuel blockage or float hangup, keeping the fuel from filling the bowl?
Just my [smiley=2cents.gif]
:-/
Ed
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And................... have you checked your carb diaphragm?
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If swapping the sparkplugs, caps, and leads from side to side does not move the problem then the ignition is OK. Have you checked the valves? It has happened that the valve lash was set at TDC of the intake stroke rather than the compression stroke.
Mext step is to try a shot of starting fluid while the engine is running into the side that is not firing. If it fires than you have confirmation of the valves and ifnition being OK. - Time to look into the carb then.
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"Think ive sussed it when i partialy block the carb intake with my hand it runs fine"
Sounds like he's traced it to a fuel problem already, Drew. Cut off a bit of air to make it run rich and it "runs fine" would indicate the carb's not passing enough fuel... No? :-/
Ed
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Yeah, running too lean on that side...
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thanks for all the help ill strip the carb again must be a blockage didnt pull the air screw out last time may be blocked it does run if you blank the inlet with your hand so must be too lean, the diaphragm looks ok replaced floats ,inlet valve, needle & jet ect will have a look at the weekend or tomorrow if im snowed in
Lou
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The idle jet is also prone to clog up as it has little bitty holes in it that don't take kindly to crud. I usually use a single strand from a copper wire to clean them with. Diaphragms don't affect idle.
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Look at the fuel lines at both sides, are they frayed at the ends? if so, one of the carbs is getting a wrong mixture making igniting the mixture difficult.
greetings from a clear, calm and freezing north
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When stripping again i find that the choke fuel feed molded in the float bowl is blocked theres a small hole at the bottom which ive poked and prodded but it wont clear would it be a problem if i drilled a small hole slightly higher to restore the feed???
Lou
ps
frost is my freind more burst pipes please i need the money for my bike
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"Sir, please move away from the drill."
Please remind me which carbs you have.
Look carefully down inside the bowl.
There is a jet inside the tube on some.
If the jet is there you can remove it with a small flat bladed screwdriver.
Then soak it in carb cleaner until you can poke a small wire through it.
Removing old stuck in jets can be very difficult sometimes.
So I would try soaking the entire bowl in carb cleaner overnight to soften up the crud.
Put any ideas of modifiying the carbs out of mind.
Stick with us here and collectively we will resolve the problem, eventually.
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"Sir, please move away from the drill."
Please remind me which carbs you have.
Ok drills back in its box....its a Bing constant depression type(R65 1980) theres fuel flowing from the main bowl chamber into the choke feed chamber on the cylinder thats running but the hole seems to be blocked on the one thats not?? Ill call and get some carb cleaner on monday and soak it overnight ive been using aerosols so far .The feed tube looks to small to have a jet in it but ill check on monday(the bike is in my workshop not at home)
Lou
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"Sir, please move away from the drill."
<snip>
Ok drills back in its box....,snip>
Phew! That was close! :o
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(https://bmwr65.org/smf/proxy.php?request=http%3A%2F%2Fi193.photobucket.com%2Falbums%2Fz318%2Ftagordon%2FBingCVcarb-1.jpg&hash=80c5f3622e1b94cd37940df161d8b54952c173f0)
Is the arrow pointing to where you beleive you have the blockage?
This tube only feeds the enrichener/auxillary carb.
Would not cause a problem past 1/4 open throttle.
It picks up fuel from the bottom of the bowl through a hole that feeds the jet I mentioned.
See next post for more info.
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(https://bmwr65.org/smf/proxy.php?request=http%3A%2F%2Fi193.photobucket.com%2Falbums%2Fz318%2Ftagordon%2FBingCVcarb2.jpg&hash=39609d68f93744b364fe068ce16dece1e5d412b9)
The arrow in this pic shows the passage in the bowl where the jet is located.
This not a circuit that would cause a problem when off idle and more than 1/4 open throttle.
See next post for more info.
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It is possible that all I am about to say has already been covered previously.
I am recapping to get it in one place for myself, to ascertain where we are in the process.
Your statement that covering the air inlet allowed the engine to run on both sides; means you are lean on that side.
Check if you have not already for fuel delivery from the tank. Is the crossover parially plugged going to that side?
Drop the bowl and check the flow and float level.
If you know the carb is receiving fuel from the tank and the bowl is filling properly.
Then have you checked to ensure that the piston in the carb is returning all the way down?
Take the pipe off the carb that goes to the airbox.
Watch the piston go up and down while you blip the throttle to say 4000 rpm.
Is it returning all the way down when the rpms return to idle?
Eyeball both sides to see if they are behaving the same.
If you checked the diaphragms did you make sure to reinstall with the little tabs located correctly.
Having it improperly oriented could cause the piston to stick in the up position.
Also the spring may be buggered up in there causing the piston to stick open/up.
If the piston on the side with the problem is not acting the same as the side without the problem we are narrowing down the cause(s) of the problem.
Most important to me when diagnosing a problem is to start at one end of the system and check/troubleshoot untill I find a point where things are not as they should be. Then figure out why its not as it should be.
The problem must be identified, then the cause of the problem identified, only then can the proper repair be identified.
"Really quite simple Watson;" "not."
At work we refer to this as:
1. Complaint
2. Cause
3. Remedy
HTH
Troy
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(https://bmwr65.org/smf/proxy.php?request=http%3A%2F%2Fi193.photobucket.com%2Falbums%2Fz318%2Ftagordon%2FBingCVcarb2.jpg&hash=39609d68f93744b364fe068ce16dece1e5d412b9)
The arrow in this pic shows the passage in the bowl where the jet is located.
This not a circuit that would cause a problem when off idle and more than 1/4 open throttle.
See next post for more info.
Item 17
Thats where there is no feed.......illclean it somemore to see if there is a jet in the bottom
will try to do this tomorrow and let you know what i find
Lou
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Ok now im realy tearing my hair out....... the feed to the choke is now clear, couldnt get the jet out but managed to clear it with some fine wire and snipe nose pliers still got the same promlem slightly improved by opening the air scew will only run if i give it slight revs and not on idle tweaking the choke back a bit at a time, i feel nearer to sorting it than i was but still frustated to the point of maybe getting my wallet out and letting a pro have a play.
Lou
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Lou
There is an air port/hole on the upper out side of the carb that is sometimes plugged with crap.
It goes unnoticed untill it becomes a problem. It is hard to see unless you look for it carefully.
Sorry no pic available at this time.
Did you soak the carb and blow everything out?
You may have missed this port. I know I missed it twice.
Troy
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Ive my airline on every hole i can find all seem clear but will strip everything one more time to double check ....out of intrest any idea where the air screw should be set or is it trial and error and what is item 19 in the last diagram looks like some kind of cap but havent got one on mine???
Lou
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About 1/2 to 3/4 of a turn is where I set mine the first time.
Don
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Have you checked your carb to manifold rubber for cracks? Even a small one can cause some weird running at low RPM's.
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As don mentioned, screw the air adjustment screw all the way in and then back it out about 3/4 of a turn for starters - you'll possibly have to fiddle with it a bit later but this should at least get you into an operating condition if all else is right.
Are the levers for the carb (main throttle and enricher/choke) both working smoothly and moving through their full range (not getting stuck/stopped, or have more than
1-2 mm of slack ) ?? I am thinking that even if the jet in the enricher circuit isn't blocked, if the lever /cable slack isn't set right you'll still have issues starting that side.
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Are the levers for the carb (main throttle and enricher/choke) both working smoothly and moving through their full range (not getting stuck/stopped, or have more than
1-2 mm of slack ) ?? I am thinking that even if the jet in the enricher circuit isn't blocked, if the lever /cable slack isn't set right you'll still have issues starting that side.[/quote]
Ive fitted new cables and set them to the point were the main throttles are openning together with the slightest twist of the grip?? im pretty sure they are ok but will double check.
A biker pal of mine has just rebuilt a motoguzzy 79 California he said he had carb problems but had them ultrasoniclly cleaned and that cured it........has anyone else had any experiance of this process
i believe its a bigger version of the gizmo they clean jewellery with?
Lou
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...ultrasoniclly cleaned and that cured it...has anyone else had any experiance of this process i believe its a bigger version of the gizmo they clean jewellery with?
Harbor Freight sells a similar 'ultrasonic' cleaner. No knowledge if it works or not.
Monte
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Hi Lou
Fastcataz has already mentioned the possibility of a cracked carb to manifold rubber link - you should have a very close look at that rubber. A crack can easily be overlooked, if you do not stretch the rubber ends by hand - after the rubber has been removed.
I have experienced a similar problem a year or two ago, and I only discovered a crack after having a second (closer) look .
Regards
Danie
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I've read where a good soaking in solvent followed by another good soaking in a detergent will loosen most accumulated crud. Follow each with a good blast of compressed air [safety glasses advised] and repeat as necessary. The reviews I've seen 'bout the small ultrasonic cleaning tubs, like the ones used for jewelery, indicate that they just don't have 'nuff "poot" to clean larger components. YMMV.
rich