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No power over 3000RPM - Engine trouble - XS2 1972 XS650

Discussion in 'The Garage' started by xs650LA, Oct 5, 2017.

  1. xs650LA

    xs650LA That's my (1st) paint job...Pinup is airbrushed.

    Here are the symptoms: idles fine, but when riding it does not feel powered. It runs but when above 3000RPM it just does not progress fast or almost at all. It slugs and it's slow... like it has little power and progresses too slow up the torque...

    The details: The carbs were cleaned (twice), and I installed a new kit (but not new needles). I also adjusted the floats, got new fuel lines, fuel filters, even re-did the whole tank (Inside and the outside), new pedcoks, new sparks, the bike charges just fine (even though it's still the old charging system). I also added some seafoam to the gas just to make sure... right now it runs fine in idle, although sometimes it takes way too long to warm up to the point I don't need the choke on (or it dies on me). In idle it runs a bit erratically, but only sometimes it varies speed and sometimes it kind of seems like it's going out of whack. Again, this is not all the time, and mostly when cold. If hot, it pretty much idles fine and seems OK as far as the synching (but I could be wrong).

    The issue is when I am going. In first sometimes it kind of hiccups as I gas it. But most times it just does not feel powerful enough. Progresses too slow. Then in 2nd and up it's a slug. It does not hiccup or seem that bad (sounds fine and synched) but it's just slow and feels like it has no power or response time is slow. In 3rd I can even roll the gas all the way up and it's like nothing happens right away and just slooooowly goes a bit faster...

    Not sure what to do or what is wrong. Is it the jets? Is it that the carbs are still dirty? is it other adjustments? HELP :)

    Thanks in advance. BTW, total rookie here, so try to go easy on me and explain more than you would to a knowledgeable and experienced person.
    Last edited: Oct 5, 2017
  2. fredintoon

    fredintoon Fred Hill, S'toon. Top Contributor

    Hi xs650OLA,
    that's one pretty bike!
    "most carb problems are really ignition problems and vice-versa"
    Are you absolutely sure that the bike is running on both cylinders?
    xs650LA likes this.
  3. xs650LA

    xs650LA That's my (1st) paint job...Pinup is airbrushed.

    Good question. Sound-wise it seems like so. I see sparks on both plugs (i have those spark connectors that have a nifty clear part for effect :) and when I put my hand on each of the pipes they both seem push out exhaust at the same pressure, etc. Not 100% sure, but I think that means it's ok. Also, I also got a really good battery and it's basically new. I can see on my dial (I installed a volt meter) that it's always around 12.2 to 11.8 (on idle). The bike starts only on kick (I kept the starter and all and was working but the switch on the handle broke and I need to fix it - and until it broke i could even start it with the self-start - nifty and rare for a XS2), but it starts pretty much at first kick every time. Only if my clutch gets jammed (I have a busted clutch lever I need to fix too) do I get no start :) but that is solved by simply hand-unsticking the clutch...

    I'm thinking it's running too lean? no idea but maybe I over adjusted the floats because one was actually leaking? would floats make it loose power? Maybe my needles are stuck and they don't really go up much?


  4. retiredgentleman

    retiredgentleman XS650 Guru Top Contributor

    You have to remove the main jets and pilot jets, to see what size they are and confirm they are clear. I sense you are reluctant to remove the jets, but you have to learn how to do that. The pilot jets are likely partially blocked. You have to clear them to get the carbs running correctly. Also you have the wrong type pod filters.
    Have you read the Carb Guide that is in the TECH section?
    theDQG and xs650LA like this.
  5. xs650LA

    xs650LA That's my (1st) paint job...Pinup is airbrushed.

    Indeed (read the carb guide). As for the Jets - i've done that. Not a biggie, can do it again. I was 100% they are cleaned... but I'll do again.
    Yep, figured the pod filters might be a problem. I'm going to try and ride around without them too.

    However, I had some time over lunch :) could not wait :) and I started it and removed the pods. You might be right about the cylinders. Here is what happens, I start it and it seems fine. But then I removed the pods and i can see the needle going up and down as I move the cable levers by hand - the inside diaphragm assembly moves up and down fine and I can see the needle going up and down with it. There is however some gas coming out of the vent (like slight drizzle or vapor but I can see it's gas microscopic droplets). In any case, on the right side when I move the cable the engine clearly revs up and I can hear it go up and working more. But when I move the throttle cable on the left side the engine does not really change much and the carb does exude more air (duh, the air vent is open and I can see the diaphragm assembly go up and the needle with it)... strangely everything seems to run, it's more like moving the lever up and/or down is not doing a thing, even though everything is working? I can see spark in that plug on that side, exhaust comes out,... any thoughts?

    Another thing I forgot to mention. When I move the choke up and down, def things change. However the choke is on the side of the carb I just mentioned does not seem to be working... or the cylinder side that's not working... thought this might have relevance...
  6. fredintoon

    fredintoon Fred Hill, S'toon. Top Contributor

    Hi xs650OLA,
    "triple clean the carbs"
    And if you haven't taken the carbs completely apart jets and all and poked little wires through every single orifice and blown carb cleaner through every internal passageway you've never actually cleaned your carbs at all, never mind three times over.
    And I'm with retdgent, the only pods that work right with XS650 stock carbs are Unipods, which yours ain't.
    xs650LA likes this.
  7. grizld1

    grizld1 Grumpy old man Top Contributor

    LA, Fred suggested a look at your ignition. I wrote half of that Carb Guide and I'm going to second Fred's suggestion, but more strongly. If you put the fuel system first in your troubleshooting, you're putting the cart before the horse. You can inspect compression and ignition function directly. You can't do that with the A/F mix unless you have some very expensive gear. It isn't enough just to know that the plugs are sparking; they need to be producing a strong spark at the right time. If the original breaker point ignition is in place on your bike, bear in mind that one points set could be close to correct and the other badly out of adjustment.
    xs650LA likes this.
  8. Corndog

    Corndog Kick it over!

    When I bought mine I had a similar issue but with a horrible idle. My pilots were completely corroded shut. If your pilots are partially blocked you could maybe maintain an idle but lose all power off bottom?

    I'd check everything girzld had said. He knows his stuff and helped me get mine going again! Beautiful bike!

    Lose them filters! Lol
    xs650LA likes this.
  9. peanut

    peanut XS650 enthusiast & inveterate tinkerer Top Contributor XS650.com Supporter

    welcome to the forum by the way :)

    Some good advice here already .

    The important thing to try and remember is to only adjust and test one thing at a time and be methodical. its good to write your progress and what you do as you go along so that you have got some records to refer back to.

    I would start by checking that you have the valves set correctly when cold.

    You need to set each cylinder when it is at top dead centre (TDC) on its compression stroke.
    If you set the valve lash in the right cylinder first then remove both plugs and turn the engine over until you feel compression building in the right cylinder (put your thumb over the spark plug hole). Turn the engine until you have the piston at the highest point viewed through the spark plug hole

    Set the valves as per manual INLET 0.006" EXHAUST 0.012
    Then turn the engine over until compression builds in the left cylinder and adjust those also at TDC .

    Check the you have the camchain tension set correctly (see manual)

    Then check that both sets of points have the correct gaps ( 0.015") and that they open precisely at the correct advance setting which I believe is 13 degrees BTDC but line up the fully retarded mark on your stator (first mark left of T mark ) with the mark on your rotor.
    There is an excellent how-to using a simple bulb and torch battery and a bit of wire in the Chiltons repair and tuneup guide

    Clean and set your advance mechanism to make sure that you are getting the correct amount of spark advance from idle to WOT .

    I would invest in some new spark plugs and gap them correctly and check your HT caps and leads and then you should be able to move onto your carburation .

    Try and get hold of either Chiltons Yamaha 650 or Clymers manuals preferably both they are excellent manuals
    xs650LA likes this.
  10. xs650LA

    xs650LA That's my (1st) paint job...Pinup is airbrushed.

    Thanks Grizld1 (great guide btw, thanks!). I was hoping this was just a carb adjustment issue... so I started backwards :) Yesterday evening I turned it on and I switched the (coil) spark wires - basically I plugged the left coil to the right spark plug and the right coil to the left spark plug. Been reading some forums about troubleshooting ignition and non working pistons and someone suggested doing that. And then, I tried starting it and nothing. It simply makes a pop noise...if I put them back the right way again (right to right, left to left) it start fine again. So I went and ordered new coils just to make sure (https://www.mikesxs.net/yamaha-xs650-oem-type-signal-output-ignition-coil-oem-254-82310-60-00.html ). I am going to check the points now. My bike is stock as far as the electrical goes (my coils look like original...). Thanks for the advice (and the guide). Looks like I have a lot of learning and fiddling to do. :)

  11. xs650LA

    xs650LA That's my (1st) paint job...Pinup is airbrushed.

    Thanks for the compliments. It's been a work of love (and obsession :) ) I am literally learning all of this from scratch. I spent the whole last year methodically learning how to spray paint and airbrush :) I had this design in mind and I worked really hard to learn and buy all the right gear - lots of youtube, talking to experienced folks, trolling craigslist, and reading blogs to buy the cheap but good stuff. I posted the progress on Instagram https://www.instagram.com/jose.daveiga/ (you'll have to scroll through my other stuff to find those paint-related ones). All started with a "design" in mind and I went for it.
    As for the pods :( I know, I was going for looks and someone told me those pods would work ... guess not... time to re-think that...

  12. xs650LA

    xs650LA That's my (1st) paint job...Pinup is airbrushed.

    Thanks for the advice and for the welcome :) Lots of good stuff in there on your reply - of course I don't (yet) understand half of it but I'll follow your advise and see. Like I said to grizld1 something's up since I switched the coil wires from left to right and it just won't start, but the other way around (right to right and left to left way around) it does... I'm hoping it's just ignition and I don't have to go into the head, etc...

  13. 5twins

    5twins XS650 Guru Top Contributor

    On your early model with the points ignition, it won't start if you switch the plug wires. That throws the timing off 180°. That only works on the later models with electronic ignition. If you did want to switch the plug wires (and coils) from side to side, you would need to switch the wire connections to them from the points sets as well.

    You're going to need to learn how to set/check the points and timing. As Griz said, the timing could be off on that one cylinder. The timing is set individually for each cylinder on your stock points set-up. Think of it like setting the timing for 2 separate single cylinder motors. You have to get each set correctly but also matched to one another.
    xs650LA likes this.
  14. xs650LA

    xs650LA That's my (1st) paint job...Pinup is airbrushed.

    All you guy's advice is great! Thank you!
    That's great info, I had no idea about the XS2 being different. Yep, makes perfect sense! I'm a total rookie and just now starting to learn about the whole theory of carbureted engines :) I kind of know of the principles but not how they go together or the details of each...

    On that, I've spent the morning reading when I get a break (...or while I try to work, or is it the other way around...) and basically seems like my next steps are:
    1. Adjust the cam chain (Seems easy)
    2. Adjust the valve clearances (seems that for XS2-650..0.006"(0.15mm)....0.012"(0.30mm)) (seems doable, just ordered some gauge plates)
    3. Adjust the points for the timing to work (this I need to do some research on but looks harder than the last 2)
    4. Then I can go about adjusting carb jets, etc for the right mixture and such (including getting new pods...) (this seems like it's hardest because it's like a trial and error and more art than science...even though the tech section on this site and all the manuals are awesome!)

    Sounds about right?

  15. grizld1

    grizld1 Grumpy old man Top Contributor

    A few more things, LA. Your ignition is camshaft driven, and the camshaft turns at half the speed of the crankshaft. That means that any error in points adjustment is doubled in effect at the crank, which is where it counts. A strobe type timing light is thus a must-have item. 5twins has written some excellent posts on setting dwell, and a search will locate them. I like to start with fresh points; if you follow that advice, be aware that new points will have a preservative on their contact surfaces that must be removed. A bit of rubbing alcohol on a rag will do it. It can be rough sledding at first, but once you learn to service and adjust your breaker point ignition you'll have mastered a set of skills that very few still hold.
  16. grizld1

    grizld1 Grumpy old man Top Contributor

    One more thing. There's a mechanical advance unit (sometimes referred as "automatic timing unit," or ATU, "governor" in the Yamaha parts books) under the right side chrome cover. Do some searches on this, look and read until you understand the beast. As it wears, the difference between full retard and full advance increases, and severe wear can put advanced timing in the piston holing range when timing is set correctly at idle. Be sure the ignition rod that runs through the camshaft is lubricated and that the cogged nut that secures the timing unit to the camshaft is tight; put a drift on it and smack it with a hammer, and don't be gentle!
  17. xs650LA

    xs650LA That's my (1st) paint job...Pinup is airbrushed.

    Thanks! Keep it coming :)
    As for me, I went about and adjusted the chain today. It was a tad bit loose but nothing significant. I have to wait to get my gauge blades to adjust the valves... so I am stuck at adjusting the valves until I get that.

    Another problem I have is that I can't take out the cover for looking at the timing marks...those screws are completely out :( Will have to figure out how to get them out... Yes! on the strobe, today I watched a youtube of a guy doing that. I guess I need to look into that. I thought I would try doing the light bulb way with a rig with a light and adjusting at the S mark first.

    Now, I had some time and wanted to try something :) so I went about adjusting the Carb floats that are on the side that is flailing (the left). My thinking was, maybe it's too lean. And as such I over did the float (more on the float below). It was flooding but when I did that I started the bike and the thing is, that carb works fine when it has enough gas....It seems timed right even. Or at least the bike sounds fine and powered when I revv it up. So it's maybe the carb that has too little gas? Now, I don't have the clear hose thing and adjusting it back to level is going to be a challenge I also have to take on...

    On the floats. Any ideas why both sides are completely collapsed? Both my floats are shrivled as if they had been pressed in a compression chamber or something. I got brand new ones (brass) but I am afraid to put those in before I figure if something caused these to collapse on themselves or it's just age... I could swear they were fine the last time I cleaned the carbs...thoughts?

  18. gggGary

    gggGary Stop that! Top Contributor XS650.com Supporter

    You sure the float vents and overflows are open? small fitting with a plastic 90 on the bottom of the float bowls.



    (bent plastic tubes just above red circle

    xs650LA likes this.
  19. xs650LA

    xs650LA That's my (1st) paint job...Pinup is airbrushed.

    Yes, pretty sure. I've tested overflowing on both sides :) one not intentionally and I fixed that one and seems level/fine. But the other either overflows or it is too lean. Tomorrow I am going to have more time to try again. BTW, mine look like the first photo you posted, underneath 90 degree plastic and the color is actually pretty close. I can post some pics tomorrow. I'll also open the bowl again and shoot a photo of my floats...they seem to work but are all "compressed"...

  20. TwoManyXS1Bs

    TwoManyXS1Bs BBQ Hunter Top Contributor

    2 known causes of collapsed brass floats (that I'm aware of), are extreme backfires, and a history of compressed air, jammed into ports/vents to clear blockages...
    xs650LA and gggGary like this.

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