Can ignition timing jump out of sync VH

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ChrisNewton
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Can ignition timing jump out of sync VH

Postby ChrisNewton » Thu Jun 21, 2018 7:15 pm

Hi
rode my bike in to the garage a week ago - just went to to take her for a quick spin and wont start - kick back nearly took my leg off
it was running fine - question is could it jump out ?
had a few goes at kicking it over but bangs and smoke spitting out the carb has lead me to think its not just a hiccup...something is not right

i have read the guide to setting it up and have had to stop for my dinner ...wife's giving me earache...but quite life etc

so what do you think ... possible :?: or not?

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PeterW
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Re: Can ignition timing jump out of sync VH

Postby PeterW » Thu Jun 21, 2018 8:05 pm

Certainly could. Doesn't take long to check - but before you do - have you checked you have the ignition lever retarded?
Its easy to have it advanced by mistake particularly if swapping between bikes where the lever works the other way.
No that I've ever done it ahem.....

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chris.shearwood
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Re: Can ignition timing jump out of sync VH

Postby chris.shearwood » Thu Jun 21, 2018 8:05 pm

Yes, I think it is possible. The mag sprocket might have slipped on its taper when you tried to start the bike. Simple enough job to check the timing.
1946 4G, 1950 NG and 1951 VH

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paul.jameson
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Re: Can ignition timing jump out of sync VH

Postby paul.jameson » Thu Jun 21, 2018 8:48 pm

I was on my way to Scotland, about 1994, when the RH350 (as it was in those days) suddenly saw fit to misfire and then stop. Diagnosis revealed that the ignition timing had indeed slipped. I retimed the bike, made sure the mag sprocket was good and tight this time, popped the bike into gear and set off - only for the timing to slip again. So I retimed it, and this time made very sure that both mag and cam sprocket were very tight. Put the bike into gear and got about 10 yards before it all went wrong again.

The armature shaft had sheared where it goes into the brass casting which houses the windings. I hope yours hasn't done the same, but its easy to test. If you can turn the points carrier by hand (not spanner, because if its ok, a spanner will do damage) but if you can turn it with your fingers you have a similar problem.
Paul Jameson
36 4G, 37 VH, 53 ex ISDT KHA (project), 54 KH(A), Healey 1000/4 (project)
Former Machine Registrar & Archivist, General Secretary and Single Spares Organiser (over a 25 year period).
Now Archivist once more - but not Machine Registrar.

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ChrisNewton
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Re: Can ignition timing jump out of sync VH

Postby ChrisNewton » Thu Jun 21, 2018 9:53 pm

Gentleman

thanks for the rapid replies - it turns out that i have most of the kit required to check and reset the timing - which i've done 3 times - learning a bit more each time
i do not have a gadget with a light or sounder so i am using paper, Paul i can turn the points carrier with my hand once the sprocket is off the Mag which i assume is fine ?

i have gauged the stroke on compression with my finger over the spark plug hole then selected gear and moved the wheel the reverse direction causing the piston to go back down - now with the tdc gauge in i have it 1/2 inch before tdc.
now turning to the points i move the points carrier clockwise until the paper becomes loose then back and forth until its just dragging
i've set the back plate in the middle so i can advance or retard it a bit either way

i have not identified an easy way to set the points at 12 thou ? but they are opening because i have a fat spark albeit in the wrong time frame

so i should now be able to run the engine ...but it didn't ....so - tomorrow with fresh eyes i will try again ...any pointers will be gratefully received

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Re: Can ignition timing jump out of sync VH

Postby Brian_Walker » Thu Jun 21, 2018 10:30 pm

Cigarette paper makes a great gauge to check when the points just start to open, make sure you have moved you advance retard lever fully if you are setting at 1/2" BTDC. Bit hard to get the piston perfect TDC but you could try a short bit of wire down the plug hole and get someone to very slowly rotate the rear wheel backwards in high gear not first and follow the wire down 1/2".
If you want to remove the chaincase cover a print your own timing wheel can be downloaded from Brightsparks website.
1951-52 VCH under restoration

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alan.moore
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Re: Can ignition timing jump out of sync VH

Postby alan.moore » Thu Jun 21, 2018 10:31 pm

I think it is normal practice to set the timing at fully advanced on the lever. This allows you to get full retard for easier starting.
1939 VH Redhunter;1942 RN WNG;1951 Triumph 6T Thunderbird;1970 BSA B175 Bantam;1986 Yamaha SRX600 single
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ChrisNewton
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Re: Can ignition timing jump out of sync VH

Postby ChrisNewton » Thu Jun 21, 2018 10:34 pm

i have a tdc gauge so that bit is sorted
-my concern is now have i got the points gap right ? cant find anything on how to set them up

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Re: Can ignition timing jump out of sync VH

Postby ChrisNewton » Thu Jun 21, 2018 10:38 pm

alan.moore wrote:I think it is normal practice to set the timing at fully advanced on the lever. This allows you to get full retard for easier starting.



thanks i can do this tomorrow

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Re: Can ignition timing jump out of sync VH

Postby alan.moore » Thu Jun 21, 2018 10:57 pm

Chris,
Re setting the points gap the fixed point (i.e the one that is not the one on the spring steel arm) has two small nuts. The lower one is a locknut, the top one, when turned, moves the fixed point up or down.
Rotate the backplate until the points gap is at its widest point. Measure with a 12 thou feeler. If it needs adjusting slacken the lower locknut and screw the fixed point in or out to set the gap. Then holding that in place tighten the locknut.

Cheers
Alan
1939 VH Redhunter;1942 RN WNG;1951 Triumph 6T Thunderbird;1970 BSA B175 Bantam;1986 Yamaha SRX600 single
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