Hi - not been on here for a while. Have recently bought a 1966 A65 Spitfire fitted with a John Hill alloy 750cc barrel and an Electrex self generating ign/lighting system. My problem is on starting, it kicks back so fierce as to break my ankle! Now I am no novice at these things but this has got me stumped. Initial thoughts of course are too far advanced ign timing. This is spot on but I have tried continually retarding it to no avail. However if I do not give it any throttle it never kicks back but will only fire once or twice but not start. If I give it just the slightest throttle on starting it kicks back. If I screw in the throttle screws a little and kick with no throttle it starts with no kick back but is then ticking over far too fast. The Electrex system has been returned to the factory where it was given a clean bill of health. John Hill was the previous owner of this bike and says he never had any problems, which I doubt. Once I can get the bike started it runs fine. Has anyone any ideas as I am at my wits end.
Thanks
John.
Today's fuel is different to that of the 1960's, so the ignition timing should be retarded a shade.
Clean the idle jets (physically) and use new fuel.
I haven't used the Electrex system but believe that some after-market electronic ignition systems can have a tendency to fire a bit too advanced when the supply voltage is low. Maybe worth checking that you have a fully charged battery - or leaving a charger connected while you try to start it - to make sure that isn't part of the problem.
Cheers,
Bernie
:)
Maybe weak mixture--
Mike
Hi all - thanks for the fast response. Caulky first - as I said I have kept on retarding the ign until I have run out of adjustment as this was my initial thoughts too. No joy. Berniej - The Electrex system is completely self generating and so needs no battery even for the lights. So no joy either. Mike- The carbs are brand new premium concentrics and I have upped the pilot jet on the advice of Amal Carbs. This has not cured the kickback but has made the bike easier to start just on tickover (when it does not kick back) but it is still a bit hit and miss for me to rely on just that to start it. However I think the carb settings may be a step in the right direction. Thanks to all of you. John.
Hi there.
It sounds very much like an issue with the timing and not the carbs.
Once you get the bike started have you tried strobing it?
This is the only sure way of checking the timing correctly, and you will also be able to see if its advancing correctly up to the timing marks. It sounds as though it's stuck on full advance to me.
Some digital electronic systems have a stabilising function where at low rpm to avoid engine stalling it advances the timing.
No sure if Electrex has this function built into the chip.
Quote from: JulianS on 13 Feb, 2019, 09:35
Some digital electronic systems have a stabilising function where at low rpm to avoid engine stalling it advances the timing.
No sure if Electrex has this function built into the chip.
If it has there's no mention of it in the Electrex instructions that I have. I bought one a while ago for a Norton but have never fitted it.
Interestingly there's no mention of using a strobe in the instructions, Just set the crank to the correct position using a timing disc or a dial gauge and align the FA mark on the rotor with the red dot on the stator. Electronic advance at 5000rpm is 21deg.
I think I'd still be checking it with a strobe though.
:)Ho agin. It might be worth a a try kicking it over a couple of times with the ignition off in the same way they used to "prime" the old aircraft engines. I have always done this with the old big hand started tractor engines. We used to pull them every piston through compression stroke. Maybe helpful---who knows.
Mike 8) 8) 8)
For what its worth there is an effect on Boyer Systems where when the voltage is low, the advance 'curve' shifts to more advanced so it will kick back. Charge the battery up and its fine. I know the Electrex is self generating but it may suffer from the same effect??
Have you tried calling them for advice?
Are the float levels set-up to 0.080" below the cusp?
Easy to adjust with 'stay up' floats.
Hi all - and thanks for the further imput. I have checked the timing with a strobe as suggested by Electrex and the timing is spot on the mark and advances perfectly. As I said in my first post I have sent the unit to Electrex who say it is perfect. I am still convinced it is carb related as it does spit back through the carb when it kicks back and it only kicks back when I try to start it with a slight throttle opening. If I screw the throttle screws in slightly it starts first time with no kick back but then of course it ticks over too fast. On the road it pulls like a train and is very quick.
John.
I fail to see an issue here, my bike A65 which is totally std kicks back if i try and start with throttle slightly open.
why cant you screw the throttle in slightly and then adjust after its running, surely a small compromise on what is probably quite a tuned and very enjoyable A65.
;)
derek
As Mike Farmer said further back in this thread, 'weak mixture'.
Opening the throttle slightly brings the needle jet into operation.
Raise the needles one notch, by using a lower notch on the needle.
The pilot screw should be 1 1/2 turns out to begin with, then tune the carbs.
I use the Hughie Hancox method for tuning. i.e. treating each cylinder as a single.
About 4 mins into this video:
https://www.youtube.com/watch?v=cjUU1eDyesI&list=UUZSGgAoIUtPZfo8Y0qTNW0g&index=10
Hi Derek Anderson 8 - but there is an issue. If it won't start normally then something is wrong. Yes every time I start it I can screw in the throttle screws and then when it starts I can screw them back but that is hardly a cure. If at the end of my investigation that is what I have to do then I will pack a small screwdriver and do it but I think in the meanwhile I will continue with carb adjustments. At the end of the day it is just an old 750cc motorcycle (albeit with an alloy barrel and a superior ignition system from when it was new) and I should be able to start it without breaking my ankle. Also even though it runs fine I worry I will end up with a hole in a piston or worse because the set up is not as it should be.
Thanks for your input.
John.
Quote from: johnjag on 16 Feb, 2019, 10:10
the timing is spot on the mark and advances perfectly.
Hi. Just to be clear, when you say the timing is spot on the mark and advances perfectly, do you mean it advances perfectly up to the timing mark?
If it starts advancing after the timing mark It'll be way too advanced and will give you the potential of a broken ankle you describe.
The timing will only be spot on the mark is when the engine is doing 5000rpm.
:)
Sudden thought and I may have missed something in the posts.
Do you have proper air filters on it. If not it may be worth a try--it should richen the start mixture just a tad.
Mike 8) 8) 8)
Hi all and particularly Mike Farmer. Mike I think your idea is a good one but I cannot try to start the bike at the moment due to an injured back. This was caused not by the bike kicking back but just stooping slightly while I was spraying the rear shocker covers! Oh the joys of old age. Will let you all know when I have a result. Thanks again for all your inputs. John.
Hi - yes the ignition advances perfectly up to the line. I had thought about air filters but didn't think it would make enough difference but I am willing to try anything. As soon as my backs ok I will start experimenting again and let you know. John.
Sorry to harp on about the timing, but when you set the timing marks on the Electrex rotor and stator, what advance did you set it at? It may just be worth checking that the timing marks are still in the right place at 34 deg BTDC.
:)
You could always break all the conventional rules and time it fully retarded, About 1 degree past TDC. If it still kicks back its then definitely fuel.
Mike 8) 8) 8)
Hi Servodyne & Mike. The timing was set using the crankshaft locking tool to find TDC and a timing disc and pointer to set at 34 BTDC and the markers on the Elextrec lined up. The adjustment screw being bang in the middle. I have since retarded it as far as it will go on the adjustment slot to no avail. I will actually time it retarded as suggested and see what happens. My back is almost ok now so this weekend should see further investigation. Thank you all yet again for your tremendous help. John.
Hi John
The crankshaft locking tool sets the pistons at 34 deg BTDC. You should be able to set the markers on the electrex in this position.
If you are using a timing disc to further advance the electrex before setting the markers it will far too advanced.
Jim
Hi Servodyne - sorry I should have said I am going to set it with the locking tool I have just purchased. It was originaly set using a TDC tool through the plug hole. However I am glad you replied because I thought the crank tool did set it at TDC, wow that would have made it worse.
Hi all - I have now checked the timing with the crankshaft timing tool (arrived this morning) and while hoping beyond hope that I would find the timing was out by using this tool, IT WAS SPOT ON! So I am now more than ever thinking it is carb related and I have put a separate post on regarding which pancake air filters I should use, centre fixing or offset. Does anyone reading this know? Will keep you updated.
John.
:)
I expect that you will have already checked this but just in case: These symptoms will appear if you have any water in your petrol and they will also appear if you have oil in the fuel. Because oil has a much higher flash point than petrol it wont burn in a cold engine so will radically weaken the mixture. (2 strokes are designed around this feature)
Sorry to be boring.
Mike 8) 8) 8)
Mike - the last thing you are is boring, you have been very helpful to me over this problem. The petrol is brand new Esso premium brand who everyone seems to think as well as being higher octane, it has no ethanol. So no problem there I think. Between us all we will get to the bottom of this problem, this is what these forums are all about.
Regards John.
Sorry for the delay in progress but as soon as my back was better, I have now got bloody flu!
John.
At last I am reasonably fit again. So finally fitted the air filters and as previously mentioned I have fitted a choke and upped the size of pilot jets. As long as I don't touch the throttle the bike now starts instantly on tickover and sounds lovely. As long as it rides ok (after I have painted the tank and side panels) that will do for me, so I am not going to risk a bad ankle by trying to start it with a whiff of throttle, just for the sake of it (unless I get braver at a later date).
Again thanks for all your input, it was much appreciated.
John.
:) :)
Sounds good to me and very pleased for you. Incidently I always try to set that side of things up so that it starts with the throttle fully closed.
Mike 8) 8) 8)
Hi all - been out and done a few miles. Fitted Air Filters and set up the carbs after I noticed it was misfiring slightly on the nearside. Contacted John Hill who kindly gave me the settings he used which included pilot one screw out. I screwed out the nearside pilot screw just half a turn more and the misfire stopped and it ticked over like a Swiss watch! It now starts every time on tickover so that will do for me. Incidently I said on my initial blog that I bought the bike off John Hill and doubted he had no trouble with it. THIS WAS A MISTAKE AS I BOUGHT IT OF SOMEONE WHO JOHN SOLD IT TO. I APOLOGISE TO JOHN FOR THIS MISTAKE.
John.
I am in the same position with my A65, timing seem correct on Electrix ignition, I have battery eliminator so no battery either. What ever I do with the timing it just kicks back and snorts and that's it I can't even start it. It has 2 new Carbs on it but pre rebuild it did run on them.
Valve timing, tappet clearances all look good, has new fuel (E5) just went start :(
Quote from: Paxo on 08 Aug, 2023, 09:37
I am in the same position with my A65, timing seem correct on Electrix ignition, I have battery eliminator so no battery either. What ever I do with the timing it just kicks back and snorts and that's it I can't even start it. It has 2 new Carbs on it but pre rebuild it did run on them.
Valve timing, tappet clearances all look good, has new fuel (E5) just went start :(
you might be better srarting a new topic as few people (myself included) are not going to ready a 4 year old post. Sorry if this doesn't sound helpful, but it should hopefully gain you more people trying to help with your question.
Regarding the electrix world, I fitted one for a friend under their request, it ran like a bag of spanners, blued the exhaust up instantly and retarded the ignition by a LOT (when checked with a strobe light). This was on a bantam and sold as fixed timing.
Personally I would ditch the P.O.S, obtain a boyer, trispark, pazon etc, get yourself a nice boyer powerbox and you can run that with your original stator and continue to be batteryless.
I know this is an old post, but still relevent for people who search for A65 kick back issues.
I had the same problem and the cause is the Electrex self-generating ignition. It's quite dangerous as the system is set at full advance unless the rotor is spinning at a certain rotational speed. Problem is, that rotational speed is not achieved when kicking over a high compression Spitfire engine, so you are effectively kicking the engine over at full ignition advance, hence the ankle-breaking kickback.
Like the OP, I checked everything ignition and fuel related until I discovered the problem. It's the same with big Norton twins, probably Triumphs too.
The only answer is to junk the Electrex World system as it is not fit for purpose on these bikes.
With my Hornet I switched to a small and light 6.5ah12v positive earth gel battery in conjunction with a Wassell VAPE electronic ignition and it starts easily every time with no risk of a kickback. The 6.5ah battery is probably okay for a long day out as a total loss system but I also fitted an alternator as I wanted to add a lighting system.
i had an a10 that was a bugger to start probably because of the auto pinion and kickbacked. my cure was hold the throttle open slightly using the throttle friction bolt then release it when the engine would tick over without cutting out. after about 1/4 mile. a rich choke might have the same effect.
Quote from: Caulky on 15 Feb, 2019, 10:08
Are the float levels set-up to 0.080" below the cusp?
Easy to adjust with 'stay up' floats.
The method you are showing there is for the fuel level which is the preferred way of setting the fuel height and is the ONLY way of adjusting the black stay-up floats.
Fuel level should be set to about 0.210" +/- 0.030"
The 0.080" was the float height where the top of the old white plastic float was that distance from the top of the bowl... not the fuel level.
.................................
I will add though, if its kicking back when you are opening the throttle - more than just taking up the slack then its most likely that the mixture is too lean. correct use of chokes and flooding of the carbs is the way forward, as well as proper setting of the pilot mixture.