Topic: Power hesitation in first half of throttle

[dave500]

ive had a few 500s/550s,i dont buy the common flat spot #$%*.

In that case why not enlighten all of us with 550K's that are experiencing a flat spot in this rev range as to what we're doing wrong.
It certainly looks like a common problem to me as there are numerous posts about it here and elsewhere.

the flat spot has been exagerated by some,imagine back in the day you test ride a brand new one and you feel a flat spot,so you say i dont want this one ill try another,and they all have a horrible flat spot?most of these engines have been tampered with by now and they are much older aswell,the ethanol fuel you have dosent help any aswell.

[phil71]

There is no way honda sold a bike that left the showroom with a noticeable flat-spot. Keep troubleshooting.

[dave500]

how clean is your filter,its not over oiled and the flat feel is a slight over rich in that position?remove the filter and ride the bike to see what it does.

[DJ_AX]

My 550 is the same set up...
I've been fortunate I suppose but I haven't seen the so called flat spot.

The comment you made about it being RPM based and not really throttle position.. makes me think of the power band of the bike.
I rode my 750 for a few years before getting the 550. The 750 still pulls like a truck even at lower RPMs... the 550, as mentioned above, really comes alive over 4k RPM.. I find myself downshifting a lot more in rush hour traffic.

[lucky]

Stock air box....foam uni filter....new....and 4 into 1 exhaust....stock jetting

No wonder it won't run right.

FACTS: 1976 CB550K EDIT

Unifilters(pods).
4 into 1 Exhaust pipe.
100 main jet stock.
#38 pilot jet stock.
4th clip  position on the needle of the slide. Stock.
1.5 turns mixture. Stock

I would use:

105 main jets.
#40 pilot jets.
Mixture 1.75 turns

[Killer Canary]

Read closely Lucky:" foam Uni filter". Notice the lack of pluralisation. It's a drop-in replacement for the stock filter.

[lucky]

Read closely Lucky:" foam Uni filter". Notice the lack of pluralisation. It's a drop-in replacement for the stock filter.

 Got it. Thanks Killer Canary!

[crazypj]

The only real way to make it run as Honda designed it is to have it completely stock (including the exhaust system)
As most people have non stock exhausts, there can easily be a 'problem' that needs fixing, particulaly is most of your riding is in that rpm range.
 A change of gearing may be the most cost effective way of 'fixing' things

[Deltarider]

My experience with the socalled flat spot is like this. If I accelerate from standstill as fast as I can (shifting gears at around 9000 rpm) there is NO flat spot, not at all. It's just when I cruise at around 4 - 5000 rpm and then want to accelerate, there's not much life in the house. Maybe my definition of a flat spot is incorrect.

[BobbyR]

I have a 750 but have owned smaller bikes. When you say 4-5K I imagine you are in high gear. You are probably at the edge of the torque band. It may well be you are almost lugging the motor until you get it further into the torque band. Maybe your exhaust alters the bad a bit.
You report great WOT performance so your motor is not missing or starving for fuel. As mentioned earlier, around town, stay in a lower gear. With out hyper overdrive cars we are not used to engines reving at reasonable steady speeds.

[crazypj]

My experience with the socalled flat spot is like this. If I accelerate from standstill as fast as I can (shifting gears at 9200 rpm) there is NO flat spot, not at all. It's just when I cruise at around 4 - 5000 rpm and then want to accelerate, there's not life in the house. Maybe my definition of a flat spot is incorrect.

 Pretty well put, that's exactly how I remember it

[lucky]

If your bike is out of gear and at idle, and you give it a quick turn of the throttle it should not hesitate or bog down AT ALL.

This problem does have a remedy!!

You need to get the slide needle in the correct position.
It controls the throttle from 1/4-3/4 throttle.

You do not have to settle for poor throttle response.

[dave500]

hey lucky,even if you have a properly running tuned old honda snapping the throttle in neutral can give a big dead flat spot and the engine may even stall.

[crazypj]

Yep, the only time you'll have zero hesitation is if you have CV carbs or real small venturi size.
Air cannot move instantly