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REPETE'S XS650B Preservation Carburetor

Discussion in 'The Garage' started by REPETE, Oct 31, 2019.


    REPETE XS650 Enthusiast XS650.com Supporter

    I'll swing by the auto parts store on the way home and see if they've got the BP's in both 7 & 8.
    If they have both I'll switch over to the 8's immediately and use until the right carb lean condition is rectified.
    If they only have the 7's, I'll purchase and keep on hand for when the future use when right carb lean condition is rectified.
    I don't know if I'll be able to give it another run today but my priority will be to zero in on spraying down those shaft ends.
    Fingers crossed!

    gggGary likes this.
  2. gggGary

    gggGary Stop that! XS650.com Supporter Top Contributor

    I'd put in the BP7ES plugs now and do some trial runs.
    Last edited: Nov 21, 2019
  3. TwoManyXS1Bs

    TwoManyXS1Bs BBQ Hunter Top Contributor

    Were there any audible changes in the valve clatter between the "good" running and "bad" running?

    Thinking sticking valve(s)...
    gggGary likes this.

    REPETE XS650 Enthusiast XS650.com Supporter

    Good Morning gggGary & 2M -
    Some interesting and positive developments last night.

    gggGary - I stopped at the local auto parts store for the plugs. Naturally, they didn't have them. Our local auto parts store is a great place for air fresheners though!
    They're having them transferred from another store and I should have them today.
    I bought both BP7ES & BP8ES being that I have no history with this bike and don't know what it's going to react best to.
    They'll become a part of a test ride I'm hoping to do after work today.

    2M - I never thought to be listening specifically for valve noises. I'm sure that if a clatter developed beyond what I was used to hearing since the initial startup of the motor I would've noticed. But I'm also sure that I'm not good enough to notice a subtle improvement without it being my focus... especially if it were over a lengthy period of time.
    However, you might very well be on to something here!
    As you've seen, the motor (carburetor) started performing better after my 10 mile ride two days ago... and for no obvious reason.
    Last night I didn't ride the bike again, but what I did do was to get it warmed up and then began the leak detection process using the propane. And it turned up nothing.
    Then, still wanting to prove out beyond any doubt that there was or was not a leak, and because the "propane test" was new to me, I went back to spraying with the starter fluid. And it turned up nothing.
    However, as the bike was idling I sensed that it appeared to be smoother than when I started it and it was definitely smoother than in recent history. Any time that I "blipped" the throttle it reacted instantly & very smoothly. And most importantly it reacted the same if I just "blipped" the right carburetor. And no snap, crackle & pop!
    Just like after my ride of a couple of days ago the right carb seemed to be operating... but now even the exhaust tone was "better".
    I removed left plug wire and it was idling fine (but a bit fast) on the right cylinder only!!!
    So, I began the process (again) of alternating cylinder operation and adjusting the idle speeds of each carburetor.
    Left cylinder (which was never a problem) will idle at less than 1k without issue. I can get it down to about 800rpm.
    Right cylinder (the problem child) I couldn't get to idle at less than 1k without stalling.
    They are currently balanced as best I can get them and it sounds and reacts (while stationary) like a different machine.
    Operating on both carbs together it'll idle at a smooth 1500rpm.

    And now the most important thing....
    Now, I know this isn't the best test, but look at the plugs....


    Right cylinder for the first time in this journey is burning rich! I'll take it! I needed a battle win.
    So, being that there is no apparent reason as to why the carburetor is suddenly beginning to cooperate it may very well have been or is a stuck/lazy valve that is freeing itself up. Who knows? The bike did sit for over 20yrs.
    So, we have a (positively) developing story here.
    I'm anxious to pick up the new plugs and take the bike for a ride later today to see if this positive development sticks and/or continues to improve.

    TwoManyXS1Bs, grizld1 and gggGary like this.
  5. 5twins

    5twins XS650 Guru Top Contributor

    Yes, you'll need a ride to confirm things. If you used the choke to start the bike, that's why both plugs are black like that. It takes several miles of riding to burn them clean again. The #7 plugs will also help alleviate the dark color.
    gggGary likes this.
  6. grizld1

    grizld1 Grumpy old man Top Contributor

    Scratching my head over this one, wondering how a cylinder with a stuck valve could yield a 155 psi compression reading. Anyway, congrats--looks like your persistance is paying off!
    timbeck, TwoManyXS1Bs and gggGary like this.
  7. gggGary

    gggGary Stop that! XS650.com Supporter Top Contributor

    On wake up from the dead motors I tend to open the valve covers spray down inside the springs with rust buster, lots of plugs out cranking, squirt in oil repeat. Sticking (soon bent) valves are not rare on wake ups.
    TwoManyXS1Bs and grizld1 like this.

    REPETE XS650 Enthusiast XS650.com Supporter

    Well, the compression test wasn't done till just a couple of days ago. Right after the short trip to the DMV. It was crackling & popping on the way there and much lass on the way back. Maybe that trip got it moving?
    It's total speculation of course, but we've addressed practically everything.
    At this juncture I'm praying that whatever was/is going on is somehow going to be behind me.
    But, there's still a few bridges to cross.
    Tonight's test ride will hopefully reveal in what direction this is going to go.

    Team Junk, TwoManyXS1Bs and grizld1 like this.

    REPETE XS650 Enthusiast XS650.com Supporter

    gggGary likes this.
  10. REPETE

    REPETE XS650 Enthusiast XS650.com Supporter

    Hello All -
    Brief update:
    Got BP8ES Plugs yesterday.... 7's didn't show up. Later today hopefully.
    Used the BP8's and went for 10 mile test ride.
    The motor is running (in my estimation) beautifully.
    Idles, operates well at low speeds, accelerates well off idle and from speed, de-accelerates smoothly without surging, re-establishes idle and no snap, crackle and pop!
    This is huge (well, at least to me).
    Upon return I pulled the plugs. There's evidence of coloration developing, but what that coloration is going to be I can't yet tell. I can say that I'm pretty sure it's not going to be black (rich) and both plugs were essentially identical in whatever hint of color is developing.
    So, my plan is to move confidently ahead and put the air boxes and filters in place and then another - much longer - test ride.
    I'm hopeful this escapade is in it's final chapter and fine tuning is all that is left.
    So, not quite there yet and I will be reporting back.
    And once again.... thank you for all the support, guidance and advice.

    grizld1, gggGary and GLJ like this.
  11. 5twins

    5twins XS650 Guru Top Contributor

    Yes, sometimes it takes a few miles for all your changes and "fixes" to settle in. That seems to hold true for the advance rod greasing. It may be a bit sluggish at first with all the fresh grease packed in there, and can take a few miles of running to loosen up.
    JAX71224 and gggGary like this.
  12. REPETE

    REPETE XS650 Enthusiast XS650.com Supporter

    Hello Everybody!
    Belated Happy Thanksgiving & Happy Holidays to you all!
    Please know I didn't intend for an abrupt end of my communications.
    I was on vacation through the Thanksgiving week and was so busy there was just no good time to sit down at the computer and give an update.
    I did very little with it last week.
    The bike had been running so well at the garage I felt confident enough to take it for a longer test ride than the two ten mile loops I had previously done.
    I was figuring on a 35 mile loop I use for quick pleasure rides.
    Well, when I got 17 or so miles out it was running so good I decided to go a bit farther.
    And later on, I decided to go farther yet.
    I was having more fun than I've had in a long time.
    The sound of that twin is addictive!
    All in all, the "test ride" ended up being 120 miles.
    Upon return, I pulled the plugs.
    Left side looks as if it's developing a tan coloration, but still more clean than anything. I'm not going to make any adjustments on that carb for now.
    The right side (problem side) was very clean. I'd say lean. No snap, crackle or pop though. Motor continued to pull well from all speeds, run smoothly at lower rpm's and de-accelerated smoothly. Based on how it ran I wasn't expecting the plug to be lean.
    I've adjusted the mixture screw out just a bit and will try again soon. I'm guessing I'll be doing the trial & error thing for a bit.
    I'm anxious to finish it up but test riding after work is difficult because of early darkness.
    And my low beam blew during one of the test rides.

    grizld1, azman857, GLJ and 4 others like this.
  13. timbeck

    timbeck XS650 Junkie XS650.com Supporter

    Congrats on your 120 mile test ride, I knew you would persevere.
    Jim and gggGary like this.
  14. gggGary

    gggGary Stop that! XS650.com Supporter Top Contributor

    Sounds great! perhaps raise that needle a slot (or half a slot with a washer...)
    As good a check as any is fuel mileage. Most XS650 should get about 50MPG on the street.
    Good reminder that a voltmeter on board can save a lot of grief.
    Jim likes this.
  15. REPETE

    REPETE XS650 Enthusiast XS650.com Supporter

    Thank you Timbeck!

    gggGary - Did you mean Voltage Regulator?
    Should I replace the original?
    Mike's XS has this....


    Looks like a "plug 'n play"

    I will be continuing to update as I do more test rides and dialing in.
    But given the early sunsets any substantial test rides will need to be on the weekends.

    Last edited: Dec 3, 2019
  16. gggGary

    gggGary Stop that! XS650.com Supporter Top Contributor

    If you have a voltmeter you will know how your voltage regulator is doing. Discreet digital voltmeters are near dime a dozen, these days most of the bikes I ride have one where I can see it. Most are all "you gotta ditch the mechanical regulator!" but I have done "just fine" for 10's of thousands of miles with mechanical regulators once properly set. (no big deal) Mechanical voltage regulators are more reliable than cheap solid state regulators..... No opinion on that mikes which might be a decent unit. :shrug:
    led indicators red.jpg
  17. 5twins

    5twins XS650 Guru Top Contributor

    Don't buy that MikesXS reg/rec unit, it's a blatant rip-off, as are pretty much all the aftermarket motorcycle specific reg/rec units. You can achieve the same results, maybe even better, using high quality low cost automotive regulators and a rectifier from the electronics world. Auto regulators can be had for between $10 and $30, a nice little rectifier for about $10. That's a big savings over the aftermarket bike units, many of which are full of cheap Chinese components anyway.

    Gary's right, the original mechanical regulator is a real tank and will probably continue to function indefinitely. Do check it's output though. Many seem to have lessened over the years and need an adjustment. Mine was only putting out peak voltage in the mid to high 13's. Ideally you want to see it around 14 or in the low 14's. This is revved to around 3K. Output will be lower at idle (around 12) because charging output is based on RPMs. Here's how to adjust the stock unit .....

    Rasputin, JAX71224 and gggGary like this.
  18. REPETE

    REPETE XS650 Enthusiast XS650.com Supporter

    gggGary - that is one very cool console! I will certainly consider a small digital such as that tucked away somewhere.

    In the interim, I'm hoping that the low beam issue is simply a case of "dying of natural causes" - that it simply aged out.
    I'll use the multi meter to take some readings.

    5T - fantastic instructional. Standing down on jumping the gun and buying solid state voodoo regulator.
    First, I'll explore what it is I'm dealing with.... if anything at all.
    Like I said, I'm hoping for simple dumb luck in that the low beam crossed over to the other side b/c it's time here was up! :laugh:

    gggGary likes this.
  19. REPETE

    REPETE XS650 Enthusiast XS650.com Supporter

    Monday Morning Check-in:

    Hello All.
    I'm just updating that progress in my tuning is moving in a positive direction.
    I don't need to bother anyone with any questions at this time.
    As suggested, I checked the voltage output at idle (12.89v) but failed to check it at a higher rpm.
    To replace the headlight I used a standard #6024 Sylvania Sealed Beam. And it was a freebie! I got the Information to use it right here on the site! What a wonderful resource! I just couldn't see laying out the high dollar amount being asked for OEM replacements. Down the road I'll look into the Halogen conversion.
    Also, as suggested, I shimmed the needles 1/2 a notch with some 3mm washers (I have these on the shelf b/c of my Enduros) and again adjusted the air/fuel mixture as best I could. The riding I'm doing is mostly at mid range throttle.
    On Saturday I took the XS for a 100+/- mile shakedown and It's running great. Upon my return I pulled the plugs and I believe I'm seeing a brown color developing on the insulator. The electrodes are basically clean and the outer most rim (base of the threaded body) is black.
    I'm going to try (more patiently) another go round of air/fuel mix adjusting and idle adjusting and then give it one more trial run.
    With some luck that should make this a successful and educational endeavor.
    I'm going to try and sneak out of work a little early one day this week so I can beat the traffic and early darkness. I'm getting anxious to wrap this up.
    TwoManyXS1Bs and gggGary like this.
  20. REPETE

    REPETE XS650 Enthusiast XS650.com Supporter

    Good Morning All,
    I am confident that this'll be my last post on the subject of my carburetors which evolved into more than I had anticipated. And ultimately, all for the good!
    I never did get to ride last week due to a lingering weather system that brought rain every afternoon. I finally got out yesterday.
    Take a look at the plugs.

    Right cylinder...

    Left cylinder...

    The right cylinder appears to be right about where I'd want it.
    The left is a bit rich and I'm thinking it's just a matter of some time and trial and error of mix screw adjustment to get it right.
    Also, I am still on the B8 plugs.... but I do (finally) have the B7's that were recommended. I'm figuring on getting that left carb dialed in to match the right and then switch over to the B7's to be able to monitor any changes. Basically working on one adjustment at a time.

    The bike is running fantastic! And I've got the collective guidance of everyone here that has taken the time to respond to my questions to thank. Also, I would especially like to thank (in no particular order) 5T, gggGary, Grizld1 and 2M. Two words come to my mind: Driving Force! Thank you guys so very much! I am making another donation to the site in the spirit of the patience and mentoring the four of you provided me.

    After the Holiday's I will begin another thread with some general questions about this XS.... just conversational stuff b/c as of now it is mechanically and electrically sound!

    Thanks again to All! :bow::bow:

    Rasputin likes this.

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