Author Topic: Difficult to start at my wits end  (Read 5196 times)

Offline BSA500

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Re: Difficult to start at my wits end
« Reply #30 on: 12.08. 2023 22:13 »
Thanks for he reply first like a that I had forgotten I had a SRM degree disc second new fuel 20 thou gap plug and non suspressed

1960 A7 (57 motor to SS spec)

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Re: Difficult to start at my wits end
« Reply #31 on: 12.08. 2023 22:37 »
As the title says. A7 built to Ss spec alloy head 1 inch etc. Now it's had a recent rebuild mainly new pitons rings magneto rebuild by Andrew at Priory magnetos all pretty standard stuff. Bear in mind I have owned this bike for 30 years and I have never had this much trouble starting her.
Now as it stands I have 150 psi on both cylinders beautiful sparks on brand new plugs all leads and picks brushes are new and tested.Carb is clean and no leaks or wear. When she does start and run she pulls well and strong,but it can take 20+ kicks to get there.
Could this just be the timing a touch out??.I have just never had this much trouble setting her up

Just my opinion but I have not found the timing to be critical to get right on the A10, a few degrees here and there does not affect performance much, and certainly will not affect starting where you have full retard anyway, either via the ATD or manual retard.

I know you know your bike well but for reliable starting mine needs 1/4 throttle and carb flooded with tickler and takes one or two kicks, it will start with little or no throttle but that will usually take quite a few kicks.

Sparkplugs seem to suffer from getting “wet” more easily nowadays (one urban myth says the porcelain insulator around the electrode is not polished anymore whereas it was on old plugs), but that may be BS) so I find if it doesn’t start after a few kicks it can then be a right  *problem* *problem* *problem* *problem* to start.

https://ngksparkplugs.com/en/resources/read-spark-plug
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Online sean

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Re: Difficult to start at my wits end
« Reply #32 on: 13.08. 2023 02:07 »
As the title says. A7 built to Ss spec alloy head 1 inch etc. Now it's had a recent rebuild mainly new pitons rings magneto rebuild by Andrew at Priory magnetos all pretty standard stuff. Bear in mind I have owned this bike for 30 years and I have never had this much trouble starting her.
Now as it stands I have 150 psi on both cylinders beautiful sparks on brand new plugs all leads and picks brushes are new and tested.Carb is clean and no leaks or wear. When she does start and run she pulls well and strong,but it can take 20+ kicks to get there.
Could this just be the timing a touch out??.I have just never had this much trouble setting her up
are the plugs wet after a couple of kicks with your normal starting procedure  ?

Offline BSA500

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Re: Difficult to start at my wits end
« Reply #33 on: 13.08. 2023 09:31 »
I am going to reset the timing using the degree wheel so it is spot on recheck everything that can be checked, valves ,done the carb,done fuel etc. I am not a great believer in the plug theory as long as they are not knock off and these are not. When it does manage o start it does run well. It is very confusing. Maybe it isn't a fan of the modern e10 all of a sudden,I know clutching at straws but that's the territory we are heading to

1960 A7 (57 motor to SS spec)

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Re: Difficult to start at my wits end
« Reply #34 on: 13.08. 2023 16:43 »
re new fuel
I know you said you have new fuel but all the symptoms you have can be the same with this E10.
 I work on a lot of small engines and the most common problem with non starts is the gas, people say I just put new gas in it but forget to mention its from a can that been sitting in their garage for months or who knows how long in the tank at the gas stn ethanol has a short shelf life .
first thing I do is go buy a few gallons of new gas and drain the carb then if it doesnt start I look for the problem ......not saying this is your problem but its a cheap option to replace the gas with new ...and at least eliminate that one off your list .
We used to be able to buy high test gas in Canada with no ethanol until this past year and thats all I would use in any engine with a carb , but now the green zealots have changed the rules and talking about e15 being the next phase .
good luck

Offline BSA500

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Re: Difficult to start at my wits end
« Reply #35 on: 13.08. 2023 17:21 »
OK applying a scientific approach a bit to this tried the old plugs in it,theory 4 plugs can't be wrong and same with all the plugs no change. The fuel in the tank was fresh on weds. So back to basics tomorrow retime the engine using the degree disc and see what happens if no joy drain down the tank and try high octane stuff just for fun

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Offline BSA500

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Re: Difficult to start at my wits end
« Reply #36 on: 13.08. 2023 17:28 »
Sorry I think I have asked this before has anyone got a copy of the instructions for the degree disc fron SRM  thanks

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Online chaterlea25

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Re: Difficult to start at my wits end
« Reply #37 on: 13.08. 2023 18:34 »
Hi 500,
Do what I suggested and see if the jet block is loose in the body
Or as RD suggested another carb

John
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Re: Difficult to start at my wits end
« Reply #38 on: 13.08. 2023 20:57 »
Sorry I think I have asked this before has anyone got a copy of the instructions for the degree disc fron SRM  thanks
G'day 500.
If you have an SRM cush nut the disc is held by two screws. If not under the nut. Wire pointer from a case hole and screw.
Find TDC and mark the disc, go 32 degrees clockwise from that and mark.
I prefer to use an external battery for the strobe/timing light. Hook it all up, start the motor (that's the fun bit). Good if you have a helper. Point light at pointer and see where the flash is, increase revs to 2000RPM and the flash should be at the 32 degree mark. Then let it drop to idle and the flash should be at about 10 degrees.
If she won't start take the plugs out, make sure their earthed to the motor. Get a mate to kick her over quickly while you watch for a flash and note were it is on the disc.
Cheers.
ps: Once you can eliminate timing we will go back to the carb thread. Once it's sorted I'll combine the two threads.
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Offline BSA500

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Re: Difficult to start at my wits end
« Reply #39 on: 15.08. 2023 13:08 »
Jet block is not loose, at the moment trying new fuel of the 99% grade to see if that improves things

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Offline BSA500

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Re: Difficult to start at my wits end
« Reply #40 on: 21.08. 2023 13:38 »
Update Andrew kindly leant me a spare mag she starts and runs rough for about ten seconds then violent backfires through the carb with flames sometimes and dies. Try to rev and nothing. Reflood to start and rinse and repeat. Timed with timing disc, checked over the carb all jets/pilot circuit clear float clear and not sticking etc. No visable air leaks. Going to try my mag again to see if anything changes maybe even trying a spare carb. Then if no joy small strip down and checl all settings valves/timings /clearances etc

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Offline CheeserBeezer

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Re: Difficult to start at my wits end
« Reply #41 on: 21.08. 2023 13:47 »
It would be a 'first' to have problems with two mags, but, as the one I've lent hasn't been used for a while, I wouldn't rule it out. Unfortunately, I didn't have a 'new' one on the shelf. Next step is to fit a mag which is currently working on another bike, e.g. off one of my bikes!

Offline Swarfcut

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Re: Difficult to start at my wits end
« Reply #42 on: 21.08. 2023 13:49 »
 It may start and run after a fashion, so fuel and sparks must be there. Whether enough and in the right place remains the enigma. I'd suspect the timing gears, make sure they are the right ones, set up by the book. Then retime the magneto and with good compression and good sparks if it still won't play the problem lies with the fuel system. Sheared keys  on crank and cam are rare but not unknown. Longstroke timing gears are identical in form, ( but note Longstroke has breather peg opposite keyway, offset on later engines) but timing marks are different.

 Swarfy.

Offline BSA500

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Re: Difficult to start at my wits end
« Reply #43 on: 21.08. 2023 16:35 »
Surely we can't be that unlucky *eek*

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Re: Difficult to start at my wits end
« Reply #44 on: 21.08. 2023 16:56 »
This has been my bike for 30years plus so no change or stopping of cam/idle gears I will check every thing just for sanity and due process but as Andrew says I probably swop back to my mag and send back his for him to check again for sanity and good pratice

1960 A7 (57 motor to SS spec)