Honda SL350 - no start questions

Discussion in 'Old's Cool' started by cptmoney, Sep 1, 2013.

  1. cptmoney

    cptmoney Two wheels, only one seat

    Joined:
    Nov 1, 2007
    Oddometer:
    574
    Location:
    Western Slope, CO
    So I've got an old SL350 I'm trying to get running, but I've got a few questions...

    It's not currently running. The PO said it needed points, which he had but had not installed. No problem, right?

    I tested for spark - and sure enough, nothing. OK - in go the points. Spark is good.

    Bike still won't fire up.

    A quick compression test reveals low numbers - 90 psi on it's own, as much as 115 with a spoonful of oil down the cyls.

    I also adjusted the valves, with a cold bike (gotta be cold - it won't start!).

    Recheck compression - still 90ish, and up to 115 with oil added.

    Those figures are low, I realize that. Are they "there's no way it will start" low?

    Any input on this one? Is this a set of rings, at the very least? Or maybe a head gasket - or both? You wouldn't do one without the other...I got that. Prob have to just pull the head to get an idea of what all is going on in there first, yeah?
    #1
  2. NJ-Brett

    NJ-Brett Brett

    Joined:
    Sep 8, 2010
    Oddometer:
    6,911
    Location:
    Southern New Jersey
    It should start, and do not worry about the compression till its running, things might need to seat after sitting.
    Check that the timing is right, that you have spark on the compression stokes.
    If you are off, you will get spark on the exhaust stoke.
    #2
  3. cptmoney

    cptmoney Two wheels, only one seat

    Joined:
    Nov 1, 2007
    Oddometer:
    574
    Location:
    Western Slope, CO
    Thanks for the quick reply, NJ-Brett -

    So.....I have a question about the timing:

    I have a manual, and it's calling for a "self-powered timing light". I only have a traditional "gun style" timing light...will that work? I have no idea what a "self-powered" timing light might be.

    A quick google search finds one different than what I have. I hope mine will work.

    When you said the timing might be off, I think you're on to something there. While trying to start it, I gave it a little spray of starter fluid in the carbs and hit the starter. It sort of kicked a bit then flames came out the carbs! Both carbs were just a ball of fire. I did it again, and flames came out the exhaust pipes (there are no mufflers on it right now).

    Your timing suggestion might have been spot on -

    Can I time it without the "self-powered" timing light?
    #3
  4. joexr

    joexr Banned

    Joined:
    Jan 4, 2011
    Oddometer:
    3,773
    Location:
    You're Mama
    Your regular timing light will work. Makes no sense that they specify.
    #4
  5. concours

    concours WFO for 41 years

    Joined:
    Dec 2, 2008
    Oddometer:
    5,440
    Location:
    Kensington, NH USA
    Tell us about the carburetors..... have you been through them? As a quick test, pull the plugs, put a teaspoon of gas in the holes, put the plugs in, it should start and run a few cycles. Tells you what to do next.
    #5
  6. concours

    concours WFO for 41 years

    Joined:
    Dec 2, 2008
    Oddometer:
    5,440
    Location:
    Kensington, NH USA
    You used way too much ether
    #6
  7. hardwaregrrl

    hardwaregrrl ignore list

    Joined:
    Jan 26, 2006
    Oddometer:
    7,639
    Location:
    Atlanta
    YOu can also check timing with a meter. Test one lead at a time and put the meter on beep, it should quit beeping when you reach LF on the flywheel, then F for the right side.....at least I think that's how they're labled on the SL flywheel. Remember, shaft spins counterclockwise.
    #7
  8. cptmoney

    cptmoney Two wheels, only one seat

    Joined:
    Nov 1, 2007
    Oddometer:
    574
    Location:
    Western Slope, CO
    Hey - thanks for the input, everyone!

    I haven't done a single thing with the carbs; I'll do the "pull a plug and drop in some gas" test this evening.

    How much ether is too much? A single spray? I've been told all sorts of varying things about that stuff that I don't know who/what to believe. I had it, so I used it. Prob should just stick with gasoline.

    Also - I like the idea of using the volt meter to check timing. That will be pretty simple for me to verify....so I'll check that this evening while I'm looking at the carbs. I'll let you know what I find!
    #8
  9. cptmoney

    cptmoney Two wheels, only one seat

    Joined:
    Nov 1, 2007
    Oddometer:
    574
    Location:
    Western Slope, CO
    And you all think it will fire, even with low compression figures like that?

    Gosh - I think my weedeater runs nearly twice the compression that this thing is showing.

    Should I put a tablespoon of the famous Marvel Mystery Oil down the cylinders for a night or two? Just to let it soak and work its magic? I've had weird success with this stuff before...
    #9
  10. cptmoney

    cptmoney Two wheels, only one seat

    Joined:
    Nov 1, 2007
    Oddometer:
    574
    Location:
    Western Slope, CO
    I'm just using the volt meter to check for continuity here, right? Nothing fancy, just connect one probe to each side of the points? I want continuity to stop at EXATCLY LF on the left, and EXACTLY F for the right cylinder - correct? Right at the break in continuity, I'll have spark at the cylinder - and I want that at exactly LF and F - correct?

    You're right, btw - it's LF and F for this bike. And yep, she's spinning ccw.

    I'm ready to check it out!
    #10
  11. baldman1

    baldman1 Been here awhile

    Joined:
    Jan 18, 2013
    Oddometer:
    277
    You do have a good battery, right? The SL350 will not fire without a good battery.
    #11
  12. cptmoney

    cptmoney Two wheels, only one seat

    Joined:
    Nov 1, 2007
    Oddometer:
    574
    Location:
    Western Slope, CO

    Yes - good battery.

    It's getting spark when I pull the plug and ground it to the head. You can see bright spark while cranking it over.

    Not sure that just that qualifies it as a "good" battery - anything else I should be checking? The PO SAID he just put it in not too long ago...and it's holding a charge nicely so far.
    #12
  13. hardwaregrrl

    hardwaregrrl ignore list

    Joined:
    Jan 26, 2006
    Oddometer:
    7,639
    Location:
    Atlanta
    Remove one wire at a time, as there is only 2:deal ground the meter, then pos lead clipped to the wire you removed from the points into the loom. Then spin the motor COUNTERCLOCKWISE with the meter on beep, it'll beep then it should cut off as the mark passes the LF or the F on the flywheel, the beep should go out. that's how you know it's firing at the right time for that side. I'll see if I can find a vid as I don't have a honda right now. Don't forget to set the points gap first....14k
    #13
  14. cptmoney

    cptmoney Two wheels, only one seat

    Joined:
    Nov 1, 2007
    Oddometer:
    574
    Location:
    Western Slope, CO
    OK - I just verified that the points are set correctly; they're showing .014 gap, which is in line with the .012-.016 that the manual calls for. That's with the cam opening them at the widest point.

    If I recall correctly, the front set of points (this bike has two sets of points) is the left cyl, and the rear is the right - does that sound correct? I'm not at home just yet, so I'm going from memory here.

    I'll have to verify with the manual before I make any adjustments.

    Thanks again for all the input - super helpful!
    #14
  15. hardwaregrrl

    hardwaregrrl ignore list

    Joined:
    Jan 26, 2006
    Oddometer:
    7,639
    Location:
    Atlanta
    I'm a bit of a bonehead.....but that sure sounds right. grease the leading edge of the rubbing block as well.....so the left block will be the top left edge and the right block will be the bottom right edge.
    #15
  16. NJ-Brett

    NJ-Brett Brett

    Joined:
    Sep 8, 2010
    Oddometer:
    6,911
    Location:
    Southern New Jersey
    Its been 40 years since I worked on one, so I really know nothing about them, but you need to make sure you get a spark on the cylinder that is on the compression stroke.
    Remove valve covers, turn engine till the valves are closed, turn the crank till the points open and you get spark and make sure the valves are closed.

    On my old Triumphs, you had to have the timing quite close for it to start.
    After it was running, you could change the timing quite a bit and it still ran, but for it to start, it had to be quite close.

    Make sure the mechanical advance is working right.

    Then there is the carb/gas/choke setup...

    When I have done compression checks in the past, I have often gotten readings all over the place, much depends on cranking speed, throttle open, valve lash, if the engine has sat a while and the rings are not seated....

    I do not bother anymore, it it smokes like crazy and does not stop it needs work. if it does not smoke and idles nice, it does not.
    #16
  17. cptmoney

    cptmoney Two wheels, only one seat

    Joined:
    Nov 1, 2007
    Oddometer:
    574
    Location:
    Western Slope, CO
    So - got home a did few things...

    First off, tried to verify the timing using a volt meter set for continuity.

    I couldn't get it spot on; I have it cranked as far as I can, and now the points plate itself is hitting the threaded bolt holder thingy. Check it out here -

    [​IMG]

    Can you see it? It won't let me scroll it back any further, and it's still not where it should be. What's that mean? You can tell how far back it's been scrolled - look at that timing mark setup on the upper side of the points plate. WAY back, and still isn't breaking continuity until between the LF and LT marks on the flywheel. That can't be good.

    Anyhow, after I got it as close as I could, I dropped a few drops of gasoline down the cyls and spun her over - still nothing.

    Pulled the plugs and tested for spark once again - and found nothing. I grounded the spark plug against the cylinder head and spun it over....but no spark. This was working fine the last time I checked it, but now there's no spark. Where should I go now?

    It's amazingly simple in there; I can't believe that it's been this hard to dial in.

    Any thoughts?
    #17
  18. cptmoney

    cptmoney Two wheels, only one seat

    Joined:
    Nov 1, 2007
    Oddometer:
    574
    Location:
    Western Slope, CO
    It's kind of hard to tell just where the high spot on the points cam really is.

    I may be completely blind - but it's not as obvious as I would think, honestly.

    This may be where the hole is...
    #18
  19. hardwaregrrl

    hardwaregrrl ignore list

    Joined:
    Jan 26, 2006
    Oddometer:
    7,639
    Location:
    Atlanta
    Can't help on the adjustment as I've been lucky enough to avoid having to reset the points plate. Have you check the resistance at the plug caps? I'm pretty sure you can use zero ohm caps to maybe 1 ohm on the SL. Pop them off the wire and read with meter set to ohms. Anything above 1 is too much resistance and can cause the no start problem.
    #19
  20. NJ-Brett

    NJ-Brett Brett

    Joined:
    Sep 8, 2010
    Oddometer:
    6,911
    Location:
    Southern New Jersey
    You get spark when the points open, and if they do not open or close all the way, you will not get spark.

    I think the advance gizmo sits on a pin on the cam shaft.
    If the cam timing is right, at the correct timing mark, one set of points should just start opening on the compression stoke on that cylinder.

    You have an unknown, so I would make sure the cam timing is correct, the advance gizmo is on its locating pin, then set the timing by the book.

    Remember, there are two tdc points, one with every crank revolution, and only one works (the compression one).
    #20