440 Too much gas

[Don O]

76 cyclone with a 440. one new cylinder, new rings, new seals, carb cleaned,fuel pump cleaned,complete kit, all jets as per book. This engine runs very rich, gas out the exhaust, airscrew has little effect.
I have checked timing and it is right on. Compression is good.
Replaced the stator as the low voltage coils were very weak, this did seem to make it sound better, run better but still too much gas. Replaced the pilot jet from a 20 to 17.5, still not good. Runs much better as it is running out of gas.
It starts great. What have I missed, done backwards or what?

Don O

[JDT]

Check your choke plunger and choke cable slack.

The choke may be struck on.

[Matt]

If you replaced the needle/seat in the carb, put the old ones back in and try. I had a new set from a carb kit that was incorrect and was letting fuel by when it shouldn't have.

[Don O]

I have checked the choke, slack in cable seems ok. I did not replace the needle and seat, thought they are ok.reset the float level some.
Considering trying the carb from my 340, idle and low speed should be near the same, is it worth the trouble?
would really appreciate some help on this.

Don

[harleysportster]

76 cyclone with a 440. one new cylinder, new rings, new seals, carb cleaned,fuel pump cleaned,complete kit, all jets as per book. This engine runs very rich, gas out the exhaust, airscrew has little effect.
I have checked timing and it is right on. Compression is good.
Replaced the stator as the low voltage coils were very weak, this did seem to make it sound better, run better but still too much gas. Replaced the pilot jet from a 20 to 17.5, still not good. Runs much better as it is running out of gas.
It starts great. What have I missed, done backwards or what?

Don O

What is your elevation and the temperture outside?

[Don O]

Elevation 1300-1400ft
Temp today is 5 degrees outside, in the garage warm. Compared to the 340 it smokes like crazy.
Maybe I should go outside and ride it.

Don

[harleysportster]

Are you sure it is firing on both cylinders?

[JDGuy]

This may not be your situation….but in general…. make sure needle/seats are sealing, no very minor debris in there, no very small stuff that’s very hard to see. Use a premium fuel filter to trap the small stuff. In my opinion, never use needle/seats from the aftermarket Taiwan rebuild kits, usually junk. Use only genuine Mikuni seats and better yet, genuine Mikuni with Viton tip. Good to replace the choke plungers. Rubber sealing area on plungers frequently hardens with age and takes a set which inhibits sealing. Replace them. Cheap way to minimize frustration. Make sure plungers are free in the carb bore.… Good luck.

[Don O]

It will run on either cylinder
Don

[nick80lf]

I check inlet needles with a Mityvac brake bleeder. When I have it apart I flip it over and press on the float arm gently to compress the needle pin half way then apply vacuum. Watch the vacuum gauge, it should not drop.

Also, you could have a pinhole in a float or the incorrect size of inlet needle. A lower number has a lower flow rate. Anyone know what size the cyclone came with when new (1.5?)?

[Don O]

Inlet needle seat is a .5 on this one. Do they come as a set?

Don

[harleysportster]

Yes, they come as a set, more than likely yours is a 1.5. I don't remember what should be in it. Did you install the small air jet in the bottom portion of the intake bore on the airbox side?

[Don O]

I had that out and yes it went back in
I did take it out and rode it some, seemed to work better in the colder air.
rerouted the ckoke cable past air tube, may have been pulling choke some.
Exhaust pipe was clean on the top part after ride, will check this more tomorrow.
Thanks for the help.

don