The BSA A7-A10 Forum
Technical (Descriptive Topic Titles - Stay on Topic) => Lucas, Ignition, Charging, Electrical => Topic started by: Terryb on 29.10. 2024 19:44
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Hopefully this is the correct forum. My 62 A10 won't easily start, keeps kicking back when giving a fist full of throttle. I have started it on a number of occasions, even though she's kicked like a mule and she seems to run OK.
OK, she's been extensively refurbished and I'm now at the commissioning stage. Main problem won't start and I am fearful that the automatic A/R unit may be the cause of kicking back. The A/R Unit is stiff and the timing adjustment doesn't fly backward or forwards easily, don't know why. I have set the timing using a clock gauge and timing light at fully advanced. So I'm confident she is timed correctly, but when you close up the Primary Case, I'm not sure the A/F bob Weights are doing their job, because they are stiff.
I have the old A/R unit, but I cannot get the centre bolt out to put the washer with the two locking holes back on, otherwise I would swap them around.
Any idea's lads? *help*
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The ATD will feel stiff when it's fitted because of all the friction in the magneto. If you move it to its fully advanced position it probably won't flick back on its own. However, when you gently move the kickstart to turn the engine over you'll see the ATD close to its retarded position. I assume you wedged the ATD in its advanced position when setting the timing; if you didn't, that would cause the kickback. Other kickback culprit is weak mixture. If the bike is set up properly it should be started from cold on closed throttle with choke on full. On first starting a new engine I usually set the tickover screw so that the throttle slide is completely closed then turn the throttle stop screw up about a quarter of a turn after each kick until the bike fires. Set the idle air screw 1 1/2 turns out initially.
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So why are you trying to start it with "a fistful of throttle"? That's pretty well guaranteed to kick back on you! Try closed throttle or just a 'crack' of throttle.
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has the mag been rebuilt ?
where did you set the timing btdc ?
does it idle and run ok once started ?
was the carb rebuilt ?
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Do you know about the coarse left-hand thread on the outside of the sleeve nut, that screws it out through the yoke?
(https://i.postimg.cc/Y09zP28W/IMG-2535.jpg)
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The new production big washers have a larger hole than the originals and pass over the bolt head.
New washer on left of photo.
Sometimes the centre of the ATD gets corroded and the action gets sluggish but you would easily feel this with the unit off the magneto.
The centre bolts often will not come out due to thread damage but this should not affect the action of the ATD.
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After four (or maybe 5) failed ATDs and fibre gears (one ATD actually broke up and took a tooth out of one of the timing gears), and the fact that a lot of old fibre gear had floated round my engine for quite a while damaging stuff as it went, and after an engine rebuild to fix a multitude of problems (see Worty's A10 Engine Rebuild thread), I took the advice of Mr Bergs and acquired his brand new ATD. Bike has been faultless since, and no worries about 60+ year old units partially worn out with probably a good deal of metal fatigue. *good3*
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Thanks Gents for your advice and yes she will start from cold with full choke and no throttle and ticks over nicely. But she won't start when warm *ex*
Taking in all your comments and note the reason for kick back, my ignorance I'm afraid *conf* I've decided to firstly check the timing and possible change out the ATD. The carb is a new monobloc, but there may be a fuel supply issue, not confident about the taps. The Mag was refurbed 3 years ago and never fitted, spark on both cylinders looks good. I'll come back to you and let you know how I get on.
Before I go, I said the ATD was stiff and you said that it may be caused by the Mag. Would that be caused by tightening the ATD nut too much? Also I set the timing up fully advanced *smile*
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I don't think tightening the ATD bolt up 'too much' will cause a problem. It's more a case of how tight you can get it without it slipping round the taper and how well you can jam the maggie to get it suitably tight in the first place. Never heard of a situation where one has to slacken off the bolt so it's not too tight. In any event, if the maggy shaft taper is good, it won't be going anywhere soon if the bolt is nipped up reasonably well.
I reserve the right to be corrected by those of greater knowledge.
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Having read back through the thread, I am of the opinion that this is caused by weak mixture. Is the slide loose in the carb? Maybe screw the pilot air screw in a bit, lift the needle a notch, whatever to make it a bit richer. Slide is the most likely culprit. Will it start with a push when hot?
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Thanks Gents for your advice and yes she will start from cold with full choke and no throttle and ticks over nicely. But she won't start when warm *ex*
Taking in all your comments and note the reason for kick back, my ignorance I'm afraid *conf* I've decided to firstly check the timing and possible change out the ATD. The carb is a new monobloc, but there may be a fuel supply issue, not confident about the taps. The Mag was refurbed 3 years ago and never fitted, spark on both cylinders looks good. I'll come back to you and let you know how I get on.
Before I go, I said the ATD was stiff and you said that it may be caused by the Mag. Would that be caused by tightening the ATD nut too much? Also I set the timing up fully advanced *smile*
my 62 sr usually starts first kick without the choke , i/4 throttle , manual retard lever retarded approx 1/3rd of travel , tickle carb and kick it over .....timing set at 3/8ths in btdc full advanced ....good luck
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CheeserBeezer, I will check the mixture, but I wouldn’t think the slide is suspect. It’s anew Amal Monobloc.
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Sean, is your bike a Flash? I timed my Flash at 11/32” BTDC not 3/8”
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Sean, is your bike a Flash? I timed my Flash at 11/32” BTDC not 3/8”
1962 super rocket
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I've gone for 11/32 but mine's manual A/R so I've got a bit more leeway. Have you checked the points gap and points are OK, they can work loose.
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To eliminate mixture issues, have you tried using the choke when hot?
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OK, at the weekend I checked the ATD and now that she's lubricated, she looks to be working, she retards when kicking her over. Check points gap and timing and reset it again, closed her up and she started first kick on full choke. Didn't run smooth on choke, but when warm ticked over nicely and picked up well. Left her for 30 mins and started, but not well. So I'm thinking it must be fuel starvation, so that's my next investigation ;)
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Worth checking the taps and carb are not blocked. I cleaned and cleaned my tank but still after a few runs one tap was blocked solid and so was the carb gauze. Remind me, which carb?
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Hi Terry,
Starting and stopping in the garage will lead to more difficulties due to the plugs getting fouled and not hot enough to burn themselves clean. It is a consequence of the crap petrol that is on the market now
John
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drained the yonda carbs the other day and within a couple of minutes it was milky with moisture , it is horrible stuff
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Its is, the only way I can get my chainsaw to run is to drain the fuel after every use, never used to have to do that.
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No such problems using E5 with a splash of 2 stroke oil. The chainsaw can be left for months and starts with a couple of pulls. Same with the 4 stroke lawn mower which is left all wet season.
With the bikes I run them with the petrol turned off leaving the carb dry.
Good starting followed by poor starting could be a cry for help from the mag.
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No such problems using E5 with a splash of 2 stroke oil. The chainsaw can be left for months and starts with a couple of pulls. Same with the 4 stroke lawn mower which is left all wet season.
With the bikes I run them with the petrol turned off leaving the carb dry.
Good starting followed by poor starting could be a cry for help from the mag.
Yes, even though the symptom isn't what we'd normally associate with a poor mag, it is such an easy swap it's worth doing to eliminate it. I'm happy to lend a mag if that helps.
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Thanks CheeserBeezer, but the Mag was Recon in 2021 by API Magnetos Ltd and the previous owner never put it in the bike. I've installed it and it appears to work fine a good spark on both cylinders. I'm now moving the bike out of the Workshop this weekend and hopefully take her out on the road, so we'll see ;D
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How old is the petrol you are using? I had a bike severe spitting back and it was cured with new petrol.
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How old is the petrol you are using? I had a bike severe spitting back and it was cured with new petrol.
dont know what ethanol content you have we are on E10 here in Canada I never leave it in anything over winter always drain carbs and tank ....ethanol has a short shelf life and attracts moisture best thing ever invented for small engine shops .
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OK Guy's sorted *smile*
Re-timed her, purchased one of those Points Timing Buzzer from Fleabay and she is now spot on. Starts cold and hot, mixture adjusted and now for waiting for dry roads' :-: *woo*