tuning my cv40

[someday69]

changed my exhaust to superT two into one...I changed the slow jet first,,,and I guess thats the wrong way to do it....but I went from a 46 to a 48...and the plugs went from white to pink esh tan....which is better I think,,,,next I wanted to change the 210 main to the 190,,,did that this evening,,,it's got the stock needle with two washers.....

    I rode 15miles and went wot from 65 to 80 then let off quick 1/4 trun,,,did it about 5 or six times,,,,did'nt seem to make it raise rpm,,,sure did'nt stumble...just made a different exhaust note....So I'll run a tank or two,,,see whats up with the mpg.....after the slow jet change I got better mpg.....
    I'll do a plug chop at wot tomorrow...see what I can see...
                       I'll get it as close as I can...by sop and save up for a dyno base run.....hopefully Bob will carve out some time for me...someday...

[Phu Cat]

Ya went up on the slow speed jet and down on the high speed?

Did ya hang on to your stock pipes?  Yer might be needin 'em.

PC

[Jeffd]

90% of the people who are running your set up get by with 45 or 46 slow, 190 main and n65c or N72S needle.  my 95" with 26G's and supertrapp 2:1 doherty ac etc is spot on with 46, 190 and N72S.  AFR at sea level was spot on as was it at 3300 feet per a 250i.

[someday69]

So I think with the 190main and two washers,,which is very close to the sportster needle,,,maybe alittle fatter even, cause of the two washers,,,,I'll be ok,,,I just did'nt want to leave the 210 main in there....It was runn'in hot with the 46,and the plugs looked white,,,,it cooled down with the 48 and the plugs looked pink/tan....I really can't tell till I get a base run on dyno..I guess....Maybe because I got the bigger valves it makes a difference.....the 510 cams are close to yours I think...thanks for the reply...

   What about the idle......I forgot how to do it....I got the knureled idle screw,,,I started with 2 1/2 turns out...and played with the big screw on the cable linkage....but I ain't got it right yet,,,,it seems to idle higher when hot....

[Jeffd]

you sure you are reading the right part of the plug?  You need a good magnifying glass and flash light to read it properly.  You also need to read the strap and the threads as well as deep down in the plug.

[crazycalvin]

Hey Someday, are you maybe referring to two different screws for the idle? One screw being for idle air mixture and the other screw for idle speed?  I think a carb bike will idle higher when warmed up than when cold.  This is how I would adjust those two screws:  first make sure the bike is good and warm ( so that it idles a little faster than what it did when it was cold - I would ride it for awhile to make sure that it is good and warm); if you have a tach, adjust idle speed so that it is around 1000 rpm to 1100 rpm.  If no tach then you will have to kind of listen to the sound and adjust it by sound.  Now slowly adjust the idle air mixture screw in until the idle changes; then slowly adjust idle air mixture screw out, the idle should become smoother and then should start becoming rougher or changing again.  Keep track of how far out you turned it.  You will now have a span of how far the idle air mixture screw was turned from lean to rich; you want to set the idle air mixture screw to the center of that span.  So this means that if you went in one turn from the original point and back out two turns, that you would have a span of two turns.  Half of two is one so adjust the idle air mixture screw back in one turn; quickly snap the throttle a couple of times and it should be crisp and return.  You can now shut off the bike and while counting how many turns, gently seat the idle air mixture screw and turn it right back out the same number of turns you just turned it in.  I personally feel that if you have it out somewhere 1 and  3/4 turns to 2 and 1/4 turns you probably have it set pretty close.  If you have to vary from 2 turns out by more than a 1/2 a turn either way, you might need to look at making other adjustments or repairs.  While this method is not perfect, it has worked for me.  Hope this helps.  Later, Calvin.