1966AJS 250 CSR WEAK SPARK

[Duncan]

Another silly question is the voltage of the coil the same as the bike (i.e. not a 12V coil on a 6V system)?

[itma]

No, connecting the coil leads wrongly, will give a spark of sorts, but give the symptoms you describe, sort of like running with the choke on, and erratic.
also acts similar to a duff condenser, or a condenser wired to the wrong side of the coil, thus negating its effect
This is a lesson I learnt hard the hard way at 17, when one of the barstewards I worked with played this trick on me at work, took me 3 days to find out, and a long push home.

why would it demagnetise the alternator rotor?
and its the work of 5 mins to try.Edited by - itma on 30 Jun 2007 11:06:20 AM

[bag-o-nails]

ok hear goes the coil is 6 volt and new
the manual i have states if the polarity is reversed it could demagnatise the rotor magnets
and could short circuit the coil to earth causeing an open circuit to the battery

But if you think it's OK I will try it
thanks again Phill

[itma]

Whats the manual? new one on me.
if unsure double check,
the coil will be marked sw=switch or cb=contact breaker, or - or +
on a positive earth machine the lead to the contact breaker should be the + side

[TommoT]

...to me it still sounds like a duff condenser. The new one is not a "new-old-stock" item, is it? Because an old Lucas condenser from the 60ies could very well be without effect today. If it is in fact an N.O.S item, replace with modern and more effective condenser.

[bag-o-nails]

thank you very much gentlemen and tommot of course!! i will have another go before throwing in the towel and off to kettering
i

[chris kelly]

Hi,

I used to have a 1966 AJS CSR.

Maybe, experiment across the range of recommended plugs for the Model range and see what happens.

I found my bike ran best on FE 80 . Actually, the 1965, 66 engine should have the FE220 which is for the faster, more Sports Model, as described.

But then, engines get old etc and the type of riding you actually do, fast or not so fast and whether you are in town always stopping for traffic lights etc.

I had a lot of professional work on my engine but the engine liked the "wrong plug".

Your engine should have.....

FE220.....or Modern NGK B9ES....or Champion N2.

So, the earlier models were ascribed....

FE 80...or Modern B7ES......or Champion N3.

See what happens.

Best wishes, Chris.

[bag-o-nails]

HI Chris

How long did you have the bike and was it reliable? do you have any pic's
i have been trying for quite a while to sort
the bike
the FE220 sounds interesting i did try a champion N2 but there was problem ethier
the inlet valve or the piston hit the plug and closed the gap!
just a thought when did you sell the bike
my reg GTV 949D

Cheers phil

my cat has gone to hide!

[chris kelly]

Hi Phil,
Had the bike about ten years. Will send you some pictures via my daughters computer in a few days.

It ended up really reliable.I did as much simple stuff as I could and had the engine rebuilt by a lad in the Club. Alph Bearings in Birmingham also did some work.Sold it about one year ago.Had to as I now live in a flat.

Just a thought..you say your compression ratio is 8.5 to I.
Your model should be 9,5 to I.
The earlier engines are described " Approximately 8 to I ".

Have you checked you engine number for the year of manufacture?

Sounds a bit strange with the Champion N2 plug not fitting..? subject to checking...all these plugs , for this Model range are Short Reach.

I think I would buy another condenser, just in case, work through everyones suggestions...and the best of luck.
Best wishes, Chris.

[Biscuit]

Short reach - never.