Amal Carb Setting

Blewbury · Post by **Blewbury** » Thu Jul 12, 2007 7:25 pm

My low mileage 650 CSR Twin still has the original carb. It has 389/49 stamped on the flange.
Problem: Plugs soot up easily, jerky running and impossible tickover.
Could it be rich mixture? The book says the needle suspending clip should be in the "4th hole" - is that the 4th hole from the bottom or top? Pilot jet mixture adjusting screw; in or out for weaker mixture?
What else should I look for?

TommoT · Post by **TommoT** » Thu Jul 12, 2007 11:55 pm

just a few comments, others will likely join in:

1. Counting notches on the needle is done from the top.
2. The idle mixture screw controls the amount of air added to the fuel. Screw in = richer, screw out = leaner. 1-½ turns out seems to be recommended as a starting point. Check out
http://www.hitchcocksmotorcycles.com for all the tips you'll ever need. Very important are the stages of tuning, be sure to understand these.
3. Yes, it does sound as if you're running rich, unless the soot is greasy and oily in which case you have oil entering the combustion chamber.
4. Causes could be: blocked air filter (if fitted), needle too high, air slide (throttle) cutout too small, too large main jet, inlet port obstructions, too high float level, sticking tickler, etc..
5. There is a saying that 50% of carburation problems turn out to be ignition related, i.e. spark plugs, ht leads, plug cap, etc., etc.. and the other way round.

Lets hear how it goes.

itma · Post by **itma** » Fri Jul 13, 2007 12:14 am

must be CSR sooty plug epidemic time.

Blewbury · Post by **Blewbury** » Fri Jul 13, 2007 12:59 am

Many thanks to you both. I will count the notches in the morning. Sparks? could be, but I now have a shed full of "used once"plugs covered in a sooty,not oily residue. (Had you noticed the shares in NGK have rocketed.) The bike has a recently serviced magneto; proper copper cored HT leads (not sootwicks) new pick up brushes and, as a temporary measure, no 5k ohm resistor plug caps. Incidently the plugs are NGK B9ES as a substitute for the KLG FE220 recomended in the owners handbook. Watch this space!

Don Madden · Post by **Don Madden** » Fri Jul 13, 2007 9:04 pm

B9ES plugs are a but cold, (soft?) for this engine. I used B8ES with good results in my G12CSR. Try a different plug.

Cheers, Don.

bag-o-nails · Post by **bag-o-nails** » Sat Jul 14, 2007 8:09 am

csr epidemic never!!
hello mick you may have seen i had all sorts of problems with my 250 csr i purchased a carb
from surrey cycles and a small book on tunning
it has great details on symptoms/cure's just the job TEL;01483 272328
cheers, Phill

Blewbury · Post by **Blewbury** » Mon Jul 16, 2007 12:13 am

Did you all see me start the bike up on your telivision sets? As a temporary measure I'm coming to you live, via laptop, in hiding from the neighbours, in a secret location in Kent. Aparently the interferance on the television was incredible. What with the new B8ES plugs as a try out (thanks Don) and the lack of supressor caps - WOW.
Now, back to the plot. Working my way through the sugestions of what I should do (that is, the more sensible ones); I looked at the tide mark inside the float chamber and yes! it was a bit high (about 1/16"). Is it that critical? Now, sometime back, I splashed out on a new "Viton tipped" float needle because they sounded sexy. All made of brass, it has now worn a nice dent in the soft copper tang on top of the copper float, causing it to shut off later and raise the fuel level. Having now filled the dent with even softer solder as a temporary measure, the level has dropped, and is the same level as the raised dot below the first letter M of aMal. ( I am one of those lucky ones with X-ray vision). Needless to say it still apears to run rich and soots my nice B8ES's up nicely.
Having exhausted the combined wisdom of all you good folk, I have "boxed up" the magneto for checking, as the sparks are definately not as good as they used to be. I shall continue the saga on it's return. - With supressor caps.
My thanks to all who have contacted me directly. Iwill, of course reply to you all when I get out of hiding!
My thanks to you all and, as I said before, Watch this space!

bag-o-nails · Post by **bag-o-nails** » Mon Jul 16, 2007 10:01 am

you did not mention if the bike was running
ok, then developed sooty plug syndrome
or if you replaced or rebuilt serviced then found
you had a problem i have exactly the same
problem even after fitting a new carb there is little or no improvement is the spark ok on a new or very clean plug what fuel do you use?

Blewbury · Post by **Blewbury** » Tue Jul 17, 2007 12:16 am

Perhaps I should have said earlier that the bike ran OK for 40+ years until the clatter of worn "ends" prompted a major engine overhaul.
The spark, as observed on a new or clean plug, (in the garage with the lights turned off) together with the audible "crack" of the spark jumping the gap is not as good as it used to be which is why I'm having the magneto serviced.
Fuel? I use the stuff they have the nerve to call petrol, the best or highest octane now available and, for sorting out this problem, I keep using it only fresh from the pump. (more than a month old and it goes into the lawnmower).

Merlin · Post by **Merlin** » Tue Jul 17, 2007 11:25 am

Ref old petrol, mine goes from one year to the next always leave the tank full over winter to limit rust,bike(G3LS for Alan) runs O.K.
Merlin.