Hard Starting

Tornado · Mar 10, 2022

My '74 850 has been a really easy starter, usually 1st kicker. Just the past three days, its been much more stubborn, taking 5+ kicks, even if warm. It does give a very feeble pop or two, just doesn't fully fire up.

New Amals for past few months. No chokes. Wassel EI. New wiring harness. New plugs/cables.

Cold start Procedure that was working great was to tickle both, kick over once or twice ign off, then ign on and full strong kick. No throttle.

Only thing is changed before issue, was i'd sync'd the carbs using my Morgan Carbtune vacuum balancer. They were off a bit at above idle rpms, so adjusted cable lengths until very even.

I tried a different set of plugs (had NGK resistors, now champion non resistors), no improvement.

What to check? Is the carb balancing the problem or perhaps timing has slipped?

MexicoMike · Mar 10, 2022

Well, could be several things but the most likely suspect is related to whatever you did to the bike between the time it started easily and now. Did you do anything else other than adjust the carb cable length? Is the balance tube between the carbs in good shape/not leaking?

zotz · Mar 10, 2022

How long between rides? Are you using fuel with ethanol in it? It's bad for clogging the pilot jet if not used daily. I had a 500 Triumph that grew progressively harder to start through the week the longer it sat. I regularly had to remove the pilot jet and run a fine wire through it. Then it would start right up.

Fast Eddie · Mar 10, 2022

If you balanced the carbs by adjusting the cables then it’s possible that both slides are not on the stops, and even, when closed.

That could easily be your issue.

Tornado · Mar 10, 2022

zotz said:
How long between rides? Are you using fuel with ethanol in it? It's bad for clogging the pilot jet if not used daily. I had a 500 Triumph that grew progressively harder to start through the week the longer it sat. I regularly had to remove the pilot jet and run a fine wire through it. Then it would start right up.

Same non ethanol fuel, fresh tank from before after issue, maybe a week since previous running.

Tornado · Mar 10, 2022

MexicoMike said:
Well, could be several things but the most likely suspect is related to whatever you did to the bike between the time it started easily and now. Did you do anything else other than adjust the carb cable length? Is the balance tube between the carbs in good shape/not leaking?

Tweaked idle and mixture screws a bit.

Tornado · Mar 10, 2022

Fast Eddie said:
If you balanced the carbs by adjusting the cables then it’s possible that both slides are not on the stops, and even, when closed.

That could easily be your issue.

Will re-visit the idle stop adjustments when hooked to carbtune at idle.

ashman · Mar 10, 2022

Your pick up could have slipped, carb clogged, air leak, bad earth, just need to start to check one thing at a time till you win, luck of the draw, how old is the fuel in your tank as modern fuels go off pretty quick, bad coil could be a lot of things, carb or ignition.

Fast Eddie · Mar 10, 2022

Tornado said:
Will re-visit the idle stop adjustments when hooked to carbtune at idle.

If your cable is holding the slide up… twiddling the screws will lead to naught…

Tornado · Mar 10, 2022

Fast Eddie said:
If your cable is holding the slide up… twiddling the screws will lead to naught…

Twiddling either carb idle screw does change rpm at idle. I can also feel the slides contacting the screws by having a finger on the ehead and when releasing the throttle grip. It might be that one slide is now sitting higher than the other. The vacuum gauge should show me if there is uneven flow carb to carb at idle.

Tornado · Mar 10, 2022

ashman said:
Your pick up could have slipped, carb clogged, air leak, bad earth, just need to start to check one thing at a time till you win, luck of the draw, how old is the fuel in your tank as modern fuels go off pretty quick, bad coil could be a lot of things, carb or ignition.

Fuel is new. Once it does fire up, runs pretty well, no stumbles, no pops or mis fires. Idles well and consistently.

MichaelB · Mar 10, 2022

Weak battery.

Tornado · Mar 10, 2022

MichaelB said:
Weak battery.

My SparkBright voltage warning light shows amber at ign on, which means around 12-12.5 v at battery. Bike does have the 2 MC capacitor fitted so should be able to start/run with a dead batt., even with EI.

RoadScholar · Mar 10, 2022

In my opinion the Color Tune requires too much judgement, I recommend the Twin Max,, follow the instructions, no judgement required.

The first question I would ask is, how many changes did you make before the hard starting behavior surfaced.? When the Premiers were released they were supplied with factory installed swarf, at no extra cost...

I suggest the you remove the carbs and verify that the fuel/air passages are clear;; blow out the passages with compressed air in the opposite direction the normally supply fuel air, please use suitable eye protection. .

Back the slide height adjusters out until the slides are fully bottomed out, make sure you have some slack in the cables, if not then back out the carb top adjusters. Use a SINGLE drill bit in the range of 1/8 to 1/4 like a feeler gauge, turn in the slide height adjusters until you get the same feel on both sides. Have an assistant rapidly turn the twist grip between it's stop and where it begins to act on the cables; all you want to d here in induce an impulse into the cables so you can feel the impulse on both slides, do this until you satisfied that both slides get the impulse at the same time. Now make sure that the cables have some slack, 2 mm is plenty. Turn the air trim screws to 1, 1/4 turns out from seating.

Button it up, fire it up. When you have ridden it to OT, put the Twin Max in place for final vacuum synchronizing.. If the carbs need additional , turn the adjustments on each carb the same. double check with the twin max. Some carbs may need individual attention, but you may well have started on a journey into the Twilight Zone...

Best

Tornado · Mar 11, 2022

RoadScholar said:
In my opinion the Color Tune requires too much judgement, I recommend the Twin Max,, follow the instructions, no judgement required.

The first question I would ask is, how many changes did you make before the hard starting behavior surfaced.? When the Premiers were released they were supplied with factory installed swarf, at no extra cost...

I suggest the you remove the carbs and verify that the fuel/air passages are clear;; blow out the passages with compressed air in the opposite direction the normally supply fuel air, please use suitable eye protection. .

Back the slide height adjusters out until the slides are fully bottomed out, make sure you have some slack in the cables, if not then back out the carb top adjusters. Use a SINGLE drill bit in the range of 1/8 to 1/4 like a feeler gauge, turn in the slide height adjusters until you get the same feel on both sides. Have an assistant rapidly turn the twist grip between it's stop and where it begins to act on the cables; all you want to d here in induce an impulse into the cables so you can feel the impulse on both slides, do this until you satisfied that both slides get the impulse at the same time. Now make sure that the cables have some slack, 2 mm is plenty. Turn the air trim screws to 1, 1/4 turns out from seating.

Button it up, fire it up. When you have ridden it to OT, put the Twin Max in place for final vacuum synchronizing.. If the carbs need additional , turn the adjustments on each carb the same. double check with the twin max. Some carbs may need individual attention, but you may well have started on a journey into the Twilight Zone...

Best

I didn't use a ColourTune, I used a Morgan CarbTune, which is a vacuum metering device using a solid slider pins for comparing vacuum btwn inlets rather than dial guages or fancy digital readouts.

Derek Wilson · Mar 11, 2022

If you are tickling the carbs when cold, fuel is likely not the issue - I would start with the ignition. I would start with the cold start issue before addressing the warm start issue.

What are you running for a coil/coils? What plugs are you running? What are you running for ignition timing?

I know nothing about the Wassell EI - what sort of longevity do they have? Some bad experiences in the 70's and 80's on my dad's Norton has always made me leery of Wassel products, but maybe that is just me...

Back to the fuel - how are the needle jets? If they have any sort of age on them, they likely should be replaced.

Also - I know you had the top end off your bike recently, did you have the timing cover off? How is the cam chain tension?

If all these check out, and you still have issues, then it is time to start head scratching...

FWIW

baz · Mar 11, 2022

Tornado said:
Twiddling either carb idle screw does change rpm at idle. I can also feel the slides contacting the screws by having a finger on the ehead and when releasing the throttle grip. It might be that one slide is now sitting higher than the other. The vacuum gauge should show me if there is uneven flow carb to carb at idle.

You need to balance the carbs at idle and being revved the critical adjustment is as the slides are lifting off the idle adjustment screws
I don't think this is your starting problem
What has changed on the bike?
Is the battery tip top?
Have you fitted R plugs with resistance plug caps for example?
Are you sure the timing is correct/correct voltage at the coils,bad earth ? Etc etc
Are the pilot jets clear?

marshg246 · Mar 11, 2022

Tornado said:
My SparkBright voltage warning light shows amber at ign on, which means around 12-12.5 v at battery. Bike does have the 2 MC capacitor fitted so should be able to start/run with a dead batt., even with EI.

The capacitor doesn't help with the battery connected. The point is with a dead battery, you take the fuse out and the capacitor holds a charge as the engine turns just long enough to fire. Once running you put the fuse back in to charge the battery. If the battery is too far gone you can run on the capacitor as long as the battery is not connected. Most EIs won't start on the capacitor except if you have a long hill, separate starter, or a tow. With great effort I started an 850 on the capacitor with a Tri-Spark EI using the kick start.

MexicoMike · Mar 11, 2022

Did the hard starting occur immediately after doing whatever work you did? IOW, was it starting OK "a few days ago" and then you worked on it and "today" it's starting poorly? Or was it starting OK some months ago, sat for X weeks/months, you did some work whenever and now it's starting badly?

IMO, if it was OK "yesterday," you worked on it and "today" it's starting poorly, as I said earlier, it seems very likely that the work caused the problem somehow. NOTE that it could be indirectly related...for example, you worked on carbs/cables and accidentally disconnected/damaged an elec connection/wire without realizing it.

I once had an issue somewhat similar that turned out to be that I had accidentally disconnected a primary coil wire when working in the vicinity. I wasted a good bit of time troubleshooting because I "knew" the ignition was OK - bike was running a couple of hours prior - and I hadn't been working on the ignition So you never know...

In any case, best wishes for a quick resolution!!

Tornado · Mar 11, 2022

Derek Wilson said:
If you are tickling the carbs when cold, fuel is likely not the issue - I would start with the ignition. I would start with the cold start issue before addressing the warm start issue.

What are you running for a coil/coils? What plugs are you running? What are you running for ignition timing?

I know nothing about the Wassell EI - what sort of longevity do they have? Some bad experiences in the 70's and 80's on my dad's Norton has always made me leery of Wassel products, but maybe that is just me...

Back to the fuel - how are the needle jets? If they have any sort of age on them, they likely should be replaced.

Also - I know you had the top end off your bike recently, did you have the timing cover off? How is the cam chain tension?

If all these check out, and you still have issues, then it is time to start head scratching...

FWIW

Wassell EI is basically a copy with improvements over the analog Boyer units. Other than the epoxy encasing of stator and wire connections, I'm uncertain of other significant differences.
Coils are newish, 6v Lucas, less than three yrs old. Timing was last set to 28 BTDC (confirmed via timing gun) as per guidance. Have not distrubed stator for last two seasons, when I replaced timing chain at that point.

Premier Carbs new end of last season.

Yes the bike has just come back from a long stay at a workshop. New wiring harness was fitted by them with all the other things being done. So wiring to EI and coils all new. There might be a fault or poor connection. But bike does seem to run fine once started.

Problem with needing lots of kicks seemed to start a few days ago, when it had been a good starter the days prior. Coincided with my carb balancing procedure and minor idling point tweaks. So that is where I will re-check to begin with. Not sure this is always the case but it seems to help to have throttle held open slightly to get a proper fire up after tickling. Could it be flooding initially and then taking more kicks to clear until it goes?

Hard Starting

Tornado

MexicoMike

zotz

Fast Eddie

Tornado

Tornado

Tornado

ashman

Fast Eddie

Tornado

Tornado

MichaelB

"Sons of Arthritus"

Tornado

RoadScholar

Tornado

Derek Wilson

baz

marshg246

MexicoMike

Tornado

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