Hard Start (again)

Big_Jim59 · May 28, 2023

I took the Norton out for a short ride this morning. I ended up at the QT, parked the bike and got a coffee. I sat for about 15 minutes drank my coffee and looked at the bike (she sure is pretty!) I went to head home, kicked it with a little throttle, nothing, kicked again with a little throttle nothing. Kicked, kicked and kicked until I got embarrassed and hot in my jacket. I kicked it with a moderately open throttle (thought it might be flooded,) still nothing. Kicked with closed throttle and got a couple of pops. I repeated kicking with closed throttle. I got pops and after about the 4th kick she lit off.

It usually starts right up with 1/4 throttle. It doesn't do this all the time. I was pretty warm out but I don't know what that would do with it.

Bike is running sleeved Amals, has fonolic blocks installed and I am using premium gas. Could the carbs be getting hot sitting?

concours · May 28, 2023

Big_Jim59 said:
I took the Norton out for a short ride this morning. I ended up at the QT, parked the bike and got a coffee. I sat for about 15 minutes drank my coffee and looked at the bike (she sure is pretty!) I went to head home, kicked it with a little throttle, nothing, kicked again with a little throttle nothing. Kicked, kicked and kicked until I got embarrassed and hot in my jacket. I kicked it with a moderately open throttle (thought it might be flooded,) still nothing. Kicked with closed throttle and got a couple of pops. I repeated kicking with closed throttle. I got pops and after about the 4th kick she lit off.

It usually starts right up with 1/4 throttle. It doesn't do this all the time. I was pretty warm out but I don't know what that would do with it.

Bike is running sleeved Amals, has fonolic blocks installed and I am using premium gas. Could the carbs be getting hot sitting?

Try tickling (lightly) only one carb, to test (a 15 minute stop)

Torontonian · May 28, 2023

Pull the plugs . Reinsert clean new ones and rest or clip them to the head fins to ground out the bodies and kick her over . Ign . now on . You should see good sparks at the plug tips . Start with this simple test .

Big_Jim59 · May 28, 2023

concours said:
Try tickling (lightly) only one carb, to test (a 15 minute stop)

Should have done this.

Big_Jim59 · May 28, 2023

Torontonian said:
Pull the plugs . Reinsert clean new ones and rest or clip them to the head fins to ground out the bodies and kick her over . Ign . now on . You should see good sparks at the plug tips . Start with this simple test .

Will do.

gjr · May 28, 2023

Don't feel bad. Nobody kick starts a bike anymore. But it is still embarrassing, it should roar to life with a gentle prod on the kick starter. But sometimes they don't. You have to work through the flooded or dry options. I find that mine is usually dry. The heat from the engine evaporates the fuel in the bowls. Turning on the taps is not enough. Tickle. Of course if you flood it you are in for more kicking. Just don't fall over when giving it the boot.

Tornado · May 28, 2023

My 850 mkII seems to have some occasional trouble starting after 15-20min sitting. Fine dead cold or shortly after a shut down, like a 5 min refueling.
So this seems similar to your issue.
Dual premier carbs. 5k Ohm plug caps. Ŵassell EI. I usually shut petcocks if stopping more than 5 min and do not usually tickle after first start of the day.

Could be a temp related vapour lock as fuel in carbs boils away out of idle circuits.

Big_Jim59 · May 28, 2023

gjr said:
Don't feel bad. Nobody kick starts a bike anymore. But it is still embarrassing, it should roar to life with a gentle prod on the kick starter. But sometimes they don't. You have to work through the flooded or dry options. I find that mine is usually dry. The heat from the engine evaporates the fuel in the bowls. Turning on the taps is not enough. Tickle. Of course if you flood it you are in for more kicking. Just don't fall over when giving it the boot.

I have been able to kick it with just the side stand down to catch the bike in case it falls (no actual pressure on the side stand.) I had to resort to pulling the bike up on the center stand to give it the best possible kick and follow through. I got the impression that I had a lean condition since opening the throttle got zero response. Next time I will hit the tickle and see what happens.

Big_Jim59 · May 28, 2023

Tornado said:
My 850 mkII seems to have some occasional trouble starting after 15-20min sitting. Fine dead cold or shortly after a shut down, like a 5 min refueling.
So this seems similar to your issue.
Dual premier carbs. 5k Ohm plug caps. Ŵassell EI. I usually shut petcocks if stopping more than 5 min and do not usually tickle after first start of the day.

Could be a temp related vapour lock as fuel in carbs boils away out of idle circuits.

Yep, sounds the same.

robs ss · May 28, 2023

Torontonian said:
Pull the plugs . Reinsert clean new ones and rest or clip them to the head fins to ground out the bodies and kick her over . Ign . now on . You should see good sparks at the plug tips . Start with this simple test .

There is risk to EI using that method - not recommended by Trispark (in case the earthing is not secure)

A safer bet is to use one of these: Apr 20, 2022

Cheers

rweb · May 28, 2023

Big_Jim59 said:
I took the Norton out for a short ride this morning. I ended up at the QT, parked the bike and got a coffee. I sat for about 15 minutes drank my coffee and looked at the bike (she sure is pretty!) I went to head home, kicked it with a little throttle, nothing, kicked again with a little throttle nothing. Kicked, kicked and kicked until I got embarrassed and hot in my jacket. I kicked it with a moderately open throttle (thought it might be flooded,) still nothing. Kicked with closed throttle and got a couple of pops. I repeated kicking with closed throttle. I got pops and after about the 4th kick she lit off.

It usually starts right up with 1/4 throttle. It doesn't do this all the time. I was pretty warm out but I don't know what that would do with it.

Bike is running sleeved Amals, has fonolic blocks installed and I am using premium gas. Could the carbs be getting hot sitting?

Modern gas, Ethonall seems to boil over, expand with heat a lot easier than the old days of lead. Old cars with carbs have the same problem, in the hot or even warm weather here in Ga. The cure is to set the float on the low side of spec. to avoid flooding when heat soaked. On the Commando I always turn the gas tap off before I get to the parking lot. At home I turn off the gas maybe a quarter mile before parking. Carbs will always get hotter when the engine is first stopped, but the rubber hose mounting like mentioned above and on most bikes built after 1975 will help.

Tornado · May 29, 2023

rweb said:
Modern gas, Ethonall seems to boil over, expand with heat a lot easier than the old days of lead. Old cars with carbs have the same problem, in the hot or even warm weather here in Ga. The cure is to set the float on the low side of spec. to avoid flooding when heat soaked. On the Commando I always turn the gas tap off before I get to the parking lot. At home I turn off the gas maybe a quarter mile before parking. Carbs will always get hotter when the engine is first stopped, but the rubber hose mounting like mentioned above and on most bikes built after 1975 will help.

I'm running non ethanol juice so that should not be a factor at least in my case.

kommando · May 29, 2023

Clean your pilot jets with a #78/16 thou drill.

rweb · May 29, 2023

Tornado said:
I'm running non ethanol juice so that should not be a factor at least in my case.

I'm not so sure ethanol is the whole problem, modern blinds may also be blamed. I have a friend who uses ethanol free in his 69 BSA and the problem is much worse than a Norton, BSA carbs are bolted straight to the head, no manifolds. It's so bad he won't ride it in June or July and August. All this is just my opinion and observation, but cutting the fuel off before stopping works for me and apparently @Tornado above and it doesn't cost anything to try.

Big_Jim59 · May 29, 2023

I think you are correct. Heat and boiling carbs have a lot to do with it.

marshg246 · May 29, 2023

As the risk of being told once again that I'm crazy....

Don't touch the throttle when starting an Amal concentric carb equipped bike and don't have a choke installed (or at least have it up).

There is so little vacuum at kicking speed that it's difficult to draw fuel from the pilot circuit - opening the throttle reduces the vacuum even more. The tickler's primary job is the fill the pilot circuit so fuel can be sucked into the throat of the carb - gravity's job is to drain it. Stopping for 15 minutes - gravity has certainly won. Tickling too long can flood the carb. To start with a flood carb, open the throttle a lot.

Big_Jim59 · May 29, 2023

It's raining here so the experimentation will just have to wait. The dogs are huddled around my office thinking I can make the thunder stop.

Lineslinger · May 30, 2023

What G. Marsh said.
What Kommando said.
I would wager it starts right up with 1/4 throttle during a cold start, same technique is counter productive on a warm engine.

I have an 850 MKII, sleeved Amals also.

If the engine is warm: And it is still plenty warm after 15 minutes.....
I don't touch the choke because I removed it.
I don't touch the throttle.
One mild down kick on the compression stroke and it fires. Be it Av gas or ethanol.
Open throttle disrupts the flow of fuel - air ratio and accurate charge. Those pops you hear are probably an inadequate fuel air charge.
Engine temp. is a big deal influence.

MichaelB · May 30, 2023

Lineslinger said:
What G. Marsh said.
What Kommando said.
I would wager it starts right up with 1/4 throttle during a cold start, same technique is counter productive on a warm engine.

I have an 850 MKII, sleeved Amals also.

If the engine is warm: And it is still plenty warm after 15 minutes.....
I don't touch the choke because I removed it.
I don't touch the throttle.
One mild down kick on the compression stroke and it fires. Be it Av gas or ethanol.
Open throttle disrupts up the flow/fuel - air ratio and charge. Those pops you hear are probably an inadequate fuel air charge.
Engine temp. is a big deal influence.

Do you close the fuel tap, or leave it open?

KiwiShane · May 30, 2023

Lineslinger said:
What G. Marsh said.
What Kommando said.
I would wager it starts right up with 1/4 throttle during a cold start, same technique is counter productive on a warm engine.

I have an 850 MKII, sleeved Amals also.

If the engine is warm: And it is still plenty warm after 15 minutes.....

Engine temp. is a big deal influence.

Or could we say carburetor temp ?

Hard Start (again)

Big_Jim59

concours

Torontonian

Big_Jim59

Big_Jim59

gjr

Tornado

Big_Jim59

Big_Jim59

robs ss

rweb

Tornado

kommando

rweb

Big_Jim59

marshg246

Big_Jim59

Lineslinger

MichaelB

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KiwiShane

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