86 - S/S Supertrapp - Carburetor problems?

[Signaller]

Good day all,
1.      Just got back from my trip up North. The bike is a dream except for... what I would think are some carburation problems. Issues as fol:

       a.   the #2 cylinder counting in from the left while sitting on the bike sometimes takes a short time longer to warm up to as hot as the others then the idle becomes much smoother.
       b.   once the motor is well warmed up and comes of the choke there is what sounds like "light popping" and becomes a little more pronounced when decelerating
       c.    at slow speeds (50 to 60 KPH) the engine seems to slightly surge at times. Its a little disconcerting.
     
2.    At highway speeds and acceleration everything seems to be smooth as silk. The bike seemed to beg me to take her to 150.. did I say that... What a machine.... (but without a firm baseline of what to expect my view could be skewed)

3.     Might I have both a coil and carburetor problem? The PO had put on a S/S SuperTrapp pipe and it has 23 disks. I don t know if he re-jetted the carbs. If not what would the count be for OEM jetting?

4.     Thank you for your time and patience.

P.S. Thanks for your help when I was in North Bay. Upon review I feel a little foolish with such a simple problem as that was.



Dan
     

[carsick]

1 a) mine does that too. I think it's a little leaner than the others due to crud in the idle circuit and or choke plunger. Are you checking the headpipes for heat? Any different color on #2?
  b) any exhaust leaks at the head or mid junction, cracks in pipe? My previous exhaust was doing that and when I changed it there were cracks at the header collector. It stopped popping with different non leaky pipes.
  c) lean? vacuum leaks at the intake boots, vac advance hose, or intake boot to head o-rings? What throttle opening is that at?
2) 150 kph? That's cruising speed, mustn't go slower. 150 MPH? Rock on dude, can't be running too poorly!
3) 23 discs? Holy cow. Not much backpressure there, could be causing a lean condition contributing to a, b, and c above. Is this a 4" single system? Pull out at least half of those and see if any symptoms change. Then send them to me because I only have 8, but she runs OK.

No such thing as a "simple problem" when the bike won't go. That starter button's a tricky one that the collective wisdom here nailed. I probably would have resorted to barbaric previous owner type fixes. Bravo to you for asking!
Doug

[Signaller]

Hey Doug,
      Thanks for getting back to me. Yes I checked the pipes for heat and the #2 does heat up after it warms up. There is no colour change to the pipe. I will have a look at the pipe for cracks, it would be a damn shame though, since they are Stainless Steal.
      I will also check for vacuum leaks. As far as "throttle opening" I cannot say. Its not much though.
     
      The most amazing thing about this bike at speed is... it wants more  . The sound of the engine is strong and uncomplaining. Like I said before its like having a mistress that the wife not only tolerates but invites for tea. (I'm guessing of course)

      I will take out half the disks as you suggested and see what happens. BTW it is a single system and I have 6 more disks in North Bay on an older 2 part system (aluminum canister that I'm not using any more) that fit as well. If you really want them I can send them your way?


Dan
     

[carsick]

    The most amazing thing about this mistress is she wants more . The sound of her is strong and uncomplaining. It's like having a wife that I'm not using any more. If you really want them I can send them your way?
Dan
     

Wow. Thanks for the offer but I've got all I can handle.
Does the aluminum Supertrapp use aluminum discs? I've seen a mismatch in 4" discs and I wonder if that's what it is.

[Signaller]

Right,
        Interesting quote from me . The disks for both systems are made exactly the same  4" and are not aluminum.
       
        At any rate i have to go to ground. Early day tomorrow. I have to check for some leaks.



Dan

         

[fj1250]

Most likely your #2 cylinder warm-up problem is the orofice in the float bowl where the enrichener circuit (choke circuit) picks up its fuel is clogged
It quite often goes unoticed during carb cleaning by the un-experienced.
There is a hole in the float bowl on an angle that connects to an upright hole that the enrichener circuit tube drops in to.
It has a restrictor jet at the bottom of the upright hole.
If you put carb cleaner in both and let it soak, sometimes it will come clean.
More often it requires a fine piece of stiff wire (like from a wire brush) held with a vise grip.
With a bit of fishing around, (form the upright orofice) the wire will unplug the jet.
This will end the dreaded "cold pipe" at start-up syndrome.
I'm in the middle of a set of carbs right now and will try to post some pics tonight to help make sense of this.

MC

[fj1250]

What kind of intake set-up are you running?
Stock airbox, stock filter, pod filters.
Makes a big  difference to the carb set-up.
the supertrapp with 23 discs will require some enrichening of the mid-range and main jet for best performance.

MC

[jvb_ca]

Hey Dan.
Sounds like it might be a good time to give your carbs a good cleaning. Once in there you can see exactly what the PO has put in there,if anything. A good cleaning and syncing and a good carb setup will really wake her up.
Some good info here, including my setup.(close to yours)

http://www.fjowners.com/index.php?topic=1974.0

cheers...Jake