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Good morning from Portugal,

I am currently doing a restoration on a 1960 250 Clipper, and im having problem in getting it to run after the engine overhaul!!

Before dismantling the engine, the bike ran, with problems with the clutch and gear box, and had several oil leaks from the seals and gaskets,
we´ve ordered all the gaskets, oil seals, bearings, timing chains and clutch disks from Hitchcock´s.
the engine was washed from all the sludge from the inside, all bearings, bushings, o-rings and oil seals were replaced.

Besides having the workshop manual, parts list book and instruction book i also took pictures while i was dissassembling the motor, just to make sure every thing was assembled corretcly.

That being said, now with every thing assembled, the bike wont start, i´ve checked again the valve clearence, the timing points, the contact breaker clearence and cleaned the contact point with a 1000grit sand paper, the carb was totally rebuilt(before dismantling the engine), the engine compression is 120PSI.

there is a nice blue spark at the spark plug, it has gas and compression but it won´t start, and after a few timings at "kicking" it, it backfires!!

I´m starting to thing it may be a problem in the contact breaker´s capacitor... or maybe after cleaning all the eletrical with contact cleaner something got damaged and isn´t giving the corret values, besides this is a very simple eletrical components, but is over 60 years old.

Did any one had this happens or know any solutions... i´ve even got the Lucas Motorcycle Eletrical Equipment service manual, but it also doesn´t have resistance values or any values for my to test the parts to be sure that they are defective,

Sorry for the long post, and thanks in advance for any help what so ever.

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The 1st thing you'd do with a case like this is to put a thumb over the empty spark plug hole -
and when you kick it over you can feel the suck-compression-bang-blow of the 4 strokes.
In the correct sequence !

And then watch that the spark happens on/near the top of the compression stroke.
It sounds a bit like the spark is happening on the wrong stroke. ?
Can you check/double check/triple check that its happening in the right place. ?

And 2nd, since 99% of electrical problems are carby related (!!), have you tried tipping a
spoonful of petrol down the spark plug hole and then trying to start it.
If you get a (brief) burst of life, then you know its carburettor ...

Have fun, keep us informed.

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I'd agree with Rohan, you're timing is probably off...but how it's off, is the question.
Since your motor is points and coil rather than magneto, the easiest thing to do is to slowly rotate the points plate and try starting it each time you move it.
It shouldn't take much, maybe a few degrees one way or the other.
But if that doesn't help, then the possibility exists that since you had the motor completely apart, you may not have the cam timing quite right.
I believe these motors drive the points off the end of the cam and the cam is driven via chain off the crank ?
There's timing marks on the associated components and it's quite possible your cam sprocket is off a tooth one way or the other.
Of course, if you have access to a new capacitor..by all means put it in to eliminate that possibility.
But if you are seeing a good spark, I don't think the capacitor is bad.
Keep us posted.
Boa Sorte !


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[quote=Rohan

And then watch that the spark happens on/near the top of the compression stroke.
It sounds a bit like the spark is happening on the wrong stroke. ?
Can you check/double check/triple check that its happening in the right place. ?

[/quote]

Yes, i´ve triple checked it, even removed the valve cover and rotated the engine by hand slowly to check just that and it´s al correct.

the timing is in the same place as it was, i marked it before taking it apart, so it would be easier to time it apon assembly.

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Originally Posted by oilyamerican
I'd agree with Rohan, you're timing is probably off...but how it's off, is the question.
Since your motor is points and coil rather than magneto, the easiest thing to do is to slowly rotate the points plate and try starting it each time you move it.
It shouldn't take much, maybe a few degrees one way or the other.
But if that doesn't help, then the possibility exists that since you had the motor completely apart, you may not have the cam timing quite right.
I believe these motors drive the points off the end of the cam and the cam is driven via chain off the crank ?
There's timing marks on the associated components and it's quite possible your cam sprocket is off a tooth one way or the other.

The timing points of the engine was one the first things i checked. And when i was closing the engine i triple checked every thing just to make sure it was all OK.

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Going to do a checkup on every point again, just to be sure, and try again...
this mornig the new 6v battery is dead (strange), just going to let it charge and try again later.

Thanks to all your help, i´ll keep you posted.

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Originally Posted by Motomaniacs
this mornig the new 6v battery is dead (strange), just going to let it charge and try again later.

That sounds like the power can escape someplace - even switched off.
You may want to explore that, it may indicate the points aren't pointing or electric-ing quite like they should ?
Which might explain the spark not being quite what it should be ?

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Originally Posted by Motomaniacs
Going to do a checkup on every point again, just to be sure, and try again...
this mornig the new 6v battery is dead (strange), just going to let it charge and try again later.
.

Strange indeed, you must have a short in your wiring somewhere...
Perhaps for the sake of just starting the motor, you can rig a temporary power supply that is completely isolated from the wiring harness ?


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High resistance shorts to ground plague my '66 GT. If it even sniffs a puddle on the road it can misfire. It is harder for a spark to jump the plug gap under compression than it is in open air, so spark check can mislead. I am suspicious of the inner workings of the light and ignition switches. The GT is later and uses different light and ignition switches than a 1960 Clipper, but worth isolating. Try disconnecting battery and coil from the wiring harness, then connect battery to coil and points with jumpers, so they are the only things in the system.
I once found a set of points with a flawed nylon bushing in the points pivot. Engine started and run until I started up hills. Extra compression from the effort made the points pivot the easiest electrical path.

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Status update:

The battery situaton was resolved(My bad, left the key turned on and the presence lights over night...), even so i disconected the eletrical system, only the engine has power.

The bike wont start, it just back fires from the carburetor.

I´ve already taken the left engine cover off and took everything apart and triple checked everything to make sure that the points are correct, and had a colegue triple check everything as well.

Took the cylider head off and grinded in the valves(again) just to be sure, when reassembling the engine i let the valve gap a little bigger, just to make sure it was properly closed,when doing that i realised that the rocker from the admission side didn´t move as freely as the exhaust side, after analising it i noticed that the rocker housing was a little of, the top wasn´t flush with the bottom,

[img]https://ibb.co/G2G0xqx[/img]

and after further inspetion i also found out that they dont match...

[img]https://ibb.co/F7chf1F[/img]

after seeing this i putted valve grinding pste in the rocker and housing and rotated to see where it rubed on and noticed tha the bottom side it only touched in the center

[img]https://ibb.co/DVbFr6t[/img]

and filed and polished the sides so that the rocker would be loose and with no friction

[img]https://ibb.co/WxV1Rhv[/img]

After this the rocker moves freely

when rotating the engine by hand, the spark only hapens when the valve is fully closed and with clearence. but when you kickit to start it back fires from the carbureteur...

I´ve already tried to rotated the ignition cam, it started to back fire from the exhaust, but and the wrong stroke....

This bike was running before it was taken apart to change the seals and gaskets, and now it has everything to work and it doens´t want...

i´ve read the Workshop manual and Instructions manual front to back, just to make sure i didn´t miss anything, and everything´s "correct"( if it was correct it would start...)

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Originally Posted by Motomaniacs
when rotating the engine by hand, the spark only hapens when the valve is fully closed and with clearence. but when you kickit to start it back fires from the carbureteur...

Have you removed the spark plug, and rotated the engine with the kickstart.
And with your thumb over the plughole, verified that you are getting suck-squeeze-bang!-blow
And further, watched that the spark is happening just before tdc on the compression (squeeze) stroke.

Now obviously we cannot see what you have done, but confirming these basics is a good start.

It does sound a bit/lot like it is firing on the wrong stroke, 180 degrees out ?
If it was a twin you swap the magneto leads over - but its not a twin, and you don't have a magneto !

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P.S. Did you time it with the advance locked to full advance, so the spark occurs the specified say 1/4" btdc.
I'm guessing the 1/4", but it will be something like that.

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FWIW, here's a link to a page from the factory shop(?) manual....

https://www.manualslib.com/manual/1209562/Royal-Enfield-Crusader-250.html?page=25


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Thats an interesting procedure for setting the timing.

We wonder if you can strobe it, to verify the timing is actually advancing with revs.
And to where it should be, fully advanced ...


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