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Hello, I seem to need some advice

Discussion in 'The Garage' started by HOTEL71, Jun 12, 2021.

  1. HOTEL71

    HOTEL71 XS650 Enthusiast

    I'm running this head-pipe (pic #1)
    with these baffles. (Pic #2)

    When I i had just the pipes, without baffles,
    she ran hot, as I could feel the heat on my legs
    and the top of my motor was hot to the touch
    (ran a total of 6 miles this way)

    Then I purchased and
    inserted baffles, The heat on my legs is gone
    and heat seems to be way down on top of motor.

    the plugs are black
    and I removed one baffle and it too was black

    **I had the carbs done and requested the carbs be jetted to run with
    just pipes no baffles (I wanted the loud sound.LOL)
    and I am running stock airboxes with new filters

    can I just re-jet the carbs to fix this? or
    longer pipes and mufflers inevitable?

    Thanks in advance

    Attached Files:

    gggGary likes this.
  2. Downeaster

    Downeaster Everything in XS Top Contributor

    Yes, it's most likely a jetting issue.
  3. Jan_P

    Jan_P XS650 Junkie Top Contributor

    Black inside Exhaust is normal
    Black plugs is more or less normal A little brown is better.
    Perhaps you know there is a correct procedure inspecting the plugs.
    Be careful changing in the carburetor I know of one Experienced + 20 years man that got it wrong --To lean
    And Overheated. --- Causing a major breakdown .
    I don't think he ever got the setting right.
    Changes overlap in Pilot / Main / Needle / Idle
    Here are experts so if you post what jetting and carburetors you have I believe that they can tell
    What jetting can be a good starting point .
    But for the moment don't run hot aka without baffles .Ending up Taking the Bus ride Home.
    HOTEL71 likes this.
  4. stinky78

    stinky78 XS650 Addict

    how old is the motor? as in has it been rebuilt?
  5. X77S

    X77S Let's do this!

    I would think headers and baffles would still be quite loud. I agree it's a jetting issue. Its probably super lean with no mufflers or baffles.
  6. HOTEL71

    HOTEL71 XS650 Enthusiast

    no stock 81 with 2k original on the clock
    gggGary likes this.
  7. stinky78

    stinky78 XS650 Addict

    the heat thing makes it sound like it’s running lean, the fact it’s never been rebuilt and the plugs are sooty could mean the valve seals are leaking, does it smoke on start up?
    gggGary likes this.
  8. OHRider

    OHRider XS650 Addict XS650.com Supporter

    Are the plugs wet Black = Oil
    Are the plugs dry Black = jetting
    blkgld and gggGary like this.
  9. gggGary

    gggGary On the road of life I'm a speed bump. XS650.com Supporter Top Contributor

    You have probably gone from one extreme to another.
    Most motors need a muffler to run their best with the factory cam.
    Exhaust, cam, valve geometry, is complicated and the result of high level engineering. Straight pipes and the XS650 head design will result in some of the charge getting pulled right through the head and burning in the top of the exhaust header. The pipe length and muffler design on good systems act to keep the charge pull through "just right" so it gets pulled into the head and stays there til the exhaust valve closes.
    It sounds like you have gone from a "too strong" pipe to one that is overly restrictive with the baffles in a small diameter pipe. So now the engine is not breathing well and some exhaust remains in the cylinder on each combustion cycle. The best answer is a well designed muffler(s) that will not only improve exhaust "tone" but help the motor make more power.
    An example of a powerful well designed muffler/exhaust.
    Borla detail.jpg
    Last edited: Jun 13, 2021
    Mailman, Jan_P, grizld1 and 2 others like this.
  10. grizld1

    grizld1 Grumpy old man Top Contributor

    +1! Bottom line, El Kabong: Those straight pipes are going to narrow the power band, with or without baffles, and the baffles are going to strangle the motor, with or without jetting changes. Yes, you can get the motor to run on that setup with jetting changes, but it won't run optimally. You can have good performance or you can cripple your motor and try for "the look," it's your choice.

    That takes care of the muffler question. Now for your question re. length. The convention is to specify pipe length as the distance from the exhaust valve face to pipe outlet as measured on the center line. That's a somewhat tricky measurement to take, but here's some good news. First, on a street motor, anything from around 34" to 40" will work just fine. Second, if you want to get all AR over length, there's an easy shortcut measurement that Michael "Mercury" Morse worked out. The distance from cylinder head to pipe outlet measured on the outside line of the pipe is approximately equal to valve-to-outlet center line measurement.

    Don't bother looking for the muffs shown in Gary's post; those are Borlas, very expensive even when they were available, currently pure unobtainium. Gary just dangled that damn pic to make us jealous. There are plenty of affordable options out there. I like the Emgo short megaphone mufflers. They're very inexpensive and just need more fiberglass than Emgo uses. If you use real muffler glass and not the cheapest thing you can find, it will hold up for a very long time.
    HOTEL71, Mailman, Jan_P and 3 others like this.
  11. gggGary

    gggGary On the road of life I'm a speed bump. XS650.com Supporter Top Contributor

    Can't get ANYTHING past the Griz!
    Mailman likes this.
  12. nj1639

    nj1639 Paleo-simplistic Top Contributor

    I've mostly given up on second guessing those 1970's Saki drinking slide-rule engineers from Japan some years ago.......
    gggGary likes this.
  13. kopcicle

    kopcicle antidisestablishmentarian

    I found them much easier to contemplate if you just drink the Saki.
    If you can't beat em .....
    timbeck, nj1639, GLJ and 1 other person like this.
  14. Jan_P

    Jan_P XS650 Junkie Top Contributor

    I once read in a magazine that on older Harley Models ( Was many years ago I read it ) i believe pre evolution engine
    That when installing straight pipes longer than these here mentioned the Torque was lost
    One trick mentioned there was to install a circular disc at the end of the pipe
    with an axle .locked with nuts on the outside.
    When turning that circular disc More or less pressure inside the pipe could be created
    Restricting the flow.
    And some testing done out on the road.
    Not done it myself
    I remember that the length was a factor . A pressure wave bouncing back from the end that had an optimum
    length hitting back to the cylinder head Affecting the flushing in new and out.the old
    As Gary mention in # 9 This is more or less " Rocket Science "
    The slide ruler Japanese has most likely done a lot of testing and over the years refined the exhaust.
    So it can take a while to get it right . If changing If ever ..
    gggGary and nj1639 like this.
  15. kopcicle

    kopcicle antidisestablishmentarian

    I agree with a few small reservations. Well thought out baffles in a pipe outwardly appearing to be a straight pipe can work.

    I'll gladly explain in PM but because the me-to, wanna be cool, sawzall wizards can see this I'll just say it's not just a bad idea it's the worst idea to run straight pipes.
    Last edited: Jun 13, 2021
    HOTEL71, gggGary and Jan_P like this.
  16. kopcicle

    kopcicle antidisestablishmentarian

    While we're here I'll show my age a bit
    Snuff_or_notts.jpg Snuff_or_notts_install.jpg.jpg

    This was actually a recommended tuning aid for the CB/CL77 (Super Hawk) big bore kits.
    It surfaced again with the CB/CL350 347cc kit
    HOTEL71, gggGary, X77S and 1 other person like this.
  17. X77S

    X77S Let's do this!

    Commonly referred to as "lollipops". I made my own with washers and all thread rod and a couple nuts. This was on a 2004 883 sportster with drag pipes. It helped make things less erratic. It ran great so long as you were WOT, not so much anywhere else. I was constantly adjusting the mixture screw (Mikuni HSR 42 carb) until I installed the Lollipops and then it was able to run pretty decent around town.
    HOTEL71 and gggGary like this.
  18. gggGary

    gggGary On the road of life I'm a speed bump. XS650.com Supporter Top Contributor

    Yupper some of the "rocket science" :wink2:
    Prolly better "Sonic Science"
    GLJ, Jan_P and HOTEL71 like this.
  19. Grimly

    Grimly XS650 Addict Top Contributor

    When I fitted a pair of Dyna mufflers to my XJ, I discovered that H-D had a baffle differently distanced in each muffler, which made them an uneven match on the four-cylinder engine. I removed the factory blanking plates and inserted a long length of 6mm studding down each hole with a 20mm (or so) washer double-nutted onto the end. by making a bracket up at the end of the pipes, I was able to insert or retract the new baffle washer and eventually position it right for each pair of cylinders.
    It worked quite well, but looks a bit ugly. Some day, I'll tidy up the bracketry and neaten the installation.
    gggGary likes this.
  20. HOTEL71

    HOTEL71 XS650 Enthusiast

    removed baffles added slip ons..
    seems to have worked better with the longer pipes

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