Hello all,

I recently got my first HD, an 84 FLHT with 15,000 miles,

I had a shade tree shovel mechanic attempt to get it road worthy, he replaced the coil (dated 1986), plugs,wires,starter relay,ignition module,circuit breaker, oil/filter, petcock,fuel filter and rebuilt the carb (Keihin)

anyhow

I can drive it, but it has a flat spot/break up/hesitation kinda around half throttle,

slow/idle good, full throttle better than half but still sputtery

I tried to choke it when it happens in case maybe it was lean, no help, worsened


curious if anyone knows a almost certainty (as much as internet symptoms can describe)

 

Hello and welcome to the forum!

You're gonna hear this a bit and it is not awesome advice but most people will say to change to a cv carb or an s&s super-e. To be honest I have zero experience with that stock carb. Tom84, Danflstc or John jz will bee able to help so be patient.

Welcome again,
Tom

 

If it is the stock carb from '86 then it is the butterfly Keihin carb and is considered by many to be junk.

Keihin also makes the cv (constant velocity) carb.

I personally like the S&S Super E.

 

When I took ownership of my 1989 FLHS it had the old style carb on it. I obtained a CV style manifold and evened up all the internal casting lines and steps, and leveled the inside surface with a uniform and slightly roughened surface (IE: NOT polished more of a matte surface.), and bought a CV style carb and gave it to my indy to tweak, install and fine tune.

It was a great mod, smoother and responsive all through the power band, no MPG penalty to speak of, just a better ride.

 

As stated before go CV or S&S, I've always gone with CV because they were cheaper than the S&S and I know CV carbs very well now, I had a CV on my Shovelhead and after tuning it to that Shovelhead it ran great.

 

Clean and rebuild the carb. Probably crap in the float bowl and jets.

 

+1 on this.
While you are in there, check what size jets it has in it. Too small of a slow speed jet can give mid range hiccups. The giveaway is if the idle mixture screw has to be more than about 1-3/4 turns out to give a smooth idle, you need a bigger slow jet.

Also check the accelerator pump diaphragm. They go crusty with age and mess with things. Ditto intake manifold seals.

A CV carb is maybe easier to live with, but the old Kehins work ok if set up right. Been running one on my Ironhead since 1977.

 

the mechanic had the carb apart more than once, told me accelerator pump was new and different size jets were tried

once my money seeds sprout I'll put something else on, I have a 3 piece intake, I guess shovel style?

so getting a complete set/kit will be ideal

thanks all

 

Your cheapest option is to get on e-bay and find the parts you need there.
You can probably get away for less than $100.

 

I think the older Kehein carbs had no accelerator pump just like the s&s super-b lacked one too.
I may be wrong here but that's why lots of Shovelhead guys go to the cv.