690R carburetor conversion mod.

Discussion in 'Thumpers' started by Visigothic, Feb 27, 2011.

  1. Michał 123

    Michał 123 Adventurer

    Joined:
    Apr 29, 2021
    Oddometer:
    42
    Location:
    Polska
    today I finally managed to find a spark thank you I listened to your advice and polished 2 points for this I changed the pulser to the one from KTM 525 and I managed
    jesusgatos likes this.
  2. Terlingua

    Terlingua Terlingua

    Joined:
    Oct 1, 2005
    Oddometer:
    275
    Location:
    Port lavaca Texas
    I don't have the part number in front of me, I ordered the 690RR CDI, that
    part number was on the box and invoice. I thought I had the wiring wrong. But I didn't, turns out the CDI in the box was not the the 690RR. It was for the 640, after a lot of work, it seems the 640 and the 690 are close. But the 640 doesn't use the ground on number 12. Cut that one wire and it started running. Anyway that may help some of you.
    outbacktm likes this.
  3. Ignas

    Ignas Adventurer

    Joined:
    Jul 21, 2011
    Oddometer:
    30
    Location:
    Lithuania
    Did you managed to start the engine? I am curious how its running
  4. Michał 123

    Michał 123 Adventurer

    Joined:
    Apr 29, 2021
    Oddometer:
    42
    Location:
    Polska
    I'm just finishing welding the last engine mount when the engine fires I will certainly praise the engine I bought after the accident for PLN 1000, which is some 260 USD, I hope it starts the engine sits in the quad polaris outlaw 525
  5. Michał 123

    Michał 123 Adventurer

    Joined:
    Apr 29, 2021
    Oddometer:
    42
    Location:
    Polska
    .

    Attached Files:

  6. jesusgatos

    jesusgatos fishing with dynamite Supporter

    Joined:
    Nov 17, 2006
    Oddometer:
    3,061
    Location:
    santa cruz mtns, ca
    Steinarsv likes this.
  7. Ignas

    Ignas Adventurer

    Joined:
    Jul 21, 2011
    Oddometer:
    30
    Location:
    Lithuania
    If 701 vibrates this bad, 640 should loose complete carb while riding :D

    Michał 123
    Hows your quad, did you managed to start it?
    Did you bought 690 engine locally or from allegro?
  8. jesusgatos

    jesusgatos fishing with dynamite Supporter

    Joined:
    Nov 17, 2006
    Oddometer:
    3,061
    Location:
    santa cruz mtns, ca
    Help me figure this out! Brother thinks it might be something related to ignition. Has spark. Running all stock brand new 690 RFR parts (flywheel, CDI, coil), so that seems kinda unlikely to me, but need to keep ruling things out. Can anybody tell me how to test the coil?

    signal-2021-08-01-171514.jpeg
    Fabnut likes this.
  9. Ignas

    Ignas Adventurer

    Joined:
    Jul 21, 2011
    Oddometer:
    30
    Location:
    Lithuania
    You just measure resistance of the coil. There is spark tester tool where you increase gap and see how coil performs. It might be that coil performs poorly when gets hot. Usually its easier to swap a coil and test.
    In your situation i would look into the engine anyway, that sound will eventually lead to catastrophic damage.
    Leak down and borescope are cheap ways to diagnose things without tearing the engine apart.
  10. Michał 123

    Michał 123 Adventurer

    Joined:
    Apr 29, 2021
    Oddometer:
    42
    Location:
    Polska
    I did not start the quad, waiting for candles, oils and filters, I bought the engine on Allegro
  11. jesusgatos

    jesusgatos fishing with dynamite Supporter

    Joined:
    Nov 17, 2006
    Oddometer:
    3,061
    Location:
    santa cruz mtns, ca
    Thanks, but what is the resistance of this coil supposed to be?
  12. Ignas

    Ignas Adventurer

    Joined:
    Jul 21, 2011
    Oddometer:
    30
    Location:
    Lithuania
    Quick search found this for 640. It might be similar to 690rr

    "Approx Resistance Values for Ignition Coil a) Primary 0.5 ohms (test between blue & white wire and earth) b) secondary 16k ohms (test between Blue & White and Ignition cap)"
    jesusgatos likes this.
  13. Fabnut

    Fabnut Been here awhile

    Joined:
    Feb 2, 2012
    Oddometer:
    813
    Location:
    Perth, Western Australia
    Hydraulic tensioner set/operating correctly ? Cam jumped a tooth ? I have heard of 690 motors doing this.
  14. jesusgatos

    jesusgatos fishing with dynamite Supporter

    Joined:
    Nov 17, 2006
    Oddometer:
    3,061
    Location:
    santa cruz mtns, ca
    Removed hydraulic tensioner, replaced with manual tensioner, and verified timing chain has not jumped.
    Fabnut likes this.
  15. Fabnut

    Fabnut Been here awhile

    Joined:
    Feb 2, 2012
    Oddometer:
    813
    Location:
    Perth, Western Australia
    Chattery engine & loss of power under acceleration.

    Hydraulic tensioner - eliminated
    Cam timing correct - eliminated
    Leak down test ??? This will reveal any compression loss from the valves and or the rings.
    Decompressor operating correctly ??? I know you said you started the motor with the rocker cover off to see if it was working, but there could be an issue there.


    found this video

    outbacktm likes this.
  16. jesusgatos

    jesusgatos fishing with dynamite Supporter

    Joined:
    Nov 17, 2006
    Oddometer:
    3,061
    Location:
    santa cruz mtns, ca
    Thanks for helping me think through this. Posted results of leakdown test here, and there are some other posts around those few pages that cover steps taken in a bit more detail, but basically:

    Have a different style decomp mechanism, doesn't slide over to the side. THat's actually helpful to see though, because the service manual references that style decomp mechanism, not mine, and it was confusing. Anyway, verified that decomp mechanism is operating correctly by starting/running briefly with valve cover removed, and also by zip-tying just to be extra-double-sure.

    signal-2021-07-31-104906.jpeg
    Anders- likes this.
  17. Fabnut

    Fabnut Been here awhile

    Joined:
    Feb 2, 2012
    Oddometer:
    813
    Location:
    Perth, Western Australia
    If your unsure of the validity of youre leakdown test, pop the carby off and put a latex glove over the inlet port, apply the pressure to the cylinder at TDC on the power stroke, ie: both valves closed. The glove will blow up if youve got a leak on the intake valves.
    Do the same with the header pipe to test the exhaust valves

    Next Id check the ignition system

    1. check the pulse coil to see if its come loose or and its got the right gap
    2. Check the battery terminals to see if theyre tight
    3. How are you sparking the engine ? The 701 is a twin spark motor and use stick coils, so are you using the stock stick coil or or the 690 RR coil ?
    4. If you are using the 690 RR coil, check its continuity to the frame and make sure its metal to metal contact. no paint or anything else that could be insulating it. Check the plug cap and the HT lead as well.
    5. Double check that all your electrical connections are sound and not loose
    6. check your earths
    7. Check the main start relay for corrosion round the 30A fuse. Its unlikely considering its location under the seat, but it was a known issue with 950/990's and that had similar symptoms to what your describing. Its worth a look.
    Anders- likes this.
  18. jesusgatos

    jesusgatos fishing with dynamite Supporter

    Joined:
    Nov 17, 2006
    Oddometer:
    3,061
    Location:
    santa cruz mtns, ca
    That's a great tip, thanks, but feel pretty confident about leakdown test results. It's holding good pressure.

    My brother is suspecting might be something related to ignition too. Certainly possible and will eliminate before tearing apart engine. Using all factoray RFR stuff, flywheel, CDI, coil, driving one spark plug. Custom wiring harness, and here's a link to my build thread, to give you an idea of how tackled that if you're curious.

    Batt connections, coil mount, and grounds are all good, but it's possible might have a bad connection somewhere inside one of the waterproof sumitomo connectors used everywhere. Will test coil and those electrical connections next, will have time this weekend.
  19. Fabnut

    Fabnut Been here awhile

    Joined:
    Feb 2, 2012
    Oddometer:
    813
    Location:
    Perth, Western Australia
    I wonder if the engine is pinging, that would definitely explain the noise and power loss. Pre ignition is usually caused by high compression and low octane fuel or to much ignition advance, but Im not sure the 690 ignition can be advanced or retarded as the stator is bolted to the ignition cover as opposed to a stator plate on the engine case that can be rotated slightly.
    Would it be a chance youve got some shit fuel ?
  20. jesusgatos

    jesusgatos fishing with dynamite Supporter

    Joined:
    Nov 17, 2006
    Oddometer:
    3,061
    Location:
    santa cruz mtns, ca
    Brother is thinking the same thing. Drained all fuel when rebuilt carb and refilled with freshie-fresh. Removed stator cover, checked pickup gap, and even removed flywheel to see if maybe somehow the woodruff key sheared. Nope.