1989 electra glide flhs with only 4000 miles on. I have been through the bike from end to end including new/cleaned/checked thoroughly carb and intake parts, new fuel and all the obvious stuff.
Starts, ticks over, runs, but does not like transition from no throttle to some throttle under load, its like its run out of fuel momentarily. From some throttle to more throttle is great. Revving in neutral is ok to, no hesitation.
Any ideas?

 

Is that the butterfly carb? Pull out the plug and richen out the idle mixture a tad. Also check the accelerater pump. Or pitch the thing and put an S&S or CV on it.

 

I had the same issue with my 89 when I first got it over ten years ago. The solution: replace that butterfly carb and the compliance fittings etc.. I chose a used CV as the easiest and least $ route. An instant and huge improvement.

 

Intake leak?

 

An 89 with 4k should have the tanks checked for crap getting into the bowl of the carb....

 

Still sounds like the accelerator pump. At least that's where I'd start looking.

 

Great find! If I owned that machine I'd **** can that carb and as the OP said, replace with an S&S. The Super E model would be a nice choice and great performance improvement over that Keihan. If your a 'purist' and want all original good luck deep cleaning. I never had much luck douching and rebuilding butterflies.

 

Many thanks for all your helpful comments.


Yep its the butterfly carb 27029-88 for the record, Dr Hess, and I have done as you suggested , removed the plug and started at 1/4 turn out from original, so its now one and a half turns out .Its pouring and 70mph winds so I will delay testing !
I have gone through the carb and replaced and/or checked everything, sonic cleaned as well, new intake fittings, all of which which improved it from being a non runner to where I am now. Fuel tank is now clean, pipes replaced, and accelerator pump jet sprays like a good'un from first throttle movement.
Its revving great in neutral, and when increasing throttle. Its from no throttle to some throttle under load that the long hesitation issue shows itself.
Its not the voes as I disconnected it , which the bike did not like at all, now reconnected.
Thanks again all.
I am happy to have rescued the bike from years of non use, and amazed at how well its responding to tlc. She who must be obeyed keeps reminding me that its getting there....

 

IM with redhogz put the S&S on my 86 ,never another problem in 20+ yrs