850 hard to start

hi my 73 850 has gone from a couple of kicks to start to turning into a real workout.
the engine is in good health has a pazon ign
to start tickle carbs small flood from ticklers ignition on NO choke very small bit of throttle then kick.
bike will fire up and run for about five-ten seconds then stop, repeat kicking up to up to half dozen times but will not fire.
I am getting a fear bit of kick back as well.the only way I can get the bike to start is to re tickle the carbs and repeat and repeat when the bike fires hold some revs to the bike settles down and will idle on its own but its lumpier the before .
I have a good battery I am wondering if it is starving of fuel on start up? or maybe a dirty air filter.
cheers mike

mike 850 said:

I have a good battery I am wondering if it is starving of fuel on start up?
cheers mike

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From the number of post on idle jets, I assume they are clean.

Mike, yep sounds lean. What about the filters on the fuel taps and the screens in the banjo's ?. Clean ?

Bad contacts on the stop switch and wiring joints could give same effect.

When it stops and you re-tickle the carbs, does it take very long to get fuel from the ticklers again ? If not its probably electrical.

Fresh plugs may help

Good luck

Get a #78 drill, glue into the end of a WD40 red tube or similar, remove pilot mixture screw and insert drill and twist with your fingers as it goes into the pilot jet. Spray with carb cleaner and reinsert pilot mixture screw, start engine and when warm tune up your idle.

Todays fuel gums up the pilot jet too easily, once gummed up you get a weak mixture on start up even when flooded.

Hi

What are your plugs like?

my 850 did that today. have to look at it. Once I started it about 8 times and kept it going it was ok. I don't have chokes on mine. Had to tickle it every time till it kept going. I will look at it again this week and let you know. Let me know what you find. Dereck,.

Hi thanks for all your comments will check fuel taps filters will try and start bike with Reserve tap instead of main.
when re tickling carbs the flooding come on like normal start up.
the plugs are usually a nice tan colour but the left hand plug has been ruining richer lately with this starting problem I pulled them out today they were both black but not flooded. will replace plugs.
could I get some more information on this bad contacts on stop switch?
cheers mike

Hi mark man

My original carbs are worn to buggery , when I bought the bike it had 50k on it and the PO said the speedo packed up on the way back from the mot center , however when I went though the old mot's etc the mileage hadn't changed for. 15 years
If my bike is hot at all it needs tickling and on cold a big handful on bottom of kick , but if you don't tickle when hot it won't start and the plugs are as dry as the proverbial nuns ... Habit.

I like to give my old bike the occasional Italian tune up , don't know if it tells you anything but I doesn't half give you a buzz.

J

mike 850 said:

hi my 73 850 has gone from a couple of kicks to start to turning into a real workout.
the engine is in good health has a pazon ign
to start tickle carbs small flood from ticklers ignition on NO choke very small bit of throttle then kick.
bike will fire up and run for about five-ten seconds then stop, repeat kicking up to up to half dozen times but will not fire.
I am getting a fear bit of kick back as well.the only way I can get the bike to start is to re tickle the carbs and repeat and repeat when the bike fires hold some revs to the bike settles down and will idle on its own but its lumpier the before .
I have a good battery I am wondering if it is starving of fuel on start up? or maybe a dirty air filter.
cheers mike

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This may sound like an old record, but if it "KICKS BACK" then its tooooo far advanced..(Nobody can/will offer an explanation otherwise) Simple. Be sure the timing is at factory setting or minus... Then adjust from there for final tuning..

Question ? How did/have you set the timing???? .. The basics have to be right before you spend $$$$ for the sake of spending..

Perhaps it just needs a little choke?

Dave

Mike,

Your description sounds a lot like my '74 850. Mine has Amal 932's, points ignition, and is a one kick bike, but God help you if it isn't tickled to death as it would never start without tickling and choking. After starting it runs lean and requires partial choke that is progressively leaned over a period of 5-10 mi until it is fully warmed up. Once warm it idles and performs well at all throttle positions, but when ice cold, idles too slow even with choke. I'm not sure any of them ever did idle nice when ice cold, but correct me if I am wrong.

Even if it stands for 30 minutes after being run for an hour, it likes tickling and choke to relight - in this circumstance the tickler is more important than the choke. I don't doubt that there is likely something slightly amiss in the pilot circuit, but if the protocol above is used it is a consistent one kick machine.

If kick-back is occurring regularly, sounds like the timing is too advanced or for whatever reason the ignition is not retarded sufficiently at low rpm.

kerinorton said:

my 850 did that today. have to look at it. Once I started it about 8 times and kept it going it was ok. I don't have chokes on mine. Had to tickle it every time till it kept going. I will look at it again this week and let you know. Let me know what you find. Dereck,.

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Next time I started it, I kept the revs up and had no problem. Have started it first kick 3 times in a row now using that technique, including this morning when I road the bike to work. Incidentally, my plugs are always dry black or anthracite because of the unleaded fuel we use here.

if it aint broken don't fix it. Dereck

I know this sound overly simple, but in my experience, its always the simplest root cause. Sounds like the gas cap vent is clogged. Before you tear the bike apart, open the filler cap and leave it open when starting. If it starts the way it used to then the clogged vent is creating a vacuum. It happened to me once with my Trident and the solution was to replace the cap.
Good luck,
C

Commando Cam said:

I know this sound overly simple, but in my experience, its always the simplest root cause. Sounds like the gas cap vent is clogged. Before you tear the bike apart, open the filler cap and leave it open when starting. If it starts the way it used to then the clogged vent is creating a vacuum. It happened to me once with my Trident and the solution was to replace the cap.
Good luck,
C

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He has said he can tickle the carbs and get fuel through so I don't think that is an issue here.

Have you checked the mixture screws? Even with "new" (I think incorrectly sized) O-rings, my screws have vibrated a significant way off setting.