1966AJS 250 CSR WEAK SPARK

bag-o-nails · Post by **bag-o-nails** » Thu Jul 12, 2007 12:24 pm

hi ken
carb for 250 376/99 CSR 389/82
bore1/1/16 bore1/1/8
slide3.1/2 slide3
pilot 25 pilot20
main180 main200

itma · Post by **itma** » Thu Jul 12, 2007 2:57 pm

whats 1/16 inch between friends?
All these years, I thought all that made it into a csr was the alloy guards!!!
your sooty plug problem is a fuel problem, however much fuel is there, its not being burnt; size of choke will not make such a difference as you are getting.
Many a herbert in the past would stick a bigger main jet in, in the misguided hope that it would make it go quicker; I would not think that two sizes up on the jet would give these problems.
I reckon you have something wrong in the way your carb is assembled.If your carb is flooding then look at the float needle assembly; favourite daft things I used to find, fibre washer under the needle housing, needle upside down, faulty float, wrong paper washer under the jet block, blocked internal passage ways, bent air control screw, or its seating damaged.If you have replaced any parts with new ones suspect those first

bag-o-nails · Post by **bag-o-nails** » Thu Jul 12, 2007 4:20 pm

the 250 has a compression ratio of8.5
the csr has a comp of 9.5
heavyweight forks and up graded front wheel
with an air scoope to cool the drum
also a duplex front chain
stronger main bearings
the clutch is the same as the 350
different cylinder head piston and valves which the book tell's me is interchangeable
with the 350 different gear ratio's and number of teeth on drive cogs and of course
the carb dif size and jets
which i purchased yesterday from s/cycles
£165.oo that is why i am sus about the head etc and still the problem is there thanks for your idea's i know it's getting boring
cheers phill

itma · Post by **itma** » Thu Jul 12, 2007 5:43 pm

Not boring, only me,
just don't get over excited about the csr bit if I were you..
I would still be suspicious of any new part supplied these days from anywhere, one of the reasons I won`t repair bikes for anyone any more is this very reason.
165£ for a carb!!!! I have had duff new carb parts from Surrey cycles, one of which was a float with a leak built in.
there is no quality control where these repro parts are made, thats why the Chinese are shooting the producers now
Telepathic diagnosis is difficult.
I'm convinced your problem will be something very simple.

bag-o-nails · Post by **bag-o-nails** » Sat Jul 14, 2007 8:41 am

the simple bit is probably me!!
with the new carb fitted the bike is now starting and running just needs fine tuning
and a small air leak on the manifold joint
can you recomend a compound that's fuel
reisistent almost there!!

itma · Post by **itma** » Sat Jul 14, 2007 11:55 am

i swear by hylomar or wellseal, strictly speaking grease ought to be enough