Hard Starts After Fuel Cutoff

Was out on my '74 850 today, about 45 minutes into a highway ride. During an overtake goig up a long hill, throttle about 3/4 WO, engine sputtered and died. Immediately pulled off road and as I looked down saw fuel running out a disconnected fuel line at one carb bowl. Shut off tank tap and pushed bike away from fuel on ground.

Refit the line and secured with zip ties carry in my tool kit. Bike did not want to restart. Had been a solid one kicker past few weeks since after de-winterization. Over 15-20 kicks, with or without tickling, with/without throttle cracked open. No pops or bangs during any of those attempts. Finally fired up and idled normally.
Continued on my way, stopped for lunch, then another round of somewhat hard starting, around 5 to 8 good kicks before it fired.
Ran fine all way home.
At home, pulled plugs and found them both about same appearance. Dark Grayish and dry. Looking closely with magnifying glass, could see a rust colored granular build up to one side of each electrode. Is this indicative of lean condition from the fuel starvation at higher rpm?
Put some new plugs and will see how it goes soon.

What kind of carb(s) are you running? I chased this hell for a year. My 850 would start first kick and idle fine. But sometimes it would just die and refuse to relight. Tickling the carb didn't help. Plugs looked fine. Discovered that the sleeved slides on my Amals were worn so badly that it was creating a lean condition that made hot starts nearly impossible. I installed a single Mikuni and it's a new bike.

I wouldn't worry much about what you saw with the magnifying glass. Could be a little bit of brown color from idling or slow riding through town before pulling into your driveway. The mixture might richen a little when idling and riding slow. Could even be an additive in the fuel. Sounds like your jetting is spot on though.

If hot starts continue to be an issue, you might consider what Big_Jim did. A single Mikuni has got to be simple to deal with and the slides last a very long time. I'm not an Amal carburetion fan though, so my thoughts don't mean nuts.

If, at any time, (like it sat for a while, in-between warm & cold) you are unsure if the engine needs MORE fuel to start, OR, it already had too much.....


Tickle only ONE of the twin Amal carbs, if it starts on one, then it needed MORE.
If, it doesn't start, open the throttle wide, it should clear itself by third kick.

concours said:

". . . it should clear itself by third kick."

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or try and rip your foot off when it pops back savagely.

Running two amal premiers with about 7 or 8k miles on them.
So the fuel starve while at speed unrelated to hard starting some 20 to 30 min later?
Another potential clue, these two hard starts after the fuel starve were on a tank of 87 0ctane fuel I'd put in before the ride. One kick started it at the fuel station, but that was still with 93 octane sitting in float bowls at that point.

concours said:

If, at any time, (like it sat for a while, in-between warm & cold) you are unsure if the engine needs MORE fuel to start, OR, it already had too much.....


Tickle only ONE of the twin Amal carbs, if it starts on one, then it needed MORE.
If, it doesn't start, open the throttle wide, it should clear itself by third kick.

Click to expand...

Yes I've done that single side tickle when in the uncertain zone. Say 15 to 30 min after shut down. Sometimes works, sometimes doesn't.

"engine sputtered and died."



Balance tube spit off

this guy I know always says,..... "Test, don't guess".

So,... I have one a simple test method that I use for different situations. I have a bottle with a squirt straw with fuel in it. If the bike won't start, I take the air filter off and lift the throttle and give a squirt in each carb mouth, then give a kick. If nothing changes after a few kicks, then you should start looking at ignition. If the engine roars to life, you should start chasing fuel delivery issues......

I wonder what happened to that guy??

o0norton0o said:

this guy I know always says,..... "Test, don't guess".

So,... I have one a simple test method that I use for different situations. I have a bottle with a squirt straw with fuel in it. If the bike won't start, I take the air filter off and lift the throttle and give a squirt in each carb mouth, then give a kick. If nothing changes after a few kicks, then you should start looking at ignition. If the engine roars to life, you should start chasing fuel delivery issues......

I wonder what happened to that guy??


View attachment 113275

Click to expand...

My test described above was dismissed after the first paragraph.




"Tickle only ONE of the twin Amal carbs, if it starts on one, then it needed MORE.
If, it doesn't start, open the throttle wide, it should clear itself by third kick."

Big_Jim59 said:

or try and rip your foot off when it pops back savagely.

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I simply hear a sickening crunch as the pawl sheds metal attempting to levitate the rider.

Big_Jim59 said:

or try and rip your foot off when it pops back savagely.

Click to expand...

TriSpark and 29 degrees all in ignition timing got rid of the kickback shenanigans on my engine.

Tornado said:

Running two amal premiers with about 7 or 8k miles on them.
So the fuel starve while at speed unrelated to hard starting some 20 to 30 min later?
Another potential clue, these two hard starts after the fuel starve were on a tank of 87 0ctane fuel I'd put in before the ride. One kick started it at the fuel station, but that was still with 93 octane sitting in float bowls at that point.

Click to expand...

Fuel starvation really not related to a hard start?

Enough fuel starvation to kill a running engine is going to dry out your intake manifolds and combustion chambers entirely. Since it finally started up, I'd say it didn't have enough fuel in the combustion chambers. Not starting right away would be somewhat situation normal.

If the plugs were not removed and examined (a test) during the multi-kick episode after the hose that came off was put back on the float bowl, you'll never know if it needed more fuel or not when it would not start.

I'm guessing that it is probably back to working like it was before. Much ado about nothing really.

Could be fuel expanding in the bowls after heat soaking a few minutes while stopped. My cure for this is to turn off the fuel 20 to 50 yards before parking. Don't turn the fuel back on until it starts . Usually works for me.

rweb said:

Could be fuel expanding in the bowls after heat soaking a few minutes while stopped. My cure for this is to turn off the fuel 20 to 50 yards before parking. Don't turn the fuel back on until it starts . Usually works for me.

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'cept in this case, there was no fuel in the bowls as all had spewed out on the ground! But I like the general idea here...shut off prior to parking up and prevent an expansion-flood event during next start attmept some minutes later. Will give that a try....

Tornado said:

Yes I've done that single side tickle when in the uncertain zone. Say 15 to 30 min after shut down. Sometimes works, sometimes doesn't.

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Did you do the WIDE OPEN THROTTLE after on those occasions the one side tickle did not work?

concours said:

"engine sputtered and died."



Balance tube spit off

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O.P., I was busy on the go, this above comment was intended as a suggestion to check/confirm.
Failing punctuation, it's meaning was probably lost.
I've had it spit off by a slight cough on starting.
Contact cemented on now.

Any update?

concours said:

O.P., I was busy on the go, this above comment was intended as a suggestion to check/confirm.
Failing punctuation, it's meaning was probably lost.
I've had it spit off by a slight cough on starting.
Contact cemented on now.

Any update?

Click to expand...

No the balancer was in place. As stated I did a roadside bodge up to resecure the fuel line to carb and eventually started to continue on.
Haven't had time/weather to ride since...hoping this w/e.