The New And Improved Unofficial R65 Forum V2
Technical Discussion => BMW Technical Q&A, Primarily R65 => Topic started by: beemer on April 29, 2009, 03:47:22 PM
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I find that starting my bike after a few days layoff can be a pain!!!it seems that i need to leave the fuel tap on for 10-15 minutes so the carbs fill,does anyone have the same problem?is it a common BMW thing?after she's started there isn't a problem if i stop and start again,say,a few hours later,i wish these carbs had "ticklers"like some of the old British bikes,you simply pressed the tickler,the carbs filled,and you could start,anyway,any ideas?thanks,Julian.
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It's not a common trait among the BMW bikes.
First comment, you need to turn the fuel tap on for an extended time, do you have any after market filters in the fuel system, if so , may want to replace it.
There should be a filter, or strainer element on the fuel line that screws into the bottom of the tank, remove it ,and see if it clogged.
When you have the starting issue, can you smell 'raw' fuel from the exhaust ?
Also I believe you are new to BMW bikes, no throttle input until the cylinders start firing.
A 'weak' coil can have an effect on starting as well.
Problems with the enrichening circuit in the carb can cause hard
starting also.
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It's not a common trait among the BMW bikes.
First comment, you need to turn the fuel tap on for an extended time, do you have any after market filters in the fuel system, if so , may want to replace it.
There should be a filter, or strainer element on the fuel line that screws into the bottom of the tank, remove it ,and see if it clogged.
When you have the starting issue, can you smell 'raw' fuel from the exhaust ?
Also I believe you are new to BMW bikes, no throttle input until the cylinders start firing.
A 'weak' coil can have an effect on starting as well.
Problems with the enrichening circuit in the carb can cause hard
starting also.
No after market fuel filters fitted,i don't see any filter fitted to the tap inside or outside the tank,No there is no smell of raw fuel once she starts up,iv'e had my bike for a year now,always been the same starting her up,i replaced the coil,i had the usual cracomatic problem!,i'm not sure how i would check/adjust the enriching circuit,it just seems like the fuel in the carbs evaporates and once full it's fine,thanks,J.
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where do you keep the bike when not in use ?? the bowls should not evapourate in a few days unless there is a leak ive just had to pull my fuel tap and clear a blockage from the reserve line ...ran out of fuel on the M1 switched to reserve and bugger.... nothing had to get the wife to rescue me with the lawnmower fuel can!!.worth draining the tank for a peep.
Lou
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where do you keep the bike when not in use ?? the bowls should not evapourate in a few days unless there is a leak ive just had to pull my fuel tap and clear a blockage from the reserve line ...ran out of fuel on the M1 switched to reserve and bugger.... nothing had to get the wife to rescue me with the lawnmower fuel can!!.worth draining the tank for a peep.
Lou
It's in the Garage,i checked the tank,and removed the tap but not blockage anywhere,no drips from carbs.
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i wish these carbs had "ticklers"like some of the old British bikes,you simply pressed the tickler,the carbs filled,and you could start,anyway,any ideas?thanks,Julian.
Here's the shirt for you! You'll need to zoom in on the image.
http://www.cafepress.com/MRROACHSIR.368826268#
;D
rich
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If you have a gas tank venting problen (several threads exist on this one) you may end up with a partial vacuum in the fuel tank, which would definitely impede the ability for fuel to flow down to the carbs.
I turn the tap on and watch the fuel gurgle through and completely fill my in-line fuel filter within about 10 seconds.
Try unscrewing your fuel tank cap next time - if things fill up much faster, then your fuel cap is plugged and not venting properly.
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If you pull the hose from the petcock, with something to catch the fuel, does it flow out pretty well? If so, remove the bowls with the petcock off, raise the float gently to close the float jet, turn the fuel on, then slowly lower the floats until you see how much fuel comes out.
...somebody help me here: HOW MUCH should flow? I've never measured it, it just looked like way more than 45 mpg.
If for some reason the fuel is slow to reach the carb ticklers wouldn't help anyway. And a decent choke is way more useful in cold weather. My Bonnie will start up first kick, but if it's cold I have to keep jabbing the ticklers until it will run on it's own with a little throttle. I think it took me almost 20 years to figure that trick out. :-[
If the fuel flow is good in both carbs then I wonder if the little jet in the bottom of the tube in the bowl is plugged up. Usually only seems to happen to one carb at a time, resulting in initially running on only one cylinder.
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/agreed nhmaf and ed.
Further to what Bob_r wrote about the strainer in the fuel tap, it is contained in the lower part of the assembly or outlet. When I stripped mine (I have no pics of it tho) it had some debris in there.
also see http://bmwmotorcycletech.info/fuelfltrs&petcocks.htm
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If you have a gas tank venting problen (several threads exist on this one) you may end up with a partial vacuum in the fuel tank, which would definitely impede the ability for fuel to flow down to the carbs.
I turn the tap on and watch the fuel gurgle through and completely fill my in-line fuel filter within about 10 seconds.
Try unscrewing your fuel tank cap next time - if things fill up much faster, then your fuel cap is plugged and not venting properly.
I will check that thankyou.
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i wish these carbs had "ticklers"like some of the old British bikes,you simply pressed the tickler,the carbs filled,and you could start,anyway,any ideas?thanks,Julian.
Here's the shirt for you! You'll need to zoom in on the image.
http://www.cafepress.com/MRROACHSIR.368826268#
;D
rich
Smelly finger!!!that's great!!! ;D
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If you pull the hose from the petcock, with something to catch the fuel, does it flow out pretty well? If so, remove the bowls with the petcock off, raise the float gently to close the float jet, turn the fuel on, then slowly lower the floats until you see how much fuel comes out.
...somebody help me here: HOW MUCH should flow? I've never measured it, it just looked like way more than 45 mpg.
If for some reason the fuel is slow to reach the carb ticklers wouldn't help anyway. And a decent choke is way more useful in cold weather. My Bonnie will start up first kick, but if it's cold I have to keep jabbing the ticklers until it will run on it's own with a little throttle. I think it took me almost 20 years to figure that trick out. :-[
If the fuel flow is good in both carbs then I wonder if the little jet in the bottom of the tube in the bowl is plugged up. Usually only seems to happen to one carb at a time, resulting in initially running on only one cylinder.
The fuel flows fast if i pull the fuel pipe off,i did check the bowls and they seem fine too,in fact i bent the tang slightly and the carbs started to leak,so i put them back to the original position with new gaskets.
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Does the exhaust smell like the bike is running a little rich? When I've had that problem, it has smelled like it was running rich. When running rich, as soon as you open the throttle it ends up with too much gas to start.
It it is not too rich, one trick that sometimes works on such "cold" starts is to crank the starter, with the throttle in its closed position, and slowly open the choke lever while cranking. Sometimes that does the trick in terms getting the right amount of gas into the cylinder.
k_enn
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Does the exhaust smell like the bike is running a little rich? When I've had that problem, it has smelled like it was running rich. When running rich, as soon as you open the throttle it ends up with too much gas to start.
It it is not too rich, one trick that sometimes works on such "cold" starts is to crank the starter, with the throttle in its closed position, and slowly open the choke lever while cranking. Sometimes that does the trick in terms getting the right amount of gas into the cylinder.
k_enn
I will try it,thanks.
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I find that starting my bike after a few days layoff can be a pain!!!it seems that i need to leave the fuel tap on for 10-15 minutes so the carbs fill,does anyone have the same problem?is it a common BMW thing?after she's started there isn't a problem if i stop and start again,say,a few hours later,i wish these carbs had "ticklers"like some of the old British bikes,you simply pressed the tickler,the carbs filled,and you could start,anyway,any ideas?thanks,Julian.
I had a in-line filter come today in the post,i put it in and found it didn't fill with fuel!!So,took the tank off and removed the tap,cleaned the whole thing including the built in filter,poked a flexible piece of copper wire throught the vent from the filler to the hole under the tank,re-assembled,re-filled with fuel and the in line filter filled right up!let's see if it evaporates in a couple of days,fingers xcrossed!! ;)
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The clear fuel filters will almost always show an air bubble on initial installation. A few taps with your fingers on the filter should dislodge any bubbles. They may reappear but you should not see the filter go completely dry. Bob and Ed previously mentioned the enriching circuit in the carb. Check your float bowls, the enricher fuel pickup jet and the bowl gasket itself. also have a look at this thread: http://www.bmwr65.org/cgi-bin/yabb2/YaBB.pl?num=1240083062
rich
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That "hole" under the tank is not a vent - it is to direct the overflow if the tank is overfilled.. Many people remove the hose that was there initially as it is another nusiance to deal with when removing the fuel tank, but if you ever overfill your tank or fuel sloshes up there in the indentation around the cap you'll be squirting gasoline down on the engine and into the starter cover area - not generally advisable. IF you don't put a hose back on that "hole under the tank", be careful about filling your tank and stop at the bottom of the "neck" in the fill hole. Otherwise, get some clear fuel line hose and stick it onto that short pipe under the front of the tank and run the hose back toward the battery box and then down the frame tube so any excess gasoline is spilt behind the hot and electrical bits (and preferably to the side of the rear tire).
;)
The venting of the fuel tank actually happens through the filler cap.
Sometimes they do plug up as they rely on small holes at the base for the cap for air/fuel vapors to go up in the cap and escape either through the key slot or an area under the top plastic cap part.
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Cleaning the "screen" in the tank should be a semi-routine maintenance procedure . As these tanks get older the factory lining tends to flake off and clog up the screen...
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Cleaning the "screen" in the tank should be a semi-routine maintenance procedure . As these tanks get older the factory lining tends to flake off and clog up the screen...
Luckily i didn't find any debris in the tank,but i have also done the tank cap mod and the flow is much stronger now,also checked the enrichment system in the bowls and all clear,so hopefully all should be ok.
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I had the gas tank off my ’84/5 R65 today and happened to measure the overflow drain outlet boss on the underside. It is 8.0 mm (5/16-in) diameter. Like montmil above and others, I fabricated a drain pipe from 5/16” fuel line to discharge near the rear tire to take any future overflow away from the electrics and hot spots around the engine. Peace of mind.
Here's the fitting I used:
McMaster Carr
Black nylon single-barbed 90° elbow tube fitting
Inside tube diameter 5/16"
Part No. 5463K17
Approx. $6 for 10 before trade discounts
Mark