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joolsUK
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Is there a budding Hercule Poirot who can assist me?
I've recently taken delivery of an R60/2, a 68 fresh in from the States and it has a peculiar trait that if I lean the bike to the right, the engine slows until it stalls. Conversely, it will speed up if I lean to the left quite dramatically. I removed the carbs and sonically cleaned them, assuming it was something amiss within, but to no avail. My next call was to rig up a tin of fuel and lean the bike independently from the tank, as I imagined the fuel delivery pressure might be changing with fuel movement but now the left head is leaking from an ill fitting plug insert and I'm reluctant to start it. at least until I've had it welded and rethreaded...Might it be electrical? Any ideas??

schrader7032
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San Antonio, TX
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I don't get consistent flow

I don't get consistent flow to the right carb based upon viewing the clear fuel filters I have installed in each line. I'm not sure the reason but the fuel has farther to flow to the right carb, plus the fuel hose goes slightly flat during the run over to the carb.

Could be you do have a fuel flow issue that might be exacerbated by the gas cap. You might try loosening the gas cap when this is going on to see if things change. You might also removed the petcock and give it a good clean.

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'78 R100/7 '69 R69S '52 R25/2

tbounds02
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how long

does the change in speed happen immediately upon leaning bike or does it take a few seconds to change rpms?

joolsUK
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It's pretty immediate. In

It's pretty immediate. In fact, when taking my key out wouldn't break the ignition circuit, I used that method to switch off.....

butch housman
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I'm assuming this is w/ the

I'm assuming this is w/ the bike setting still. If so & the lean angle is 20-30 degrees or so then I think i might be seeing a change in ur float level as compared to a level bike. Mine slows when on the sidestand, never tried it to the right

i know nothing
b

tbounds02
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no way

I don't understand how the bike could immediately speed up or shut off by leaning bike either direction . If there is enough fuel in bowl it should run for a minute just on reserve fuel in bowl . Unless you are getting enough fuel into bowls to start with. Make sure you have float needle set correctly . If they are too high it will shut fuel off to bowl with just min. fuel .
I really don't understand. the aux . fuel tank and line may help if it's the tank,lines or petcock. I would think you could tell just by opening valve and let fuel run out and tell if you were getting enough fuel flow.
I still think floats would be my first guess.

butch housman
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I think this is indirectly

I think this is indirectly linked to the cosmic meaning of the universe & as such is not immediately perceptible to the common man....BUT it MAY have something to do with the relationship between the position of the idle air jet relative to the float (...no, REALLY!). All I know is he idle speed can change if the bike is at an angle when sitting still. It is also common for gas to leak out of the left carb when the bikes r on the side stand. I can't exactly explain that either but they do.

How many times do I have to claim I know nothing ??? Surely someone on here can explain it.

b

  • Butch, STILL meditating
joolsUK
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Well if it helps deduction,

Well if it helps deduction, fuel does leak out of the left carb when it's on the sidestand..!

stagewex
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So does mine and I think

So does mine and I think everyones? That's why you don't leave it parked on the side-stand and also run the carbs a bit dry before parking that way and even on the center-stand.

An old mechanic friend told me they don't actually leak... they are "atmospheric", supposed to be that way. Only British bikes "leak".

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mike wex/stagewex
1969 BMW r60/2, US Model, 1995 BMW K75, 2006 Yamaha TW200, 2007 Ural Patrol, 1991 Honda XR250L

ScottA
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yes

joolsUK wrote:

Well if it helps deduction, fuel does leak out of the left carb when it's on the sidestand..!

It's a design feature. Don't worry about it.

title symptom pretty strange though.

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'61 R27, '63 R60/2 etc.

iagins
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This is a real longshot, but

This is a real longshot, but have you checked the throttle cables? I had a bike where the idle increased when the handlebars faced one way and decreased in the other direction. Turned out the cables were the culprit.

Ira Agins
Santa Fe, NM

joolsUK
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Thanks - I'm pretty sure it's

Thanks - I'm pretty sure it's not going to be the cables because there's no movement it the front end, just a tipping moment. The only one other thing I can see that differs - I'm not sure if it is original equipment on this bike, a '68 - but the fuel petcock is a single output and the fuel line has a splitter 6" or so down the line as opposed to the 'twin output' I see on most. The petcock is a BMW part (at least it has some German forged into it...)

I've no idea why this would make any difference though.

In my head, I see the bike tipping, the increased fuel pressure on the left side (petcock side) somehow being able to force the fuel through the carbs (is this possible?) increasing the revs. Conversely lower fuel pressure stalling it as I lean the other way...I guess this kind of negates the whole idea of the fuel bowl though..?

Here's a pic of the old girl. I doubt it will be apparent from this, but you never know...!

  • img_1608.jpg
joolsUK
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To my previous comment, the

To my previous comment, the only OTHER thing that I know is different (yet to discover more, I'm sure) is that it has a Bowman aluminium flywheel, which may(?) contribute to the effect...??

schrader7032
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San Antonio, TX
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I would reconfigure the fuel

I would reconfigure the fuel lines...I don't see the need to route the right side line all the way to the rear of the air filter. Make a smaller section that comes out of the petcock...maybe one inch long. Put the T-junction on that. The route the lines directly to each carb. I have the petcock with a Y-junction out of the petcock then two lines from there. By moving the T-junction up near the petcock, you'd be essentially duplicating that. Plus it would look a little better IMO.

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Kurt in S.A.
'78 R100/7 '69 R69S '52 R25/2

ScottA
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San Diego
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throttle cables too

the throttle cable routing needs improvement, take the most direct though sinuous path with sweeping arcs as possible.

Make sure there's at least 1mm slack in both throttle cables at both left & right fork lock.

thanks for the pic of your bike, good to see. Other side too please.

Follow Kurt's suggestion. He's correct except that it would not look a little better, it would look a lot better. Wink
You may want fresh fuel line as well?

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'61 R27, '63 R60/2 etc.

joolsUK
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Very good Sirs! I'll reroute

Very good Sirs! I'll reroute as soon as I've managed to complete my auxiliary fuel tank experiment...And whilst you wait for that - have the other side...

  • img_1606.jpg
schrader7032
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VBMWMO #7032
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Do you have the clamps for

Do you have the clamps for the air tubes that meet the carb? In order to ensure a connection that doesn't leak air, there should be clamps on them. Just one more thing that should be set right.

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Kurt in S.A.
'78 R100/7 '69 R69S '52 R25/2

ScottA
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cool

thanks for side 2 Jools.
Is that chrome showing from under the black on the front and top, half moon cover?
I ask because I have spares of those items in chrome, which looks odd these days. Painting may be a good option.

I'm guessing the PO mounted bars taller & wider than standard issue for the /2, consequently order cables long enough to work, which ended up excessively long. If the cables are OEM there'll be part numbers in white near one end.

The bar-backs seem totally unnecessary for you, but probably the PO hadn't correct handlebar mounts to include in the sale? I wonder what diameter the 'bar is, likely not 22mm but what's commonly available here stateside, 7/8" or .875" aka 22.23mm or just enough "oversize" to complicate things.

Throttle cable routing usually goes from the right handlebar arcing to the left side of the steering stem before passing down in front then under the tank. This provides a greater arc for ease of cable actuation while not lengthening the path appreciably.

Do you like the bars or are you considering changing those later? Just curious.
Though the cables are too long and the subsequent routing convoluted, when well adjusted I doubt they'd factor in your title conundrum.

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'61 R27, '63 R60/2 etc.

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