Stalling out

[robert]

"While that method works most of the time, I had a carb continue to leak after setting it that way, the floats were old and had perhaps absorbed some gas and gotten heavier. Setting it with the float ever so slightly lower fixed the problem."


Wouldn't that be more like worked around the problem rather than "fixed the problem"?

[Tim Shepherd]

Yep! File under "Field Repair"... as in workable, if not optimal.

[robert]

[moosehead]

Update to the stalling situation and following some ideas that have been suggested...

First, good warm up ride...then try the simple stuff first....so, heeding duane's approach...check out the idle jets/circuits.

Right side idle jet plugged up with red tank liner bits (I flushed that tank last winter but need t do again I guess)
Left side was better. Cleaned both with carb cleaner and compressed air. May add inline fuel filters to see what they collect.

Rest idle level to around 1200 this time and did test ride. Lot better fo sure. Few stalls after real hard stops but that's only time.

Thought I would check fuel levels in bowls against numbers Kurt posted. Hmmm, both sides around 24mm (if I measured correctly) so fiddled with float levels till I got around 28mm for 40mm carbs. Never checked this way before but thought would give it a try...test ride tomorrow and update

[dwire]

The best way to set the floats is to measure the amount of fuel standing in the bowl when the floats shut off. Snowbum lists the heights for fuel depending on carb type:

32mm - 24mm
40mm - 28mm

Let fuel flow for 5-10 seconds. Shut off petcocks. Drop the bowl. Measure in the center of the well.

Kurt in S.A.

Interesting Kurt, for a lot of carbs (meaning anything without a bail) that would be impossible so I very easily might never have thought of that one... Hmm

[dwire]

One can get a good estimation of float bowl level without any measurement at all. Remove the bowl and raise the float by hand until it just barely touches the needle. The casting line on the float should be parallel with the bottom of the carb body casting.

In the expensive shop labor rate, we can't waste your money on official measurements every time. Short cuts are mandatory.

Err yeah this is what I always have done - thought Kurt had a revelation; no? Most of the "old" crap I ever see it's like archeology anyhow, you can see from crap in the fuel eating away at the brass floats if it has them in there and between that and the proper needle closure point usually I can feel confident a bowl has had enough fuel in it. As I lamented to Kurt - I never have worked too much on designs that have bails, maybe Delorto's and some other slide carbs, but everything else in the smallish variety you'd never know as the fuel dumps out and the needle opens as one removes the bowl...

[chasbmw]

my experience of low float bowl fuel levels is that the bike just runs out of go at around 60-70 mph, when adjusting you want to get the tab that bears on the bottom of the float needle to be roughly square to the needle, this means that the bend of the tab is more difficult to do.

As a problem it often occurs after people have rebuilt their carbs

[moosehead]

No lack of fuel when ramping her up. Cruising at 120kkms +, no fuel starvation symptons.

I usually check fuel in float bowl height by seeing where fuel shuts off relative to the position of the floats themselves i.e. they're just parallel with the carb body when fuel shuts off...that's my normal method. I measured fuel in bowl and came out around 24mm vs the "published" number of approx 28mm for these 40mm carbs. Cleaning of idle jets and circuitry, restting idle speed to bit higher at 1200 and resetting idle mixture was big improvement...almost eliniated the stalling coming to stop.

Just thought I would apply this new approach to approx 28mm feul height in float bowl to see what effect it would have. I'm not convinced it will do anything but, having nothing but time on my hands, I adjusted the tang to get fuel height close to the magic 28mm.

Off for another test ride so we'll see what this does. Let ya know.

[moosehead]

Final update...

After raising fuel level in bowls to approx 28mm went for a long test ride. No stalling issues. Even after some hard stoppies no stalling.

Can't say it was one thing or the other fixed the problem. Probably combination of all, but think the idle jet cirsuit clean up and idle reset to 1200rpm was big factor. O well, together they all worked. Thanks for everyone's input...makes this forum special!

So the old R100 is off to her new owner...I swapped her plus some cash for my old 74 R75/6 I sold to my friend last year in BC. The sort of "GS ified" R100 will better suit Jim for his riding out in the west...lotsa back roads, logging roads etc...and...Jim really wanted this one.

So back to the old R75...I love riding thes bike naked....I mean naked bike (took the Hannigan off for the summer)

[Kurt in S.A.]

North of the Checkerboard...just noticed that and had to search for that...a place "renowned for rednecks and peculiar behaviour"...what's up with that??

Kurt in S.A. (North of the Mexican Border)