sputter - sputter- then runs good...help

[harleydavid21]

Hi to all: I have a 1995 HD W/G, stock Evo, stock carb, drag pipes. When I go thru the gears, the bike runs fine, but when I really get on it, in any gear, it sputters, then seems to punch thru to high speed and no sputter.
I don't think the carb has been re jetted. (Just bought the bike about a month ago), I did put a big washer butterfly type in the end of each drag pipe to give it some back pressure.
Do any of you guys have any information that you could pass along? Maybe you had this problem at one time. What did you do to solve the problem?
Bike runs good, but sputters at high acceleration.
Any info would be appreciated.
David
1995 HD W/G

[Bigs]

Accelerator pump on carb might be bad.
  Bigs

[Rags722]

Check/replace the diaphram.  Sounds like it could be leaking.

[97dyna]

I had similar symptoms when I would try to run through the gears aggressively - slow through okay.  Full throttle - sputter, backed off throttle and rolled back on slow - ok.  My cam bearings where beginning to fail and had worn a collar on the cam.  Listen closely to the motor - pings, knocks, etc.  If you haven't changed the stock cam bearing - check it soon.   

[rigidthumper]

Wanna try a  $13 fix? Go to your nearest Drag Specialties dealer, and get DS-202018 baffles, and install em. Should smooth out what you are dealing with, and if the sound isn't what you want, then try cutting the baffles in half.
HTH
Robin

[MrClean]

Maybe a spark jump.  Start the bike at night and rev it and look for a spark jump from the plug wire.

[randallwhitman]

David.....Here's my guess:  when you gave those drag pipes some back pressure (assuming it was jetted correctly before), you made it run too rich.  Check your plugs, and I'll bet you need to lean up your low speed jet.  The hesitation is caused by the too rich overlap of the low and high speed jets.  Randy   

[Panzer]

       JETTING

[harleydavid21]

I have been told that it might also be carbon build up in the cylinders. And really hard riding, with rolled on fast accelaration will blow the carbon build up out.
Have any of you guys solved this problem this way?
Thanks for all the info.
David
1995 HD W/G evo

[quikbike]

I agree sounds rich

[randallwhitman]

David......I know a REAL motorhead (retired superbike racer and Ducati racer), and he calls that "rev-tuning".  In other words it doesn't do anything.  There are ways to remove carbon build up, but just nailing the throttle ain't one of them.  Randy   

[Panzer]

Quik.............I agree, to rich.
Say again...............JETTING
Explained like this:
If you punch and it "sputters" it can't drink the fuel fast enough and it coughs.
Yet when you roll on it easy it's ok, she drinks it all.

Putting it another way:Your eating lunch and four bikes roll up for your planned ride.
You gobble down lunch and choke and cough on it while running out the door to meet the guys.
You can only cram so much into the intake until it lets you know.......the "sputter" or the "cough".
                          Lean the mix.

[harleydavid21]

Lean the mix, does that mean "go with smaller jets?"

[harleydavid21]

If it is running too lean, do I need to put in smaller jets?
If it is running to rich, do I need to put in bigger jets?
I am confused: about running lean or rich.
Would someone explain this to me?
Thanks for all the advice.
David
1995 HD W/G

[Phu Cat]

If it's running to lean, that means there's not enough fuel, so you put in a half size larger jet.  If it's real bad, you may have to go up a full size.  I think you can still buy jets in half steps.  The number stamped on the jet will be small enough you'll probably will have to look at it with a magnifying glass in a lot of cases.  Last time I changed jets, they were about $3.

PC

[randallwhitman]

Because of the gear you installed in the pipes, the bike is too RICH.  To make it more lean, you install a lower number jet.  The number on the jet is the size of the "hole" that the gas passes through.  Let's all pass more gas!!!!   

[86fxwg]

Post 1, its eisyiest.Take the air cleaner of and make sure u have a squirt of fuel.Its simple.

Dave

[Panzer]

If it is running too lean, do I need to put in smaller jets?
If it is running to rich, do I need to put in bigger jets?
I am confused: about running lean or rich.
Would someone explain this to me?
Thanks for all the advice.
David
1995 HD W/G

Just the opposite of above Dave....Just the opposite.
Like this..........if to lean add more fuel by using a larger jet.
                     if to rich it needs less fuel by using a smaller jet.
That's carburetor jetting and you need to go leaner (smaller jet) just a bit.
If by chance you have an adjustable jet needle, that's the one you want to mess with.
Need more info, just ask, we can help one way or another.
Hope this helps ya Dave.

[harleydavid21]

1995 HD W/G sputters no more. Thanks guys for your advice and info. I put in larger jets in the carb. (Put in 48 main and 165) Now it does not sputter and runs out great. Now it accelerates great, just have to hold on tight.  I took the carb apart and cleaned it up good, cleaned and shined the slide, cut a little off the spring over the diaphram , put in new jets and new gaskets. Now it runs great.
Again thanks guys for your input.
David
95 HD W/G